An installation method for the closure segment of a three-main-truss steel truss girder with precise control

Abstract

The invention discloses a method for installing the closure segment of a three-main-truss steel truss girder with precise control, belonging to the technical field of girder closure. Through optimizing the structure of the closure segment, the double-crane lifting technology without a spreader, the longitudinal displacement control method of the steel girder under limited release conditions, optimizing and adjusting the docking process technology of the closure gap, and the prediction analysis and control method of the closure gap based on the control requirements of the ballastless track. By the above means, the technical solution optimizes the structure of the closure segment to avoid the interference problem of the diagonal web members during the hoisting and alignment process, adopts the double-crane lifting method and control method without a spreader to reduce the relative error of the deflection and rotation angle of the two sides of the closure gap; longitudinally displaces the integral of one side of the cantilever steel girder to expand the closure gap, reduces the alignment difficulty of the closure segment, and uses the low-temperature method to improve the vertical adjustment measures; solves the problem of high requirements for the installation accuracy of the closure segment due to the high linearity requirements of the ballastless track and the characteristics that the steel strand stay cables can only be tensioned and not released. The technical solution is feasible and saves construction costs.

Description

Technical Field

[0001] The present invention relates to the technical field of the closure of truss girders, and particularly relates to an installation method for the closure section of a three-main-truss steel truss girder with precise control. Background Art

[0002] The closure of the mid-span of a steel truss girder is a key technical link in the construction of large bridges. Due to the large stiffness of the steel truss girder, complex closure environments, multiple closure points, and high precision requirements for closure, the installation of the closure section and precise closure have always been the core technical problems in the transformation of large-span bridge systems. This is mainly reflected in the need to avoid the problem of member collision during the hoisting process of the closure section, and the need to strictly control various parameters and their variation laws during the closure process, such as the width, length, angle, and their spatial and temporal variation conditions at the interfaces of each member at the closure gap, and taking targeted deviation correction and adjustment measures to achieve high-precision connection of the truss girder structure.

[0003] For the mid-span closure installation and docking of a cable-stayed steel truss girder, the currently mainly adopted schemes are as follows: The first one is to design the structure of the closure section with the characteristics of "small on the top and large on the bottom", and use a single-side girder hoisting crane to hoist the closure section. First, dock one side according to the cantilever idea, and then close it with the other side. The closure mainly uses measures such as the longitudinal movement method of the steel girder, the cable force adjustment method of the stay cable, the temperature control method, and the single-side adapter plate method to assist the closure. The second scheme does not change the main structural form of the closure section, but only optimizes and adjusts the diagonal web members to be installed as patch segments later. It still uses a single-side girder hoisting crane to hoist the closure section. First, dock one side according to the cantilever idea, and then close it with the other side. The main adjustment measures at the closure gap are the same as those in the first scheme.

[0004] For the first technical scheme, the structure of the closure section is designed with the characteristics of "small on the top and large on the bottom", and a single-side girder hoisting crane is used to hoist the closure section, and a cable-stayed cable-assisted closure adjustment scheme is adopted. This method is simple and convenient for on-site construction, and is more suitable for the parallel wire cable-stayed structure. However, it requires design adjustment and optimization, with a large adjustment amount, and needs to increase the types of cut-to-length steel plates. The processing and manufacturing and precision control of the closure section and adjacent steel girders become more difficult. The adjustment method by means of adjusting the cable is no longer applicable in the closure of large segments of the steel strand cable-stayed cable in one piece, and it is not suitable for the beam feeding construction under the condition of limited longitudinal movement of the steel girder. At the same time, in order to meet the hoisting of the closure section, special lifting tools are required, increasing the cost.

[0005] For the second technical scheme, without changing the main structural form of the closure section, only the diagonal web members are optimized and adjusted to be installed as patch segments later, and the closure process is the same as that of the first scheme; this method is simple and convenient for on-site construction, with less design adjustment work, and is more suitable for the parallel wire cable-stayed structure. However, its disadvantages are the same as those of the first scheme.

[0006] When controlling the hoisting and docking closure of large segments of the three-main-truss steel strand cable-stayed cable in one piece in the mid-span, the new technical problems faced are:

[0007] 1) There is a large equipment load in the mid-span, and the design requirements for the difference in the unbalanced cable forces between the side and middle spans of the main tower are relatively high. As a result, there is a problem that 1-2 pairs of stay cables near the mid-span closure cannot release the over-tensioning to meet the closure requirement, which is likely to cause the risk of insufficient crack resistance bearing capacity of the tower wall, and then cannot meet the requirements of reasonable bridge alignment control and structural safety of the ballastless track.

[0008] 2) How to solve the technical problems of synchronous control under the condition of double-crane lifting in two structural systems, and how to solve the problem of sling interference during lifting;

[0009] 3) It is necessary to solve the control range of the longitudinal movement of the steel girder, and clarify the longitudinal movement direction and magnitude of feeding the girder and adjusting the steel girder during closure.

[0010] 4) It is necessary to solve the prediction analysis and control method of the closure gap based on the control requirements of the ballastless track.

[0011] Based on this, the present invention designs an installation method for the closure section of a three-main-truss steel truss girder with precise control to solve the above problems. Summary of the Invention

[0012] In view of the above-mentioned disadvantages of the prior art, the present invention provides an installation method for the closure section of a three-main-truss steel truss girder with precise control.

[0013] To achieve the above object, the present invention is realized through the following technical solutions:

[0014] An installation method for the closure section of a three-main-truss steel truss girder with precise control, comprising the following steps:

[0015] Step 1: Compare the total horizontal unbalanced cable forces of the middle-span stay cables and the side-span stay cables on both sides of the main tower with the resultant force of the bearing frictions and manipulate the longitudinal movement device to drive the longitudinally moved cantilever beam segment on one side to longitudinally move, so that the longitudinal movement amount of the longitudinally moved cantilever beam segment on one side towards the side span

[0016] meets the closure requirement;

[0017] Step 2: Use the double-crane lifting technology without slings to lift the closure section;

[0018] Step 3: Dock the docking interface of the closure section with the cantilever beam segment on the side without longitudinal movement, perform bolt welding on the docking interface of the closure section and the cantilever beam segment on the side without longitudinal movement, and after completion, both side girder lifting cranes are unhooked and separated from the closure section;

[0019] Step 4: Analyze and obtain the relatively stable deformation time period of the closure gap between the closure section and the longitudinally moved cantilever beam segment on one side, and adopt the low-temperature method to determine the closure construction time period;

[0020] Step 6: Install the diagonal web member patch section, and then perform the reset of the splicing plate and the tightening of high-strength bolts in sequence, and simultaneously weld the butt weld of the bridge deck, weld the U-ribs, and weld the plate rib patch section.

[0021] Furthermore, compare the total horizontal unbalanced cable forces of the middle-span cables and the side-span cables on both sides of the main tower with the resultant force of the bearing frictions in magnitude. If , after releasing the constraint of the cantilever beam segment on the side that has been longitudinally displaced, operate the longitudinal displacement device to drive the cantilever beam segment on the side that has been longitudinally displaced to longitudinally displace, so that the longitudinal displacement of the cantilever beam segment on the side that has been longitudinally displaced towards the side span meets the closure requirements; if , the cantilever beam segment on the side that has been longitudinally displaced will not have an active displacement.

[0022] Furthermore, the calculation formula for the total horizontal unbalanced cable forces of the middle-span cables and the side-span cables on both sides of the main tower and the resultant force of the bearing frictions is as follows:

[0023] ;

[0024] ;

[0025] wherein, ——The total horizontal unbalanced cable force of the middle-span cables and the side-span cables on both sides of the main tower;

[0026] ——The cable force of the three-truss stay cables on the middle-span side, where is the cable number from 1 to 11 pairs, is the stay cables from the upper truss, middle truss and lower truss positions from 1 to 3;

[0027] ——The included angle between the cable force of the three-truss stay cables on the middle-span side and the horizontal direction;

[0028] ——The cable force of the three-truss stay cables on the side-span side, where is the cable number from 1 to 11 pairs, is the stay cables from the upper truss, middle truss and lower truss positions from 1 to 3;

[0029] ——The included angle between the cable force of the three-truss stay cables on the side-span side and the horizontal direction;

[0030] ——The frictional force of the single-sided steel girder;

[0031] 、 、 、 、 、 —— The reaction forces of the three trusses at Pier No. 1, Pier No. 2 and Pier No. 3 respectively;

[0032] —— The friction coefficient between the steel girder and the bearing.

[0033] Furthermore, the longitudinal movement system consists of jacks, a control pump station, a longitudinal movement device and shimming steel plates. The jacks are placed inside the longitudinal movement device. After removing the shimming on one side, the longitudinal displacement is achieved by jacking up with the jacks; the synchronicity of the longitudinal movement of the three trusses is controlled by using shimming steel plates of the same specification to ensure that the transverse limit between the tower and the girder remains locked during the longitudinal movement.

[0034] Furthermore, according to the method for installing the closure segment of the three-main-truss steel truss girder with precise control described in claim 1, it is characterized in that: the longitudinal movement amount of the steel girder towards the side span before hoisting the closure segment meets the following conditions:

[0035] ;

[0036] ;

[0037] wherein, — The minimum value of the longitudinal spacing of each chord rod opening of the two cantilever beam segments measured continuously for 48 hours on both sides;

[0038] — The minimum value of the longitudinal spacing of each chord rod opening on both sides of the closure gap measured continuously for 48 hours;

[0039] — The length of the closure segment beam;

[0040] — The distance between the longitudinal limit block and the outer wall of the main tower cushion stone;

[0041] — The minimum working height of the jack;

[0042] — The thickness of the shimming steel plate for distributing the jacking force of the jack.

[0043] Furthermore, the operation method of the double-crane lifting technology without a lifting tool is as follows: The movable pulley blocks of the two girder erection cranes are directly connected to the lifting lugs on both sides of the closure segment. The double-crane lifting speed is uniformly 0.6 m / min for synchronous and uniform hoisting of the closure segment; Two inclinometers are placed at the center of the highway bridge deck of the steel girder. According to the monitoring system of the girder erection crane, the balance states in the X and Y directions during the hoisting process of the closure segment are monitored in real time, and the maximum inclination angle is controlled not to exceed 0.5°. When the inclination angle approaches 0.5°, the hoisting is paused, and the levelness of the steel girder is adjusted by single-point or two-point lifting on one side. Hoisting can continue only when the requirements are met, and the synchronicity check and adjustment are carried out every 5 m of lifting.

[0044] Furthermore, to analyze and obtain the relatively stable deformation period of the closure gap, a prediction analysis and control method for the closure gap based on the requirements of ballastless track control is adopted. The specific implementation method is as follows: Select a time when the weather is clear and the temperature difference between day and night is large, and continuously measure the linear data of the closure gaps on both sides of the cantilever beam segment on one side that has been longitudinally moved for no less than 48 hours. Draw the deflection-temperature-time graph and the centerline offset-temperature-time graph based on the measurement data; and analyze and obtain the relatively stable deformation period of the closure gap according to the mileage-temperature-time graph of six nodes of the adjacent chord members of the closure gap, and determine the closure time by the low-temperature method.

[0045] Furthermore, the method for determining the priority order of the closure members is as follows: Among the docking interfaces at the lower chord 3 where the closure is prioritized, by calculating the minimum distance Δmin = min{Δupstream side truss, Δmiddle truss, Δdownstream side truss} of the lower chord bay, where Δupstream side truss is the distance between the front-row bolt holes of the upstream side truss; Δmiddle truss is the distance between the front-row bolt holes of the middle truss; Δdownstream side truss is the distance between the front-row bolt holes of the downstream side truss, and prioritize the closure of the closure point with a smaller closure gap by longitudinal movement.

[0046] Furthermore, by making the diameter D of the process drift pin satisfy 31.5mm ≤ D ≤ 32.8mm, the adjustment range of the closure tolerance of the remaining two closure gaps of the lower chord is increased. Use the longitudinal movement device at the main tower, the process drift pin measure, and the lifting of the hoisting points of the girder erection crane, the closure pin, and the tensioning traction device to achieve the closure of the other two docking interfaces of the lower chord; quickly insert no less than 15% of the drift pins to meet the force requirements of the steel beam after temperature rise, where the drift pins are evenly arranged, and half of them are arranged in the area close to the top and bottom of the web; then carry out subsequent construction and complete the insertion of 50% of the drift pins during the closure period.

[0047] Furthermore, the installation method of the inclined web member of the closure segment steel beam is in the form of post-installation on-site for the filling segment.

[0048] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. Through the optimization of the closure segment structure, the double-crane lifting technology without lifting tools, the steel beam longitudinal movement control method under limited release conditions, the optimization and adjustment of the closure gap docking process technology, and the prediction analysis and control method for the closure gap based on the requirements of ballastless track control, the present application technology solves the problem of high requirements for the installation accuracy of the closure segment due to the high requirements of the ballastless track line shape and the characteristics that the steel strand stay cables can only be tensioned and not released. This technical solution is feasible, the construction is simple, the construction risk is reduced, and the construction cost is greatly saved.

[0049] 2. Compared with the previous closure schemes, the present technical solution optimizes the closure segment structure to avoid the interference problem of the inclined web members during the hoisting and alignment process. The double-crane lifting method without lifting tools and the control method reduce the relative errors of the downward deflection and rotation angle of the two sides of the closure gap, improving the synchronous control; longitudinally moving the whole of one side of the cantilever steel beam to expand the closure gap and reducing the alignment difficulty of the closure segment.

[0050] 3. A temporary locking structure of the closure hinge is set at the closure point, realizing the rapid connection of the chord members of the steel truss girder at multiple points. The operation is simple and fast. At the same time, the hinged method allows for fine adjustment of the closure gap. Combining multiple adjustment measures such as longitudinal, vertical, and lateral directions can accurately control the three-dimensional spatial coordinate position of the closure gap and the rotation angle of the closure gap, ensuring the installation accuracy of the closure members, and the relevant adjustment devices are simple and convenient to manufacture.

[0051] 4. Through the numerical simulation technology in the cantilever stage and the iterative method of matching high-precision measurement data, the optimal state of the closure gap is accurately predicted, and the cable force value of the optimal stay cables in the closure state without the need to adjust the cable force is determined. Utilizing the deformation difference characteristics of the beam and the cable under temperature changes, the technical problem of the cable force that cannot be over-tensioned is solved by the low-temperature method; effectively solving the technical problems of prediction analysis and control of the closure gap under the control requirements of the ballastless track, and the requirements can be met using the on-site conditions, which is practical and economical. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0053] Figure 1 It is a schematic diagram of the closure of the steel truss girder;

[0054] Figure 2 It is a schematic diagram of the structure of the longitudinal movement system in Step 1;

[0055] Figure 3 It is a schematic diagram of the double-crane lifting of the closure section in Step 2;

[0056] Figure 4 It is a schematic diagram of the hook release of the crane for the closure section in Step 3;

[0057] Figure 5 It is a schematic diagram of the closure of the lower chord docking opening in Step 5;

[0058] Figure 6 It is a schematic diagram of the closure of the upper chord docking opening in Step 6;

[0059] Figure 7 It is a schematic diagram of the closure of the middle diagonal member docking;

[0060] Figure 8 It is a front view schematic diagram and a side view schematic diagram of the closure.

[0061] The reference numerals in the drawings respectively represent:

[0062] 1. Closure segment; 2. Longitudinal movement system; 2-1. Jack; 2-2. Longitudinal movement device; 2-3. Shimming steel plate; 3. Girder erection crane; 4. Side truss lifting lug; 5. Cantilever beam segment on the non-longitudinally moved side; 6. Cantilever beam segment on the longitudinally moved side; 7. Process punching nail measure; 8. Hoisting of the lifting point of the girder erection crane; 9. Closure pin shaft; 10. Opposite tension tractor; 11. Moving load; 12. Inclined rod filling segment; 13. Movable pulley block; 14. Chain block; 15. Longitudinal opposite tension measure; 16. Longitudinal opposite jacking measure; 17. Vertical deviation correction measure. Detailed implementation manners

[0063] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0064] The "left", "right", "front", "rear", "upper" and "lower" mentioned in the following description are oriented in the perspective direction of the front view.

[0065] Embodiment: Please refer to Figures 1-8 in the accompanying drawings of the specification, and an installation method for the closure segment of a three-main-truss steel truss girder with precise control includes the following steps:

[0066] Step 1: As shown in Figure 2 , judge the longitudinal movement trend of the steel girder by comparing the sum of the horizontal unbalanced cable forces of the middle-span cables and the side-span cables on both sides of the main tower with the resultant force of the bearing frictions; compare the sum of the horizontal unbalanced cable forces of the middle-span cables and the side-span cables on both sides of the main tower with the resultant force of the bearing frictions . If , after the steel girder releases the constraint, execute Step 2; if , the steel girder does not undergo active displacement.

[0067] The feature of judging the longitudinal movement trend of the steel girder by comparing the sum of the horizontal unbalanced cable forces of the middle-span cables and the side-span cables on both sides of the main tower with the resultant force of the bearing frictions is:

[0068] ;

[0069] ;

[0070] Among them, ——The total horizontal unbalanced cable force of the middle-span cables and the side-span cables on both sides of the main tower;

[0071] —— The cable forces of the three-truss stay cables on the mid-span side, where are the cable numbers from 1 to 11 pairs, are the stay cables from the upper truss, middle truss and lower truss positions from 1 to 3;

[0072] —— The horizontal included angle between the cable forces of the three-truss stay cables on the mid-span side;

[0073] —— The cable forces of the three-truss stay cables on the side-span side, where are the cable numbers from 1 to 11 pairs, are the stay cables from the upper truss, middle truss and lower truss positions from 1 to 3;

[0074] —— The horizontal included angle between the cable forces of the three-truss stay cables on the side-span side;

[0075] —— The frictional force of the single-sided steel beam;

[0076] 、 、 、 、 、 —— Respectively, the three-truss reaction forces at Pier No. 1, Pier No. 2 and Pier No. 3;

[0077] —— The friction coefficient between the steel beam and the bearing.

[0078] If , after the steel beam releases the constraint, perform Step 2, and the steel beam overcomes the frictional force and displaces towards the side span; if , after the steel beam releases the constraint, the steel beam does not have an active displacement.

[0079] The installation method of the diagonal web members of the closure segment steel beam is the form of field post-installation of the splicing section, that is, the end of the diagonal web member of the closure segment steel beam is designed with a splicing section. After the closure is completed, the splicing section is installed on the diagonal web member to complete the closure of the diagonal web member; thus solving the interference problem between the diagonal web member and the closure opening.

[0080] Before comparing the total horizontal unbalanced cable forces of the mid-span cables and the side-span cables on both sides of the main tower with the resultant frictional force of the bearings in Step 1, the cantilever beam segment 6 on one side that has been longitudinally displaced and the cantilever beam segment 5 on the other side that has not been longitudinally displaced are both in a constrained state, and the splicing plates at the ends of the cantilever beam segment 6 on one side that has been longitudinally displaced and the cantilever beam segment 5 on the other side that has not been longitudinally displaced that are close to each other are in a contracted state.

[0081] Step 2: Place the longitudinal shift device 2-2 between the main tower pad and the longitudinal limit stopper of the lower chord of the steel beam. Operate the longitudinal shift device 2-2 multiple times to complete the longitudinal shift of the joint section 1. According to the measurement data of the joint mouth, the unbalanced cable force between the side span and the middle span, and the friction force of the support, calculate and determine the longitudinal shift amount of the steel beam to meet the feeding beam requirement, so that the longitudinal shift amount of the steel beam to the side span before the joint section is hoisted is Meet the joint requirements; then constrain the steel beam again.

[0082] The longitudinal movement system 2 consists of a jack 2-1, a control pump station, a longitudinal movement device 2-2 and a pad steel plate 2-3. A jack 2-1 is placed inside the longitudinal movement device 2-2 to release the pad on one side and achieve longitudinal displacement by lifting the top with the jack 2-1. The longitudinal movement is completed in multiple times, and the same specification pad steel plates 2-3 are used to control the synchronization of the longitudinal movement of the three girders to ensure that the transverse limit of the tower beam remains locked during the longitudinal movement.

[0083] Longitudinal displacement of the steel beam to the side span before the closure section is hoisted The following conditions should be met:

[0084] ;

[0085] ;

[0086] The longitudinal displacement of the steel beam to the middle span after the joint section is completed The following conditions should be met:

[0087] ;

[0088] ;

[0089] In the above formula:

[0090] - Continuously measure the minimum longitudinal spacing between the chord openings of the cantilever beam sections on both sides for 48 hours;

[0091] —48 hours of continuous measurement of the minimum longitudinal spacing between the chord openings on both sides of the closure;

[0092] — Length of the joint section beam;

[0093] —The distance between the longitudinal limit stopper and the outer wall of the main tower pad stone;

[0094] — Minimum working height of the jack;

[0095] —The thickness of the steel plate used to distribute the lifting force of the jack.

[0096] Step 3: If Figure 3As shown in the figure, the double-crane lifting technology without sling is adopted to hoist the steel beam of the closure segment 1.

[0097] The characteristics of the double-crane lifting technology without sling are as follows: the moving pulley blocks 13 of the two girder erection cranes 3 are directly connected to the lifting lugs 4 on both sides of the closure segment. When using the double-crane lifting method, the lifting speed of both cranes 3 is uniformly set at the lowest speed of 0.6 m / min for synchronous and uniform hoisting of the closure segment 1. Two inclinometers are placed at the center position of the highway bridge deck of the steel beam. According to the monitoring system of the girder erection crane, the balance states in the X and Y directions during the hoisting process of the closure segment are monitored in real time, and the maximum inclination angle is controlled not to exceed 0.5°. When the inclination angle approaches 0.5°, the hoisting is suspended, and the levelness of the steel beam is adjusted by single-point or two-point lifting on one side. Hoisting can continue only when the requirements are met, and synchronization verification and adjustment are carried out every 5 m of lifting, which improves the safety and synchronization of the double-crane lifting and ensures that the attitude of the closure segment is vertical and the alignment is smooth.

[0098] Step Four: As Figure 4 shown in the figure, after the closure segment 1 is hoisted and aligned, first connect the docking interfaces of the cantilever beam segments 5 on the non-longitudinally displaced side. After all the bolt welding is completed, both girder erection cranes 3 release the hooks.

[0099] Step Five: Adopt the prediction analysis and control method for the closure gap under the requirements of ballastless track control to analyze and obtain the relatively stable time period of the deformation of the closure gap; utilize the deformation difference characteristics of the beam and the cable under the temperature change, and adopt the low-temperature method to determine the closure time.

[0100] The principle of the low-temperature method is as follows: at low temperature, the length of the stay cable of the cable-stayed bridge shortens, which plays a vertical adjustment function for the steel beam and makes up for the vertical deformation requirement by directly adjusting the cable force; the low-temperature method mainly utilizes the deformation difference between the steel beam and the stay cable under the same temperature drop. At low temperature, the length of the stay cable shortens, which plays a vertical adjustment function for the steel beam and makes up for the vertical deformation requirement by directly adjusting the cable force.

[0101] The prediction analysis and control method for the closure gap under the requirements of ballastless track control is as follows:

[0102] When the large segment in the middle of the stay cable of the steel strand is butt-joined and closed, due to the large equipment load in the middle span and the high design requirements for the difference in the unbalanced cable forces between the main tower side and the middle span, there is a problem that 1-2 pairs of stay cables near the middle-span closure cannot be released due to over-tensioning to meet the closure requirement, and thus it cannot meet the control requirements for the reasonable bridge alignment of the ballastless track.

[0103] Based on this, through the numerical simulation technology of the cantilever stage and the iterative method of matching high-precision measurement data, the optimal state of the closure gap is accurately predicted, and the cable force value of the stay cables in the optimal closure state without the need to adjust the cable force during closure is determined; by using the 48-hour continuous measurement data of the X, Y, and Z displacements of the closure gap to draw the deformation-temperature-time curves in each direction, the relatively stable deformation period of the closure gap is analyzed and obtained, and the technical problem that the cable force cannot be over-tensioned is compensated by the low-temperature method by using the deformation difference characteristics under the temperature changes of the beam and the cables; the prediction analysis and control technical problems of the closure gap under the requirements of ballastless track control are effectively solved;

[0104] Continuously observe the alignment data of the closure gaps on both sides of the cantilever beam segment 6 on the longitudinally moved side. Select the time when the day-night temperature difference is large and it is sunny, and conduct continuous measurement for no less than 48 hours to draw the deflection-temperature-time graph, the centerline offset-temperature-time graph; the mileage-temperature-time graph of six nodes of the adjacent chord members of the closure gap, analyze and obtain the relatively stable deformation period of the closure gap, and use the deformation difference characteristics under the temperature changes of the beam and the cables to compensate the technical problem that the cable force cannot be over-tensioned by the low-temperature method.

[0105] Step Six: As Figure 5 shown, according to the spatial attitude at the closure, analyze that the opening shape of the upper and lower chords presents a "V" shape. Using the relatively stable state of the continuous measurement data, clarify the closure sequence according to the lower chord, upper chord, and diagonal web members; according to the minimum spacing of each member, judge the priority closure member sequence, and then through the docking process of the interface, temporarily lock the three lower chord docking interfaces of the three main trusses in turn;

[0106] The method for judging the priority closure member sequence is: among the three lower chord docking interfaces for priority closure, by calculating the minimum spacing of the lower chord bay Δmin = min{Δupstream side truss, Δmiddle truss, Δdownstream side truss}, where Δupstream side truss is the spacing of the front row of bolt holes of the upstream side truss; Δmiddle truss is the spacing of the front row of bolt holes of the middle truss; Δdownstream side truss is the spacing of the front row of bolt holes of the downstream side truss. Prioritize the closure of the closure point with a smaller closure gap by longitudinal movement to stop the longitudinal movement of the steel beam;

[0107] The specific operation of temporary locking is: by ensuring that the diameter D of the process drift pin satisfies 31.5mm ≤ D ≤ 32.8mm, improve the adjustment range of the closure tolerance of the remaining two closure gaps of the lower chord. Use the longitudinal movement device 2-2 at the main tower, the process drift pin measure 7, the lifting point 8 of the girder erection crane, the closure pin 9, and the tensioning traction device 10 to achieve the closure of the other two docking interfaces of the lower chord. Quickly insert no less than 15% of the drift pins to meet the force requirements of the steel beam after temperature rise. The drift pins are evenly arranged, and half of them are arranged in the area close to the top and bottom of the web, and then subsequent construction is carried out, and 50% of the drift pins are inserted during the closure period.

[0108] Step Seven: As Figure 6As shown in the figure, analyze the characteristics presented in the horizontal direction according to the situation of the upper chord three-truss opening, determine the priority order of the closure members, adopt the upper chord closure adjustment measures, determine the sequence of the priority adjustment measures, and complete the closure docking.

[0109] The specific implementation method of the upper chord closure adjustment measures is as follows: In the upper chord closure adjustment measures, a moving load 11 is added to the railway bridge deck and shows an asymmetric distribution according to the change of the closure opening. The longitudinal tension 15 and longitudinal jacking 16 measures are adopted to solve the problem of great control difficulty in the mileage adjustment of the upper chord three-truss. In addition, the vertical deviation correction measure 17 is used to adjust the elevation deviation; the sensitive factor analysis method of the closure opening is adopted to determine the sequence of the priority adjustment measures.

[0110] The specific implementation method of the sensitive factor analysis method of the closure opening is as follows: The numerical analysis technology is used to analyze the factors of the closure opening under different directions such as transverse, vertical, and longitudinal adjustment measures. The main analysis factors include the longitudinal movement of the steel beam, the tension and jacking of the closure opening, the change of the stay cable, the change of temperature, the vertical jacking, the weight pressing, and the transverse tension and other measures.

[0111] Step eight: As Figure 7 shown in the figure, install the diagonal member patch segment 12; then quickly reset the splicing plates reserved in the interface area, complete the bolt connection matching between the main truss members at the two interfaces of the closure section by using positioning drift pins, and use high-strength bolts for connection; after the two ends of the closure section are bolted, use code plates to code and fix the railway and highway interfaces to improve the overall rigidity of the structure; after the high-strength bolts are tightened, synchronously weld the butt welds of the bridge deck; follow the principle of symmetric welding to weld the top plate and bottom plate of the interface; after the main welds of the interface are welded, weld the U-ribs and the plate rib patch segments to complete the closure of the main span.

[0112] The installation method of the diagonal member patch segment 12 is as follows: It is completed on the railway bridge deck by using a 25t truck crane. After the lower chord and upper chord of the steel beam are butt-jointed, install the closure opening web member patch segment. Use a chain block 13 between the diagonal member and the vertical member, adjust the axis slope of the diagonal member and then butt-joint the diagonal web member, and use drift pins to temporarily position the upper and lower interfaces of the patch segment, and use high-strength bolts for connection.

[0113] The closure of each docking interface of the three main trusses is carried out in the order of the middle truss lower chord → side truss lower chord → side truss upper chord → middle truss upper chord → diagonal member patch segment 12 → railway bridge deck → highway bridge deck.

[0114] Aiming at the problem of great technical difficulty in rapid and accurate docking of a total of 9 docking interfaces of the three main trusses,

[0115] 1) First, analyze the "V"-shaped characteristics of the upper and lower chord openings according to the spatial attitude at the closure, and use the relatively stable state of the continuous measurement data to clarify the overall order of closing the lower chord first and then the upper chord in the diagonal web member.

[0116] At the docking interface of the lower chord 3 for priority closure, by calculating the minimum distance Δmin = min{Δupstream side truss, Δmiddle truss, Δdownstream side truss} of the lower chord bay for closure (Δupstream side truss is the distance between the front row of bolt holes of the upstream side truss; Δmiddle truss is the distance between the front row of bolt holes of the middle truss; Δdownstream side truss is the distance between the front row of bolt holes of the downstream side truss), first satisfy the closure of the closure point with a smaller closure mouth spacing through longitudinal movement, stop the longitudinal movement of the steel girder, and make the diameter D of the process drift satisfy 31.5 mm ≤ D ≤ 32.8 mm to increase the adjustment range of the closure tolerance of the remaining two closure mouths of the lower chord. Use the longitudinal movement device at the main tower, the process drift measure, the lifting of the lifting points of the girder erection crane, and the closure pin to achieve the closure of the other two docking interfaces of the lower chord. Quickly drive no less than 15% of the drift to meet the force requirements of the steel girder after temperature rise (the drift is evenly arranged, and half of them are arranged in the area close to the top and bottom of the web), and then carry out subsequent construction, and complete the driving of 50% of the drift during the closure period.

[0117] 2) Secondly, after the closure and locking of the 3 closure points of the lower chord rod, analyze the characteristics presented in the horizontal direction according to the opening conditions of the three trusses of the upper chord. Using the same idea as the upper chord, determine the order of the priority closure members; in addition to adopting the lower chord closure measures, in the upper chord closure adjustment measures, mobile loads are added on the railway bridge deck and are asymmetrically distributed according to the changes in the closure mouth to solve the problem of large control difficulty in the mileage adjustment of the three trusses of the upper chord. In addition, for the elevation deviation, vertical deviation correction measures are added; use the sensitive factor analysis method of the closure mouth to determine the order of the priority adjustment measures. After the closure docking, quickly drive no less than 5% of the drift to meet the force requirements of the steel girder after temperature rise (the drift is evenly arranged, and half of them are arranged in the area close to the top and bottom of the web).

[0118] 3) Thirdly, install the inclined rod patch section, which is completed on the railway bridge deck by a 25t truck crane. After the docking of the lower chord and upper chord of the steel girder is completed, install the closure mouth web member patch section. Install a chain hoist between the inclined rod and the vertical rod, adjust the axis slope of the inclined rod and then dock the inclined web member, and use the drift to temporarily position the upper and lower interfaces of the patch section, and connect them with high-strength bolts.

[0119] 4) Finally, after all the closure points are locked, quickly reset the splicing plates reserved in the interface area, use the positioning drift to complete the bolt connection matching between the main truss members at the two interfaces of the closure section, and connect them with high-strength bolts. After the two ends of the closure section are bolted, use the code plates to code and fix the railway and highway interfaces to improve the overall rigidity of the structure. After the high-strength bolts are tightened, synchronously weld the butt welds of the bridge deck, and weld the top and bottom plates of the interface following the principle of symmetric welding. After the main welds of the interface are welded, weld the U-ribs and the patch sections of the plate ribs to complete the closure of the main span.

[0120] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements will not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for installing the closure segment of a three-main-truss steel truss girder with precise control, characterized in that: It includes the following steps: Step 1: Compare the sum of the horizontal unbalanced cable forces of the middle-span cables and the side-span cables on both sides of the main tower with the resultant force of the bearing frictions . If , after releasing the constraint of the cantilever beam segment (6) on one side that has been longitudinally displaced, operate the longitudinal displacement device (2-2) to drive the cantilever beam segment (6) on the side that has been longitudinally displaced to longitudinally displace, so that the longitudinal displacement of the cantilever beam segment (6) on the side that has been longitudinally displaced towards the side span meets the closure requirements; if , the cantilever beam segment (6) on the side that has been longitudinally displaced does not undergo active displacement. Step 2: Hoist the closure segment (1) using the double-crane lifting technology without a spreader. Step 3: Dock the docking interface between the closure segment (1) and the cantilever beam segment (5) on the non-longitudinally moved side, perform bolt welding at the docking interface between the closure segment (1) and the cantilever beam segment (5) on the non-longitudinally moved side. After completion, both gantry cranes (3) on both sides are unhooked and separated from the closure segment (1). Step 4: Analyze and obtain the relatively stable time period of the deformation of the closure gap between the closure segment (1) and the cantilever beam segment (6) on the longitudinally moved side, and determine the closure construction time period using the low-temperature method. Step 5: Determine the priority order of the closure members for the upper chord and the lower chord, and then temporarily lock the docking interfaces in sequence. Step 6: Install the diagonal web member patch segment, and sequentially perform the reset of the splicing plate, high-strength bolt tightening, synchronously weld the butt weld of the bridge deck, weld the U-ribs, and the plate rib patch segment.

2. The method for installing the closure segment of the precisely controlled three-main-truss steel truss girder according to claim 1, characterized in that: The total horizontal unbalanced cable forces of the middle-span cables and the side-span cables on both sides of the main tower and the resultant force of the friction forces at the bearings are calculated as follows: ； ； Among them, —— The total unbalanced cable force in the horizontal direction of the middle-span cables and the side-span cables on both sides of the main tower; —— Cable forces of the three truss stay cables on the mid-span side, where are cable numbers from 1 to 11, are the stay cables obliquely pulled from the upper truss, middle truss, and lower truss positions from top to bottom 1 to 3; —— Cable force and horizontal included angle of the three-truss stay cables on the mid-span side; —— Cable forces of the three girders' stay cables on the side span, where are cable numbers from 1 to 11, are the stay cables from the upper girder, middle girder, and lower girder positions from top to bottom 1 to 3; —— Cable force and horizontal included angle of three truss stay cables on side span —— Frictional force of single-sided steel beam; , , , , , —— the three-truss reaction forces at Pier No. 1, Pier No. 2 and Pier No. 3 respectively; ——Coefficient of friction between steel beam and support.

3. The method for installing the closure segment of the precisely controlled three-main-truss steel truss girder according to claim 1, characterized in that: The longitudinal movement system (2) consists of a jack (2-1), a control pump station, a longitudinal movement device (2-2), and shimming steel plates (2-3). The jack (2-1) is placed inside the longitudinal movement device (2-2). After removing the shimming on one side, the longitudinal displacement is achieved by jacking up with the jack (2-1). Shimming steel plates (2-3) of the same specification are used to control the synchronism of the three-truss longitudinal movement, and ensure that the transverse limit between the tower and the beam remains locked during the longitudinal movement process.

4. The installation method of the closure segment of the precisely controlled three-main-truss steel truss girder according to claim 1, characterized in that: Longitudinal displacement of steel girder towards side span before hoisting of closure segment Meet the following conditions: ； ； Among them, — The minimum value of the longitudinal spacing of each chord at both cantilever beam segments measured continuously for 48 hours — The minimum value of the longitudinal spacing of each chord rod opening on both sides of the closure gap measured continuously for 48 hours; — The length of the closure segment beam; — The distance between the longitudinal limit block and the outer wall of the main tower cushion stone; — The minimum working height of the jack; — Thickness of the shim steel plate for distributing the jacking force of the jack.

5. The installation method of the closure segment of the precisely controlled three-main-truss steel truss girder according to claim 1, characterized in that: The operation method of the double-crane lifting technology without a spreader is as follows: The moving pulley blocks (13) of the two gantry cranes (3) are directly connected to the lifting lugs (4) on both sides of the closure segment. The lifting speed of the double-crane lifting (3) is uniformly 0.6 m / min for synchronously and evenly hoisting the closure segment (1). Place two inclinometers at the center position of the steel beam highway bridge deck. According to the gantry crane monitoring system, the balance state of the closure segment during the hoisting process in the X and Y directions is monitored in real time, and the maximum inclination angle is controlled not to exceed 0.5°. When the inclination angle approaches 0.5°, the hoisting is paused, and the horizontal degree of the steel beam is adjusted by single-point or two-point lifting on one side. Hoisting can continue only when the requirements are met, and the synchronism is checked and adjusted every 5 m of lifting.

6. The installation method of the closure segment of the precisely controlled three-main-truss steel truss girder according to claim 1, characterized in that: The method for analyzing and obtaining the relatively stable time period of the closure gap deformation adopts the prediction analysis and control method of the closure gap based on the ballastless track control requirements. The specific implementation method is as follows: Select a time with clear weather and a large temperature difference between day and night, continuously measure the linear data of the closure gaps on both sides of the cantilever beam segment (6) on the longitudinally moved side for no less than 48 hours, and draw the deflection-temperature-time diagram and the centerline offset-temperature-time diagram according to the measurement data; and according to the mileage-temperature-time diagram of six nodes of the adjacent chord members of the closure gap, analyze and obtain the relatively stable time period of the closure gap deformation, and determine the closure time using the low-temperature method.

7. The method for installing the closure segment of the precisely controlled three-main-truss steel truss girder according to claim 1, characterized in that: The method for determining the priority order of the closure members is as follows: Among the three docking interfaces for preferentially closing the lower chord, by calculating the minimum distance Δmin = min{Δupstream side truss, Δmiddle truss, Δdownstream side truss} of the lower chord bay during closure, where Δupstream side truss is the distance between the front row of bolt holes on the upstream side truss; Δmiddle truss is the distance between the front row of bolt holes on the middle truss; Δdownstream side truss is the distance between the front row of bolt holes on the downstream side truss, preferentially close the closure point with a smaller closure gap between the closure members by longitudinal movement.

8. The method for installing the closure segment of the precisely controlled three-main-truss steel truss girder according to claim 1, characterized in that: By ensuring that the diameter D of the process pins is 31.5 mm ≤ D ≤ 32.8 mm, the tolerance adjustment range of the remaining two joints of the lower chord is increased, and the longitudinal movement device (2-2) at the main tower, the process pinning measures (7), the beam erection crane lifting point (8), the joint pin shaft (9), and the tensioning traction device (10) are used to achieve the joint of the other two joints of the lower chord; no less than 15% of the pins are quickly inserted to meet the stress requirements of the steel beam after temperature rise, and the pins are evenly arranged on the web plate, and half of them are arranged near the top and bottom areas; then subsequent construction is carried out to complete 50% of the pin insertion within the joint period.

9. The method for installing the closure segment of the precisely controlled three-main-truss steel truss girder according to claim 1, characterized in that: The installation method of the diagonal web members of the steel beams in the joint section is post-installation on site in the patching section.

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