A beam shifting construction method for reconstruction of high-speed railway elevated station

Abstract

The present invention discloses a beam shifting construction method for reconstruction of a high-speed railway elevated station, and relates to the technical field of construction engineering. It includes preparation work; judging the positional relationship between the beam shifting operation and the operating line; beam shifting equipment tooling, carrying out jacking tooling, horizontal shifting tooling and horizontal rotation tooling; existing beam shifting construction; preparation before beam shifting, completing the erection of the construction platform, beam body jacking operation and stone padding construction operation; beam shifting construction, after determining the beam shifting parameters, beam shifting construction is carried out, wherein the beam shifting construction includes the steps of installing beam shifting equipment, horizontal shifting of the beam body, horizontal rotation of the existing beam body, longitudinal shifting of the existing beam body, and beam drop and support installation; new beam shifting construction; beam body cast-in-place construction; new beam horizontal shifting construction, including the steps of installing beam shifting equipment, horizontal shifting of the beam body, and beam drop and support installation. The present invention reduces the construction impact on the surrounding lines by moving the existing elevated beam body, while shortening the construction period and saving manpower, material resources and financial resources.

Description

Technical Field

[0001] The invention relates to the technical field of construction engineering, and in particular to a beam-shifting construction method for reconstruction of a high-speed railway viaduct station. Background Art

[0002] At present, my country's large-scale infrastructure construction has gradually entered a stable stage. Reasonable adjustment of high-speed rail passenger transport capacity has become a new construction direction, and the number of high-speed rail station expansion and renovation projects has gradually increased.

[0003] The elevated station has a great impact on construction due to the structural characteristics of the bridge itself. There is no case in the prior art of completing the construction of a high-speed railway elevated station by moving the existing beams.

[0004] The present invention provides a high-speed railway elevated station reconstruction beam moving construction method, which reduces the construction impact on surrounding lines by moving the existing elevated beam body, shortens the construction period, and saves manpower, material resources and financial resources. Summary of the invention

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A high-speed railway elevated station reconstruction beam shifting construction method comprises the following steps:

[0007] S10: Preparation work, measuring the dimensions of each part of the box girder within the range of the pier displacement beam, and setting displacement and settlement observation points on the top of the existing pier;

[0008] S20: Determine the relative position relationship between the beam shifting operation and the operating line;

[0009] S30: Beam moving equipment tooling, lifting tooling, translation tooling and translation tooling;

[0010] S40: Construction of existing beam shifting;

[0011] S41: Preparation before beam shifting, including setting up the construction platform, beam lifting and stone padding;

[0012] S42: beam shifting construction, after determining the beam shifting parameters, the beam shifting construction is carried out, wherein the beam shifting construction includes installing beam shifting equipment, horizontal shifting of the beam body, horizontal rotation of the existing beam body, longitudinal shifting of the existing beam body, and installation of the beam drop and support;

[0013] S50: Construction of new beams and beam shifting;

[0014] S51: Beam body pouring construction, including support construction, formwork engineering, support pre-stressing, steel bar construction, installation and threading of corrugated pipes, embedding of embedded parts, beam body concrete pouring, beam body concrete curing and prestressing construction;

[0015] S52: Construction of new beam transverse movement, including installation of beam moving equipment, beam transverse movement and beam drop and support installation;

[0016] S60: Bridge deck and ballastless track construction.

[0017] Furthermore, in step S10, the positions of the box girder supports and the anti-drop beam blocks are measured, and the coordinates of the box girder ends, the centerline coordinates and the width of the beam seam are measured with a total station to check the neatness of the construction of the beam ends and the uniformity of the upper and lower beam seams.

[0018] Furthermore, when setting the jacking tooling in step S30, two independent fulcrums are set on each pier top as a supporting structure, one independent fulcrum on the pier top serves as a balancing fulcrum, and the other three are movable fulcrums, forming a four-point support and three-point balance support mode.

[0019] Furthermore, when the translation tooling is set in step S30, the transverse movement of the beam is achieved through a transverse movement system, which includes a transverse movement beam section, a slide plate, a jack, a transverse movement cylinder with a displacement sensor, a polytetraethylene plate and a stainless steel sliding surface.

[0020] Furthermore, when the horizontal rotation tooling is set in step S30, it includes a set of fixed-support three-dimensional beam-dropping devices, three sets of floating-support three-dimensional beam-dropping devices and a three-dimensional beam-dropping device transverse hydraulic system.

[0021] Furthermore, the beam jacking operation in step S41 includes jack arrangement, trial jacking, formal jacking and installation of temporary supports.

[0022] Furthermore, in step S42, the transverse movement of the beam is driven by a transverse cylinder so that the transverse beam section slides on the slide plate; when the beam rotates horizontally, a three-dimensional beam-dropping device is used to lift the box beam away from the transverse track beam, and the beam is fixed with a balance fulcrum as the rotation axis, and one of the moving fulcrums is moved to drive the beam to rotate horizontally; when the beam is dropped and the support is installed, a lifting jack is used to drop the beam at the designed position, and a three-dimensional beam-dropping device is installed at the bottom of the beam. The parameters of the beam-dropping jack are the same as those of the jack during lifting.

[0023] Furthermore, any deviations in the beam dropping process are corrected using a three-dimensional beam dropping device, and the supports are installed to drop the beam into place.

[0024] Furthermore, the bridge deck system and ballastless track construction in step S60 includes the installation of shields and sidewalk slabs, the installation of protective walls and the construction of ballastless track.

[0025] The beneficial effects of the present invention are:

[0026] A beam shifting construction method for reconstruction of a high-speed railway elevated station provided by the present invention is developed and applied with large-span transverse tooling, three-dimensional beam shifting and dropping devices, automated numerically controlled pump stations and other tooling and equipment required for beam shifting construction for reconstruction of existing high-speed railway elevated stations. An innovative beam shifting process of jacking up + translation + rotation + beam dropping of existing beams is adopted, which is quickly introduced into the existing railway, effectively reducing the impact on the structural safety and operational safety of the existing high-speed railway elevated line during the beam shifting construction of the elevated station, and saving construction time. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is the floor plan for the reconstruction of part of the departure line from Shaoxing North Station.

[0028] Figure 2 This is a schematic diagram of the temporary enclosure plan.

[0029] Figure 3 for Figure 2 A magnified view of part A.

[0030] Figure 4 for Figure 2 Enlarged view of part B.

[0031] Figure 5 This is a schematic diagram of the central translation tooling.

[0032] Figure 6 Schematic diagram of the transverse track beam structure.

[0033] Figure 7 Schematic diagram of installing track beams on the top of a single pier.

[0034] Figure 8 Schematic diagram of installing track beams on the top of the pier.

[0035] Fig. 9 Schematic diagram of the supporting structure of the beam shifting jack.

[0036] Fig.10 It is a schematic diagram of the transverse shifting device of the beam shifting jack.

[0037] Fig.11 Schematic diagram of the control system of the transverse movement device.

[0038] Fig.12 for Fig.11 A partial enlarged view of .

[0039] Fig.13 Schematic diagram of beam horizontal movement.

[0040] Fig.14 Schematic diagram of the three-dimensional beam dropping device.

[0041] Fig.15 Schematic diagram of the steering of the three-dimensional beam dropping device.

[0042] Fig.16 Schematic diagram of beam rotation.

[0043] Fig.17 Schematic diagram of the beam moving forward.

[0044] Fig.18 Schematic diagram of beam lateral displacement.

[0045] Fig.19 This is a schematic diagram of the construction platform.

[0046] Fig. 20 Schematic diagram of the jack arrangement.

[0047] Fig.21 This is a schematic diagram of temporary support arrangement.

[0048] Fig. 22 This is a schematic diagram of temporary support installation.

[0049] Fig.23 This is a schematic diagram of the installation of the beam shifting pier.

[0050] Fig.24 This is a schematic diagram of the installation of the beam shifting equipment at L2.

[0051] Fig.25 Schematic diagram of the lateral displacement of the L2 beam.

[0052] Fig.26 Schematic diagram of the horizontal rotation of the L2 beam.

[0053] Fig. 27 Schematic diagram of the L2 beam being dropped into place.

[0054] Fig.28 This is a schematic diagram of the installation of the beam shifting equipment at L3.

[0055] Fig.29 Another schematic diagram of the installation of the beam shifting equipment at L3.

[0056] Fig.30 Schematic diagram of the lateral displacement of the L3 beam.

[0057] Fig.31 Another schematic diagram of the lateral displacement of the L3 beam.

[0058] Fig.32 Schematic diagram of the horizontal rotation of the L3 beam.

[0059] Fig.33 Schematic diagram of the longitudinal and lateral movement of the L3 beam.

[0060] Fig.34 Schematic diagram of the L3 beam being dropped into place.

[0061] Fig.35 This is a schematic diagram of the installation of the beam shifting equipment at L4.

[0062] Fig.36 This is another installation diagram of the beam shifting equipment at L4.

[0063] Fig.37 Schematic diagram of the lateral displacement of the L4 beam.

[0064] Fig.38 This is a schematic diagram of the horizontal rotation of the L4 beam.

[0065] Fig.39 Schematic diagram of the rotation of the L4 beam.

[0066] Fig.40 Schematic diagram of the longitudinal and lateral movement of the L4 beam.

[0067] Fig.41 Schematic diagram of the L4 beam being dropped into place.

[0068] Fig.42 This is a schematic diagram of the installation of the beam shifting equipment at L5.

[0069] Fig.43 Another schematic diagram of the installation of the beam shifting equipment at L5.

[0070] Fig.44 Schematic diagram of the lateral displacement of the L5 beam.

[0071] Fig.45 This is a schematic diagram of the horizontal rotation of the L5 beam.

[0072] Fig.46 Schematic diagram of the longitudinal and lateral movement of the L5 beam.

[0073] Fig.47 Schematic diagram of the L5 beam being dropped into place.

[0074] Fig.48 This is a schematic diagram of the L6 beam ex-cast support construction.

[0075] Fig.49 This is the assembly diagram of 9m standard section columns.

[0076] Fig.50 Schematic diagram of the lateral displacement of the L6 beam.

[0077] Fig.51 This is a schematic diagram of the L6 beam falling into place.

[0078] Fig.52 This is the layout diagram of the vibration points of the track slab.

[0079] Fig.53 This is an enlarged view of the joint and some parts.

[0080] Fig.54 This is a schematic diagram of the joint pier installation.

[0081] Fig.55 This is a schematic diagram of lateral movement accompanying protection.

[0082] Fig.56 This is a schematic diagram of the track support for Pier 456#.

[0083] Fig.57 This is a schematic diagram of the fixation of the three-dimensional beam dropping device.

[0084] Fig.58 Another schematic diagram of the beam shifting jack support structure.

[0085] Among them, in the figure:

[0086] 100-transverse movement system; 101-transverse movement beam section; 102-slide plate; 103-jack; 104-transverse movement cylinder; 105-stainless steel sliding surface; 106-guide baffle; 107-beam section pier; 108-joint pier; 109-pad pier; 110-vertical jack; 200-transverse movement device control system; 201-ultra-high pressure pump station; 202-two-position two-way manual reversing valve; 203-check valve; 204-separate hydraulic jack (spring-return); 205-stop valve; 206-transverse movement hydraulic cylinder; 207-two-way hydraulically controlled check valve; 208-proportional reversing valve; 209-pressure reducing valve; 210-pressure sensor; 211-electromagnetic ball valve; 301-floating fulcrum three-dimensional beam dropping device; 302-fixed fulcrum three-dimensional beam dropping device. DETAILED DESCRIPTION

[0087] The following will be combined with the attached embodiment of the present invention Figure 1-58 , the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0088] Example

[0089] Combination Figure 1-58 In this embodiment, the newly built Hangzhou-Taiwan high-speed railway Shaoxing North Station is constructed. The existing 451-456# pier station line beams of the 5th and 6th tracks of Shaoxing North Station are used. Through jacking, translation, rotation, longitudinal movement, and beam placement, the 2-6# pier single-line simply supported beam of the Hangzhou-Taiwan high-speed railway up and down connecting line is formed. The maximum weight of the beam body is 450 tons, the maximum translation distance is 6.625m, and the translation angle is 5.2688°. This method adopts synchronous jacking technology, that is, the bridge deck is lifted as a whole to convert the force system, and then the bridge is translated by span, including the following steps:

[0090] S10: Preparation.

[0091] 1) Before entering the site, first notify the equipment management unit, coordinate with the relevant equipment management units regarding the project construction content, prepare a plan based on the relevant documents of China Railway Shanghai Bureau Group Co., Ltd., and sign a safety agreement with the relevant stations and sections in a timely manner after the plan is reviewed and approved; at the same time, report the operating line construction plan, and construction can only be carried out after the construction plan is approved; during the construction process, strictly follow the plan, do a good job of on-site protection, and ensure the safety and smoothness of railway transportation.

[0092] 2) The four power relocation units have completed the relocation of communications, signals, power and contact networks between piers 450#~457#.

[0093] 3) Temporary fencing of the existing Hangzhou-Ningbo line has been completed, completely isolating the construction areas of tracks 5 and 6 from the Hangzhou-Ningbo Passenger Dedicated Line; the construction area under the bridge has been closed to ensure a safe working environment.

[0094] 4) The existing bridge accessories such as bridge pier hanging fences, beam flange plates, drainage pipes, concrete guardrails on both sides, ballastless track, ballast retaining steel plates, expansion joint devices, etc. have been dismantled.

[0095] 5) Based on the design drawings and construction plans, the Engineering Department will provide technical briefings to on-site management personnel and construction teams, and technicians will be responsible for providing technical briefings to operators. At the same time, training will be organized for operators of various types of work, and personnel in special types of work must be certified before they can take up their posts.

[0096] S20: Determine the relative position relationship between the beam shifting operation and the operating line.

[0097] This beam shifting construction involves piers 2#-7# of the Shaoxing North Station up and down connecting lines, with a total of 10 beams. Before the beam shifting construction, the existing beam flange plates that affect the beam shifting construction must be removed before the construction can begin. After the existing 5th and 6th tracks are closed, the beam shifting is for the adjacent operating lines, of which the 2-5# and 6-7# pier shifting beams are Class C constructions of the adjacent operating lines, and the 5-6# pier shifting beams are Class B constructions of the adjacent operating lines. The beam shifting of this bridge adopts the synchronous jacking technology, that is, the bridge deck is lifted as a whole to convert the force system, and then the bridge is shifted horizontally in sections.

[0098] The 2#-6# pier beams of the up and down connecting lines of Shaoxing North Station are undergoing beam moving operations, and their relative positions with the operating lines are shown in Table 1.

[0099] The box girder closest to the center of the existing 4th and 3rd tracks of the Hangzhou-Ningbo Passenger Dedicated Line is the beam end at the 6# pier of the up and down connecting line. The distance between this beam end and the center of the 4th and 3rd tracks of the Hangzhou-Ningbo Passenger Dedicated Line is 5.3m and 5.33m respectively. The horizontal distance between the other existing beams and the center of the Hangzhou-Ningbo Passenger Dedicated Line is greater than this beam end. The relative position relationship is shown in Table 1.

[0100]

[0101]

[0102] Table 1 The shortest horizontal distance between the shifted beam of Shaoxing North Station Bridge and the center of the existing 3rd and 4th tracks

[0103] S30: Beam moving equipment tooling.

[0104] 1) Lifting tooling.

[0105] The lifting jack is selected according to the maximum weight of the beam body, 512.8T, taking into account the principle of 1.5 times the safety factor. The required jacking force F = 1.5*512.8 = 769.2T. Therefore, 4 sets of jacks are used for each beam hole. The model is QF200T-20b, and the lifting force is 200*4 = 800T> 769.2T.

[0106] Each pier top support structure is set with two independent fulcrums, and the other pier top support structure is a balanced fulcrum. The four fulcrums are a four-point support and three-point balanced support method. The specifications of the jacking jack are EDX1508, with an outer diameter of 240mm, an inner diameter of 200mm, a piston rod diameter of 160mm, a body height of 362mm, a stroke of 200mm, and a hydraulic system pressure of 63Mpa. The maximum thrust of the jack is 200t. The load of the four fulcrums of the support structure is 520t. When each jack needs to lift 130t, the system working pressure is about 41.275Mp.

[0107] 2) Translation tooling.

[0108] Figure 5 This is a schematic diagram of the translation tooling.

[0109] The existing station reconstruction part of Shaoxing North Station Bridge has 4-hole departure beams for both up and down lines changed to connecting beams, among which the three-hole beams L2, L3 and L4 need to be installed at the end of one beam to realize the transverse movement of the beam. The transverse movement system 100 includes a transverse beam section 101, a slide plate 102, a jack 103, a transverse oil cylinder 104 with a displacement sensor, etc. The transverse beam section 101 is composed of a guide baffle 106 made of polytetraethylene and a stainless steel sliding surface 105; the bottom end 101 of the transverse beam section is provided with a beam section support pier 107, and the bottom end without a pad stone is provided with a joint support pier 108.

[0110] The translational public installation includes the transverse movement track beam, the track beam pier top arrangement, the beam shifting jack support structure and the beam shifting jack transverse movement device.

[0111] Transverse track beam: According to the construction requirements, the transverse track beam adopts two specifications, namely transverse track beam ① and transverse track beam ②. The two specifications of transverse track beams have different lengths and are both box-shaped sections. Figure 7As shown. A 3mm thick stainless steel plate and a guide baffle are set on the upper wing plate of the transverse track beam. The guide baffle is provided with φ40 bolt holes along the length for fixing the base during the transverse cylinder operation. In addition, during the transverse operation, bolts or steel bars can be inserted into the bolt holes at the end of the track beam for transverse limit to ensure the safety of the operation.

[0112] Figure 6 Schematic diagram of the transverse track beam structure.

[0113] Track beam pier top layout: According to the actual project, there are two situations when the transverse track beam is arranged on the pier top, namely single pier layout and cross-pier layout. When installed on the top of 452#, 453#, 454#, 455# single pier, the layout is: transverse track beam ① + transverse track beam ②, such as Figure 8 As shown. The transverse track beam joint only plays the role of slideway connection and does not bear bending moment and shear force. When the cross beam section joint is located outside the pad stone, it is necessary to install the joint pier at the bottom. The design value of the support center distance below the transverse track beam is 2900mm. When the support distance is greater than 2900mm, it is necessary to install the beam section pier at the bottom. Considering that the pad stone positions of each pier are different, all holes are drilled in the length direction of the lower wing plate of the transverse track beam to facilitate the installation of the pier. In addition, each section of the transverse track beam must be reliably connected to the top of the pier, which can be directly connected to the lower flange (pad stone) or the bottom of the pier (where there is no pad stone).

[0114] Figure 7 This is a schematic diagram of installing the track beam on the top of the middle pier.

[0115] When installing across the pier above 456# pier and the new pier, the layout is: transverse track beam ①+transverse track beam ①+transverse track beam ②. Figure 8 To ensure the safety of the operation, a transition pier is installed at the bottom of the transverse track beam outside the 456# pier pad stone, and a beam section pier is installed at the bottom of the transverse track beam outside the new pier pad stone. The center distance between the transition pier and the beam section pier is 2070mm. Even if the excessive vertical load at the end of the new pier is considered to be unsafe for the pier structure, the distance between the transition pier and the pad stone support position is 2600mm, which is much smaller than the designed support distance of 2900mm, and the force of the transverse track beam meets the requirements.

[0116] Beam shifting jack support structure: The support structure of the transverse shifting system 100 is composed of two jacks set on the slide. The two sets of transverse shifting devices have four fulcrums in total. Two fulcrums on one set of slides constitute two independent fulcrums, and two fulcrums on one set of slides constitute a balanced fulcrum. The four fulcrums are a four-point support and three-point balanced support method. The specification of the support jack is RSM200-40, with an outer diameter of 250mm, a cylinder diameter of 200mm, a piston rod diameter of 160mm, a body height of 140mm, and a stroke of 40mm; when the hydraulic system pressure is 63Mpa, the maximum thrust of the jack is 200t. The load of the four fulcrums of the support structure is 520t. When each jack needs to lift 130t, the system working pressure is about 41.275Mpa. The two independent fulcrums of the hydraulic system of the support structure are to supply oil to the two jacks at the beam end with a manual high-pressure oil pump respectively, and a hydraulically controlled one-way valve is set on the main oil supply line to maintain the position of the jack rod and maintain the lifting pressure.

[0117] Fig. 9 Schematic diagram of the supporting structure of the beam shifting jack.

[0118] A balancing fulcrum of the hydraulic system of the supporting structure is to connect the oil inlets of the two jacks on the left and right sides of the main beam with a tee, and use a manual high-pressure oil pump to supply oil together, so that the two jacks can move in a balanced manner, and the piston's top height is determined by the external load to maintain the load balance support of the two jacks. The two sets of jacks on the left and right sides are connected with a tee, and a hydraulically controlled one-way valve is set on the main line of the tee to maintain the position of the jack rod and maintain the lifting pressure.

[0119] Transverse movement device of beam jack: The transverse movement device of the transverse movement system is driven by a transverse movement cylinder with a displacement sensor to drive the slide plate to realize the transverse movement of the concrete box. The specification of the transverse movement cylinder is HSGK-150 / 75-1511-600×1165, the cylinder inner diameter is 150mm, the piston rod diameter is 75mm, and the stroke is 600mm; each set of transverse movement device needs to overcome a total sliding friction resistance of 260kN, considering 2×10 -3 The slope resistance is also included. When the pressure of the lateral hydraulic system is 25Mpa, the pulling force that the lateral cylinder can provide is 331.3kN. When the actual push is 260kN, the actual pressure of the lateral hydraulic system is 19.62Mpa.

[0120] Fig.10 It is a transverse shifting device for the beam shifting jack.

[0121] The traverse device control system 200 is a closed loop system controlled by a proportional valve. Fig.11 and 12As shown, the system includes an ultra-high pressure pump station 201, a two-position two-way manual reversing valve 202, a one-way valve 203, a separate oil hydraulic jack (spring-return) 204, a stop valve 205, a transverse hydraulic cylinder 206, a two-way hydraulically controlled one-way valve 207, a proportional reversing valve 208, a pressure reducing valve 209, a pressure sensor 210 and an electromagnetic ball valve 211. The transverse device control system 200 can make the two sets of transverse devices move synchronously. If separate actions are required, the actions of individual cylinders can be controlled separately to adjust the state of synchronous transverse movement. In order to better realize the transverse movement, a slide baffle is provided between the transverse beam section and the slide plate to limit the slide plate from moving horizontally along the transverse beam section track. In case of a stuck group phenomenon, the parallelism error of the two sets of transverse devices can be adjusted to ensure normal transverse movement.

[0122] 3) Horizontal rotating tooling.

[0123] The horizontal rotating tooling comprises a three-dimensional beam dropping device supporting structure and a three-dimensional beam dropping device transverse movement hydraulic system.

[0124] The three-dimensional beam dropping device includes a set of fixed-support three-dimensional beam dropping devices 302 and three sets of floating-support three-dimensional beam dropping devices 301; the fixed-support three-dimensional beam dropping devices 302 can have their support points fixed in the longitudinal and transverse directions by longitudinal and transverse jacks, and in the entire system, the three-dimensional beam dropping device can be used as the rotation center of the other three points when turning, thereby realizing the function of the concrete beam turning angle; the longitudinal and transverse jacks and the slide plate of the floating-support three-dimensional beam dropping device 301 are floated and pushed, and when turning, the slide plate of the floating-support three-dimensional beam dropping device 301 adapts to the position requirements of the slide plate of the fixed-support three-dimensional beam dropping device 302.

[0125] Support structure of three-dimensional beam-dropping device: The three-dimensional beam-dropping slide group is still equipped with a 200t lifting jack as the supporting structure. The supporting structure on the top of one pier is set as two independent fulcrums, and the supporting structure on the top of the other pier is a balanced fulcrum. The four fulcrums are a four-point support and three-point balanced support method. The specifications of the lifting jack are EDX1508, with an outer diameter of 240mm, an inner diameter of 200mm, a piston rod diameter of 160mm, a body height of 362mm, a stroke of 200mm, and a maximum thrust of 200t when the hydraulic system pressure is 63Mpa. The load of the four fulcrums of the supporting structure is 520t. When each jack needs to lift 130t, the system working pressure is about 41.275Mpa.

[0126] The two independent fulcrums of the three-dimensional beam-dropping device are to connect the oil inlet and outlet ports of the two jacks on a pier with a high-pressure oil pump to supply oil respectively. According to the design elevation, the piston's top height is determined. A hydraulically controlled one-way valve is set on the oil inlet line of the jack to maintain the position of the jack's rod, thereby maintaining the jacking pressure. A balanced fulcrum of the three-dimensional beam-dropping device is to connect the oil inlet and outlet ports of the two jacks on the left and right sides of the other pier top with a tee, and use a high-pressure oil pump to supply oil together, so that the two jacks move in a balanced manner, and the piston's top height is determined by external load, so as to maintain the balanced support of the loads of the two jacks. The connecting pipelines between the two jacks on both sides of the pier top are connected with steel pipes, and a hydraulically controlled one-way valve is set on the main tee line to maintain the position of the jack's rod, thereby maintaining the jacking pressure. The independent fulcrum and the balanced fulcrum high-pressure oil pump are placed on the two piers of the waiting hole.

[0127] 3D beam-dropping device transverse hydraulic system: The 3D beam-dropping device transverse system is equipped with 50t jacks in the longitudinal and transverse directions as longitudinal and transverse driving devices. The longitudinal and transverse jacks with fixed fulcrums are connected to the slide plate in two layers by shaft hinges, so it is necessary to examine the pulling force of the jacks to determine the pushing capacity and the actual working pressure of the hydraulic system. The longitudinal and transverse jacks of the floating fulcrum 3D beam-dropping device 301 transverse system are installed in a floating manner at the longitudinal and transverse pushing positions of the slide plate, so the slide plate is always driven to move by the thrust of the jacks during transverse movement. The specifications of the jack are: THMQF50T-20b, inner diameter 100mm, piston rod diameter 70mm, stroke 260mm; each set of lateral movement device needs to overcome the total sliding friction resistance of 250kN, including the 2‰ slope resistance. When the pressure of the lateral movement hydraulic system is 63.5Mpa, the pulling force that the jack can provide is 254.4kN. When the actual push is 250kN, the actual pressure of the pulling force lateral movement hydraulic system is 62.4Mpa. The actual pressure of the pulling force is close to the rated pressure. At this time, the lateral movement jack thrust method needs to be adopted. When the actual push is 250kN, the actual pressure of the thrust lateral movement hydraulic system is 31.75Mpa.

[0128] The longitudinal and lateral travel of the transverse movement system of the three-dimensional beam dropping device is ±130mm. There are frames in the front, back, left and right to limit the movement range of the slide, so there is no need to set up other limit devices.

[0129] Fig.14 This is a schematic diagram of the setup of the three-dimensional beam drop device. Fig.15 This is a schematic diagram of the steering of the three-dimensional beam dropping device. Fig.16 Schematic diagram of beam rotation.

[0130] When the three-dimensional beam dropping device turns, point A is used as the rotation axis, and the horizontal displacement jack at point C is used to push the slide plate at point C to rotate, and points B and D follow to rotate the concrete beam to a certain angle.

[0131] like Fig.17As shown in the schematic diagram of beam forward movement, when the beam is moved forward along the bridge direction, the longitudinal jacking jacks in the first two three-dimensional beam-dropping devices are used to push the concrete box beam forward.

[0132] like Fig.18 As shown in the schematic diagram of the transverse movement of the beam, when the transverse bridge moves the beam to the left or right, the transverse pushing jacks in the two three-dimensional beam-dropping devices on the left or right are used respectively to push the concrete box beam to the left or right.

[0133] S40: Construction of existing beam relocation.

[0134] S41: Preparation before beam shifting, complete the erection of the construction platform, beam lifting operation and stone padding work.

[0135] (1) Setting up a construction platform

[0136] Double-row scaffolding is set up near the pier body, with a vertical step distance of 120cm (the step distance of the top horizontal bar shall not be greater than 100cm), a longitudinal spacing of 90cm, and a horizontal spacing of 120cm. Each layer of bracket is equipped with fastener steel pipe scissor braces. The top horizontal bar is fully covered with 30cm*3cm*4m footrests as a construction platform. Fig.19 The foundation of the pedestrian scaffolding is replaced with fill, and tie rods are used to fix the existing bridge piers to ensure the stability and safety of the pedestrian support.

[0137] (2) Beam lifting

[0138] 1) Jack arrangement: The vertical jack 110 can be supported on the middle part of the existing cushion stone. The pier top is first leveled with mortar. The jack is installed on a special steel pad to ensure that the jack axis is vertical and the oil cylinder is on the bottom plate of the box beam. The four groups of jacks on the same beam are controlled by a pump station to ensure synchronous lifting. The displacement dial gauge is used to monitor the lifting height. After the jack is lifted into place, a temporary support is used to support the beam body. The jack and temporary support are arranged as follows: Fig. 20 , 21 shown.

[0139] 2) Trial lifting: In order to observe and assess the working status of the entire lifting construction system, a trial lifting should be carried out before formal lifting, with a trial lifting height of 2mm. During the trial lifting process, the displacement, load and stress of each point should be closely monitored. If there is any over-limit or abnormal situation, the lifting should be stopped immediately and the relevant treatment measures should be taken before continuing.

[0140] After the trial jacking is completed, the measurement point strain, overall displacement, structural deformation and other conditions are provided to provide a basis for the formal jacking.

[0141] 3) Formal lifting: After the trial lifting, if there is no problem, start the formal lifting, including the following steps:

[0142] ① Load according to the preset loading speed, control the beam lifting speed ≤2mm / min, synchronize the jacks according to the design requirements, and the synchronous displacement difference of each jack is ≤±1mm.

[0143] ② During the jacking process, a dedicated person shall monitor the lateral and longitudinal displacements and stress changes of the beam and keep records. Once the limit values ​​are exceeded, the person in charge shall be notified immediately.

[0144] ③ During the jacking process, dedicated personnel are assigned to operate the intelligent synchronous jacking system. The operator should pay close attention to the monitoring data and take the next action according to the monitoring data and prompts until the jacking reaches the designed height.

[0145] ④ The monitoring data of the synchronous jacking process should be saved in real time.

[0146] 4) Install temporary support: lift 180mm each time, top up twice, add piers 109 at the top and bottom and use auxiliary support to change the support state. After lifting 470mm and before dismantling the existing support, add piers 109 at the position of 2800mm horizontal spacing to protect the beam body so that it can be stably supported on the temporary pads.

[0147] (3) Pad stone construction

[0148] 1) Remove the support: When the temporary support is stable, use auxiliary facilities to take out the lower support plate along the preset track, then take out the upper support plate, and clean the support placement position and surrounding debris.

[0149] 2) Remove the cushion stone: Use an electric pick to chisel away the cushion stone concrete and take out the existing support bolts.

[0150] 3) New pad stone: Tie the reinforcement of the new pad stone. When the pad stone is on the existing pier, use the embedded reinforcement method to install the vertical reinforcement. After the reinforcement is tied, pour the pad stone concrete.

[0151] S42: Beam shifting construction. After the beam shifting parameters are determined, the beam shifting construction is carried out. The beam shifting construction includes installing beam shifting equipment, horizontal shifting of the beam, horizontal rotation of the existing beam, longitudinal shifting of the existing beam, and installation of dropped beams and supports.

[0152] (1) Beam shifting parameters

[0153]

[0154] Table 2 Main parameters of beam shifting for uplink connecting line

[0155]

[0156] Table 3 Main parameters of beam shifting for downlink connecting line

[0157] Before moving the beams, strengthen communication with the equipment management unit, conduct a detailed investigation on the size and condition of the existing box girders of the Hangzhou-Ningbo Railway, and ensure that the space for moving the beams meets the requirements.

[0158] (2) L2 beam shifting construction

[0159] 1) Install beam shifting equipment

[0160] A three-dimensional beam-dropping device is installed inside the 540mm cushion pier 109 placed on piers 452# and 453#, respectively. The horizontal center distance of the three-dimensional jack is 2400mm, about 925mm from the beam end. A fixed fulcrum three-dimensional beam-dropping device 302 and three floating fulcrum three-dimensional beam-dropping devices 301 are installed.

[0161] 2) L2 beam lateral displacement

[0162] The hydraulic cylinder of the three-dimensional beam-dropping device is driven to move horizontally, and the horizontal movement distance is 23 mm. During the horizontal movement process, the setting position of the cushion 109 is maintained to play a protective role.

[0163] 3) L2 beam body horizontal rotation

[0164] The three-dimensional beam dropping device 302 with a fixed fulcrum is used to fix the support point of the three-dimensional beam dropping device 302 on the inner side of the small mileage end as the rotating axis, and the three-dimensional beam dropping device 302 with a fixed fulcrum at the large mileage end is used to drive the beam body to rotate 1.61° counterclockwise.

[0165] 4) Installation of L2 beam and support

[0166] Replace the flat jack, install the support, invert the top and drop the beam 420mm, and drop the beam into place. If there is any deviation, use the three-dimensional beam drop device to correct it, install the support, and drop the beam into place.

[0167] (3) L3 beam shifting construction

[0168] 1) Install beam shifting equipment

[0169] Install flat jacks at the newly poured pad stones on piers 453# and 454#, and install vertical jacks 110 at the unpoured pad stones. When installing the jacks, the distance from the beam end along the bridge direction is 925mm, and the distance between the centers of the two jacks across the bridge is 865mm. Afterwards, push the fishbelly pad beam above the jacks.

[0170] 2) L3 beam lateral displacement

[0171] Install the transverse track beam and slide seat 300mm away from the end of the box beam along the bridge, unload the lifting jack and drop 5mm, and the box beam falls to the top of the slide support. Remove the vertical lifting jack and cushion beam, drive the transverse hydraulic cylinder, and move 765mm synchronously at both ends.

[0172] 3) L3 beam body horizontal rotation

[0173] A three-dimensional beam-dropping device is installed 925mm away from the beam end along the bridge direction, and the lateral center distance of the three-dimensional jack is 1600mm; the three-dimensional beam-dropping device is used to lift the box beam away from the transverse track beam, and the support point of the three-dimensional beam-dropping device on the inner side of the small mileage end is used as the rotation axis to fix it, and the three-dimensional beam-dropping device at the large mileage end is used to drive the beam body to rotate 2.97° counterclockwise.

[0174] 4) Longitudinal displacement of L3 beam

[0175] After rotating into position, the box girder is lifted by a three-dimensional beam-dropping device and moved vertically and horizontally into position. The horizontal movement distance is 47 mm and the vertical movement distance is 41 mm.

[0176] 5) Installation of L3 drop beam and support

[0177] Remove the lateral system 100, install the support, replace with a flat jack, and drop the beam 490mm into place. If there is any deviation, use the three-dimensional beam drop device to correct it, install the support, and drop the beam into place.

[0178] (4) L4 beam shifting construction

[0179] 1) Install beam shifting equipment

[0180] Install flat jacks at the newly poured pad stones on piers 454# and 455#, and install vertical jacks 110 at the unpoured pad stones. When installing the jacks, the distance from the beam end along the bridge is 925mm, and the center distance between the two jacks across the bridge is 865mm. Then, push the fish-belly pad beam to the top of the jacks. Simultaneously lift 130mm, remove the 540mm pad pier 109, install the transverse track beam and slide seat at 300mm away from the end of the box beam along the bridge, unload the lifting jack and drop 5mm, and the box beam falls to the top of the slide seat support.

[0181] 2) L4 beam lateral displacement

[0182] Remove the vertical lifting jack and the cushion beam, drive the lateral hydraulic cylinder, and move the two ends lateral synchronously by 2068mm. During the lateral movement, keep the setting position of the cushion 109 to play a protective role.

[0183] 3) L4 beam body horizontal rotation

[0184] A three-dimensional beam-dropping device is installed 925mm away from the beam end along the bridge direction, and the lateral center distance of the three-dimensional jack is 1600mm; the three-dimensional beam-dropping device is used to lift the box beam away from the transverse track beam, and the support point of the three-dimensional beam-dropping device on the inner side of the small mileage end is used as the rotation axis to fix it, and the three-dimensional beam-dropping device at the large mileage end is used to drive the beam body to rotate 4.56° counterclockwise.

[0185] like Fig.38 , 39As shown, when the three-dimensional beam dropping device turns, point A is used as the rotation axis, and the horizontal displacement jack at point C is used to push the slide plate at point C to rotate, and points B and D follow, so that the concrete beam rotates a certain angle.

[0186] 4)L4 beam longitudinal displacement

[0187] When moving the beam forward along the bridge, the longitudinal jacking jacks in the two front three-dimensional beam-dropping devices are used to push the concrete box beam forward. Using the three-dimensional beam-dropping device, the horizontal movement is 70mm and the longitudinal movement is 144mm, with precise alignment.

[0188] 5) Installation of L4 drop beam and support

[0189] Remove the lateral system 100, install the support, replace with a flat jack, and drop the beam 490mm into place. If there is any deviation, use the three-dimensional beam drop device to correct it, install the support, and drop the beam into place.

[0190] (5) L5 beam shifting construction

[0191] 1) Install beam shifting equipment

[0192] Install flat jacks at the pad stones on piers 455# and 456#. When installing the jacks, the distance from the beam end along the bridge is 925mm, and the distance between the two jacks across the bridge is 865mm. Then, push the fish-belly pad beam to the top of the jacks. Install the transverse track beam and slide seat 300mm away from the end of the box beam along the bridge. The lifting jacks are unloaded and dropped 5mm, and the box beam falls to the top of the slide seat support.

[0193] 2) L5 beam lateral displacement

[0194] Remove the vertical lifting jack and the cushion beam, drive the transverse hydraulic cylinder, and move the two ends synchronously transversely by 4030mm; during the transverse movement, keep the setting position of the cushion 109 to play a protective role.

[0195] 3) L5 beam body horizontal rotation

[0196] A three-dimensional beam-dropping device is installed 925mm away from the beam end along the bridge, and the lateral center distance of the three-dimensional jack is 1600mm; the three-dimensional beam-dropping device is used to lift the box beam away from the transverse track beam, and the support point of the three-dimensional beam-dropping device on the inner side of the small mileage end is used as the rotation axis to fix it, and the three-dimensional beam-dropping device at the large mileage end is used to drive the beam body to rotate 5.26° counterclockwise.

[0197] 4)L5 beam longitudinal displacement

[0198] Utilize the three-dimensional beam drop device, with 81mm horizontal movement and 295mm vertical movement for precise positioning.

[0199] 5) Installation of beams and supports

[0200] The beam is dropped at the designed position using a lifting jack, and a three-dimensional beam dropping device is installed at the bottom of the beam. The parameters of the beam dropping jack are the same as those of the jack during lifting. Four vertical jacks 110 form a four-point lifting and three-point balanced support system. If there is any deviation, the three-dimensional beam dropping device is used to correct it, and the support is installed to drop the beam into place.

[0201] S50: Construction of new beams and beam relocation.

[0202] S51: Ex-cast construction of beams, including support construction, formwork engineering, support pre-stressing, reinforcement construction, installation and threading of corrugated pipes, embedding of embedded parts, beam concrete pouring, beam concrete curing and prestressing construction.

[0203] (1) Support construction

[0204] Two rows of bored pile foundations are set at the end brackets of the cast-in-place beams. The bored piles are 1.0m in diameter, 30m long, 2m in horizontal spacing, 2m in vertical spacing, and a 5m long steel cage is set on the top. The steel pipe column is made of Φ610×10 spiral steel pipe, and a 20mm thick steel plate pile cap is welded on the top of the steel pipe column. The cross beam is made of 3-piece I45a I-beam, and the longitudinal beam is made of I56a I-beam.

[0205] The longitudinal beam adopts double-layer Bailey plates with a lateral spacing of 2*0.9m+4*0.45m+0.9m+3*0.45m+2*0.9m. I12 I-beams are laid on the upper part as distribution beams with a longitudinal spacing of 0.6m. A disc-type scaffolding is installed on the upper part with a longitudinal distance of 0.6m and a lateral distance of 1.2m+4*0.6+0.9m+4*0.6m+1.2m.

[0206] A [10a channel steel connecting beam (4.5m high truss) is set between each row of adjacent steel pipe columns, which are connected by assembled bolts. Ear plates are installed on both sides of the standard section of the steel pipe, and M20 bolt holes are set. The [10a channel steel is fixed by bolts, and the scissor braces are arranged continuously with a height of 4.5m.

[0207] (2) Formwork Engineering

[0208] The formwork system of the cast-in-place box girder body of the bracket consists of a bottom form, a side form, an end form and an inner form. All are constructed with 1.5cm thick bamboo plywood. The arc chamfer of the side form is customized with a steel formwork panel from the manufacturer. The wing plate and the inner form formwork system support uses a steel pipe frame with a horizontal and vertical spacing of 60cm. The bamboo plywood uses 10*10cm square wood back ribs with a spacing of 20cm. The inner form is vertically supported on the bottom plate by inserting a steel pipe into the steel bar support. After the casting is completed, the steel bar support is cut off. The inner form is horizontally supported by steel pipes and adjustable support using the webs on both sides. After the formwork is assembled and debugged, a layer of high-quality release agent is applied to the surface of the formwork. In order to ensure the position of the inner formwork of the box girder, a concrete pad with the same grade as the box girder is set between the inner formwork and the steel bar to tighten the inner formwork, and the bottom plate is also supported by a concrete pad with the same grade as the box girder. According to the design requirements, it is necessary to set a pre-arch on the bottom formwork. The pre-arch setting is achieved by installing steel plate pads between the Bailey plate and the I10 I-beam crossbeam. The pre-arch setting should take into account the impact of shrinkage and creep as well as the estimated time for the second phase of constant load on the bridge.

[0209] After the template is installed, the team leader, on-site technician, and quality inspection engineer will inspect the template installation respectively. Only after the inspection is qualified can it be reported to the supervision engineer. The allowable deviation of the dimensions of each part of the template installation is shown in Table 4.

[0210]

[0211] Table 4 Permissible deviation and inspection method of prestressed concrete simply supported beam formwork dimensions

[0212] (3) Bracket preload

[0213] After the bracket is installed, it must be pre-stressed. The purpose of pre-stressing is to eliminate the inelastic deformation of the bracket installation, measure the elastic deformation during construction load, and calculate the pre-arch of the box beam bottom formwork based on the camber after the box beam is tensioned. At the same time, pre-stressing can test the safety performance of the bracket.

[0214] 1) Preload

[0215] According to the specifications and design requirements, the support is pre-stressed at 110% of the maximum construction load.

[0216] Preloading method: preloading is carried out using preloading blocks.

[0217] 2) Preloading method and loading procedure

[0218] This project uses preloading blocks for preloading, and the stacking load during preloading simulates the stress state during box girder construction. After the preloading blocks or sandbags are transported to the site by car, they are hoisted onto the bridge by crane, and are reasonably arranged and stacked in layers according to the loads and cross-sectional shapes of various parts of the box girder, and preloading is performed as much as possible according to the equal load effect.

[0219] Loading is divided into the following steps:

[0220] ①The loading process is divided into three levels: 0→60%→100%→110%;

[0221] ②First level loading: 0→60%;

[0222] The first level of loading is 60%. After loading is completed, the first round of testing begins. At this time, the loading is 60% of the box girder construction load state, and measurements are recorded to observe the stress of the support.

[0223] ③ Second level loading: 60﹪→100﹪;

[0224] The second level of loading is 100%, which is 100% of the box girder construction load state. Measurements and records are taken to observe the stress conditions of the support.

[0225] ④Third level loading: 100﹪→110﹪;

[0226] At this time, the load is loaded to 110% of the box girder construction load state.

[0227] The deformation of the bracket is observed 1 hour after each level of loading is completed, and the displacement of each monitoring point is monitored and recorded at intervals of 6 hours. Subsequent loading can only be carried out when the difference between the average values ​​of the displacements of two adjacent monitoring points is no more than 2mm.

[0228] After all preloads are applied, the displacement of each monitoring point should be monitored and recorded at intervals of 6 hours; the preload can be removed only when the difference in the average displacement value monitored for 12 consecutive hours is no more than 2mm. The displacement of each monitoring point should be monitored and recorded 6 hours after the bracket is unloaded.

[0229] 3) Bracket deformation observation network

[0230] In order to eliminate inelastic deformation, determine the elastic deformation value, set the pre-arch accordingly, and verify the safety performance of the mold frame, it is necessary to establish a deformation observation network, arrange deformation observation points, and measure, observe and statistically analyze the observation points at each pre-stressing stage during the pre-stressing process.

[0231] ① Observation point arrangement

[0232] During the preloading process, observation points should be reasonably set and observation records should be kept to facilitate the calculation of the deformation of the bracket. The observation points are set on the outer mold system, with 5 sections set longitudinally (two ends of the template, the middle of the span on both sides, and one in the middle of the span), and 8 observation points are set on each section (6 in the web area and 2 in the flange area).

[0233] ② Loading and unloading observation

[0234] Before preloading, the observation points should be observed for the first time and the initial values ​​should be recorded. The loading process should pay attention to graded loading, which is divided into 60%, 100%, and 110%, and carried out in 3 levels. After each level of loading is completed, the deformation of the bracket is observed one hour later, and then an observation is carried out every 6 hours. The next level of loading can be carried out only after the deformation of two adjacent observations is no more than 2mm. After all the loading weights are applied, an observation is carried out every 6 hours. Unloading can be carried out only when the displacement value of the bracket is less than 2mm for two consecutive observations and the static stop time reaches 24 hours. Unloading should be carried out in the same graded unloading as loading. The loading and unloading process should be uniform and slow, and carried out in accordance with the principles of symmetry, grading, and layering. Concentrated loading and unloading are strictly prohibited to avoid uneven force on the bracket and sudden force causing instability. After the non-elastic deformation of the bracket is eliminated and the compression is stable, the elastic deformation is measured, and the bracket preloading construction is completed.

[0235] To ensure accurate deformation data, the project department set up a deformation observation team to be responsible for the daily work of deformation observation, and report the observation data and final results to the engineering department for archiving.

[0236] 4) Construction pre-camber setting box.

[0237] The key to the control of the beam construction elevation and linear shape is the setting of the pre-camber. The safety of each component of the support system after being stressed can be clarified through pre-compression, and the elastic and inelastic deformation values ​​of the system structure can be measured, providing a basis for determining the construction pre-camber.

[0238] After the bracket is installed, the height of the template is pre-adjusted first. Five sections are set in the longitudinal direction of the box beam, and 8 observation points are set on each section. Two observation points are set on both sides of the template bottom plate. The initial elevation is H0, and pre-compression is performed using pre-compression blocks. During ballasting, the bracket is pre-compressed using a graded loading method. When the weight of the beam body and the weight of personnel and equipment are reached, the elevation of the observation point is measured. When the settlement is stable, the elevation of the observation point is recorded as H1. After unloading, the elevation of the observation point is H2. After loading and unloading, the elastic deformation and inelastic deformation of the formwork are calculated, which can be expressed as follows:

[0239] Inelastic deformation δ1 = H0-H2 (eliminated by preload);

[0240] Elastic deformation δ2 = H2-H1;

[0241] After preloading to eliminate inelastic deformation, the reserved camber value δ=δ0+δ2;

[0242] δ0 is the design arch value, which is determined by the design drawings.

[0243] (4) Steel bar construction

[0244] 1) Steel bar processing and transportation

[0245] Steel bar cutting and semi-finished product processing are centralized in steel bar processing plants and transported to the construction site by transport vehicles after acceptance. Vertical transportation uses cranes and manual tying.

[0246] The steel bar extension adopts lap welding. Before welding, the welding process and parameters are selected, and trial welding is carried out according to the actual construction conditions, and the appearance quality of the joint and the specified mechanical properties are inspected. Batch welding can only be carried out after the trial welding quality is qualified and the welding process (parameters) are determined. For steel bars with complex shapes, the large sample must be placed first and then processed. The longitudinal steel bars need to be lifted to the beam and tied after welding, and welding operations on the beam should be avoided as much as possible.

[0247] Cold drawing and straightening: coiled steel bars and bent steel bars need to be straightened. The straightened steel bars are guaranteed to be straight, without local bends, without scars on the surface that weaken the cross section of the steel bars, and the surface is clean without damage, oil stains, etc.

[0248] Steel bar cutting: Steel bar cutting machine is used for cutting. The cut steel bars are numbered according to the types specified in the design drawings, and are stacked and marked separately.

[0249] The allowable deviation of the dimensions of the processed steel bars must meet the requirements of the specifications. If any dimensional deviation of the steel bars exceeds the limit, they shall not be used on bridges.

[0250] 2) Tie steel bars and install inner mold

[0251] The beam segment reinforcement is tied as a whole on the formwork. First, the bottom plate and web reinforcement are tied, and then the inner formwork is installed. After the inner formwork is debugged, the top plate reinforcement is tied. When the beam reinforcement collides with the prestressed tendon pipe, the beam drainage hole and ventilation hole and embedded parts, the beam reinforcement is appropriately moved or appropriately bent. The minimum net protective layer of the beam is 30mm for the top plate and 35mm for the rest of the parts. Confirm the data and the tail section of the binding wire is all placed on the inside of the reinforcement skeleton and shall not extend into the protective layer. During construction, all the corresponding spiral reinforcements are installed at the reserved holes (drainage holes, ventilation holes, etc.) of the beam body. The beam reinforcement at the bridge deck drainage hole is appropriately moved, and spiral reinforcements and inclined well-shaped reinforcements are added for reinforcement; in order to ensure the accurate position of the reinforcement during construction, the setting of the erection reinforcement is strengthened according to the actual situation, and measures such as increasing the number of erection reinforcements or adding W-shaped or rectangular erection reinforcements are adopted.

[0252] When tying the steel bars, install the corrugated pipe according to the installation position of the prestressed channel. The position of the steel bundle pipeline is fixed with positioning steel bars, which are firmly welded to the steel skeleton. When the pipeline position collides with the steel skeleton steel bars, move the steel bars to ensure that the pipeline position remains unchanged. After positioning, the deviation of the pipeline axis is no more than 5mm, and it is forbidden to hit the channel with the vibrator. When welding ordinary steel bars near the prestressed pipeline, take measures to protect the pipeline.

[0253]

[0254] Table 5 Allowable deviation and inspection method for steel bar installation

[0255] (5) Installation and bundling of bellows

[0256] The box girder is equipped with longitudinal and transverse prestressed tendons. The prestressed metal corrugated pipe is extended by a larger corrugated pipe of the same type as the joint pipe. The length of the joint pipe is not less than 300mm. In order to facilitate the smooth passage of the prestressed steel bundle, each pipe joint is connected in the same direction.

[0257] 1) Bellows installation

[0258] Longitudinal prestressing: After the bottom steel bars of the box girder bottom plate and top plate are tied, the installation of the longitudinal prestressed corrugated pipe is started. First, the corrugated pipe is placed on the bottom steel bars of the bottom plate and top plate in the correct position, and then the upper steel bars of the bottom plate and top plate are tied. After the bottom plate and top plate steel bars are tied, the corrugated pipe is fixed. The corrugated pipe is fixed with positioning steel bars, which are directly hung on the main bars of the bottom plate and top plate, and then the positioning steel bars are spot welded and fixed with electric welding. The spacing of the positioning bars is controlled at 0.5m, and the spacing is increased by 0.3m at the bend of the pipe to ensure that the corrugated pipe cannot move up, down, left or right, so as to ensure that the position of the corrugated pipe is accurate and straight, round and without dead bends. The inner diameter of the positioning steel bar is 3-5mm larger than the outer diameter of the corrugated pipe. The tire is processed on site to ensure that the accuracy and shape of the positioning steel bar meet the requirements, and the positioning steel bar must be reliably connected to the beam body steel bar. When installing the pipeline, the center line of the pipeline should be perpendicular to the anchor plate. After the corrugated pipe is correctly positioned, a PE liner is inserted inside the corrugated pipe to ensure that there is no leakage in the corrugated pipe when pouring concrete. During the concrete pouring process, the PE liner is rotated to prevent leakage and blockage of the channel.

[0259] Transverse prestressing: Transverse prestressing steel strands and corrugated pipes are installed after the longitudinal prestressing pipeline is installed, and the fixed ends of the steel strands are installed alternately. The fixing method is the same as the longitudinal prestressing tendon pipeline, and the steel strands are inserted after the pipeline is installed.

[0260] Protection of prestressed pipes: For the parts of transverse prestressed pipes that cannot be inspected before concrete pouring, a comprehensive inspection must be carried out during the construction of the next process. If the pipes are damaged, they must be repaired immediately and well protected during the construction process. For the parts that can be inspected before concrete pouring, an inspection must be carried out before pouring, and any damage must be repaired. All transverse prestressed pipes must be well protected during concrete pouring to prevent cement slurry from entering and clogging the pipes due to damage. During the pouring process of the transverse prestressing force, the steel strands are pulled to prevent the slurry from clogging the channels and causing the prestressed tendons to fail to be tensioned.

[0261] 2) Prestressed steel strand bundle

[0262] The bundles are manually threaded according to the one-to-one correspondence between the bundle numbers and the hole numbers. To facilitate threading, the threaded end is wrapped into a cone shape to prevent the corrugated tube from being damaged. The prestressed steel strands can only be tensioned after all the steel strands to be tensioned in this batch have been threaded. After threading, check whether the reserved length meets the tensioning requirements.

[0263] (6) Embedding of embedded parts

[0264] 1) Embedding of support embedded steel plates and anti-fall beams

[0265] The box girder requires a total of 11 sets of pre-embedded steel plates for supports, which are manufactured by the factory and then transported to the construction site. The size and type of the materials must be determined before they are stored or transported to the construction site. They must also undergo anti-corrosion treatment and meet relevant technical specifications before they can be put into use.

[0266] The embedded steel plate of the support is embedded after the support is installed and before the bottom web reinforcement is tied. During installation, attention should be paid to the corresponding type of the support.

[0267] Pre-embedded steel plates to prevent falling beams: Each box beam requires 22 sets of pre-embedded steel plates, which are treated with multi-element alloy co-infiltration. Their installation is carried out simultaneously with the pre-embedded steel plates of the supports. During installation, attention should be paid to the relationship between the position of the anti-falling beam and the center line of the support and the pier support pad stone.

[0268] 2) Contact network support foundation

[0269] The embedded anchor bolts and embedded steel plates of the contact network column foundation are connected by spot welding; when the beam reinforcement hits the embedded parts, the reinforcement should be moved or bent appropriately. After the foundation is embedded, the reinforcing steel bars should be laid while the top plate reinforcement is tied. The upper embedded steel plate should be flush with the top surface of the foundation, the exposed part of the bolt should be perpendicular to the horizontal plane of the foundation, and the distance of the bolt top surface from the vertical position should be less than 1mm. The pillar bolts are installed by spot welding the upper and lower embedded steel plates to form a stand, and the four bolts are fixed on the stand and embedded as a whole.

[0270] 3) Comprehensive grounding system

[0271] The comprehensive grounding system consists of grounding terminals, stainless steel connecting wires, and L-shaped connectors. The grounding terminals are pre-buried during the construction of the box girder, and the stainless steel connecting wires and L-shaped connectors are installed and connected after the box girder is completed.

[0272] (7) Beam concrete pouring

[0273] The concrete pouring is completed in one go. The concrete is pumped into the mold using a delivery pump and poured in layers from one end of the beam to the other.

[0274] 1) Concrete pouring at the junction of bottom and web

[0275] The concrete at the junction of the bottom and the web is delivered to the position through the web by a delivery pump. The pouring height should be 10 cm above the web chamfer. The concrete on the bottom plate mainly flows out naturally. If part of it cannot be put in place, a vibrating rod is inserted into the web to make the concrete flow out of the web.

[0276] 2) Pouring of bottom slab concrete

[0277] The bottom plate concrete is transported through the window holes on the top of the inner mold. A 30cm diameter skylight hole is opened every 4m on the top of the inner mold. After the concrete in the middle of the bottom plate is transported to the bottom plate through the skylight hole, it is manually leveled and spread, and vibrated with an inserted vibrator. After the bottom plate is vibrated and compacted, it is manually scraped flat with a wooden ruler according to the thickness of the bottom plate. After the bottom plate concrete pouring of this section is completed, the skylight hole of the inner mold top plate is sealed with the original mold.

[0278] 3) Web slab concrete pouring

[0279] The web concrete is directly input by a delivery pump and vibrated by an inserted vibrating rod. The web concrete is poured symmetrically on both sides to prevent the inner mold from shifting.

[0280] 4) Top slab concrete pouring

[0281] Before pouring concrete, short steel bars are set on the flange plate facade template and bridge deck steel bars, and the beam surface concrete elevation is found and marked. The top plate concrete is poured with a car pump and vibrated with an inserted vibrator. When the concrete is poured to the elevation, the top plate and the top surface of the wing plate are scraped and pressed with an aluminum alloy scraper to control the elevation. The first plastering is carried out after the concrete is vibrated and leveled, and the top plate concrete should be plastered twice. The second plastering should be carried out before the concrete is nearly set to prevent the surface from drying and cracking due to early water shortage. When pouring concrete, appropriately reduce the slump to ensure that the concrete does not turn over during pouring.

[0282] The concrete pouring of the beam body is vibrated and formed by an inserted vibrating rod to ensure the compactness of the concrete. During the pouring process, attention should be paid to strengthening the vibration of the box beam ends, chamfers and areas with dense steel bars, especially the small working surface and poor conditions of the inner box. The focus should be on strengthening the vibration at the corners, the interface between the web and the bottom plate, and the control of the bottom plate elevation. When pouring concrete, the prestressed pipes are dense and the gaps are small, so a small-diameter inserted vibrator is equipped. When operating the inserted vibrator, insert quickly and pull out slowly, vibrate vertically, do not pull horizontally, do not miss vibration, and be careful to prevent over-vibration. At the same time, the vibrator must not be placed on the formwork or steel bars in the starting state, and must not collide with the prestressed pipes, formwork, steel bars, and auxiliary facilities (such as the vibration of the concrete of the positioning frame is strictly carried out within the range of action of the vibrator), and strictly prevent missing, insufficient and excessive vibration. The insertion points of the vibrator should be arranged evenly, and can be "determinant" or "staggered", moved in sequence, and should not be mixed to avoid confusion and missed vibration. The distance of each moving position should not be greater than 1.5 times the radius of action of the vibrator, 10cm away from the edge of the formwork, inserted into the lower layer of concrete 5-10cm, to prevent collision with the formwork steel bars and embedded parts, the moving distance of the surface vibrator should be such that the vibration plate covers the compacted part by 10cm. After the vibrating rod is inserted into the concrete, it should be moved up and down to change its position with an amplitude of 5-10cm to facilitate the discharge of air in the concrete and ensure compaction. The vibration time should be mastered at each insertion point, and the vibration time at each point is generally 20-30s. The vibrating rod can be pulled out only when the concrete no longer sinks, no significant bubbles rise, the top surface is flat and consistent, and cement slurry begins to emerge. When surface water is found, try to remove it immediately, check the cause or adjust the concrete mix ratio. When operating the insertion vibrator, "fast insertion and slow withdrawal" should be achieved. Fast insertion is to prevent the surface layer of the concrete from being vibrated first, while the lower layer of concrete is stratified and segregated. Slow withdrawal is to allow the concrete to fill the gap formed when the vibrating rod is pulled out to prevent the formation of voids. During the pouring process, pay attention to strengthening the vibration of chamfers, interfaces, and areas with dense steel bars and corrugated pipes.

[0283] During the concrete pouring process, pay attention to retaining the same condition curing specimens and standard curing specimens. The sampling and retention frequency of the same condition curing specimens and standard curing specimens should comply with the following regulations:

[0284] ① For every 100 plates mixed and not exceeding 100m 3 For concrete with the same mix ratio, sampling shall not be less than once;

[0285] ② When the number of concrete batches of the same mix ratio mixed by each work shift is less than 100, sampling shall be conducted at least once;

[0286] ③ Each structural part of cast-in-place concrete shall be sampled at least once;

[0287] ④At least one set of test specimens should be retained each time sampling is carried out.

[0288] (8) Beam concrete maintenance

[0289] After the concrete is poured, 4 hours later (secondary pressing, smoothing and rubbing), it is covered with geotextile and covered with a waterproof film to start curing. Concrete curing adopts natural curing. During the curing period of the beam body and when the insulation measures are removed, measures are taken to ensure that the temperature difference between the core and surface of the beam body concrete, and between the surface and the environment should not exceed 15°C.

[0290] The side formwork is removed when the concrete compressive strength reaches 2.5MPa, and the bottom formwork is removed when the concrete strength reaches 100%, to ensure that the edges and corners of the beam concrete are intact. When removing the formwork, the temperature difference between the core and surface of the beam concrete, the inside and outside of the box, and the surface and the environment should not exceed 15°C, and the edges and corners of the beam should be intact. It is not advisable to remove the formwork when there is strong wind or the temperature changes sharply. When removing the inner formwork, the operators are in a closed environment with high humidity and temperature. A large-capacity blower should be installed at one end of the beam to blow air into the box to improve the working environment. After the formwork is removed, it should continue to be watered and covered for maintenance, and the curing time should be no less than 14 days.

[0291] (9) Prestressed construction

[0292] Before prestressing construction, the first hole beam needs to be tested for prestress instantaneous loss such as pipe friction and bellmouth friction, and the tensioning control stress should be adjusted according to the measured friction resistance to ensure the effective prestress value.

[0293] 1) Prestressed steel strand production

[0294] Prestressed tensioned steel hinges shall be inspected for strength, elastic modulus, cross-sectional area, elongation and hardness of each batch in accordance with relevant regulations. Unqualified products are strictly prohibited from use and shall be removed from the site.

[0295] Steel strands should be stored in a dry place to prevent rust. Circular saws are used for cutting steel strands. Cutting length = designed length of the channel + length required for the tensioning machine to work. Steel strands should be made smooth, straight and even, tied firmly, and prestressed steel from the same furnace, batch and strength should be used for the same strand. The braided steel strands should be placed on a flat site for safekeeping to avoid rain and heavy pressure. No physical or chemical damage should occur during stacking, transportation and installation.

[0296] 2) Hole cleaning and steel bundle insertion

[0297] Before inserting the steel bundle, the hole should be checked for patency with a hole puncher, and the hole should be blown with compressed air until it is clean. When inserting the bundle, the force should be even and steady, and the direction of the force should be consistent with the axis of the hole. The bundle insertion work can generally be done manually. When the steel bundle is long, it can be pulled by a winch with the help of a long steel wire as a lead.

[0298] A comprehensive inspection is carried out to identify any pipes that may be damaged. Before pouring concrete, any unintentional holes, openings or damage on the pipes must be repaired. Before and after pouring concrete, check whether the prestressed tendons can slide freely in the pipes.

[0299] 3) Prestressed tendon tensioning

[0300] During tensioning, the "three controls" of tensioning stress, strain and time are implemented: that is, the oil pressure gauge reading is mainly used during tensioning, and the elongation value of the steel strand is used for verification, and the load is held for 5 minutes under the action of σk.

[0301] Prestressing should be carried out in two steps. When the concrete strength of the beam reaches 60% of the design strength, the initial tensioning is carried out. The outer formwork (bottom formwork and side formwork) can be removed only after the initial tensioning is completed; when the concrete strength and elastic modulus of the beam reach 100% and the curing time is not less than 10 days, the final tensioning is carried out. The prestressing tendon tensioning procedure is carried out according to the following procedures.

[0302] 0→0.2σ k (Measure elongation) →σ k (Measure the elongation, and measure the retraction after stopping for 5 minutes) → Anchor.

[0303] ①Construction organization of tensioning

[0304] The tensioning is carried out synchronously and symmetrically at both ends with sufficient oil pumps to prevent eccentric tensioning, which causes uneven force on the inner and outer edges. For this reason, the tensioning is divided into several groups, with 4 to 6 people in each group responsible for a set of equipment, and a recorder is also appointed. The oil pumps are operated synchronously and wireless communication is used for communication.

[0305] ② Preparation before tensioning

[0306] A. Use 200-ton jacks for tensioning equipment, calibrate all tensioning equipment, and use them together;

[0307] B. In order to meet the tensioning requirements and save materials, the length of all curved channels is calculated to determine the length of each bundle. Usually, the length of the steel bundle extending out of the anchor plate is set at 70cm, and the bundles are arranged and threaded according to the tensioning sequence;

[0308] C. Compile the tensioning sequence into a table and mark the cable numbers next to the tensioning holes so that the cables can be placed in the correct positions and tensioned in order;

[0309] D. Calculate the tension elongation value. Curved tension is different from straight line tension. There is a large difference between the tension end and the center due to friction. This friction loss directly affects the reliability of the tension elongation calculation. In order to obtain a more accurate calculation value, it must be combined with the friction loss of the curve segment. Since the curve is multi-directional in space, the usual theoretical calculation has a certain degree of difficulty. This project intends to use electronic segmented calculation, and then superimpose to obtain the final elongation value.

[0310] ③ Prestressed tension

[0311] The key to tensioning is accurate force application, appropriate elongation and reliable anchoring. To this end, the following eight aspects have been strengthened in terms of explanation and supervision.

[0312] A. The longitudinal axis of the jack should be in the same straight line as the center line of the tensioned wire bundle;

[0313] B. The anchor base plate should be vertical to the outlet of the corrugated pipe during the burial process;

[0314] C. The anchor ring and anchor plug must be aligned;

[0315] D. When steel wires are bundled, they should be straightened with a combing board and tied with lead wire every 2m to prevent partial bending of the steel wires and uneven force.

[0316] E. Oil pump tension to 20%σ k When crossing the line;

[0317] F. When tensioning at both ends, the elongation values ​​at both ends should be basically close;

[0318] G. The oil pump should be pressurized slowly and not too fast;

[0319] H. The actual tension elongation value and the theoretical elongation value should be controlled within the range of ±6%, and the retraction amount of the anchor at each end should be controlled within 6mm.

[0320] ④Tensioning sequence

[0321] The lengths of the prestressed beams of the beams are different. Therefore, the tensioning is carried out according to the principles and sequence proposed in the design, first the web, then the top and bottom plates; first the long beam, then the short beam; first the upper part, then the lower part. The longitudinal prestressing is tensioned as a whole at both ends. According to the construction experience, it is planned to use the internal card jack for tensioning. The equipment selection will be further determined according to the specific requirements of the design during construction. The transverse flat anchor is tensioned at one end with an integral tensioning jack. When tensioning, pay attention to tightening the anchor at the anchor end. The tensioning control adopts the principle of tensioning stress as the main and elongation as the verification for double control. When the actual elongation value does not match the theoretical elongation value and exceeds ±6%, the tensioning should be stopped to find out the reason. If the wire is found to be slipped or broken during the tensioning process, stop the operation immediately, find out the reason and make a record. If the number of slipped and broken wires exceeds the relevant regulations, the bundle shall be replaced after inspection and approval by the supervising engineer.

[0322] 4) Grouting

[0323] Pipeline grouting should be completed within 24 hours after the final prestressing, and must be completed within 48 hours in special circumstances. Before grouting, debris and accumulated water should be removed from the pipeline. Oil stains that may occur in the channel can be washed with a neutral detergent that is known to have no corrosive effect on prestressed tendons and pipelines and diluted with water. After cleaning, use oil-free compressed air to blow out all the accumulated water in the channel. Remove floating slurry and debris from the anchor pad.

[0324] Mixing water should not contain any harmful ingredients to prestressed steel bars or cement. Clean drinking water can be used. If non-drinking water is used, it must be inspected by a qualified testing department in advance and meet the requirements for concrete mixing water.

[0325] The water-cement ratio of the slurry should not exceed 0.35, and no water seepage is allowed. The flow rate of the slurry out of the machine is 18±4s, and should not be greater than 30s after 30 minutes; the slurry pressed into the pipeline shall not contain unmixed cement lumps, and the compressive strength of the cement slurry shall not be lower than the design requirements; the initial setting time shall not be greater than 4 hours, and the final setting time shall be less than 24 hours; the slurry temperature during grouting should be between 5℃ and 30℃.

[0326] Before grouting, debris and accumulated water in the pipeline must be removed, and the cement slurry pressed into the pipeline should be full and dense. The longitudinal and transverse prestressed pipelines are grouted from one end to the other. The grouting sequence is from bottom to top, and the grouting of the same pipeline should be carried out continuously and completed in one go. The time interval from the end of cement slurry mixing to the time of pressing into the pipeline should not exceed 40 minutes.

[0327] Cement slurry specimens should be randomly sampled and made at the grouting site. The compressive strength of cement slurry must meet the design requirements. At least three groups of standard curing specimens (40mm×40mm×160mm) should be retained for each work shift for compression and flexural strength tests, and an additional group of curing specimens under the same conditions should be retained if necessary.

[0328] 5) Anchoring

[0329] Due to the need for tensioning space for adjacent post-tensioned prestressed box girders, a reserved anchor section is set at the beam end.

[0330] After the grouting of the hole is completed, the cement slurry at the beam end should be rinsed clean immediately, and the dirt on the supporting pad, anchor and anchor hole concrete should be removed. The joint between the anchor ring and the anchor pad should be waterproofed with polyurethane waterproof coating.

[0331] Before sealing the end, the concrete of the anchor hole is roughened, and a short steel bar with a hook at one end and a thread at the other end is installed in the bolt hole of the anchor plate and tied together with the anchor steel mesh in the anchor hole.

[0332] The end is sealed with non-shrinkage concrete of grade C50. When pouring the anchor concrete, mix the non-shrinkage concrete according to the test mix ratio, operate carefully and vibrate carefully to ensure that the concrete at the anchor is dense and plastered. After the concrete is finally set, the anchor concrete is cured and moisturized by an automatic spraying system.

[0333] After the curing of the end-sealed concrete is completed, polyurethane waterproof coating is used to waterproof the joints between the new and old end-sealed concrete.

[0334] S52: Horizontal movement construction of new beam (L6 beam).

[0335] (1) Install beam shifting equipment

[0336] After the box beam is cast in situ and prestressed, tensioned and grouted to reach the designed strength, a vertical jack 110 is installed at the beam bottom support position to lift the beam body 470mm and lay the transverse slideway. The support spacing between the box beam and the slideway is 2000mm. A slide plate is set on the slideway (sliding load-bearing structure), and a jack of a four-point lifting and three-point balancing system is set on the slide plate, and the box beam falls on the beam transfer trolley.

[0337] (2) Transverse displacement of beam

[0338] The slide plate is set on the slideway by the traverse hydraulic cylinder, and the traverse distance is 9000mm. In the traverse process, the setting position of the cushion 109 is kept to play a protective role.

[0339] (3) Installation of beams and supports

[0340] The beam body is moved to the designed position. If there is a deviation between the beam body and the designed position, the three-dimensional beam-dropping device is used to correct the deviation. The beam is dropped by a jack, 180 mm each time, and the top is reversed twice. The top and bottom are padded with piers 109 and the supporting state is changed with auxiliary supports. After it is dropped to the designed position, temporary supports and permanent bearings are installed. After the grouting construction is completed and the grouting material reaches the designed strength, the temporary facilities are removed.

[0341] During and after the beam shifting construction, a dedicated person is assigned to manage the tools and light objects on the pier top and working platform on site, so that the materials are cleared after the work is completed and all kinds of debris are prevented from falling onto the existing line. At the same time, the construction of civilized construction sites is strengthened to ensure the safety of the operating line construction. After the beam shifting construction is completed, the beam shifting bracket is removed simultaneously. A 25t crane is used on site to cooperate with manual removal of the bracket. The removal order is: remove the slideway, remove the distribution beam, remove the load-bearing beam, and remove the steel pipe column.

[0342] The brackets are dismantled in the order of first up and then down, first outside and then inside, first bracket surface materials and then frame materials, first accessories and then structural parts. The cross knots are loosened one by one, taken out and then hoisted down. A crane is used on site with a manual fall chain to pull the slideway out from the bottom of the beam and hoist it to the ground. After the slide rails are removed, the distribution beams are hoisted to the ground for centralized stacking. The load-bearing beams are hoisted by a crane with a fall chain to the side away from the existing line. During the translation process, a special person is arranged to tighten the rope away from the existing line to prevent the steel components from swinging back and forth and causing limit violations. After the load-bearing beams are removed, the piers are removed. When removing the piers, all the scissor braces connecting the piers are removed first. After the scissor braces are removed, the piers are removed one by one. When removing, the crane hook is hung on the pier, the connection between the pier and the abutment and pier body is released, and the pier is hoisted away from the pier to complete the removal. When removing long components, a traction rope is set under the component, the rope is tightened manually, and the component is moved slowly after lifting to avoid excessive swing amplitude of the component causing limit violations. During the entire process, the construction site was strictly organized in accordance with the construction requirements of the operating line. The construction area had an on-site supervisor and full-time protection officers. The on-site protection officers were equipped with real-time walkie-talkies, signal flags, whistles and other protective equipment to carry out on-site protection work.

[0343] S60: Bridge deck and ballastless track construction.

[0344] After the beam is moved, the bridge deck system is constructed according to the new line. First, the shield is installed. After the shield is installed, the A wall, B wall and protective wall are constructed. After the A wall and the shield are tied with steel bars, they are cast into a whole. The relative position relationship between the bridge deck system and the existing line is that the shield (baffle) is the closest to the existing line.

[0345] The closest shield of the bridge deck system of the 1-7# pier of the up and down connecting line to the Hangzhou-Ningbo Passenger Dedicated Line is the shield of the 7# pier of the up line. The distance between the shield and the center of the Hangzhou-Ningbo Passenger Dedicated Line is 11.79m. The horizontal distance between the shield of the bridge deck system and the center of the Hangzhou-Ningbo Passenger Dedicated Line is greater than this point. The relative position relationship is shown in Table 6 below.

[0346]

[0347]

[0348] Table 6 Relationship between the 1-7# pier shield (baffle) of the Shaoxing North Station up and down link line super-large bridge and the Hangzhou-Ningbo Passenger Dedicated Line

[0349] S61: Installation of shields and sidewalk panels.

[0350] Sidewalk baffles are installed on both sides of the 4-6# piers of the up and down connecting lines, and railing shields are installed on the rest. The shields are 2m and 2.3m long. In order to facilitate construction workers to go up and down the beam surface, a ladder cage is set up next to the bridge deck pier body as a passage for people to go up and down. The ladder cage is paved with molded steps, and the outside is installed with hanging mesh. The verticality of the ladder cage must be strictly controlled to ensure overall stability, and the vertical deviation must be less than 1 / 400 of the full height. Handrails are installed on the inside of the steps, and safety warning signs are hung around the ladder cage to ensure the safety of workers going up and down during construction. A special person is arranged on site to manage the ladder cage, and it is equipped with double locks. The on-site person in charge and the supervisor each hold one, and it is strictly forbidden for idle people to enter the ladder cage.

[0351] Before installing the shield, the steel plate matching the embedded steel plate is processed and a φ20 lifting ring is welded as a lifting device. The surveyor measures and lays out the shield installation line and draws the ink line. The shield and the sidewalk baffle are prefabricated in a centralized manner in the prefabrication yard. After the shield and the sidewalk baffle are transported to the site, they are lifted to the beam surface by a car crane. During the lifting operation, the crane station is perpendicular to the existing line and as far away from the existing line as possible. The ground is solid and reliable, and the boom is extended as little as possible. The shield is installed by a forklift (2.1m high, 1.23m wide, and 2.6m long) through the lifting ring through the sling. To prevent the sling from falling off, a sleeve clamp is set on the outermost side of the fork of the forklift. When lifting the shield, a traction rope is hung on the exposed steel bar, and the manpower is pulled away from the existing railway direction to prevent the template from swinging and causing an intrusion accident. At the same time, the traction rope is used to adjust the position of the shield, and it is installed in place after being adjusted to align with the ink line. After it is in place, the operator fixes the shield by welding the embedded reinforcement of the A wall on the top of the beam to the exposed steel bar of the shield. Two lifting ears are embedded in the prefabrication of the sidewalk baffle for easy installation and use. When installing the sidewalk baffle, a lifting belt is used to pass through the lifting ears for lifting. During the installation process, the measurement edge line and elevation are strictly controlled. The exposed steel bars of the sidewalk are adjusted and welded to the pre-embedded steel bars of the beam top A wall to ensure that the sidewalk is firmly reinforced. At the same time, tie bars are set at the lifting rings of the sidewalk baffles to connect and fix with the pre-embedded steel bars of the vertical wall B. Two tie bars are set for each baffle for reinforcement. The standard baffle and the sidewalk baffle are 2 meters each. After installation, the surveyors often re-measure the position and elevation of the baffle and the sidewalk baffle to ensure that the installation elevation and line type of the baffle are straight. During the installation of the baffle, a special person is arranged on site to command the forklift, the person in charge of the construction area facilities, the full-time protection officer, the station liaison officer, and the real-time intercom, signal flags, whistles and other protective supplies are equipped to operate in strict accordance with the construction requirements of the business line. The project department arranges special personnel to register and manage small machines on a daily basis, and the working conditions of the machines are checked before and after each shift, and the maintenance and repair of the machines are done well. At the same time, a quota-based material collection system is implemented every day. According to the work tasks of the day, the corresponding materials and items are prepared to ensure that the work is completed and the materials are clean. The entire construction process is strictly protected in accordance with the construction requirements of the operating line to ensure the safety of the operating line construction. The bridge deck shield of the 1-7# pier of the up and down connecting lines is closest to the shield of the 7# pier of the up line. The shield of the 7# pier of the up line is 15.5m high to the ground, and the left shield is 11.79m away from the center of the Hangzhou-Ningbo Passenger Dedicated Line.

[0352] S62: Installation of protective wall.

[0353] After the installation of the shield is completed, the A wall, B wall and protective wall are constructed; after the reinforcement of the A wall and the shield is tied, they are cast into a whole. According to the layout of the three walls of the bridge, the vertical wall A is the closest to the existing line.

[0354] The closest distance between the vertical wall A of the bridge deck system of the 1-7# pier of the up and down connecting line and the Hangzhou-Ningbo Passenger Dedicated Line is the shield of the 7# pier of the up line. The distance between the vertical wall A at this location and the center of the Hangzhou-Ningbo Passenger Dedicated Line is 11.79m. The horizontal distance between the vertical wall A of the other bridge deck systems and the center of the Hangzhou-Ningbo Passenger Dedicated Line is greater than this location. The relative position relationship is shown in Table 7 below.

[0355]

[0356] Table 7 Relationship between the 1-7# pier vertical wall A of the Shaoxing North Station up and down link line super-large bridge and the Hangzhou-Ningbo Passenger Dedicated Line

[0357] After the installation of the shield and sidewalk baffles, vertical wall A, vertical wall B and protective wall construction are carried out. The surveyor measures and marks the edge lines of the vertical wall and protective wall, and pops them out with ink lines. The vertical wall formwork uses a standard steel formwork and steel pipe support. The vertical wall steel bars are centrally processed and manufactured by the steel bar processing plant, transported to the site for binding and forming. The vertical wall uses C40 concrete, which is mixed by a centralized mixing station, transported by a concrete truck, and pumped by a concrete pump. The concrete is horizontally layered and poured symmetrically, and vibrated by an inserted vibrator.

[0358] (1) Chiseling

[0359] Before construction, the vertical walls A, B and protective walls should be roughened. The workers will roughen the bottom of the wall according to the measured edge line. The roughening must be done to the fresh concrete surface without floating slurry. After the roughening process is completed, the debris will be collected and transported out of the site.

[0360] (2) Installation of steel bars and formwork

[0361] The steel bars of the vertical wall A, wall B and protective wall are cut and made in advance in the processing plant according to the design requirements, and are stacked separately after being labeled and numbered. Before the steel bars are used, they are transported to the site by a large flatbed truck and tied according to the design requirements. The spacing and quantity of steel bars are required to comply with the construction specifications and design drawing requirements. At the same time, attention should also be paid to the embedded parts of the vertical wall A, wall B and protective wall, and the embedded parts should be embedded accurately and firmly. The embedded parts are strictly installed and the measuring points are accurately embedded to ensure the accurate embedded position.

[0362] The steel bars of the vertical wall and the protective wall are tied at the top of the beam. The steel bars, formwork, etc. are hoisted to the top of the beam by the crane, tied on site, and assembled. During the hoisting operation, the crane station is perpendicular to the existing line and as far away from the existing line as possible. The ground is solid and reliable, and the boom is extended as little as possible. At the same time, the crane uses a steel wire rope to connect the anchor firmly to improve the safety factor and prevent the crane from tipping over to the existing line. When hoisting the steel bars, the two steel wire ropes are evenly separated and tied, and placed on the top of the beam away from the existing line. They are manually transported and tied. The vertical wall formwork is installed by manual cooperation with a forklift. After each formwork is hoisted and fixed, the next formwork can be hoisted. When installing the formwork, strictly follow the order of operating line side first and then outside the operating line. During the hoisting construction, a special person is assigned to command the crane, and full-time protection personnel and station liaison personnel are assigned at both ends of the construction area. They are equipped with real-time intercoms, signal flags, whistles and other protective supplies, and the operator is notified in advance to suspend the operation before a train passes. Hoisting operations are strictly prohibited in severe weather conditions such as strong winds, heavy rains, and heavy snow. When the formwork is hoisted, the closest distance between the formwork and the center of the adjacent line of the Xiaoyong Railway is 14.6m, and the closest distance to the safety limit on the outside of the contact network pole is 9.3m, which meets the construction safety distance.

[0363] The template should be removed in sections. First, install the traction rope on the pre-removed template, tighten the rope manually, and use a crane to lift the template. Move slowly after lifting to avoid excessive swing of the template. The crane stops when the train passes to ensure driving safety. During the whole process, full-time guards must be arranged on site for protection.

[0364] S63: Construction of ballastless track.

[0365] The ballastless track of piers 1-7# of the up and down connecting lines is a double-block ballastless track bed.

[0366] The base plate of the bridge section is cast in blocks. The base plate is 2.8m wide, 0.21m thick, and generally 5-7m long. Two grooves are set on each base of the bridge to match the limit stop of the roadbed plate. The bridge base is connected to the bridge through the pre-embedded sleeve of the beam body. No waterproof layer and protective layer are set on the beam surface within the base range. Since the bridge railings, sidewalk baffles and sound barriers have been completed, they can be used as ballastless track isolation and protection facilities. At the same time, safety warning signs are hung on both sides of the beam to ensure the safety of workers during construction, and to ensure the safety of the operating line and operation. By setting up a ladder cage on the side of the pier body away from the operating line as a passage for workers to go up and down the beam surface, grounding measures are taken for the ladder cage.

[0367] (1) Beam surface treatment

[0368] Before construction, the beam surface elevation, flatness, embedded steel bars and embedded sleeves are inspected and accepted. After acceptance, the connecting steel bars are implanted in the embedded sleeves as required, and the acceptance of the pre-planted steel bars is strengthened. At the same time, the beam surface within 2.6m of the track centerline is checked for roughening. The roughening depth is 1.8-2.2mm, and the roughening texture should be uniform, clear and neat. Geotextiles are laid at the expansion joints between beams to prevent floating ballast and debris from falling into the beam joints. The floating ballast and debris removed by chiseling are cleaned while being chiseled, and are promptly transported to the abandoned soil site for centralized stacking by putting them into woven bags, and on-site protection work is done well.

[0369] (2) Steel bar processing and installation

[0370] The surveying personnel use the total station to place the control points of the base plate edge on the beam surface of each hole, and mark them with red paint. The operator uses the ink fountain to pop out the base edge, the template position line and the plane position of the bottom of the groove, as well as the edge position of the longitudinal and transverse reinforcement of the base plate according to the measuring point. After the measurement and layout are completed and reviewed by the technician, the operator installs the connecting steel bars. The connecting steel bar (L-shaped Φ16 steel bar, total length 358mm, exposed end 180mm, sleeve end 150mm, threaded 28mm) is screwed into the embedded sleeve on the beam surface. The connecting steel bar is screwed into 1 / 2 of the sleeve length (28mm), the direction is perpendicular to the line, and it is tightened with an ordinary wrench and inspected with a torque wrench. The torque wrench accuracy level is required to be not less than level 10, and the tightening torque of the joint with the embedded sleeve in the beam is not less than 100N·m.

[0371] The base plate steel bars are processed in a steel bar processing plant. The processed steel bars are transported by flatbed trailers. During the hoisting process, the steel bars are placed on the hoisting platform (6m long and 60cm wide) and hoisted directly to ensure that they are not bent. After the truck crane is hoisted onto the bridge, the operators classify and stack the steel bars in the middle of the line according to specifications and models, and use the bottom pad and top cover measures.

[0372] The base plate reinforcement is divided into two layers, the upper and lower layers, and the net protective layer thickness of the reinforcement is 35mm. Place the two outermost longitudinal and transverse reinforcements according to the longitudinal and transverse reinforcement edges, and then use the positioning fixture to determine the position of the reinforcement at the end of the base plate according to the spacing of the middle longitudinal reinforcement. Then, from both ends of each base plate (3 people at each end) to the middle according to the marked position, place and tie the remaining longitudinal and transverse reinforcements. After the bottom reinforcement is tied, install C40 concrete protective layer pads under the longitudinal reinforcement of the steel mesh, 5 on each cross section (1 on the outermost side, 0.6m spacing in the middle), 0.8m longitudinal spacing, plum blossom arrangement, ensure that there are no less than 4 per square meter. At the same time, weld the top layer of steel mesh φ16 frame reinforcement. Pay attention to the protection of the supporting reinforcement after welding. Weld the longitudinal and transverse positioning reinforcements at both ends of the top layer on the frame reinforcement, and tie the remaining longitudinal and transverse reinforcements. When tying, change the direction of the wire (3 turns) point by point (8 shape), and the exposed part of the binding wire bends into the base plate structure and shall not extend into the steel protection layer. After the steel bars are tied, people are strictly prohibited from stepping on them to avoid contaminating the steel bars. When installing the formwork and pouring concrete, bamboo springboards are used to solve the problem. When the base steel bars meet the connecting steel bars, they are tied firmly with wire. The crane is supported away from the existing line and perpendicular to the line direction. When hoisting the steel bars and formwork, two traction ropes are hung below, and manual traction is performed in the direction opposite to the existing railway to prevent the swing of the steel bars and formwork from causing an intrusion accident. At the same time, the crane uses a steel wire rope to connect firmly to the ground anchor to increase the safety factor and prevent the crane from overturning to the line side. When hoisting materials and tools such as steel bars and formwork, a special person is arranged to command the crane, and a full-time protection officer and a station liaison officer are set up in the construction area. At the same time, protective equipment such as real-time walkie-talkies, signal flags, and whistles are also provided.

[0373] (3) Template installation

[0374] The template uses a 5mm thick steel template with a length of 2800mm and a height of 33cm. The curved section uses an ultra-high template. The groove template uses a 5mm thick steel plate, which is a quadrangular pyramid in height. The upper and lower dimensions are 1022mm×700mm and 1000mm×678mm respectively, and the height is 110mm. Before installing the template, it is polished and rust-removed first, and the mold release agent is applied manually. The mold release agent uses ZM-90 type building template water-soluble inorganic mold release agent. When brushing, it is applied in two layers. After the first coat is applied but before it is completely cured (there are fingerprints when pressing it with your fingers, and it is better not to stick to your hands), apply the second coat directly to make the two layers combine well.

[0375] First, support one side of the longitudinal template along the measured and set-out edge of the base plate. Every two longitudinal templates on one side must be aligned and no misalignment should occur. Then install the transverse template, install the transverse template at the designed position and reinforce it for stability. Then start installing the groove template. The groove template is installed at the bottom of the beam fixed on the top of the longitudinal template through a screw (threaded at both ends, thread length 10cm). The top elevation of the groove template is controlled by adjusting the screw. The curve section adjusts the beam bolt to control the inclination of the groove template. When the elevation and centerline position of the groove template are adjusted, tighten the bolts and nuts to ensure that the groove template does not float. The base plate template can be demolded only when the concrete strength reaches 2.5MPa or more and its surface and edges are not damaged by demolding. The demolding sequence is: remove the groove template → use a movable wrench to loosen the connecting bolts between the longitudinal and longitudinal templates, and the longitudinal and transverse templates → remove the longitudinal template and place it in the middle of the line → pull up and pull out the transverse template. The installation and removal of the template are carried out manually with the help of forklifts. Full-time protection officers and on-site liaison officers are stationed in the construction area, and protective equipment such as real-time walkie-talkies, signal flags, and whistles are also provided.

[0376] (4) Concrete pouring

[0377] The base plate of the bridge section is cast with C40 concrete. The base plate concrete is centrally mixed by a mixing station, and the concrete transport truck is used to directly arrive under the bridge, and the concrete is pumped to the casting site by a pump truck. The on-site facility worker is responsible for the construction, the guard, and the safety officer, and the on-site guard monitors on site. During the casting process, a special person is arranged to direct the pump truck to pump concrete into the funnel. The on-site operator uses a forklift to transport the funnel to the construction site for casting concrete. When adjusting the direction of the pump truck pump pipe, strictly control the steering of the pump truck to stay as far away from the existing line as possible. At the same time, during the casting process, strictly implement one machine, one person, and one protection to ensure the safety of the operating line construction.

[0378] Before pouring concrete, remove all debris within the template and use a sprayer to spray water mist on the concrete surface. The top surface elevation of the template is measured at the ends of each base plate on both sides of the straight section (4 points) and the ends and middle position of each base plate on both sides of the curved section (6 points) and compared with the design elevation. After verification, the technical instructions are issued. The concrete transport truck arrives directly at the pouring point for pouring. The concrete pouring adopts the method of pushing from one end to the other end. During pouring, the discharge port is 20cm away from the top surface of the longitudinal template, and the material can be evenly distributed within the pouring section. Inserted vibrators are used for vibration on site. There are 3 vibrators for the same pouring cross section, and the division operation is implemented. There is one person on each side of the base plate, each responsible for a 1.0m wide vibration area, and one person in the middle (a bamboo springboard is set up on the longitudinal template as an operating platform) is responsible for a 1.2m wide vibration area. The groove is vibrated by the middle vibrator, and the groove is vibrated densely around. The vibrator is inserted vertically, and inserted quickly and pulled out slowly, and it is vibrated while lifting to avoid leaving voids in the concrete. The vibrator rod shall not be placed flat in the mixture, nor shall the inserted vibrator rod be used to drive away the concrete mixture accumulated at the discharge port; the moving distance of the inserted vibrator during vibration shall not exceed 1.5 times the vibrator's action radius (40-50cm), and it shall be kept 5-10cm away from the side form. After the concrete is poured, it is vibrated immediately. The vibration time should be appropriate, generally controlled within 25-40s, so that the concrete surface no longer sinks, there are no bubbles, and the surface is slurry, to avoid missed vibration and over-vibration. During the vibration process, a special person is assigned to check the stability of the formwork support and the tightness of the joints, and any problems are dealt with in a timely manner.

[0379] After the concrete is vibrated, a 2.5m long aluminum alloy ruler is used to scrape the concrete flat. The concrete surface elevation is slightly higher than the lower edge of the double-sided adhesive strip. Then the exposed surface of the concrete is smoothed with a wooden trowel. After 1 hour, it is smoothed and compacted with a steel trowel. In order to prevent the concrete surface from losing water and producing fine cracks, the third surface is smoothed and compacted before the initial setting of the concrete (the initial setting time is determined by the laboratory according to the steel ball indentation test. A 2kg iron ball with a diameter of 75mm is gently placed on the concrete surface and left to stand for a while. Then the iron ball is picked up and the indentation on the concrete surface is measured. When the diameter is less than 30mm, it means that the concrete has initially set). It is strictly forbidden to sprinkle water to moisten the surface during the surface to avoid peeling of the concrete surface. After the third surface of the concrete is completed, it is covered with "two cloths and one film", that is, the bottom layer of geotextile, the middle layer of plastic cloth, and the outer layer of geotextile. The watering frequency should be adjusted to ensure that the geotextile on the concrete surface can remain fully moist. Place heavy objects on the plastic film at the end of the beam and the middle position of each base plate to fix it to prevent wind from blowing into the operating line. During the concrete construction of the base plate, a safety person is arranged to command the concrete truck. The construction site is commanded by the construction manager, and full-time protection personnel and safety personnel are set up. They are equipped with real-time walkie-talkies, signal flags, whistles and other protective equipment to ensure the safety of the operating line and the safety of the operation. Safety education and training are carried out for construction personnel, and construction personnel are required not to litter or smoke during the construction on the top of the beam. It is noted that various tools, materials and other objects must be collected and inspected on the bridge deck at any time. It is strictly forbidden to throw them at will, and at the same time, prevent the stacking of objects and materials from invading the railway limit. Special personnel are arranged on site to monitor and patrol. During the concrete curing period, special personnel are arranged to keep maintenance records and keep records of air temperature, curing water temperature and concrete surface temperature as required. The curing time shall not be less than 7 days. At the same time, the project department arranges special personnel to register and manage small machines on a daily basis, and the working conditions of the machines are checked before and after each shift every day, and the maintenance and repair of the machines are done well. The warehouse manager implements a daily quota system for collecting materials, and prepares corresponding materials and items according to the work tasks of the day, so as to truly complete the work and clean the materials. The entire construction process is strictly protected in accordance with the construction requirements of the operating line to ensure the safety of the operating line construction.

[0380] (5) Track slab construction

[0381] The roadbed slab in the bridge section is cast in blocks. The roadbed slab is 2.8m wide, 0.26m thick and generally 5-7m long. Each roadbed slab on the bridge is equipped with two limit blocks protruding toward the base plate. The limit blocks are in the shape of a quadrangular pyramid in the height direction, with an inclination of 1:10, and the upper and lower dimensions are 1022*700mm, 1000*678mm, and the height is 110mm. After the strength of the base plate meets the requirements, the isolation layer and elastic pad are constructed. The joints between the foam board and the bottom of the groove and the foam board and the geotextile on the top surface of the base are sealed with tape on site, and then the joints between the foam board and the elastic pad are sealed with tape. The gantry crane is used for hoisting and reverse transportation of the track slab. After the gantry crane enters the site, its relevant mechanical certificates and operator certificates are checked and verified. After the gantry crane is installed, it is reported to the special equipment inspection unit for acceptance. It can only be used after passing the acceptance. The gantry crane legs are set between the protective wall and the vertical wall B. The gantry crane is 5m high, 5.3m wide for a single line, 9.85m wide for a double line, and has 4 legs in total. Each leg is equipped with a motor and a pulley for movement. The hoist can move horizontally between the gantry crane legs. Before the gantry crane moves, operators are arranged to clean up the debris on the walking path between the protective walls and vertical walls on both sides of the bridge to ensure that the gantry crane can move normally. When the gantry crane is moving and hoisting, a dedicated person is arranged to direct and a full-time guard is set up for on-site protection.

[0382] (6) Processing and installation of steel bars at the bottom of the track slab

[0383] The surveyors used a total station to place the track centerline control point on the base plate of each beam hole, accurately positioned the steel nails, and used an ink line to pop out the track centerline. The operators used the track center control point as a reference to place the sleeper control edge line and the position of each longitudinal and transverse steel bar on the bottom layer of the trackbed, and popped it out with an ink line.

[0384] The ballast plate adopts double-layer steel bars, which are processed in a centralized steel bar yard and transported to the construction site by flatbed trucks. During transportation, the steel bars must be kept straight and twisting or bending is not allowed. After the isolation layer is laid and passed the quality inspection and acceptance, the edge line of the bottom steel mesh of the ballast plate and the control points of the steel bar position are drawn on the geotextile according to the ballast plate steel bar layout diagram. First, install the groove steel bars and tie them up. Place 35mm thick C40 concrete protective layer pads on the bottom surface of the groove steel bars, one at each of the four corners and the middle of the groove. Then tie the bottom steel bars of the ballast plate according to the edge line of the steel mesh and the control points. The ballast plate steel bars are tied in blocks.

[0385] (7) Track positioning and rough adjustment

[0386] The sleepers are centrally prefabricated in the prefabrication yard, transported to the construction site by flatbed trucks, and hoisted to the beam surface by cranes for centralized stacking. The sleepers to be used are hoisted on the rail assembly platform by a gantry crane and a special hoist for sleepers. The hoisting needs to be carried out at a low speed and run. At the same time, the sleepers are manually leveled according to the positioning line of the sleeper blocks on the assembly platform, and the sleeper spacing error is controlled within 5mm, and the sleeper surface is cleaned. The technician checks and adjusts the position of the sleeper blocks, and draws lines to arrange the bolt holes on one side into a line with a deviation of less than 1mm. Then the track rack is hoisted. First, the position of the sleeper bolt holes is marked on the rack with white chalk, and then the gantry crane is manually coordinated to align the position of the bolt holes of the rail rack fasteners with the position of the bolt holes on the sleepers, and the rack is placed on the sleepers steadily and slowly. The sleeper position is reviewed and the fasteners are tightened, and the installation quality of the rail bolts and the sleeper spacing are checked. After passing the inspection, the gantry crane lifts the assembled rail to the predetermined location for positioning and laying. The track assembly and laying are carried out using a gantry crane, and the gantry crane slides on the track between the protective wall and vertical wall B on both sides.

[0387] After the track is assembled, it is laid. The laying gantry crane lifts the track from the sleeper assembly platform and transports it to the laying site. It is positioned according to the centerline and elevation, and the error is controlled within -10 to 0 mm in elevation and ±10 mm in the centerline. Adjacent track panels are connected with plywood, and 4 sets of bolts are installed at each joint. They are initially tightened, and the track gap is left with 6 to 10 mm. Install the track locker. On the side of the bridge section close to the protective wall, one end of the track locker is supported on the top of the protective wall, and the other end is supported on the leg of the track support beam; on the side close to the centerline of the line: drill a hole (φ20, hole depth 5 cm, hole spacing corresponding to the position of the track support beam leg) 80 cm away from the outside of the track support beam leg to embed a 20 cm long φ20 round steel as a support for the track locker.

[0388] The surveying personnel use the total station to locate and adjust the center line of the track. Measure the center datum on the track frame drag beam, and arrange 4 people on each side of the track to adjust the rail lock. Make sure that the center datum is adjusted in place, and the center line deviation shall not exceed ±5mm. The surveying personnel use a precision electronic level to measure the elevation of the rail at the drag beam corresponding to each track, and calculate the elevation difference by comparing it with the designed track surface elevation. When the measured track surface elevation is lower than the designed track surface elevation, use an open-end wrench to rotate the vertical screw clockwise to raise the track to the designed track surface elevation; when the measured track surface elevation is higher than the designed track surface elevation, use an open-end wrench to rotate the vertical screw counterclockwise to lower the track to the designed track surface elevation. The vertical screw will rise or fall 1mm for every 120° rotation. When adjusting the track elevation, adjust point by point. The track elevation error after coarse adjustment is controlled within the elevation of -5 to -2mm;

[0389] After the rough adjustment is completed, the adjacent rows of frames are connected with plywood. A dedicated person is assigned to direct the operation of the gantry crane. At the same time, the construction manager, protection officer and safety officer are set up on site, and equipped with real-time walkie-talkies, signal flags, whistles and other protective equipment. Calls are made every 3-5 minutes to ensure uninterrupted communication, while also ensuring the safety of the operating line and operation.

[0390] (8) Top steel bar installation and grounding welding

[0391] According to the designed longitudinal reinforcement spacing, the longitudinal reinforcement position is marked on the sleeper reinforcement truss with a stone pencil and the longitudinal reinforcement is placed. The insulation card is installed at the intersection of the longitudinal reinforcement and the sleeper truss reinforcement, and the plastic insulation buckle is used to tie it diagonally. After the longitudinal reinforcement is placed, the position of the transverse reinforcement is marked on the two outermost reinforcements of the ballast plate according to the designed transverse reinforcement spacing. Three people are arranged to install the transverse reinforcement one by one from one end of the ballast plate to the other end, and the insulation card is installed at the intersection of the longitudinal and transverse reinforcements. After the installation of the transverse reinforcement, the intersection of the longitudinal and transverse reinforcements is tied with a plastic insulation buckle according to the installation sequence and method. The rail head clamp is installed at the adjacent rail row and the sleeper spacing is checked. The longitudinal and transverse grounding reinforcements are welded on one side with a 2mm long φ16 "L" steel. The grounding terminal is fixed to the grounding reinforcement on both sides of the ballast by welding; the welding between the grounding terminal and the grounding reinforcement: the weld length is not less than 100mm, and the weld thickness is not less than 4mm. The welding of the grounding terminal is carried out after the track is fine-tuned. A protective film is added to the surface of the terminal to ensure that it is closely attached to the template during welding.

[0392] After the steel bars are tied, the insulation resistance test is carried out. First, visually check whether the insulation card is installed well and whether there is any falling off; then use a megohmmeter to further measure the insulation data between the steel bars. All checks must be made that the resistance between any two non-grounded steel bars must reach more than 2MΩ. Safety education and training are carried out for the operators, requiring the construction personnel to not litter or smoke during the construction on the top of the beam, and to pay attention to the various tools, materials and other objects that must be collected and picked up on the bridge deck at any time. It is strictly forbidden to throw them away casually, and at the same time prevent the stacking of objects and materials from invading the railway limit. Special personnel are arranged on site to monitor and patrol to ensure the safety of the operating line construction.

[0393] (9) Template installation

[0394] Before installing the template, it should be polished and rust-free, and the mold release agent should be applied manually. The track plate template adopts a standard steel template. The height of the horizontal template is 33cm, and the lower end is inserted into the base plate seam by 7cm. The top of the template is connected by a positioning steel plate, and the bottom is supported by 8cm×8cm×21cm wooden blocks at both ends. The template is gently lifted twice within 2 hours before and after the initial setting of the concrete to smoothly remove the horizontal template. The longitudinal template adopts a combined standard steel template and is installed manually. The longitudinal template consists of 2 unit blocks, and the adjacent blocks are bolted. The template is supported by the edge of the track plate so that the template is close to the side of the base plate and the lower end is covered with 7cm of base plate concrete. Both sides are supported at 0.5m from the edge, and the bottom surface is implanted on the steel bar. The horizontal position of the template is positioned and adjusted by the lateral screw adjuster. The template installation height is adjusted by the vertical screw adjuster. The template installation is installed manually with a forklift. The construction site is commanded by the construction manager, and full-time protection personnel and safety personnel are set up. Construction work is carried out strictly in accordance with the safety requirements of adjacent operating lines to ensure the safety of construction on the operating lines.

[0395] (10) Track fine-tuning

[0396] After the template is installed, the track fine-tuning will begin. Other construction near the fine-tuning operation surface must be suspended, and vehicles are prohibited from passing. Construction can only be resumed after the fine-tuning operation is completed.

[0397] Before fine-tuning begins, clean the rails and the wheels of the fine-tuning trolley to ensure that they are clean. After cleaning, no one is allowed to step on them.

[0398] Before fine-tuning, the sleepers are first numbered, and the numbers are sprayed with red paint on the top end of the sleepers on the line side. Use Leica total station to observe 4 pairs of continuous CPⅢ points, automatically adjust and calculate to determine the station location. If the deviation is greater than 0.7mm, delete one pair of CPⅢ points with the lowest accuracy and re-set the station. After changing the station location, at least 6 control points used in the rear must be cross-observed, and at least one set of track rows that have been fine-tuned must be re-measured. The track state measuring instrument is placed on the track and the prism is installed. Use the total station to measure the track state measuring instrument prism. The trolley automatically measures the gauge, superelevation, and horizontal position, receives the observation data, and calculates the track plane position, level, superelevation, gauge and other data through the supporting software, and quickly feeds back the error value to the computer display screen of the track state measuring instrument to guide the track adjustment.

[0399] (11) Track slab concrete pouring

[0400] Before pouring, clean up the debris on the pouring surface. There should be no water accumulation on the base after sprinkling water before pouring. To ensure that the sleepers are well combined with the newly poured concrete, the sleepers need to be sprayed once before pouring. Cover the sleepers and fasteners with protective covers before pouring, and cover the rails and racks with plastic film. Check whether the adjustment screws on the rails are suspended. Check whether the grounding terminal is in close contact with the template. The top surface elevation of the template is measured at the end positions on both sides of each ballast plate (4 points) corresponding to the straight section, and the end positions and middle positions on both sides of each ballast plate (6 points) corresponding to the curved section. Compare with the design elevation (considering the drainage slope), the technician calculates the position of the concrete pouring surface, and the double-sided tape is used to mark it after the technical supervisor reviews it. The quality inspector uses a steel tape measure to check whether the position of the double-sided tape is correct according to the difference between the measured template top surface elevation and the design elevation. The lower edge line of the double-sided tape is the top surface control line of the concrete pouring surface. At the same time, the track geometry parameters of the track arrangement are checked and confirmed.

[0401] The concrete of the roadbed slab is centrally mixed by a mixing station, and is poured by direct unloading from a concrete transport truck during construction. After the concrete is transported to the construction site by a concrete transport truck, the slump, air content and temperature indicators of each truck of concrete are tested, and the concrete can be unloaded only after they meet the standards. When pouring with a bucket, the concrete is lifted to the top of the rail to be poured with a bucket (the discharge port is about 30 cm from the top of the rail), and the valve is opened to discharge the concrete. When pumping is used, the rubber pump nozzle is above the rail and the discharge direction is basically perpendicular to the rail. The concrete is evenly distributed along the longitudinal direction of the line from the downhill end to the uphill section, and the sleepers are pushed forward in parallel one by one. The concrete is symmetrically distributed on the double sleepers horizontally. When the concrete flows automatically from under the sleeper to the next sleeper, it can be moved forward to the next sleeper to continue pouring. To ensure that the pouring of concrete ballast slabs does not produce excessive temperature cracks, the ambient temperature and track temperature must be monitored throughout the day during the pouring of concrete, and a temperature curve must be drawn so that the pouring of concrete can be carried out in a time period with a smaller temperature variation range, and the temperature of the concrete entering the mold is controlled between 5℃ and 30℃.

[0402] The vibrating rods should be of two types: ZD50 and ZD30. During the vibration process, the concrete around the bottom of the sleeper should be vibrated to ensure that the concrete is dense. In order to reduce the cracks at the splayed corners and the gaps around the sleeper blocks, a secondary vibration process is used. The first vibration radius (50-type vibrating rod) is controlled at about 30cm, and there are 8 transverse vibration points on the roadbed. The vibration is carried out until there are no obvious bubbles overflowing from the concrete surface and the surface is flat and slurry is overflowed. Then the next point is vibrated. After 15-20 minutes after the first vibration, the second vibration is carried out using a 30-type vibrating rod. Supplementary vibration is carried out around the sleeper. There are 7 vibration points for each sleeper. Then the oblique insertion method is used to prevent the sleeper from falling out.

[0403] Fig.52 This is the layout diagram of the vibration points of the track slab.

[0404] After the surface concrete is vibrated, the elevation of the ballast plate is controlled according to the design requirements. The elevation of the track top surface on the inner rail side to the top surface of the ballast plate is 260mm, and the elevation of the track top surface on the outer rail side to the top surface of the ballast plate is 240mm. The concrete slope gauge is used for control during on-site construction. After the concrete is put into the mold, the slope gauge and wooden trowel are used to complete the rough leveling according to the designed drainage slope of 0.7%. The slope gauge is used between the two lines of sleepers, and the wooden trowel is used under the rails, between the longitudinal sleepers and the outer part of the rails. After 1 hour, it is smoothed and compacted with a steel trowel. In order to prevent the concrete surface from losing water and causing fine cracks, the third plastering is carried out before the initial setting of the concrete (determined by the steel ball indentation test). It is strictly forbidden to sprinkle water to moisten the surface during plastering, and excessive operation is prevented from affecting the quality of the surface concrete. During the plastering process, attention should be paid to strengthening the construction of the parts below the track and around the sleepers. Strengthen the control of the surface drainage slope to ensure that the slope meets the design requirements, the surface drainage is smooth, and no water accumulation is allowed. After the surface is finished, use a brush and a wet rag to promptly clean the mortar on the rails, sleepers and fasteners to prevent contamination. After the initial setting of the concrete, loosen the support bolts by 1 / 4 to 1 / 2 turn, and at the same time loosen the fasteners and fishplate bolts to prevent the expansion and contraction of the rails from damaging the concrete when the temperature changes. After the initial setting of the concrete, cover it with geotextile plastic film for curing. During the concrete pouring process, a safety person is arranged to command the machinery, and one person, one machine and one protection are implemented. The construction site is commanded by the construction person in charge, and a full-time protection officer is set up, equipped with real-time walkie-talkies, signal flags, whistles and other protective equipment to ensure the safety of the operating line and operation.

[0405] When the concrete of the roadbed slab reaches 5MPa, first, the stud legs are screwed up 1 to 2mm in sequence; then the track fasteners are loosened, the racks are removed in the order of removal, and the formwork is removed. Finally, after the technicians confirm that all the fasteners are loosened, the gantry crane lifts the racks and transports them to the track assembly area for cleaning and standby, and then enters the next cycle of construction. Arrange a special person to be responsible for cleaning the dismantled formwork, racks and accessories with a brush, and the accessories are stored in the container basket for next use. The lifting operation is commanded by a special person, and one person, one machine and one protection are implemented, and the operation is carried out in strict accordance with the safety requirements of the operating line construction. During the construction process, the operators all wear protective clothing, safety helmets, safety belts, safety ropes and other safety protection equipment. Set up a construction manager, a full-time protection officer and a safety officer on site, equip various protective equipment according to the safety protection requirements of the operating line, and do a good job of on-site protection.

[0406] (12) Track laying

[0407] Manually spread the rails. After the rails are in place, use a crowbar to straighten them, use a track gauge to check the track gauge, align the rail heads, align the rail faces, and tighten the fasteners.

[0408] S70: Construction risk control measures.

[0409] S71: Treatment of rail beam joints.

[0410] In order to prevent the upper slide (with a PTFE plate at the bottom of the slide) from shearing at the joint of the traverse track during the traverse process, a 3mm stainless steel plate is bent at the joint, such as Fig.53 As shown, there are gaps above and below the joints to facilitate adjustment of the relative height of the track beams to ensure the smoothness of the two ears of the sliding track.

[0411] S72: Lateral movement with protection.

[0412] In order to prevent the box girder from falling due to accidental oil leakage from the jacking cylinder during the lateral movement, a 190mm high accompanying protective pier is set on the inner side of the jacking cylinder. When the height of the box girder changes, a certain safety space can be reserved at the bottom by adding or removing 2mm to 10mm steel plates above the accompanying protective pier to prevent it from falling accidentally.

[0413] S73: Measures to solve the problem of lateral cylinder jam.

[0414] In order to prevent the cylinder from getting stuck and affecting the transverse movement of the box girder during the transverse movement, it is planned to purchase a spare jack, that is, to purchase an additional transverse jack when configuring the transverse movement equipment, and to purchase 2 sets of hydraulic seals for emergency repair and replacement on site.

[0415] S74: Track deformation control measures.

[0416] Pier 456# is a newly built pier body. The distance between the new cushion stone and the existing cushion stone is 2.9m. In order to reduce track deformation, steel bars are reserved during the construction of the new pier cap of Pier 456#. A 2m*1.5m*1.5m concrete foundation is used to connect it to the existing pier cap. Two Φ610×10mm steel pipe columns are erected, and a double-piece I45a total beam is set on the upper part. I32a I-beams are laid with a spacing of 30cm on the top to support the sliding track.

[0417] S75: Three-dimensional beam drop device pier top anchoring.

[0418] Φ20mm bolts are implanted around the sliding platform of the three-dimensional beam-dropping device on the top of the pier, with a depth of 20cm and an exposed length of 5cm. The exposed part of the Φ20mm bolts is fixed with a 10cm*5cm*1cm pressure plate to the sliding platform of the three-dimensional beam-dropping device to ensure that the three-dimensional beam-dropping device will not slide.

[0419] S76: Synchronous lifting control.

[0420] (1) Lifting height control

[0421] 1) The control principle of the lifting height of the horizontally moved bridge in this project is to meet the construction requirements.

[0422] 2) For this PLC synchronous lifting control system lifting technology, the height difference of each lifting point should be controlled within ±2mm.

[0423] (2) Beam drop control

[0424] In order to ensure the quality of beam leveling, the beam dropping is carried out in two stages.

[0425] 1) In the first stage, the beam is lowered to the predetermined elevation. This elevation (H I ) is the elevation of the beam bottom before lifting (H O ) plus the compression of the new support (△h), that is, H I =H O +△h.

[0426] 2) The second stage of beam dropping is carried out after the leveling material at the bottom of the beam has solidified, and the beam is dropped to the original elevation.

[0427] (3) Monitoring system settings

[0428] Appropriate displacement observation devices should be set up during the lifting and translation of the bridge in order to control the entire motion trajectory, overall posture, etc. during the lifting and translation of the bridge to ensure the safe and smooth lifting and translation of the bridge.

[0429] Displacement observation: Observation points are set on both sides of the same section of the beam, and displacement observation scales are set on the observation points. A high-precision total station is used to observe the readings of each scale during lifting and translation in real time to verify whether the overall posture of the beam is balanced during lifting and translation, and whether the lifting and translation displacements are synchronous and provide data in a timely manner.

[0430] Secondly, the temporary concrete foundation settlement observation, expansion joint gap, and hydraulic jack stroke observation should be carried out. The temporary concrete foundation in the jacking and translation system is a reinforced concrete structure cast on both sides of the original cap. During the jacking and translation process, the bearing condition of the temporary foundation and the safety of the jacking and translation system are reflected through the settlement observation data of the temporary foundation. Observe the changes in the gap between the plate and the beam, and observe once in each jacking and translation stage. Especially when the jacking and translation to a certain height may collide, observe frequently and adjust the jacking and translation sequence in time to avoid longitudinal displacement caused by the collision of the box beams at both ends; the numerical error of the jacking stroke of the jack directly reflects whether all the jacks are synchronized, so as to adjust the oil supply through the manual valve to make the jacks jack and translate synchronously. Each time the jack is lifted, the jack is adjusted to synchronization, and then the oil supply time is increased.

[0431] (4) Synchronous lifting and translation monitoring

[0432] In order to ensure the safety of the bridge structure and support system, construction monitoring is carried out during the construction process. Guiding the construction through construction monitoring and coordinating the solution of key technical problems in the construction quality control process is an indispensable part of the quality assurance system. It provides relevant technical service consultation during the construction process and timely warnings when the structure is in an unfavorable state.

[0433] During the lifting and translation construction process, the displacement of the beam rest and pier column control section and concrete cracks are monitored, and the construction process and process are monitored at the same time. The construction monitoring is mainly displacement monitoring. The monitoring methods are:

[0434] 1) Lifting and lowering travel control

[0435] The operator shall use the double control of elevation and oil pressure to lift the beam synchronously according to the unified command, and stop when the beam just leaves the support. Observe whether there is any sign of local compression and damage on the contact surface concrete of the jack. If there is no abnormality after standing for a few minutes, continue to lift for a stroke and stop, observe whether the load holding of the jack is stable, and whether the lifting height of each part of the beam is consistent. If everything is normal, repeat the above operation until the beam is synchronously dropped to the support. If any problem is found during the lifting or dropping of the beam, solve it and try again until everything is normal.

[0436] 2) Observation and control of cracks

[0437] When lifting the beam, observe the changes in the cracks. If there are abnormal conditions such as cracks, stop lifting and find the cause. Only after taking measures and finding the cause can the lifting continue. Carefully observe the support conditions of each support point. If there is looseness or displacement, stop immediately. If there are abnormal conditions such as sudden changes in the strain control of the monitoring system, stop lifting immediately, and find out and solve the problem before lifting again.

[0438] 3) Safety requirements

[0439] ① During jacking, coordination and command personnel shall be deployed. The jack operators must be skilled workers. There is a technician at each jacking point to strictly control the beam height and beam body changes.

[0440] ② The lifting control system and jack must have sufficient reliability.

[0441] ③Handheld intercoms should be used as information transmission tools for jacking. Before jacking, channels that are not prohibited in the construction area should be unified as information transmission channels. Check the effective communication and clarity of each intercom, and the key language such as prohibited words, emergency words, and urgent orders of the channel should be clearly defined.

[0442] ④ Before jacking, it should be ensured that on-site safety education is given to each person participating in the jacking, emphasizing the necessity, strictness and responsibility of safety.

[0443] ⑤ Before jacking, the anti-lateral movement device and limit device should be carefully checked to ensure that they have sufficient strength, rigidity and stability.

[0444] S77: Deformation monitoring.

[0445] During the construction of the beam shifting project of the super-large bridge on the up and down connecting lines of Shaoxing North Station, deformation monitoring facilities need to be installed on the existing Hangzhou-Ningbo Passenger Dedicated Line bridges and piers, and one horizontal displacement and settlement monitoring point is set for each beam in the existing Shaoxing North Station building, and the third party Shanghai Railway Beidou Measurement Engineering Technology Co., Ltd. is responsible for real-time and all-weather monitoring. During the beam shifting process, the process monitoring of the support system and existing bridge piers should be strengthened. In case of emergency, the sliding should be stopped in time, and the beam shifting operation can only be continued after the hidden dangers are eliminated.

[0446] The control measures for safety and quality are as follows:

[0447] 1. Before construction, the monitoring data of the operating lines must be collected, and the operating lines must be monitored during the construction process to ensure that the impact of the construction on the operating line equipment is within the allowable range.

[0448] 2. Before lifting the beam, a trial lift should be conducted. If there are no problems, the formal lifting can be started. Load according to the preset loading speed, control the beam lifting speed ≤2mm / min, synchronize the jacks according to the design requirements, and the synchronous displacement difference of each jack is ≤±1mm; during the lifting process, a dedicated person should monitor the horizontal and longitudinal displacement and stress changes of the beam body and keep records. Once the limit value is exceeded, the lifting should be stopped immediately, and the lifting can be continued only after the problem is solved.

[0449] 3. When moving beams, set up observation points in the middle and on both sides of the top surface of the beams. Monitor the shape of the beams in real time during the moving process, that is, the plane position and elevation. If any problems are found, stop moving the beams in time and continue construction only after the problems are solved.

[0450] 4. In order to avoid the failure of the thin top of the top beam during the lateral movement, steel piers are used as the supporting structure, and the lifting cylinder is accompanied by protection to ensure that a certain safety space is reserved at the bottom to prevent it from falling accidentally.

[0451] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to the above embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for beam shifting construction for reconstruction of a high-speed railway viaduct station, characterized in that: The following steps are involved: S10: Preparation work, measuring the dimensions of each part of the box girder within the range of the pier displacement beam, and setting displacement and settlement observation points on the top of the existing pier; S20: Determine the relative position relationship between the beam shifting operation and the operating line; S30: Beam moving equipment tooling, lifting tooling, translation tooling and translation tooling; When the translation tooling is set in step S30, the transverse movement of the beam is realized by the transverse movement system, which includes a transverse movement beam section, a slide plate, a jack, a transverse movement cylinder with a displacement sensor, a polytetraethylene plate and a stainless steel sliding surface; When setting the horizontal rotating tooling in step S30, it includes a set of fixed fulcrum three-dimensional beam dropping devices, three sets of floating fulcrum three-dimensional beam dropping devices and a three-dimensional beam dropping device transverse hydraulic system; The three-dimensional beam-dropping device includes a set of three-dimensional beam-dropping devices with fixed fulcrum points and three sets of three-dimensional beam-dropping devices with floating fulcrum points. The three-dimensional beam-dropping device with fixed fulcrum points is fixed by longitudinal and transverse jacks in the longitudinal and transverse directions. In the whole system, the three-dimensional beam-dropping device is used as the rotation center of the other three points when turning, so as to realize the function of the concrete beam turning angle. The longitudinal and transverse jacks and the slide plate of the three-dimensional beam-dropping device with floating fulcrum points are pushed forward in a floating manner. When turning, the slide plate of the three-dimensional beam-dropping device with floating fulcrum points adapts to the position requirements of the slide plate of the three-dimensional beam-dropping device with fixed fulcrum points. S40: Construction of existing beam shifting; S41: Preparation before beam shifting, including setting up the construction platform, beam lifting and stone padding; S42: beam shifting construction, after determining the beam shifting parameters, the beam shifting construction is carried out, wherein the beam shifting construction includes installing beam shifting equipment, horizontal shifting of the beam body, horizontal rotation of the existing beam body, longitudinal shifting of the existing beam body, and installation of the beam drop and support; S50: Construction of new beams and beam shifting; S51: Beam body pouring construction, including support construction, formwork engineering, support pre-stressing, steel bar construction, installation and threading of corrugated pipes, embedding of embedded parts, beam body concrete pouring, beam body concrete curing and prestressing construction; S52: Construction of transverse shifting of new beams, including installation of beam shifting equipment, transverse shifting of beams, and installation of beam drops and supports.

2. A high-speed railway elevated station reconstruction beam shifting construction method according to claim 1, characterized in that: In step S10, the positions of the box girder supports and the anti-falling beam blocks are measured, and the coordinates of the box girder ends, the centerline coordinates and the width of the beam joints are measured with a total station to check the neatness of the construction of the beam ends and the uniformity of the upper and lower beam joints.

3. A high-speed railway elevated station reconstruction beam shifting construction method according to claim 2, characterized in that: When setting the jacking tooling in step S30, two independent fulcrums are set on each pier top as a supporting structure, one independent fulcrum on the top of one pier is used as a balancing fulcrum, and the other three are movable fulcrums, forming a four-point support and three-point balance support method.

4. A high-speed railway elevated station reconstruction beam shifting construction method according to claim 3, characterized in that: The beam jacking operation in step S41 includes jack arrangement, trial jacking, formal jacking and installation of temporary supports.

5. A beam shifting construction method for reconstruction of a high-speed railway viaduct station according to claim 4, characterized in that: In step S42, the transverse movement of the beam is driven by a transverse cylinder so that the transverse beam section slides on the slide plate; when the beam rotates horizontally, a three-dimensional beam-dropping device is used to lift the box beam away from the transverse track beam, and the beam is fixed with the balance fulcrum as the rotation axis, and one of the moving fulcrums is moved to drive the beam to rotate horizontally; when the beam is dropped and the support is installed, a lifting jack is used to drop the beam at the designed position, and a three-dimensional beam-dropping device is installed at the bottom of the beam. The parameters of the beam-dropping jack are the same as those of the jack during lifting.

6. A beam shifting construction method for reconstruction of a high-speed railway viaduct station according to claim 5, characterized in that: If any deviation occurs during the beam dropping process, the three-dimensional beam dropping device is used to correct it, install the supports, and drop the beam into place.

7. The method for beam shifting for reconstruction of a high-speed railway viaduct station according to claim 1, characterized in that: The process also includes step S60: bridge deck system and ballastless track construction, including installation of shields and sidewalk slabs, installation of protective walls and construction of ballastless track.

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