Main cable installation method of spatial cable self-anchored suspension bridge using main cable saddle splitting and displacement

Abstract

The present invention relates to a method for erecting main cables of a spatial cable self-anchored suspension bridge utilizing the splitting and displacement of the main cable saddle, and belongs to the technical field of bridge construction. By means of regional stress control, stress concentration caused by dynamic loads is dispersed by opening a semicircular groove in the high stress concentration area, a quenched steel bushing is embedded in the medium stress concentration area through an annular V-shaped groove to optimize the stress transfer path, and a roller array is combined with a rectangular groove in the low stress concentration area to reduce the contact pressure stress, and then a manual hydraulic jack, a pressure dividing valve and a rigid connecting rod are used in combination to achieve thrust balance; a retractable screw cross brace and a gear rack scale control the main cable spacing and the jacking displacement; a guide rail and a limit roller group ensure the accuracy of the jacking path; after the main cable saddle is split, it is quickly installed through a reaction platform bracket, and the catwalk is arranged parallel to the main cable; graded jacking is combined with a temporary cable stabilization structure, and finally the system conversion is completed by bolting, thereby solving the problem of stress concentration in the construction of large-span suspension bridges.

Description

Technical Field

[0001] The invention belongs to the technical field of bridge construction, and in particular relates to a method for erecting main cables of a spatial cable self-anchored suspension bridge by utilizing the splitting and displacement of main cable saddles. Background Art

[0002] During the installation of the main cables of a self-anchored suspension bridge, lateral jacking technology is a key step in adjusting the spatial shape of the cables. Traditional construction methods can alleviate the instantaneous load impact caused by a one-time jacking by gradually pushing the cables in stages and over small distances, but its synchronization is highly dependent on the accuracy of the mechanical device.

[0003] For large-span bridges or projects in complex environments, the long-distance force transmission characteristics of the main cables and construction channels can amplify the influence of differences in the structure itself and the external environment. For example, uneven stiffness of different main cable sections, deformation differences caused by temperature changes, and wind interference can all lead to displacement deviations in different sections during the jacking process, thereby causing abnormal local stress accumulation. This is especially true during the main saddle splitting and hoisting stages, where the sudden change in structural cross-section and the combined effect of dynamic loads make the local stress concentration problem particularly prominent. In the main saddle reconnection and jacking contact area, similar problems, although slightly less severe, can still significantly weaken the safety and durability of the structure. Existing technologies mostly rely on electronic control systems for synchronous compensation, but the reliability of such systems faces severe challenges in extreme environments or strong interference conditions. A targeted solution that does not require complex electronic control is urgently needed. To this end, a main cable installation method for a spatial cable self-anchored suspension bridge that utilizes the splitting and displacement of the main saddle is proposed. Summary of the Invention

[0004] In order to solve the above problems existing in the prior art, the present invention provides a method for erecting the main cable of a spatial cable self-anchored suspension bridge by utilizing the splitting and displacement of the main cable saddle, thereby solving the problems in the background art.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A method for erecting main cables of a spatial cable self-anchored suspension bridge using splitting and displacement of main cable saddles comprises the following steps:

[0007] S1: Main cable saddle reaction platform brackets are installed at both ends of the top of the elliptical steel tower to increase the spacing between the main cable saddles after separation and provide installation space for the parallel catwalk;

[0008] S2: Cut the integrated main saddle into two separate main saddles, hoist them to both ends of the tower top in sequence, and set reaction seats and jacks on their outsides. The area where the main saddle is split and hoisted is designated as a high stress concentration area, and semicircular grooves are opened on both sides of the cut section of the main saddle.

[0009] S3: After installing the gantry at the main saddle position, construct the catwalk arranged in parallel;

[0010] S4: After the parallel installation of the main cables is completed, temporary cables are installed between the main beam and the main cables;

[0011] S5: Install retractable active cross braces between parallel main cables, push the main cables and catwalks to the designed positions in stages, define the contact area between the main cables and catwalks as a low stress concentration area, and create rectangular grooves at the contact points between the reaction seats and the main cables.

[0012] S6: After the main cable and catwalk are pushed horizontally into place, the two separate main saddles are gradually pushed to the center of the tower top;

[0013] S7: Bolt the two main cable saddles together and connect them to the tower top with high-strength bolts. Define the main cable saddle system transition area as a medium stress concentration area, and create a V-shaped groove around the bolt hole.

[0014] S8: After installing and tensioning the designed slings, remove the temporary slings and catwalks.

[0015] As a further solution of the present invention, the groove depth of the semicircular groove is 40%~50% of the cutting section thickness, the groove body depth of the V-shaped groove is 20%~30% of the plate thickness of the bolt hole area, and the groove body depth of the rectangular groove is 10%~15% of the plate thickness of the contact area.

[0016] As a further solution of the present invention, a hardened steel bushing is embedded in the V-shaped groove in S7 to reduce the stress peak at the edge of the bolt hole through interference fit.

[0017] As a further solution of the present invention, the rectangular groove in S5 realizes contact pressure gradient diffusion by cooperating with the roller array and the rubber cushion layer.

[0018] As a further solution of the present invention, the reaction seat in step S2 is symmetrically arranged on the outside of the separate main cable saddle, and is connected to the main cable saddle reaction platform bracket through a rigid connecting rod. The jack is driven by manual hydraulics, and the thrust of multiple groups of jacks is balanced through a pressure-dividing valve.

[0019] As a further solution of the present invention, the gantry in step S3 is a detachable truss structure, the bottom of the gantry is fixed to the main saddle reaction platform bracket by anchors, and a cross support rod is set on the top of the gantry to constrain the lateral displacement during the construction of the catwalk.

[0020] As a further solution of the present invention, the retractable active cross brace in step S5 is a bidirectional screw structure, both ends of the cross brace are connected to the main cable through hinged nodes, a manual rotation drive device is provided in the middle of the cross brace, and the adjustment amount of the lateral spacing of the main cable is controlled by the thread lead.

[0021] As a further solution of the present invention, during the graded pushing process of step S5, the synchronous displacement of the main cable and the catwalk is achieved by a linked hydraulic cylinder group, the hydraulic cylinder group is mechanically connected in series through a rigid connecting rod, and the pushing displacement of each stage is manually calibrated by a gear rack scale.

[0022] As a further solution of the present invention, the pushing path of the separate main cable saddle in step S6 is controlled by a guide rail preset on the top of the tower. A limiting roller group is provided on both sides of the guide rail. The roller group is in sliding contact with the bottom of the main cable saddle to ensure that there is no deviation in the pushing direction.

[0023] As a further solution of the present invention, before the temporary sling is removed in step S8, the sling is unloaded in stages through the counterweight block and the pulley block. The weight of the counterweight block is distributed according to the proportion of the sling tension, and the unloading order is carried out step by step from the mid-span to the top of the tower.

[0024] The beneficial effects of the present invention are:

[0025] Through regional stress control, semicircular grooves are opened in high stress concentration areas to disperse the stress concentration caused by dynamic loads. In medium stress concentration areas, hardened steel bushings are embedded through annular V-shaped grooves to optimize the stress transfer path. In low stress concentration areas, rectangular grooves are combined with roller arrays to reduce contact pressure stress. Then, manual hydraulic jacks, pressure-dividing valves and rigid connecting rods are used to achieve thrust balance. Retractable screw cross braces and gear rack scales control the main cable spacing and jacking displacement. Guide rails and limit roller groups ensure the accuracy of the jacking path. After the main cable saddle is disassembled, it is quickly installed through the reaction platform bracket, and the catwalk is arranged parallel to the main cable. Staged jacking is combined with temporary cable stabilization structure, and finally the system conversion is completed through bolting, which systematically solves the stress concentration, synchronization and environmental adaptability problems in the construction of long-span suspension bridges. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] To facilitate understanding by those skilled in the art, the present invention is further described below with reference to the accompanying drawings.

[0027] Figure 1 This is a front view of the suspension bridge of the present invention before system conversion;

[0028] Figure 2 This is a top view of the suspension bridge of the present invention before system conversion;

[0029] Figure 3 A top view of the main cables and catwalk of the suspension bridge of the present invention after being cross-braced;

[0030] Figure 4 This is a top view of the main cable saddle of the suspension bridge of the present invention after being closed;

[0031] Figure 5 For the present invention Figure 2Side view of the main saddle at center A;

[0032] Figure 6 For the present invention Figure 4 Side view of the main saddle at B in the middle;

[0033] Figure 7 It is a side view of the main cable saddle of the present invention before folding.

[0034] Description of main component symbols:

[0035] In the figure: 11, bridge tower; 12, catwalk; 13, main cable; 14, temporary cable; 15, active cross brace; 16, main beam; 21, main cable saddle; 22, reaction platform bracket; 23, reaction seat; 24, jack; 25, pad; 26, lap plate. DETAILED DESCRIPTION

[0036] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, the specific implementation methods, structures, features and effects of the present invention are described in detail below in conjunction with the accompanying drawings and preferred embodiments.

[0037] See also Figure 1-Figure 7 As shown, this embodiment provides a method for installing the main cable 13 of a space cable self-anchored suspension bridge by splitting and shifting the main cable saddle 21, comprising the following steps:

[0038] S1: Install the main cable saddle 21 reaction platform bracket 22 at both ends of the top of the elliptical steel tower to increase the spacing between the main cable saddles 21 after splitting and provide installation space for the parallel catwalk 12;

[0039] S2: Cut the integrated main cable saddle 21 into two separate main cable saddles 21, hoist them to the two ends of the tower top in sequence, and set reaction seats 23 and jacks 24 on their outer sides. The area where the main cable saddle 21 is split and hoisted is designated as a high stress concentration area, and semicircular grooves are opened on both sides of the cut section of the main cable saddle 21;

[0040] S3: After installing the gantry at the main saddle 21, construct the catwalk 12 arranged in parallel;

[0041] S4: After the parallel installation of the main cables 13 is completed, temporary tie cables 14 are installed between the main beam 16 and the main cables 13;

[0042] S5: Install retractable active cross braces 15 between the parallel main cables 13, push the main cables 13 and catwalk 12 to the designed positions in stages, define the push-contact area between the main cables 13 and catwalk 12 as a low stress concentration area, and open a rectangular groove at the contact point between the reaction seat 23 and the main cable 13;

[0043] S6: After the main cable 13 and catwalk 12 are pushed into place laterally, the two separate main saddles 21 are gradually pushed to the center of the tower top;

[0044] S7: Bolt the two main cable saddles 21 together and connect them to the tower top with high-strength bolts. Define the main cable saddle 21 system transition area as a medium stress concentration area, and open a V-shaped groove around the bolt hole.

[0045] S8: After installing and tensioning the designed slings, remove the temporary slings and catwalk 12.

[0046] Among them, one point that needs to be supplemented is that the main saddle 21 has a serious geometric mutation after cutting (the cross-section decreases suddenly), the dynamic load (hoisting inertia force, wind force) is superimposed, and the stress concentration coefficient is high. The groove type is selected based on the mechanical properties. The radius of curvature of the arc is inversely proportional to the stress concentration coefficient. The semicircular groove disperses the stress streamline through smooth transition, which can reduce the stress concentration coefficient. The cutting section must take into account both strength retention and stress release. The depth of the semicircular groove is controllable. The groove depth of the semicircular groove is 40% to 50% of the thickness of the cutting section. 40% or 50% of the plate thickness can avoid excessive weakening of the structure. If replaced with a V-shaped groove or a rectangular groove, the sharp angle or right angle will lead to an increase in the stress concentration coefficient, which cannot meet the requirements of the high stress area.

[0047] The area around the bolted hole is affected by the bolt preload and load transfer, and the stress concentration coefficient is also high. It is necessary to reduce the risk through bushing reinforcement and stress buffering. The mechanical characteristics of this position are that the theoretical stress concentration coefficient of the V-groove sharp angle is high, but its shape is convenient for embedding the quenched steel bushing. Through the interference fit between the bushing and the base material, the stress transfer path is changed from "hole edge-base material" to "hole edge-bushing-base material", which can significantly reduce the stress concentration coefficient. The V-groove provides a positioning reference for the bushing to ensure that the bushing is in close contact with the hole wall. If it is replaced with a semicircular groove here, the bushing positioning accuracy will decrease, and the arc groove cannot constrain the circumferential position of the bushing If it is replaced with a rectangular groove, the stress concentration at the right angle will be superimposed on the bushing installation error, and the stress concentration coefficient will increase; the stress concentration coefficient at the push contact point is low, but it needs to be constructed quickly and a certain stress concentration is allowed. The mechanical characteristics of this position are that the right angle of the rectangular groove leads to a high stress concentration coefficient, but through external devices, roller arrays, and gradient stiffness cushions for compensation, the actual stress concentration coefficient can be reduced. The rectangular groove only requires straight line cutting, and the processing speed is three times that of the arc groove, which is suitable for the economic needs of low-risk areas. If it is replaced with a semicircular groove or a V-shaped groove, the processing cost will increase, and the stress improvement benefits are limited, and the cost performance is insufficient.

[0048] In addition, one point that needs to be supplemented is that in step S2, both ends of the bridge tower 11 are fixedly connected with reaction platform brackets 22, and a pushing device is provided. The two parts of the main cable saddle 21 are mounted on the reaction platform bracket 22, and the pushing device includes two groups of reaction seats 23 and jacks 24. The two groups of reaction seats 23 are respectively arranged on the outside of the two parts of the main cable saddle 21, and the jacks 24 are arranged between the reaction seats 23 and the main cable saddle 21; the reaction platform bracket 22 is connected by a lap plate 26 to form a saddle quick-install module, and the two parts of the main cable saddle 21 are relatively slidably arranged on the lap plate 26, and the two parts of the main cable saddle 21 are connected by a linkage component. The two groups of reaction seats 23 in the pushing device are fixed on the lap plate 26 and are respectively arranged on both sides of the main cable saddle 21, and the jacks 24 are located on one side of the reaction seat. A pad 25 is pre-installed between the seat 23 and the main cable saddle 21, and between the reaction seat 23 on the other side and the main cable saddle 21. The pushing process of the main cable saddle 21 is that the jack 24 pushes one part of the main cable saddle 21, and the displacement is the thickness of the pad 25. After pushing, a pad 25 is installed between the reaction seat 23 on the other side and the main cable saddle 21; the jack 24 retreats and repeats until the main cable saddle 21 is closed to the designed position. A flare from the inside to the outside is opened between the inner sides of the bottom of the reaction platform bracket 22, and the flare angle is 10°~15°, which is used to adapt to the arc structure at the top of the tower and enhance the anti-overturning stability of the bracket. The active cross brace 15 is a retractable screw structure, and the two ends are connected to the main cable 13 through hinged nodes. The extension and contraction amount is controlled by the thread lead to achieve millimeter-level adjustment of the lateral spacing of the main cable 13.

[0049] It is worth mentioning that, since the project is for a large-span bridge or a project in a complex environment, when the main cable 13 is pushed horizontally, due to the large span and uneven distribution of cable gravity, different sections are pushed asynchronously, causing spatial cable shape deviation. In order to solve this problem, in one embodiment, the vicinity of the main cable saddle 21, the middle of the main cable 13, the anchoring section of the main cable 13 end, the transition section of the main cable 13 close to the anchor, and the connection area between the construction channel and the main cable 13 are selected as the tower top area, the mid-span area, the anchoring area, the side span area and the auxiliary area of the catwalk 12, respectively. The main drive gearbox is installed on the tower top, and the gearbox output shaft is driven by a manual crank. The output shaft is connected to the bidirectional screw cross brace in the mid-span adjustment area and the chain pushing frame in the side span driven area through a rigid universal joint drive shaft. The output shaft and the drive shaft are matched with hexagonal prism-shaped shaft holes to achieve non-slip torque transmission; the two sides of the bidirectional screw cross brace are connected to the chain pushing frame in the side span driven area through a rigid universal joint drive shaft. A reverse thread is set at the end, and the middle gear is engaged with the tower top transmission shaft. The cross brace is driven to extend and retract by rotating the crank to adjust the horizontal spacing of the main cable 13. A plumb pendulum is hung under the cross brace, and the pendulum pointer points to the ground scale. The crank speed is manually adjusted according to the pendulum offset. The chain in the driven area of the side span is forced to push synchronously. The hydraulic cylinder of the side span pushing frame is connected in series through the chain, and the chain is engaged with the sprocket at the end of the tower top transmission shaft; a self-lubricating roller group is arranged under the main cable 13. The roller is made of bronze and embedded with a graphite bushing to reduce the difference in friction resistance; the balance weight in the anchor balance area is dynamically adjusted, and a slide rail balance weight box is set behind the anchor. The balance weight box is connected to the end of the main cable 13 through a pulley group. The pulley group is provided with a ratchet lock and a coil spring; according to the offset of the mid-span pendulum, the balance weight block is manually increased or decreased to balance the tension fluctuation; cyclic calibration and manual feedback control, each push 10 After 100 m, construction was suspended to check the offset between the pendulum pointer and the scale and the wear condition of the roller group. By adjusting the crank handle speed, the number of counterweights and the chain tension, the system calibration was completed and the pushing was continued.

[0050] In addition, when the crank rotates, power is synchronously transmitted to the mid-span adjustment area through the drive shaft to control the lateral spacing and the driven area of the side span, and to control the jacking displacement. When the tower top drive shaft rotates, the cross brace is forced to extend and retract synchronously; the pendulum offset is fed back to the tower top operator to adjust the drive speed, and the tower top drive shaft drives the sprocket, forcing all the jacking hydraulic cylinders to move synchronously through the chain, eliminating the side span asynchrony, and the counterweight box gravity is linked to the mid-span pendulum offset: when the mid-span sag increases, the counterweight block is manually increased to balance the tension.

[0051] Currently, for large-span bridges or projects in complex environments, the long-distance force transmission characteristics of the main cable 13 and the construction channel will amplify the differences in the structure itself and the influence of the external environment. For example, the uneven stiffness of each section of the main cable 13, the deformation differences caused by temperature changes, and wind interference may all lead to displacement deviations in different sections during the jacking process, thereby causing abnormal local stress accumulation. In particular, during the disassembly and lifting of the main cable saddle 21, the sudden change in the structural cross-section and the combined effect of dynamic loads make the problem of local stress concentration particularly prominent. In the reconnection and jacking contact area of the main cable saddle 21, similar problems, although slightly less severe, may still significantly weaken the safety and durability of the structure. Existing technologies mostly rely on electronic control systems for synchronous compensation, but in extreme environments or under strong interference conditions, the reliability of such systems faces severe challenges.

[0052] In order to solve the above problems, in this embodiment, stress control is carried out in different regions. In the high stress concentration area, a semicircular groove is opened to disperse the stress concentration caused by the dynamic load. In the medium stress concentration area, a hardened steel bushing is embedded in the annular V-shaped groove to optimize the stress transfer path. In the low stress concentration area, a rectangular groove is combined with a roller array to reduce the contact pressure stress. Then, a manual hydraulic jack 24, a pressure-dividing valve and a rigid connecting rod are used to achieve thrust balance. The retractable screw cross brace and the gear rack scale control the spacing and the pushing displacement of the main cable 13. The guide rail and the limit roller group ensure the accuracy of the pushing path. After the main cable saddle 21 is disassembled, it is quickly installed through the reaction platform bracket 22. The catwalk 12 is arranged parallel to the main cable 13. The graded pushing is combined with the temporary cable 14 to stabilize the structure. Finally, the system conversion is completed by bolting, which systematically solves the stress concentration, synchronization and environmental adaptability problems in the construction of large-span suspension bridges.

[0053] Since the project is aimed at long-span bridges or projects in complex environments, in order to avoid insufficient stress release caused by too shallow a groove depth, or weakening the bearing capacity of the component due to too deep a groove depth, in one embodiment, the groove depth of the semicircular groove is 40%-50% of the cutting section thickness, the groove body depth of the V-shaped groove is 20%-30% of the plate thickness in the bolt hole area, and the groove body depth of the rectangular groove is 10%-15% of the plate thickness in the contact area. The groove depth of the semicircular groove is designed with a lower limit of 40% to ensure that the groove depth is sufficient to disperse stress and avoid shallow grooves from being unable to effectively release energy. The upper limit is 50% to prevent excessive weakening of the section strength and the risk of fracture caused by insufficient remaining thickness of the material. The groove depth of the V-shaped groove is designed with a lower limit of 20% to ensure sufficient embedding depth of the bushing to prevent the bushing from loosening or falling off, and an upper limit of 30% to retain sufficient base material thickness to withstand the bolt tension and prevent hole wall deformation. The groove depth of the rectangular groove is designed with a lower limit of 10% to provide basic stress release and avoid insufficient effect caused by too shallow a groove body. The upper limit is 15% to prevent excessive groove depth from causing contact surface deformation or roller support failure.

[0054] Considering that bolt holes are prone to cracks due to pre-tightening force, in one embodiment, a bushing is used to strengthen the hole wall and disperse the load, and a hardened steel bushing is embedded in the V-groove in S7. The stress peak at the edge of the bolt hole is reduced through interference fit. The high hardness and wear resistance of the hardened steel are adapted to the dynamic load of the bolt, and the V-groove provides precise positioning to prevent the bushing from shifting.

[0055] Since the push contact point is prone to local compressive stress concentration due to sliding friction, the rectangular groove in S5 realizes the diffusion of contact pressure gradient by cooperating with the roller array and rubber pad layer. The rectangular groove cooperates with the rolling friction of the roller array and the flexible buffering of the rubber pad layer to realize the diffusion of contact pressure gradient. The roller reduces friction resistance and the rubber pad layer absorbs vibration energy. The two work together to reduce stress peaks.

[0056] Furthermore, uneven thrust of multiple jacks 24 may cause the main cable saddle 21 to be offset or the reaction seat 23 to be deformed. In one embodiment, in step S2, the reaction seat 23 is symmetrically arranged on the outside of the separate main cable saddle 21, and is connected to the reaction platform bracket 22 of the main cable saddle 21 through a rigid connecting rod. The jacks 24 are driven by manual hydraulics, and the thrust of multiple groups of jacks 24 is balanced through a pressure-dividing valve. The reaction seat 23 is symmetrically arranged and the thrust of the jacks 24 is balanced through the pressure-dividing valve.

[0057] Since the catwalk 12 is susceptible to shaking due to wind or construction loads during construction, in one embodiment, the portal frame in step S3 is a detachable truss structure, the bottom of the portal frame is fixed to the main saddle 21 reaction platform bracket 22 through anchors, and a cross support rod is provided on the top of the portal frame to constrain the lateral displacement of the catwalk 12 during construction. The portal frame adopts a detachable truss structure, and a cross support rod is provided on the top to constrain the lateral displacement of the catwalk 12. At the same time, it is convenient for quick installation and dismantling. The cross support enhances the rigidity of the portal frame and ensures construction accuracy.

[0058] Since traditional hydraulic cross braces rely on electronic control systems, they are prone to failure in complex environments for projects under long-span bridges. In one embodiment, the retractable active cross brace 15 in step S5 is a bidirectional screw structure, and both ends of the cross brace are connected to the main cable 13 through a hinged node. A manual rotation drive device is provided in the middle of the cross brace, and the adjustment amount of the lateral spacing of the main cables 13 is controlled by the thread lead. The bidirectional screw structure is driven by manual rotation to accurately control the lateral spacing of the main cables 13.

[0059] In order to avoid the cable shape being out of control due to the accumulation of displacement deviations in different sections during large-span jacking, in one embodiment, during the staged jacking process of step S5, the synchronous displacement of the main cable 13 and the catwalk 12 is achieved by a linked hydraulic cylinder group, which is mechanically connected in series through a rigid connecting rod, and the displacement of each stage of jacking is manually calibrated by a gear rack scale. Synchronization is forced through mechanical linkage, the scale provides real-time feedback, and manual intervention is used to compensate for errors, thereby avoiding the cable shape being out of control due to the accumulation of displacement deviations in different sections.

[0060] In order to prevent the main cable saddle 21 from deviating from the designed trajectory due to friction or external force during the pushing process, in one embodiment, the pushing path of the detachable main cable saddle 21 in step S6 is controlled by a guide track preset on the top of the tower, and a limiting roller group is provided on both sides of the guide track. The roller group is in sliding contact with the bottom of the main cable saddle 21 to ensure that there is no deviation in the pushing direction. The direction is forced to be constrained by the track, and the roller group reduces sliding friction to ensure the linear accuracy of the pushing.

[0061] Finally, when the temporary sling is removed, in order to avoid sudden unloading causing a sudden change in the internal force of the main cable 13, which may lead to structural instability, in one embodiment, before the temporary sling is removed in step S8, the sling is unloaded in stages through the counterweight block and the pulley group. The weight of the counterweight block is distributed according to the proportion of the sling tension, and the unloading sequence is carried out step by step from the mid-span to the top of the tower. The staged unloading of the sling through the counterweight block and the pulley group can gradually reduce the sling tension, avoid structural damage caused by sudden unloading, and improve the safety during the removal process.

[0062] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as above in terms of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can, without departing from the scope of the technical solution of the present invention, make some changes or modifications to equivalent embodiments using the technical contents disclosed above. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for installing the main cable of a space cable self-anchored suspension bridge by splitting and shifting the main cable saddle, characterized in that: The following steps are involved: S1: Main cable saddle reaction platform brackets are installed at both ends of the top of the elliptical steel tower to increase the spacing between the main cable saddles after separation and provide installation space for the parallel catwalk; S2: Cut the integrated main cable saddle into two separate main cable saddles, hoist them to both ends of the tower top in sequence, and set reaction seats and jacks on their outsides. The area where the main cable saddle is split and hoisted is designated as a high stress concentration area. Semicircular grooves are opened on both sides of the cut section of the main cable saddle. The reaction seats are symmetrically arranged on the outside of the separate main cable saddles and connected to the main cable saddle reaction platform bracket through a rigid connecting rod. The jacks are manually hydraulically driven, and the thrust of multiple groups of jacks is evenly distributed through a pressure-dividing valve. S3: After installing the gantry at the main saddle position, construct the catwalk arranged in parallel; S4: After the parallel installation of the main cables is completed, temporary cables are installed between the main beam and the main cables; S5: Install retractable active cross braces between parallel main cables, and push the main cables and catwalks in stages to the designed positions. The contact area between the main cables and the catwalk during pushing is designated as a low-stress concentration zone. Rectangular grooves are created at the contact points between the reaction blocks and the main cables. These grooves, combined with a roller array and rubber pads, achieve gradient diffusion of contact pressure. During the staged pushing process, the synchronous displacement of the main cables and catwalks is achieved via a linked hydraulic cylinder group, which is mechanically connected in series via a rigid connecting rod. The displacement of each stage is manually calibrated using a rack and pinion scale. S6: After the main cable and catwalk are pushed into place horizontally, the two separate main saddles are gradually pushed to the center of the tower top. The pushing path of the separate main saddles is controlled by the guide track preset on the tower top. The guide track is equipped with limit rollers on both sides. The rollers are in sliding contact with the bottom of the main saddles to ensure that the pushing direction is not offset. S7: Bolt the two main cable saddles together and connect them to the tower top with high-strength bolts. Define the main cable saddle system transition area as a medium stress concentration area. Create a V-shaped groove around the bolt hole and insert a hardened steel bushing into the V-shaped groove to reduce the peak stress around the bolt hole through interference fit. S8: After installing and tensioning the designed slings, remove the temporary slings and catwalks. Before removing the temporary slings, unload the slings in stages using counterweights and pulleys. The weight of the counterweights is distributed according to the proportion of the sling tension. The unloading sequence is carried out section by section from the mid-span to the tower top.

2. The main cable installation method of a space cable self-anchored suspension bridge using the splitting and displacement of the main cable saddle according to claim 1 is characterized in that: The depth of the semicircular groove is 40% to 50% of the cutting section thickness, the depth of the V-shaped groove is 20% to 30% of the plate thickness in the bolt hole area, and the depth of the rectangular groove is 10% to 15% of the plate thickness in the contact area.

3. The main cable installation method of a space cable self-anchored suspension bridge using the splitting and displacement of the main cable saddle according to claim 1 is characterized in that: In step S3, the portal frame is a detachable truss structure, the bottom of the portal frame is fixed to the main saddle reaction platform bracket through anchors, and a cross support rod is set on the top of the portal frame to constrain the lateral displacement during the construction of the catwalk.

4. The main cable installation method for a space cable self-anchored suspension bridge using main cable saddle splitting and displacement according to claim 1 is characterized in that: In step S5, the retractable active cross brace is a bidirectional screw structure, both ends of the cross brace are connected to the main cable through hinged nodes, a manual rotation drive device is provided in the middle of the cross brace, and the adjustment amount of the lateral spacing of the main cable is controlled by the thread lead.

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