Accurately-controlled three-main-truss steel truss girder closure section installation method

Abstract

The invention discloses a precise-control three-main-truss steel truss girder closure section mounting method, belongs to the technical field of truss girder closure, and aims to realize precise control of a three-main-truss steel truss girder closure section through optimization of a closure section structure, a sling-free double-machine lifting technology, a steel girder longitudinal movement control method under limited release conditions and optimization and adjustment of a closure gap butt joint process. The invention discloses a method for predicting, analyzing and controlling a closure gap based on ballastless track control requirements. By means of the mode, according to the technical scheme, the closure section structure is optimized, the problem of diagonal web member interference in the hoisting alignment process is avoided, and the relative error of downwarping and rotating angles of closure openings on the two sides is reduced by adopting a sling-free double-machine hoisting mode and a control method; a cantilever steel beam on one side is integrally and limitedly moved longitudinally, a closure gap is expanded, the alignment difficulty of a closure section is reduced, and a vertical adjustment measure is improved by utilizing a low-temperature method; the problems that the linear requirement of a ballastless track is high, and the requirement for the installation precision of a closure section is high due to the fact that a steel strand stay cable can only be tensioned and cannot be released are solved, the technical scheme is feasible, and the construction cost is saved.

Description

Technical Field

[0001] The invention relates to the technical field of truss closure, and in particular to a method for accurately controlling the installation of closure sections of three-main-truss steel trusses. Background Art

[0002] The mid-span closure of steel trusses is a key technical link in the construction of large bridges. Due to the high stiffness of steel trusses, the complex closure environment, the large number of closure points and the high requirements for closure accuracy, the installation of closure sections and precise closure have always been the core technical difficulties in the transformation of large-span bridge systems. This is mainly reflected in the need to avoid the collision of rods during the hoisting process of the closure section. During the closure process, it is necessary to strictly control various parameters and their changing laws, such as the width, length, angle and spatial and temporal changes of the interfaces of each rod at the closure mouth, and take targeted correction and adjustment measures to achieve high-precision connection of the truss structure.

[0003] The main schemes currently used for the installation and docking of the mid-span joint of the cable-stayed steel truss are as follows: The first is to design the joint section structure as a "small on top and large on the bottom" structure, and use a single-sided beam crane to hoist the joint section, first dock one side according to the cantilever idea, and then joint with the other side. The joint is mainly assisted by the longitudinal movement of the steel beam, the adjustment of the cable force of the cable, the temperature control method, and the single-sided adapter plate method. The second scheme does not change the main structural form of the joint section, but only optimizes and adjusts the diagonal web to be installed as an embedded section, and still uses a single-sided beam crane to hoist the joint section, first dock one side according to the cantilever idea, and then joint with the other side. The main adjustment measures for the joint mouth are the same as those in Scheme 1.

[0004] The first technical solution is to design the joint section structure as "small on top and large on bottom", use a single-side beam crane to hoist the joint section, and use a cable-assisted joint adjustment solution. This method is simple to construct on site and easy to operate. It is more suitable for parallel steel wire cable-stayed structures, but it requires design adjustment and optimization, with a large adjustment amount, and requires an increase in the types of steel plate cut lengths. The difficulty of processing, manufacturing and precision control of the joint section and adjacent steel beams is increased. It is no longer applicable to the adjustment of the cable method in the whole stage of the joint of the large segment of the steel strand cable, and it is not suitable for feeding beams under conditions where the longitudinal displacement of the steel beam is limited. At the same time, in order to meet the requirements of the joint section hoisting, special hoists are required, which increases the cost.

[0005] The second technical solution does not change the main structural form of the joint section, but only optimizes and adjusts the diagonal web to be installed after the patching section, and the jointing process is the same as that of solution one; this method is simple to construct on site, easy to operate, and has a small workload for design adjustment, and is more suitable for parallel steel wire cable-stayed structures. However, the disadvantages are the same as those of solution one.

[0006] When hoisting and connecting the entire section of the three main truss steel strand cable in the middle of the span and controlling the joint connection, new technical problems are faced: 1) There is a large equipment load in the mid-span, and the design requirements for the difference in unbalanced cable forces between the main tower side and the middle span are relatively high, resulting in the problem that 1~2 pairs of inclined cables near the mid-span closure are over-tensioned and cannot be released to meet the closure requirements, which easily leads to the risk of insufficient anti-cracking bearing capacity of the tower wall, and thus fails to meet the requirements for reasonable bridge alignment control and structural safety of ballastless track.

[0007] 2) How to solve the technical problem of synchronization control under the condition of dual lifting machines in two structural systems, and how to solve the problem of lifting equipment interference; 3) It is necessary to solve the control range of the longitudinal displacement of the steel beam and clarify the direction and size of the longitudinal displacement of the steel beam during feeding and jointing.

[0008] 4) It is necessary to solve the problem of how to predict, analyze and control the closure based on the ballastless track control requirements.

[0009] Based on this, the present invention designs a precisely controlled installation method for the joint section of three main truss steel trusses to solve the above problems. Summary of the invention

[0010] In view of the above-mentioned shortcomings of the prior art, the present invention provides a method for accurately controlling the installation of a joint section of three main truss steel trusses.

[0011] To achieve the above objectives, the present invention is implemented through the following technical solutions: A method for accurately controlling the installation of a three-main-truss steel truss joint section comprises the following steps: Step 1: Compare the total horizontal unbalanced cable forces of the mid-span cables and side-span cables on both sides of the main tower The friction force of the support The size of the longitudinal shift device is operated to drive the cantilever beam section on the longitudinally shifted side to move longitudinally, so that the cantilever beam section on the longitudinally shifted side moves longitudinally to the side span. Meet the requirements for closure; Step 2: Use the double-machine lifting technology without lifting equipment to lift the joint section; Step 3: Butt the joint section with the cantilever beam section on the side that has not been longitudinally moved, and perform bolt welding on the joint section and the cantilever beam section on the side that has not been longitudinally moved. After completion, the beam erection cranes on both sides are unhooked and separated from the joint section; Step 4: Analyze and obtain the relatively stable time period of the joint mouth deformation of the joint section and the cantilever beam section on the longitudinally displaced side, and use the low temperature method to determine the joint construction time period; Step 5: Determine the priority closure sequence of the upper and lower chords, and then temporarily lock the interfaces in sequence; Step six: Install the diagonal web filler section, and reset the spliced ​​plate, tighten the high bolts in sequence, and simultaneously weld the bridge deck butt welds, U-ribs, and plate-rib filler sections.

[0012] Furthermore, the sum of the horizontal unbalanced cable forces of the mid-span cables and the side-span cables on both sides of the main tower is compared. The friction force of the support The size, if After the cantilever beam section on the longitudinally moved side releases its constraint, the longitudinal moving device is operated to drive the cantilever beam section on the longitudinally moved side to move longitudinally, so that the longitudinal movement amount of the cantilever beam section on the longitudinally moved side toward the side span is Meet the requirements for closure; if , the cantilever beam section on the longitudinally displaced side does not undergo active displacement.

[0013] Furthermore, the sum of the horizontal unbalanced cable forces of the middle span cables and side span cables on both sides of the main tower is The friction force of the support The calculation formula is as follows: ; ; in, ——Total unbalanced cable force in horizontal direction of the middle span cables and side span cables on both sides of the main tower; ——Tension of the three-truss cable-stayed cable on the middle span side, where For 1 to 11 pairs of call numbers, 1 to 3 are inclined cables from the upper side beam, middle beam and lower side beam; ——The angle between the cable force of the three-beam diagonal cable on the middle span side and the horizontal; ——Cable force of three-beam cable on the side span, where For 1 to 11 pairs of call numbers, 1 to 3 are inclined cables from the upper side beam, middle beam and lower side beam; ——The angle between the cable force of the three-beam inclined cable on the side span and the horizontal; ——Single-side steel beam friction; , , , , , ——respectively the three-beam support reactions at piers 1, 2 and 3; ——Friction coefficient between steel beam and support.

[0014] Furthermore, the longitudinal movement system consists of a jack, a control pump station, a longitudinal movement device and a pad steel plate. A jack is placed inside the longitudinal movement device. After releasing the pad on one side, the longitudinal displacement is achieved by lifting the top with the jack. The same specification pad steel plates are used to control the synchronization of the longitudinal movement of the three girders to ensure that the lateral limit of the tower beam remains locked during the longitudinal movement.

[0015] Furthermore, according to the method for installing the three-main-truss steel truss closure section with precise control according to claim 1, it is characterized in that: the longitudinal displacement of the steel beam to the side span before the closure section is hoisted is The following conditions must be met: ; ; in, - Continuously measure the minimum longitudinal spacing between the chord openings of the cantilever beam sections on both sides for 48 hours; —48 hours of continuous measurement of the minimum longitudinal spacing between the chord openings on both sides of the closure; — Length of the joint section beam; —The distance between the longitudinal limit stopper and the outer wall of the main tower pad stone; — Minimum working height of the jack; —The thickness of the steel plate used to distribute the lifting force of the jack.

[0016] Furthermore, the operation method of the double-machine lifting technology without hoisting gear is as follows: the movable pulley groups of the two beam-erecting cranes are directly connected to the lifting ears of the trusses on both sides of the joint section, and the double-machine lifting speed is 0.6m / min to synchronously and uniformly lift the joint section; two inclinometers are placed at the center of the steel beam highway bridge deck, and according to the monitoring system of the beam-erecting crane, the balance state of the X and Y directions during the lifting of the joint section is monitored in real time, and the maximum tilt angle is controlled not to exceed 0.5°. When the tilt angle is close to 0.5°, the lifting is suspended, and the horizontality of the steel beam is adjusted by single-point or two-point lifting on one side. The lifting can be continued only when the requirements are met, and the synchronization is checked and adjusted every 5m of lifting.

[0017] Furthermore, the prediction analysis and control method of the closure based on the ballastless track control requirements is adopted to analyze and obtain the relatively stable time period of the closure deformation. 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 measure the linear data of the closure on both sides of the cantilever beam section on the longitudinally shifted side for no less than 48 hours continuously, and draw the deflection-temperature-time diagram and the centerline offset-temperature-time diagram based on the measured data; and analyze and obtain the relatively stable time period of the closure deformation based on the mileage-temperature-time diagram of the six nodes of the adjacent chords of the closure, and determine the closure time by the low-temperature method.

[0018] Furthermore, the priority of the closure members is determined as follows: in the priority closure lower chord 3 docking interfaces, by calculating the minimum spacing of the closure lower chord span Δmin=min{Δupstream side girder, Δmiddle girder, Δdownstream side girder}, Δupstream side girder is the spacing of the front row of bolt holes of the upstream side girder; Δmiddle girder is the spacing of the front row of bolt holes of the middle girder; Δdownstream side girder is the spacing of the front row of bolt holes of the downstream side girder, and the closure points with smaller spacing of the closure openings are preferentially closed through longitudinal displacement.

[0019] Furthermore, by satisfying the process pin diameter D of 31.5mm≤D≤32.8mm, the tolerance adjustment range of the remaining two joints of the lower chord is increased, and the other two joints of the lower chord are closed by using the longitudinal movement device at the main tower, process pin measures, beam erection crane lifting point lifting, joint pin shaft, and tensioning traction device; 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, 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.

[0020] Furthermore, the diagonal web members of the steel beams of the joint section are installed in a post-installation manner on site of the patching section.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The technology of the present application optimizes the structure of the joint section, the double-machine lifting technology without hoisting equipment, the longitudinal movement control method of the steel beam under limited release conditions, and optimizes and adjusts the joint mouth docking process technology. Based on the joint mouth prediction analysis and control method under the control requirements of the ballastless track, the problem of high requirements on the installation accuracy of the joint section due to the high requirements on the linear shape of the ballastless track and the characteristics that the steel strand inclined cable can only be tensioned but not released is solved. The technical solution is feasible, simple to construct, reduces construction risks, and greatly saves construction costs.

[0022] 2. Compared with the previous joint closure scheme, this technical scheme optimizes the joint section structure to avoid the interference problem of diagonal web bars during the lifting and alignment process. The use of a double-machine lifting method and control method without lifting equipment reduces the relative errors of the deflection and rotation angle of the joint mouth on both sides, and improves the synchronization control; the overall limited longitudinal shift of the cantilever steel beam on one side expands the joint mouth and reduces the difficulty of alignment of the joint section.

[0023] 3. A temporary locking structure of the joint hinge is set at the joint point to realize the rapid connection of multi-point chords of the steel truss. The operation is simple and quick. At the same time, the hinged method allows fine-tuning of the joint mouth. Combined with multiple adjustment measures such as longitudinal, vertical and transverse directions, the three-dimensional spatial coordinate position and the joint mouth angle of the joint mouth can be accurately controlled to ensure the installation accuracy of the joint rods. In addition, the relevant adjustment device is simple and convenient to manufacture.

[0024] 4. Through the numerical simulation technology of the cantilever stage and the repeated iteration method of high-precision measurement data matching, the optimal state of the joint mouth is accurately predicted, and the cable force value of the optimal joint state without the need for cable force adjustment is determined. By utilizing the deformation difference characteristics of the beam and cable under temperature changes, the low-temperature method is adopted to compensate for the technical problem that the cable force cannot be over-tensioned; the technical problems of joint mouth prediction analysis and control under the control requirements of ballastless track are effectively solved, and the requirements can be met by using on-site conditions, which is practical and economical. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0026] Figure 1 This is a schematic diagram of the steel truss joint; Figure 2 It is a structural schematic diagram of the longitudinal movement system in step one; Figure 3 This is a schematic diagram of the double-machine lifting of the closure section in step 2; Figure 4 This is a schematic diagram of the crane hook release in the joint closure section in step 3; Figure 5 This is a schematic diagram of the closure of the lower chord joint in step 5; Figure 6 This is a schematic diagram of the closure of the upper string joint in step six; Figure 7 This is a schematic diagram of the connection between the middle oblique rods; Figure 8 It is a front view schematic diagram and a side view schematic diagram of the joint closure.

[0027] The numbers in the figure represent: 1. Joint section; 2. Longitudinal shift system; 2-1. Jack; 2-2. Longitudinal shift device; 2-3. Pad steel plate; 3. Beam erecting crane; 4. Side girder lifting lug; 5. Cantilever beam section on the side that has not been longitudinally shifted; 6. Cantilever beam section on the side that has been longitudinally shifted; 7. Process punching measures; 8. Lifting of beam erecting crane lifting points; 9. Jointing pin shaft; 10. Puller; 11. Moving load; 12. Diagonal rod patching section; 13. Movable pulley block; 14. Falling chain; 15. Longitudinal pulling measures; 16. Longitudinal top-up measures; 17. Vertical correction measures. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. 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.

[0029] The terms “left”, “right”, “front”, “back”, “up” and “down” mentioned in the following description are oriented in the viewing direction of the front view.

[0030] Example: Please refer to the attached drawings of the specification Figure 1-Figure 8 A method for accurately controlling the installation of a three-main-truss steel truss joint section comprises the following steps: Step 1: If Figure 2 As shown in the figure, the longitudinal displacement trend of the steel beam is judged by the magnitude of 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 and the resultant force of the bearing friction; 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 is compared. The friction force of the support The size, if , after the steel beam releases the constraint, execute step 2; if , the steel beam does not undergo active displacement.

[0031] The characteristics of the longitudinal displacement trend of the steel beam are determined by the magnitude of 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 and the friction force of the support: ; ; in, ——Total unbalanced cable force in horizontal direction of the middle span cables and side span cables on both sides of the main tower; ——Tension of the three-truss cable-stayed cable on the middle span side, where For 1 to 11 pairs of call numbers, 1 to 3 are inclined cables from the upper side beam, middle beam and lower side beam; ——The angle between the cable force of the three-beam diagonal cable on the middle span side and the horizontal; ——Cable force of three-beam cable on the side span, where For 1 to 11 pairs of call numbers, 1 to 3 are inclined cables from the upper side beam, middle beam and lower side beam; ——The angle between the cable force of the three-beam inclined cable on the side span and the horizontal; ——Single-side steel beam friction; , , , , , ——respectively the three-beam support reactions at piers 1, 2 and 3; ——Friction coefficient between steel beam and support.

[0032] like , after the steel beam releases the constraint, execute step 2, the steel beam overcomes the friction force and moves toward the side span; if , after the steel beam releases the constraint, the steel beam does not undergo active displacement.

[0033] The installation method of the diagonal web members of the steel beam of the joint section is to install the patch section on site later, that is, the end of the diagonal web member of the steel beam of the joint section is designed with a patch section. After the joint is closed, the patch section is installed to the diagonal web member to complete the joint of the diagonal web member; thereby solving the interference problem between the diagonal web member and the joint mouth.

[0034] In step 1, compare the total horizontal unbalanced cable forces of the mid-span cables and side-span cables on both sides of the main tower. The friction force of the support Before the size of the cantilever beam section 6 on the side that has been longitudinally moved and the cantilever beam section 5 on the side that has not been longitudinally moved are both in a constrained state, and the splicing plates at the ends of the cantilever beam section 6 on the side that has been longitudinally moved and the cantilever beam section 5 on the side that has not been longitudinally moved are close to each other are in a contracted state.

[0035] 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.

[0036] 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.

[0037] Longitudinal displacement of the steel beam to the side span before the closure section is hoisted The following conditions should be met: ; ; The longitudinal displacement of the steel beam to the middle span after the joint section is completed The following conditions should be met: ; ; In the above formula: - Continuously measure the minimum longitudinal spacing between the chord openings of the cantilever beam sections on both sides for 48 hours; —48 hours of continuous measurement of the minimum longitudinal spacing between the chord openings on both sides of the closure; — Length of the joint section beam; —The distance between the longitudinal limit stopper and the outer wall of the main tower pad stone; — Minimum working height of the jack; —The thickness of the steel plate used to distribute the lifting force of the jack.

[0038] Step 3: If Figure 3 As shown, the double-machine lifting technology without lifting equipment is used to lift the steel beam of the joint section 1; The characteristics of the double-machine lifting technology without hoisting equipment are as follows: the movable pulley groups 13 of the two beam-erecting cranes 3 are directly connected to the truss lifting ears 4 on both sides of the joint section, and the double-machine lifting 3 adopts a minimum lifting speed of 0.6m / min to synchronously and uniformly lift the joint section 1; two inclinometers are placed at the center of the steel beam highway bridge deck, and according to the beam-erecting crane monitoring system, the balance state in the X and Y directions during the lifting of the joint section is monitored in real time, and the maximum tilt angle is controlled not to exceed 0.5°. When the tilt angle approaches 0.5°, the lifting is suspended, and the horizontality of the steel beam is adjusted by lifting at a single point or two points on one side. The lifting can be continued only when the requirements are met, and a synchronization check and adjustment is carried out every 5m of lifting, which improves the safety and synchronization of the double-machine lifting and ensures that the posture of the joint section is vertical and smoothly aligned.

[0039] Step 4: If Figure 4 As shown in the figure, after the joint section 1 is hoisted and aligned, the joint end of the cantilever beam section 5 on the side that has not been longitudinally moved is first connected, and after the bolt welding is completed, the beam cranes 3 on both sides are unhooked; Step 5: Adopt the prediction analysis and control method of the closure based on the ballastless track control requirements to analyze and obtain the relatively stable time period of the closure deformation; use the deformation difference characteristics of the beam and cable under the temperature change to determine the closure time using the low-temperature method.

[0040] The principle of the low-temperature method is: at low temperatures, the length of the inclined cable is shortened, which plays a role in vertical adjustment of the steel beam, thereby compensating for the need to directly adjust the vertical deformation of the cable force; the low-temperature method mainly utilizes the difference in deformation of the steel beam and the inclined cable when the temperature is reduced at the same time. At low temperatures, the length of the inclined cable is shortened, which plays a role in vertical adjustment of the steel beam, thereby compensating for the need to directly adjust the vertical deformation of the cable force.

[0041] Based on the ballastless track control requirements, the prediction analysis and control methods for closure are as follows: When the steel strand cable-stayed cable is connected to the large section in the middle of the span, there is a large equipment load in the middle of the span, and the design requirements for the difference in unbalanced cable forces between the main tower side and the middle span are high. As a result, 1~2 pairs of cable-stayed cables near the middle of the span are over-tensioned and cannot be released to meet the connection, which makes it impossible to meet the reasonable line shape control requirements of the ballastless track bridge. Based on this, the optimal state of the closure is accurately predicted through the numerical simulation technology of the cantilever stage and the high-precision measurement data matching iterative method, and the cable force value of the optimal closure state without the need for cable force adjustment is determined during the closure; the deformation-temperature-time curves in each direction are drawn using the 48-hour continuous X, Y, and Z displacement measurement data of the closure, and the relatively stable time period of the closure deformation is analyzed and obtained. The deformation difference characteristics of the beam and cable under temperature changes are used to adopt the low-temperature method to compensate for the technical problem that the cable force cannot be over-tensioned; the technical problems of closure prediction analysis and control under the control requirements of ballastless track are effectively solved; The linear data of the joints on both sides of the cantilever beam section 6 on the longitudinally shifted side were continuously observed. When the temperature difference between day and night was large and it was sunny, continuous measurement was carried out for no less than 48 hours, and the deflection-temperature-time diagram and the centerline offset-temperature-time diagram were drawn. The mileage-temperature-time diagram of the six nodes of the adjacent chord at the joint was obtained by analysis to obtain the relatively stable time period of the deformation of the joint, and the low-temperature method was adopted to compensate for the technical difficulty that the cable force cannot be over-tensioned by utilizing the deformation difference characteristics of the beam and cable under temperature changes.

[0042] Step 6: If Figure 5 As shown in the figure, according to the spatial posture analysis of the joint, the opening shape of the upper and lower chords presents a "V" shape. The relatively stable state of the continuous measurement data is used to clarify the joint sequence of the lower chord, upper chord, and diagonal web. According to the minimum spacing of each member, the priority joint member sequence is determined, and then the three joint interfaces of the lower chord of the three main trusses are temporarily locked in turn through the joint joint connection process. The judgment method of the priority closure member sequence is as follows: in the priority closure lower chord 3 joint interface, by calculating the minimum spacing of the closure lower chord bay Δmin=min{Δupstream side girder, Δmiddle girder, Δdownstream side girder}Δupstream side girder is the spacing of the front row of bolt holes of the upstream side girder; Δmiddle girder is the spacing of the front row of bolt holes of the middle girder; Δdownstream side girder is the spacing of the front row of bolt holes of the downstream side girder, the closure point with the smaller spacing of the closure mouth is closed by longitudinal displacement first, thereby stopping the longitudinal displacement of the steel beam; The specific operation of temporary locking is: by satisfying the process punch diameter D of 31.5mm≤D≤32.8mm, the tolerance adjustment range of the remaining two joints of the lower chord is increased, and the other two joints of the lower chord are closed by using the longitudinal movement device 2-2 at the main tower, the process punch measure 7, the beam crane lifting point lifting 8, the joint pin 9, and the tension tractor 10. Quickly insert and drive no less than 15% of the punches to meet the stress requirements of the steel beam after temperature rise. The punches are evenly arranged, and half of them are arranged near the top and bottom areas on the web. Then, follow-up construction is carried out, and 50% of the punches are inserted and driven within the joint period.

[0043] Step 7: If Figure 6 As shown, according to the opening of the three trusses in the upper chord, the characteristics presented in the horizontal direction are analyzed, the priority sequence of the jointing members is determined, the upper chord jointing adjustment measures are adopted, the sequence of the priority adjustment measures is determined, and the jointing is completed.

[0044] The specific implementation methods of the upper chord closure adjustment measures are as follows: in the upper chord closure adjustment measures, a moving load 11 is added to the railway bridge deck and an asymmetric distribution is presented according to the changes in the closure mouth. The longitudinal tensioning 15 and longitudinal top-up 16 measures are adopted to solve the difficulty in controlling the mileage adjustment of the upper chord three-beam. In addition, vertical correction measures 17 are used to adjust the elevation deviation; the closure mouth sensitive factor analysis method is adopted to determine the order of priority adjustment measures.

[0045] The specific implementation method of the closure sensitive factor analysis method is: numerical analysis technology is used to analyze the factors of the closure adjustment measures in different directions such as horizontal, vertical and longitudinal directions. The main analysis factors include the longitudinal displacement of the steel beam, the tension and top of the closure, the change of the cable, the temperature change, the vertical top, the pressure and the horizontal tension measures.

[0046] Step 8: If Figure 7 As shown, the diagonal rod patching section 12 is installed; then the splicing plate reserved in the interface area is quickly reset, and the bolting matching between the main truss members at the two interfaces of the joint section is completed by using positioning nails, and high-strength bolts are used for connection; after the interfaces at both ends of the joint section are bolted, the railway and highway interfaces are fixed with code plates to improve the overall rigidity of the structure; after the high bolts are tightened, the bridge deck butt welds are welded synchronously; the interface top plate and bottom plate are welded in accordance with the principle of symmetrical welding; after the main weld of the interface is welded, the U-rib and plate rib patching section are welded to complete the main span joint.

[0047] The installation method of the diagonal bar patching section 12 is: using a 25t truck crane to complete it on the railway bridge deck. After the lower chord and the upper chord of the steel beam are butted, the web bar patching section of the joint mouth is installed, and a fall chain 13 is used between the diagonal bar and the vertical bar. After adjusting the slope of the diagonal bar axis, the diagonal web bar is butted, and the upper and lower interfaces of the patching section are temporarily positioned using punches, and connected using high-strength bolts.

[0048] The joints of the three main trusses are connected in the order of middle truss lower chord → side truss lower chord → side truss upper chord → middle truss upper chord → diagonal bar patching section 12 → railway bridge deck → highway bridge deck.

[0049] There are 9 joints on the three main trusses, which are difficult to quickly and accurately connect. 1) First, according to the spatial posture analysis of the joint, the opening shape of the upper and lower chords presents a "V" shape. Using the relatively stable state of continuous measurement data, the overall order of closing the lower chord first and then the upper chord on the diagonal brace is clarified.

[0050] In the three joints of the lower chord that are to be closed first, by calculating the minimum spacing of the lower chord span Δmin=min{Δupstream side girder, Δmiddle girder, Δdownstream side girder} (Δupstream side girder is the spacing of the bolt holes in the front row of the upstream side girder; Δmiddle girder is the spacing of the bolt holes in the front row of the middle girder; Δdownstream side girder is the spacing of the bolt holes in the front row of the downstream side girder), the joint points with smaller joint spacing are closed first by longitudinal displacement, the longitudinal displacement of the steel beam is stopped, the diameter of the process rivet D is 31.5mm≤D≤32.8mm, the adjustment range of the closing tolerance of the remaining two joints of the lower chord is increased, and the longitudinal displacement device at the main tower, the process rivet measures, the lifting point of the beam erection crane, and the closure pin shaft are used to close the other two joints of the lower chord. Quickly insert and drive no less than 15% of the rivets to meet the force requirements of the steel beam after temperature rise (rivets are evenly arranged, half of which are arranged near the top and bottom areas on the web), and then carry out subsequent construction, and complete 50% of the rivet insertion within the closure period.

[0051] 2) After the three joint points of the lower chord are locked, the horizontal characteristics are analyzed according to the opening of the three girders of the upper chord, and the priority joint member sequence is determined using the same idea as the upper chord; in addition to the lower chord jointing measures, the upper first jointing adjustment measures increase the moving load on the railway bridge deck and present an asymmetric distribution according to the changes in the joint mouth, so as to solve the difficulty of controlling the mileage adjustment of the three girders of the upper chord. In addition, the elevation deviation is increased, and vertical correction measures are added; the joint mouth sensitive factor analysis method is used to determine the priority adjustment measures. After the joint is connected, no less than 5% of the nails are quickly inserted to meet the force requirements of the steel beam after the temperature rise (the nails are evenly arranged, and the web plate and half are arranged near the top and bottom areas).

[0052] 3) Install the diagonal bar patching section again, using a 25t truck crane on the railway bridge deck. After the lower chord and upper chord of the steel beam are butt-jointed, install the web bar patching section at the joint mouth, install the fall chain between the diagonal bar and the vertical bar, adjust the slope of the diagonal bar axis, butt the diagonal web bar, and use punches to temporarily position the upper and lower interfaces of the patching section, and use high-strength bolts to connect.

[0053] 4) After all the joint points are locked, quickly reset the splicing plate reserved in the interface area, use positioning pins to complete the bolting matching between the main truss members at the two interfaces of the joint section, and use high-strength bolts for connection. After the interfaces at both ends of the joint section are bolted, the railway and highway interfaces are fixed with code plates to improve the overall rigidity of the structure. After the high bolts are tightened, the bridge deck butt welds are welded synchronously, and the top and bottom plates of the interface are welded according to the principle of symmetrical welding. After the main weld of the interface is welded, the U ribs and plate rib patching sections are welded to complete the main span joint.

[0054] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements will not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for accurately controlling the installation of a three-main steel truss closure section, characterized in that: The following steps are involved: Step 1: Compare the total horizontal unbalanced cable forces of the mid-span cables and side-span cables on both sides of the main tower The friction force of the support The longitudinal displacement device (2-2) is operated to drive the cantilever beam section (6) on the longitudinally displaced side to move longitudinally, so that the cantilever beam section (6) on the longitudinally displaced side moves longitudinally toward the side span. Meet the requirements for closure; Step 2: Using a lifting device-free dual-machine lifting technology to lift the joint section (1); Step 3: The joint section (1) is butted against the butt joint of the cantilever beam section (5) on the side that has not been longitudinally moved, and bolt welding is performed on the butt joint of the joint section (1) and the cantilever beam section (5) on the side that has not been longitudinally moved. After completion, the beam erection cranes (3) on both sides are unhooked and separated from the joint section (1); Step 4: Analyze and obtain the relatively stable time period of the joint mouth deformation of the joint section (1) and the cantilever beam section (6) on one side that has been longitudinally moved, and use the low temperature method to determine the joint construction time period; Step 5: Determine the priority closure sequence of the upper and lower chords, and then temporarily lock the interfaces in sequence; Step six: Install the diagonal web filler section, and reset the spliced ​​plate, tighten the high bolts in sequence, and simultaneously weld the bridge deck butt welds, U-ribs, and plate-rib filler sections.

2. The method for installing the three-main-truss steel truss closure section with precise control according to claim 1 is characterized in that: Compare the total horizontal unbalanced cable forces of the middle span cables and side span cables on both sides of the main tower The friction force of the support The size, if After the cantilever beam section (6) on one side that has been longitudinally moved is released from its restraint, the longitudinal moving device (2-2) is operated to drive the cantilever beam section (6) on one side that has been longitudinally moved to longitudinally move the cantilever beam section (6) on one side that has been longitudinally moved to a longitudinal displacement amount of Meet the requirements for closure; if , the cantilever beam section (6) on one side that has been longitudinally displaced does not undergo active displacement.

3. The method for installing the three-main-truss steel truss closure section with precise control according to claim 1 is characterized in that: The sum of horizontal unbalanced cable forces of the middle span cables and side span cables on both sides of the main tower The friction force of the support The calculation formula is as follows: ； ； in, ——Total unbalanced cable force in horizontal direction of the middle span cables and side span cables on both sides of the main tower; ——Cable force of the three-truss cable on the middle span side, where For 1 to 11 pairs of call numbers, 1 to 3 are inclined cables from the upper side beam, middle beam and lower side beam; ——The angle between the cable force of the three-beam diagonal cable on the middle span side and the horizontal; ——Cable force of three-beam cable on the side span, where For 1 to 11 pairs of call numbers, 1 to 3 are inclined cables from the upper side beam, middle beam and lower side beam; ——The angle between the cable force of the three-beam inclined cable on the side span and the horizontal; ——Single-side steel beam friction; , , , , , ——respectively the three-beam support reactions at piers 1, 2 and 3; ——Friction coefficient between steel beam and support.

4. The method for installing the three-main-truss steel truss closure section with precise control according to claim 1 is characterized in that: The longitudinal shift system (2) is composed of a jack (2-1), a control pump station, a longitudinal shift device (2-2) and a cushion steel plate (2-3). A jack (2-1) is placed inside the longitudinal shift device (2-2). After releasing the cushion on one side, the jack (2-1) is used to lift the top to achieve longitudinal displacement. The same specification cushion steel plates (2-3) are used to control the synchronization of the longitudinal shift of the three girders to ensure that the transverse limit of the tower beam remains locked during the longitudinal shift.

5. The method for installing the three-main-truss steel truss closure section with precise control according to claim 1 is characterized in that: Longitudinal displacement of the steel beam to the side span before the closure section is hoisted The following conditions must be met: ； ； in, - Continuously measure the minimum longitudinal spacing between the chord openings of the cantilever beam sections on both sides for 48 hours; —48 hours of continuous measurement of the minimum longitudinal spacing between the chord openings on both sides of the closure; — Length of the joint section beam; —The distance between the longitudinal limit stopper and the outer wall of the main tower pad stone; — Minimum working height of the jack; —The thickness of the steel plate used to distribute the lifting force of the jack.

6. The method for installing the three-main-truss steel truss closure section with precise control according to claim 1 is characterized in that: The operation method of the double-machine lifting technology without lifting equipment is as follows: the movable pulley groups (13) of the two beam-erecting cranes (3) are directly connected to the truss lifting ears (4) on both sides of the joint section, and the double-machine lifting (3) is used to lift the joint section (1) synchronously and uniformly at a lifting speed of 0.6m / min; two inclinometers are placed at the center of the steel beam highway bridge deck, and according to the monitoring system of the beam-erecting crane, the balance state in the X and Y directions during the lifting of the joint section is monitored in real time, and the maximum tilt angle is controlled not to exceed 0.5°. When the tilt angle approaches 0.5°, the lifting is suspended, and the horizontality of the steel beam is adjusted by lifting at a single point or two points on one side. The lifting can be continued only when the requirements are met, and the synchronization is checked and adjusted every 5m of lifting.

7. The method for installing the three-main-truss steel truss joint section with precise control according to claim 1 is characterized in that: The analysis and acquisition of the relatively stable time period of the deformation of the joint mouth adopts the prediction analysis and control method of the joint mouth based on the control requirements of the ballastless track. The specific implementation method is as follows: select a time with clear weather and large temperature difference between day and night, and continuously measure the linear data of the joint mouth on both sides of the cantilever beam section (6) on one side that has been longitudinally moved for no less than 48 hours, and draw a deflection-temperature-time diagram and a centerline offset-temperature-time diagram based on the measured data; and analyze and acquire the relatively stable time period of the deformation of the joint mouth based on the mileage-temperature-time diagram of the six nodes of the adjacent chord rods of the joint mouth, and use the low temperature method to determine the joint time.

8. The priority order of closure of rods mentioned in step 5 of claim 1 is characterized by: The priority of the closure members is determined as follows: in the 3 joint interfaces of the lower chord with priority closure, by calculating the minimum spacing of the lower chord span of the closure Δmin=min{Δupstream side girder, Δmiddle girder, Δdownstream side girder}, Δupstream side girder is the spacing of the front row of bolt holes of the upstream side girder; Δmiddle girder is the spacing of the front row of bolt holes of the middle girder; Δdownstream side girder is the spacing of the front row of bolt holes of the downstream side girder, and the closure points with smaller spacing of the closure openings are preferentially closed through longitudinal displacement.

9. The temporary locking mentioned in step 5 of claim 1 is 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.

10. The closure section as claimed in 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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