Construction method applied to large-span central tower space cable suspension bridge catwalk

Abstract

The invention belongs to the technical field of bridge construction, and particularly relates to a construction method applied to a large-span central tower space cable suspension bridge catwalk, which comprises the following steps of: 1, mounting a traction system, a cable rotating saddle and a bracket bearing cable on the tower top; secondly, catwalk cables are erected through the traction system and the bracket bearing cables; thirdly, a displacement steel frame is installed; fourthly, catwalk surface layers are erected and assembled from the tower top to the two sides, and handrail structures are installed on the basis of handrail ropes on the outer side; fifthly, catwalk bearing cables are adjusted, erection of a catwalk portal frame is completed, and then main cables are erected; sixthly, an inner side handrail rope close to the axis of the bridge is pulled, and a catwalk handrail structure located on the inner side is installed; 7, catwalk system conversion is conducted; eighthly, the main cable and the split catwalk corresponding to the main cable are transversely shored through a horizontal transverse supporting system, and therefore the main cable reaches the designed line shape. The construction of the two main cables in the early stage is prevented from being interfered by the catwalk, and the catwalk can be shifted along with the main cables after the main cables are formed.

Description

Technical Field

[0001] The present invention belongs to the technical field of bridge construction, and particularly relates to a construction method for a catwalk of a long-span central tower spatial cable-suspended bridge. Background Art

[0002] For existing central tower spatial cable-suspended bridges, good results can be achieved in terms of the bridge landscape appearance. To reduce the structural size of the central tower, a split-slot co-body structure is adopted for the main cable saddle, which brings difficulties in the erection of the main cable while reducing the engineering quantity of the bridge structure. When using a traditional catwalk for the construction of the main cable, due to the too-small distance between the main cables, there is interference during the construction of the main cable after the catwalk is erected. And when two catwalks are erected simultaneously, two sets of traction and hoisting equipment must be equipped at the same time. After the main cable is formed, a transverse jacking support is required between the two main cables to make the main cable reach the design linearity, and then the corresponding catwalk needs to be displaced to facilitate the construction of the main cable with an increased distance. At this time, each main cable requires a corresponding catwalk. Therefore, how to avoid interference of the catwalk on the construction of the two main cables in the early stage while reducing the equipment cost of catwalk erection, and enable the catwalk to be displaced accordingly when the main cable is laterally displaced to realize the corresponding construction of the two main cables has become a technical problem to be solved in the existing technology. Summary of the Invention

[0003] The purpose of the present invention is to provide a construction method for a catwalk of a long-span central tower spatial cable-suspended bridge, which is used to solve the technical problem in the existing technology that it is impossible to avoid interference of the catwalk on the construction of the two main cables in the early stage while reducing the equipment cost of catwalk erection, and enable the catwalk to be displaced accordingly when the main cable is laterally displaced to realize the corresponding construction of the two main cables.

[0004] The described construction method for a catwalk of a long-span central tower spatial cable-suspended bridge includes the following steps:

[0005] Step 1: Install a traction system and a turning cable saddle on the top of the tower, and install a bracket load-bearing cable by using the traction system;

[0006] Step 2: Erect the catwalk cable by using the traction system and the bracket load-bearing cable;

[0007] Step 3: Install the displacement steel frame;

[0008] Step 4: Erect and assemble the catwalk surface layer from the top of the tower to both sides respectively, and install the railing structure based on the outer handrail cable;

[0009] Step 5: Adjust the catwalk load-bearing cable to make the catwalk surface layer reach the design elevation, then complete the erection of the catwalk gantry, and then carry out the erection of the main cable;

[0010] Step 6: After the main cable is formed, use the traction system to pull the inner handrail cable close to the bridge axis, and install the catwalk railing structure on the inner side;

[0011] Step 7: Conduct the conversion of the catwalk system, suspend the split catwalk on the main cable with steel wire ropes, and loosen the anchor heads at both ends of the catwalk cables.

[0012] Step 8: Use a horizontal bracing system to laterally brace the main cable and the corresponding split catwalk of the main cable, so that the main cable reaches the designed alignment.

[0013] Preferably, in Step 2, the erected catwalk cables include catwalk load-bearing cables, gantry weighing cables, and outer handrails. The outer handrails are farther from the bridge axis, and the sag of each catwalk cable needs to be adjusted to make the alignment of each catwalk cable consistent in the sag direction.

[0014] Preferably, in Step 4, there are two groups of catwalk surfaces symmetrically arranged with the bridge axis as the axis. Each catwalk surface includes a crossbeam structure fixedly connected to the catwalk load-bearing cable, a tread wooden square fixed on the catwalk load-bearing cable, and a catwalk mesh; the crossbeam structure and the tread wooden square are both arranged horizontally, and the ends of adjacent crossbeam structures on the left and right are detachably fixedly connected together. The catwalk surfaces on the left and right sides are connected together and combined with the catwalk railing structure on the outside to form an integral catwalk.

[0015] Preferably, in Step 5, the erection of the catwalk gantry is based on the gantry load-bearing cable. The upper crossbeam of the catwalk gantry is connected to all gantry load-bearing cables, while the lower crossbeam of the catwalk gantry is connected to each catwalk load-bearing cable. The upper and lower crossbeams are connected by gantry columns with adjustable lengths, and a supporting wheel for erecting the main cable is also installed on the upper crossbeam.

[0016] Preferably, in Step 6, first use the traction system to traction the inner handrail closer to the bridge axis, then install handrail columns at the end of the crossbeam structure close to the bridge axis, fix the handrail columns and the erected inner handrail, and then install the handrail mesh on the inner handrail.

[0017] Preferably, in Step 7, before hoisting the stiffening girder, first remove the catwalk gantry on the integral catwalk and the supporting wheels for erecting the main cable, and then gradually connect the catwalk surfaces on both sides of the bridge axis to the corresponding main cable along the catwalk extension direction based on the formed main cable to realize the gradual adjustment and transfer hanging of the split catwalk. After completing the transfer hanging of one area, disassemble and separate the two crossbeam structures connected together in the corresponding area.

[0018] Preferably, in Step 7, use steel wire ropes to suspend the catwalk load-bearing cables on the main cable. When suspending, the steel wire ropes should wind around the main cable once. For each side of the catwalk surface, at least two corresponding catwalk load-bearing cables should be suspended on the same main cable, and the two catwalk load-bearing cables should be located on both sides of the corresponding main cable after the catwalk surface is suspended on the main cable.

[0019] Preferably, in step eight, after the main cable meets the design alignment requirements, adjust the height of the catwalk surface layer of the split catwalk to reach the design alignment. Thereafter, maintain the stability of the main cable and the corresponding split catwalks through the horizontal bracing system; when the protection project of the formed main cable is completed, remove the catwalk.

[0020] The advantages of the present invention are as follows: The present invention only needs to set up a set of traction and hoisting systems. During the main cable erection stage, assume an integral catwalk. Since only the outer catwalk railing structure is installed, the construction of the two main cables in the early stage is not interfered by the catwalk railing structure located inside. At the same time, only one set of traction systems is needed at this stage, reducing the equipment cost of catwalk erection. After the main cable erection is completed, it is necessary to let the main cable reach the design alignment for subsequent protection construction. And this method also combines the detachable and separable catwalk surface layer with the traction and hoisting system. On the one hand, it realizes the installation of the catwalk railing structure inside, and on the other hand, it can separately adjust and hang the formed split catwalks on the corresponding main cables. During the catwalk protection stage, when the main cable is laterally displaced after forming, the catwalk can change its position accordingly, realizing the corresponding construction of the two main cables, thus solving the technical problems caused by different catwalk positions and different requirements at different stages. In addition, this method also arranges a catwalk portal frame at a certain distance on the integral catwalk, connecting each catwalk cable, the integral catwalk and each catwalk portal frame to form an integral space structure, effectively improving the wind resistance stability of the integral catwalk. Description of the Drawings

[0021] Figure 1 It is a schematic diagram of the catwalk when the construction method of a catwalk for a long-span central tower spatial cable suspension bridge according to the present invention is completed in step five.

[0022] Figure 2 It is Figure 1 The side view of the integral catwalk in the shown structure, where the longitudinal distances of the catwalk cables are all curve lengths in the figure.

[0023] Figure 3 It is Figure 1 The top view of the integral catwalk in the shown structure, where the longitudinal distances of the catwalk cables are all curve lengths in the figure.

[0024] Figure 4 It is Figure 1 The cross-sectional view of the integral catwalk in the shown structure.

[0025] Figure 5 It is the cross-sectional view of the split catwalk when the construction method provided by the present invention is in step seven.

[0026] Figure 6 It is Figure 1 The structural schematic diagram of the catwalk portal frame in the shown structure.

[0027] The markings in the above-mentioned drawings include:

[0028] 1 Gantry load-bearing cable, 2 Catwalk gantry, 3 Main cable, 4 Integral catwalk, 5 Handrail surface net, 6 Handrail cable, 7 Handrail column, 8 Large cross beam, 9 Small cross beam, 10 Tread wooden square, 11 Load-bearing net, 12 Walking net, 13 Catwalk load-bearing cable, 14 Steel wire rope. Detailed implementation manner

[0029] The following is a more detailed description of the specific implementation manner of the present invention by comparing with the accompanying drawings and describing the embodiments, so as to help those skilled in the art have a more complete, accurate and in-depth understanding of the inventive concept and technical solution of the present invention.

[0030] As Figure 1 、 Figure 2 shown, the present invention provides a construction method for a catwalk of a long-span central tower spatial cable-suspended bridge, including the following steps.

[0031] Step 1: Install a traction system and a cable saddle on the top of the tower, and install the bracket load-bearing cable by using the traction system.

[0032] Step 2: Erection the catwalk cables by using the traction system and the bracket load-bearing cable.

[0033] The catwalk cables erected in this step include the catwalk load-bearing cable 13, the gantry weighing cable and the outer handrail cable 6, and the outer handrail cable 6 is the handrail cable 6 farther from the bridge axis. After the installation of each catwalk cable, it is necessary to adjust the sag of each catwalk cable so that the linear shapes of the catwalk cables in the sag direction are consistent.

[0034] Step 3: Install the displacement steel frame.

[0035] After the installation of the catwalk load-bearing cable 13, install the displacement steel frame on the top of the tower platform to make the linear shape of the catwalk load-bearing cable 13 meet the requirements of the catwalk cross-section, and let each catwalk load-bearing cable 13 bypass the cable saddle at the set position.

[0036] Step 4: Erection and assemble the catwalk surface layer from the top of the tower to both sides respectively, and install the railing structure based on the outer handrail cable 6.

[0037] There are two groups of catwalk surface layers, which are symmetrically arranged with the bridge axis as the axis. Each catwalk surface layer includes a cross-beam structure fixedly connected to the catwalk load-bearing cable 13, a tread wooden square 10 fixed on the catwalk load-bearing cable 13, and a catwalk surface net. The catwalk surface net is fixedly connected to the tread wooden square 10 and includes a load-bearing net 11 and a walking net 12. The load-bearing net 11 is the lower-layer rough surface net, and the walking net 12 is the upper-layer fine surface net. The mesh size of the upper-layer fine surface net is smaller than that of the lower-layer rough surface net. The catwalk surface nets on the same side are fixedly connected to the catwalk load-bearing cable 13 on that side, generally by tying with wire.

[0038] The crossbeam structure and the tread wooden square 10 are both arranged horizontally, and the ends of the adjacent crossbeam structures on the left and right are detachably and fixedly connected together. Handrail columns 7 can be installed at the ends of the crossbeam structures. The crossbeam structure includes a large crossbeam 8 with a larger cross-section and a small crossbeam 9 with a smaller cross-section. The handrail columns 7 are generally installed on the large crossbeam 8. The crossbeam structure is fixedly connected to the catwalk load-bearing cable 13 through U-bolts.

[0039] The catwalk railing structure includes handrail columns 7, handrail cables 6 and handrail surface meshes 5. The handrail cables 6 include an outer handrail cable 6 far from the bridge axis and an inner handrail cable 6 close to the bridge axis. The catwalk railing structure installed in this step is the outer one. The handrail surface meshes 5 are connected to the handrail cables 6 by tying with wire. The adjacent handrail surface meshes 5 and the adjacent catwalk surface meshes are overlapped and connected, and the overlapping parts are all tied with wire. The catwalk surface mesh and the handrail surface meshes 5 are also tied with wire. The handrail columns 7 and the handrail cables 6 are fixedly connected through U-bolts.

[0040] Step Five: Adjust the catwalk load-bearing cable 13 to make the catwalk surface layer reach the design elevation, then complete the erection of the catwalk gantry 2, and then carry out the erection of the main cable 3.

[0041] In this step, after the height of the catwalk load-bearing cable 13 is adjusted, the catwalk gantry 2 is erected based on the gantry load-bearing cable 1. The upper crossbeam of the catwalk gantry 2 is connected to all the gantry load-bearing cables 1, while the lower crossbeam of the catwalk gantry 2 is connected to each catwalk load-bearing cable 13. The upper and lower crossbeams are connected by gantry columns with adjustable lengths. The upper crossbeam is also equipped with idler wheels for erecting the main cable 3.

[0042] Steps Four to Five both belong to the main cable 3 erection stage. Although two sets of left-right symmetric catwalk surface layers are used to erect the catwalk in this stage, the catwalk is formed by connecting the catwalk surface layers on the left and right sides, and together with the outer catwalk railing structure, it forms an integral catwalk 4. Since only the outer catwalk railing structure is installed, the construction of the two main cables 3 in the early stage is not interfered by the catwalk railing structure on the inner side of the catwalk. At the same time, only one set of traction system is needed in this stage, reducing the equipment cost of catwalk erection.

[0043] At the same time, the integral catwalk 4 is adapted to the corresponding catwalk gantry 2. The catwalk gantries 2 are arranged at certain intervals on the integral catwalk 4, connecting each catwalk cable, the integral catwalk 4 and each catwalk gantry 2 to form an integral spatial structure, effectively improving the wind resistance stability of the integral catwalk 4.

[0044] Step Six: After the main cable 3 is formed, use the traction system to pull the inner handrail cable 6 close to the bridge axis and install the catwalk railing structure on the inner side.

[0045] In this step, first use the traction system to traction the inner handrail cable 6 close to the bridge axis, and then install the handrail columns 7 at the end of the crossbeam structure close to the bridge axis on the overall catwalk 4 during the erection stage of the main cable 3. Fix the handrail columns 7 and the erected inner handrail cable 6 with U-bolts, and install the handrail surface mesh 5 on the inner handrail cable 6 to complete the installation of the catwalk railing structure on the inner side.

[0046] At this time, although the catwalk surfaces on both sides of the bridge axis have not been separated yet, the catwalk railing structures on the inner handrail cable 6 and the outer handrail cable 6 and the catwalk surface between these two catwalk railing structures have formed a split catwalk corresponding to the two main cables 3 respectively.

[0047] Step 7: Carry out the catwalk system conversion. Use the steel wire rope 14 to hang the split catwalk on the main cable 3, and loosen the anchor heads at both ends of the catwalk cable.

[0048] Before hoisting the stiffening girder, first remove the catwalk gantry 2 on the overall catwalk 4 and the carrying wheels for erecting the main cable 3, and then gradually adjust and transfer the overall catwalk 4 based on the formed main cable 3. Gradual adjustment and transfer means gradually connecting the catwalk surfaces on both sides of the bridge axis to the corresponding main cable 3 along the extension direction of the catwalk. For example, use the steel wire rope 14 to hang the catwalk load-bearing cable 13 onto the main cable 3. When hanging, the steel wire rope 14 should be wound around the main cable 3 once to prevent slipping, and measures should be taken to avoid the steel wire rope 14 scratching the main cable 3. For each side of the catwalk surface, at least two corresponding catwalk load-bearing cables 13 should be hung onto the same main cable 3, and the two catwalk load-bearing cables 13 should be located on both sides of the corresponding main cable 3 respectively after the catwalk surface is hung to the main cable 3. After completing the transfer of one area, disassemble and separate the two crossbeam structures connected together in the corresponding area to achieve the separation and lateral displacement of the future split catwalk. In order to enable the main cable 3 and the split catwalk to be separated and laterally displaced in the future, it is also necessary to loosen the anchor heads at both ends of the split catwalk cable after completing the adjustment and transfer, which involves disconnecting the connection between the catwalk cable and the tower top platform and the anchor. When relaxing and adjusting the catwalk, it should be ensured that each catwalk cable is relaxed synchronously to avoid generating large unbalanced forces in the process. Attention should also be paid to setting anti-collision and buffering measures on the main truss girder at the intersection of the cable and the girder to avoid the catwalk scratching the main girder.

[0049] Step 8: Use a horizontal bracing system to horizontally brace the main cable 3 and the split catwalk corresponding to the main cable 3, so that the main cable 3 reaches the designed alignment.

[0050] Here, the split catwalk is laterally displaced with the main cable 3 during the bracing process. After the main cable 3 meets the designed alignment requirements, adjust the height of the catwalk surface of the split catwalk to reach the designed alignment. Thereafter, maintain the stability of the main cable 3 and the corresponding split catwalk through the horizontal bracing system.

[0051] During the maintenance of the above catwalks (including the integral catwalk 4 and the split catwalk), it is necessary to regularly observe the maximum sag at the mid-span of each load-bearing cable and the sag difference at the mid-span between the main cables 3 of the same group; in addition, the anchoring systems, displacement steel frame steering systems, rotating saddles, distribution beam connection bolts, and guiding mechanisms of the traction systems of each catwalk cable also need to be regularly inspected. Moreover, not only should each load-bearing cable and the wire rope 14 clamps be regularly inspected, but also immediately inspected after each strong wind.

[0052] After the protection project of the formed main cable 3 is completed, the catwalk can be demolished, and it is necessary to ensure that the main cable 3, the suspension cables, the cable clamps, and the stiffening girder are not damaged during the demolition process, and the recycling of necessary components is guaranteed.

[0053] Steps six to eight above belong to the main cable 3 protection stage. In this stage, the two main cables 3 need to have horizontal displacement. Therefore, in this method, the originally connected catwalk surface layers are respectively transferred and hung on the corresponding main cables 3, so that the formed split catwalk can synchronously displace with the main cables 3 under the action of the horizontal bracing system. Then, based on the suspension effect of the main cables 3 and the support effect of the counterweight beams, the catwalk is carried, thus solving the problem of how to make the catwalk displace with the main cables 3 during the main cable 3 protection stage and meeting the need of engineering personnel to carry out protection construction on the two main cables 3.

[0054] The present invention has been described exemplarily above in conjunction with the accompanying drawings. Obviously, the specific implementation of the present invention is not limited by the above methods. As long as various non-substantive improvements are made by adopting the inventive concept and technical solution of the present invention, or the inventive concept and technical solution of the present invention are directly applied to other occasions without improvement, they are all within the protection scope of the present invention.

Claims

1. A construction method for a catwalk of a long-span central tower spatial cable-suspended bridge, characterized in that: It includes the following steps: Step 1: Install a traction system and a turning cable saddle at the top of the tower, and install a bracket load-bearing cable using the traction system; Step 2: Erect the catwalk cable using the traction system and the bracket load-bearing cable; Step 3: Install the displacement steel frame; Step 4: Erect and assemble the catwalk surface layer from the top of the tower to both sides respectively, and install the railing structure based on the outer handrail cable; Step 5: Adjust the catwalk load-bearing cable to make the catwalk surface layer reach the design elevation, then complete the erection of the catwalk gantry, and then carry out the erection of the main cable; Step 6: After the main cable is formed, use the traction system to tow the inner handrail cable close to the bridge axis, and install the catwalk railing structure on the inner side; Step 7: Carry out the conversion of the catwalk system, hang the split catwalk on the main cable with steel wire ropes, and loosen the anchor heads at both ends of the catwalk cable; Step 8: Adopt a horizontal bracing system to horizontally brace the main cable and the corresponding split catwalk of the main cable, so that the main cable reaches the design alignment.

2. The construction method of a catwalk for a long-span central tower spatial cable-suspended bridge according to claim 1, characterized in that: In Step 2, the erected catwalk cables include catwalk load-bearing cables, gantry load-bearing cables and outer handrail cables. The outer handrail cable is farther from the bridge axis, and the sag of each catwalk cable needs to be adjusted so that the alignment of each catwalk cable in the sag direction is consistent.

3. The construction method of a catwalk for a long-span central tower spatial cable-suspended bridge according to claim 1, characterized in that: In Step 4, there are two groups of catwalk surface layers, which are symmetrically arranged with the bridge axis as the axis. Each catwalk surface layer includes a crossbeam structure fixedly connected to the catwalk load-bearing cable, a step wooden square fixed on the catwalk load-bearing cable, and a catwalk mesh; the crossbeam structure and the step wooden square are both arranged horizontally, and the ends of adjacent crossbeam structures on the left and right are detachably fixedly connected together. The catwalk surface layers on the left and right sides are connected together and combined with the catwalk railing structure on the outer side to form an integral catwalk.

4. The construction method of a catwalk for a long-span central tower spatial cable-suspended bridge according to claim 1, characterized in that: In Step 5, the catwalk gantry is erected based on the gantry load-bearing cable. The upper crossbeam of the catwalk gantry is connected to all gantry load-bearing cables, while the lower crossbeam of the catwalk gantry is connected to each catwalk load-bearing cable. The upper crossbeam and the lower crossbeam are connected by gantry columns with adjustable lengths. A pulley for erecting the main cable is also installed on the upper crossbeam.

5. The construction method of a catwalk for a long-span central tower spatial cable-suspended bridge according to claim 1, characterized in that: In Step 6, first use the traction system to tow the inner handrail cable close to the bridge axis, then install handrail columns at the ends of the crossbeam structures close to the bridge axis, fix the handrail columns and the erected inner handrail cable, and then install the handrail mesh on the inner handrail cable.

6. The construction method of a catwalk for a long-span central tower spatial cable suspension bridge according to claim 1, characterized in that: In Step 7, before hoisting the stiffening girder, first remove the catwalk gantry on the integral catwalk and the pulley for erecting the main cable. Then, along the catwalk extension direction based on the formed main cable, connect the catwalk surface layers on both sides of the bridge axis to the corresponding main cable for the integral catwalk, realizing the gradual adjustment and transfer hanging of the split catwalk. After completing the transfer hanging of one area, disassemble and separate the two crossbeam structures connected together in the corresponding area.

7. A construction method for a catwalk of a long-span central tower spatial cable-suspended bridge according to claim 6, characterized in that: In Step 7, hang the catwalk load-bearing cable on the main cable using steel wire ropes. When hanging, the steel wire ropes should wind around the main cable for one circle. For each side of the catwalk surface layer, at least two corresponding catwalk load-bearing cables should be hung on the same main cable, and the two catwalk load-bearing cables should be located on both sides of the corresponding main cable respectively after the catwalk surface layer is hung on the main cable.

8. The construction method of a catwalk for a long-span central tower spatial cable-suspended bridge according to claim 1, characterized in that: In Step 8, after the main cable meets the requirements of the designed alignment, adjust the height of the catwalk surface of the split catwalk to reach the designed alignment, and then maintain the stability of the main cable and the corresponding split catwalk through the horizontal bracing system; after the protection project of the formed main cable is completed, remove the catwalk.

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