A method for dismantling a low tower cable-stayed bridge by rotation

Abstract

The application provides a method for dismantling a low-tower cable-stayed bridge by rotation, which comprises the following steps: setting a circular sliding rail foundation concentric with a main pier on a main pier bearing platform, installing a circular rotation sliding rail on the sliding rail foundation, hoisting two steel arch frames onto the rotation sliding rail by a bridge deck crane to support the bridge, removing the closure section of the main span and the side span of the cable-stayed bridge, cutting the main pier of the cable-stayed bridge along a plane parallel to the rotation sliding rail by a rope saw, converting the load of the whole upper structure of the main span of the cable-stayed bridge from being supported by the pier and the steel arch frame to being supported by the steel arch frame alone, rotating the upper structure of the main span of the cable-stayed bridge along the rotation sliding rail by a certain angle to avoid the main channel under the bridge, and then removing the main span of the cable-stayed bridge section by section. The application can realize the safe and stable conversion of the load of the main span of the bridge, and provides a safety guarantee for the construction of the dismantling of the bridge by rotation.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of bridge construction and relates to a method for dismantling a low-tower cable-stayed bridge by rotation. BACKGROUND

[0002] The low-tower cable-stayed bridge is usually a single-tower single-cable-plane cable-stayed bridge of a reinforced concrete structure. As the service life of the bridge increases, unrepairable diseases may occur, or the bridge cannot adapt to the development of navigation due to low navigation clearance under the bridge, and thus needs to be dismantled and reconstructed. If the conventional bridge dismantling method is used for in-situ dismantling, the construction period is long, and the impact on the navigation under the bridge is large.

[0003] Patent CN117947717A discloses a continuous beam dismantling method by rotation. The technical solution is to first set a spherical hinge on the top of the main span pier, then dismantle the side span and the side span closure segment to form a T structure of the main span, then dismantle the permanent support on the top of the main span pier to convert the load of the main span beam segment to the spherical hinge, and finally dismantle the main span beam segment after the rotation of the main span beam segment by the spherical hinge, so as to avoid the impact on the road traffic under the bridge during the dismantling of the bridge.

[0004] CN116289672 discloses a continuous rigid frame bridge dismantling device and method by rotation across a railway. The technical solution is to first set a circle of pile foundations around the main span pier, set a temporary rotation platform and a rotation support on the pile foundations, and set a pile foundation in the middle of the pier column as a rotation shaft, then dismantle the pier, convert the load of the bridge to the rotation support, cut off the main beam of the bridge across the railway to form two T structures, and finally dismantle the two T structures after the rotation of the two T structures, so as to avoid the impact on the road traffic under the bridge during the dismantling of the bridge.

[0005] The bridge dismantling by rotation of the above two technical solutions has certain reference significance for the dismantling of the low-tower cable-stayed bridge, but the first solution needs to set a spherical hinge on the top of the pier, and thus is only applicable to the continuous box girder bridge with a separated structure of the pier and the beam body and a support on the top of the pier. The second solution needs to set pile foundations around the pier and in the middle of the pier and dismantle the pier, and thus is only applicable to the bridge dismantling construction of the bridge on land and the bridge with a thin-walled hollow pier. For the low-tower cable-stayed bridge, the pier, the beam body and the tower are integrally poured, and thus it is impossible to set a rotation hinge on the top of the pier or set a pile foundation in the water around the pier or in the middle of the pier. Moreover, the two technical solutions need to drill the support on the top of the pier or dismantle the pier to convert the load of the bridge to the rotation hinge, and thus are only applicable to the continuous girder bridge with small T structure weight. For the low-tower cable-stayed bridge, the main span has a large span, and the tower is further arranged on the main span. The self weight of the whole main span structure is large. The dismantling of the pier for load conversion construction has great difficulty and risk, and thus the two technical solutions cannot be directly applied to the dismantling of the low-tower cable-stayed bridge. SUMMARY

[0006] The application aims at the above problems, and provides a rotating body dismantling method suitable for low-tower cable-stayed bridges.

[0007] The technical scheme of the application is as follows:

[0008] A rotating body dismantling method for low-tower cable-stayed bridges, characterized in that it comprises the following steps:

[0009] Step one: remove the first cable-stayed cable closest to the main tower and the main girder flange within the range of the tower body, lay bridge deck crane tracks on both sides of the top surface of the main girder, and set a bridge deck crane on both sides of the main tower in the transverse direction of the bridge, respectively, with both ends of the bridge deck crane cantilevered to extend outside the bridge on both sides; the two bridge deck cranes can move along the bridge deck crane tracks in the longitudinal direction of the bridge;

[0010] Step two: set a circular sliding rail foundation concentric with the main pier on the main pier cap around the main pier, and install a circular rotating body sliding rail on the sliding rail foundation;

[0011] Step three: transport two prefabricated steel arches to the main pier in the transverse direction of the bridge on two transport ships, respectively;

[0012] Step four: use the bridge deck cranes to lift the two steel arches, and move the two bridge deck cranes along the bridge deck crane tracks to the main tower, respectively, and place the two steel arches symmetrically on the rotating body sliding rail, with both arch feet of each steel arch supported on the rotating body sliding rail;

[0013] Step five: remove the bridge deck cranes and the bridge deck crane tracks, set a connecting wall between the steel arch and the main pier to improve the lateral stability of the steel arch, and insert a steel wedge between the top surface of the steel arch and the bottom surface of the main girder, with the steel wedge in close contact with the bottom surface of the main girder;

[0014] Step six: remove the closure section of the main span and the side span of the cable-stayed bridge, and form a T structure in the main span;

[0015] Step seven: cut the main pier of the cable-stayed bridge along a plane parallel to the rotating body sliding rail using a rope saw, so that the dead load of the entire superstructure of the main span of the cable-stayed bridge is supported by the pier and the steel arch and is then converted to be supported by the steel arch alone;

[0016] Step eight: pull the entire superstructure of the main span of the cable-stayed bridge to rotate along the rotating body sliding rail by a certain angle to avoid the main waterway below the bridge, and then remove the main span of the cable-stayed bridge section by section.

[0017] The steel arch with a steel box concrete structure is used as the main bearing structure for load conversion of the superstructure of the main span of the cable-stayed bridge, which has high bearing capacity and low cost; the main pier is cut in the whole to stably convert the load of the superstructure of the main span to the steel arch, which can ensure construction safety. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is the general construction flowchart of the application;

[0019] Figure 2 This is a transverse schematic diagram of the bridge after the removal of the main beam flange between the first stay cable and the main tower.

[0020] Figure 3 This is a schematic diagram along the bridge direction showing the removal of the main beam flange;

[0021] Figure 4 This is a transverse diagram showing the installation method of the bridge deck crane and slide foundation;

[0022] Figure 5 This is a schematic diagram along the bridge direction showing the installation method of the bridge deck crane and slide foundation;

[0023] Figure 6 This is a schematic diagram of the planar structure of the slide base and the rotating slide;

[0024] Figure 7 This is a schematic diagram of the cross-sectional structure of the rotating slide;

[0025] Figure 8 This is a schematic diagram showing the state of the steel arch frame after it has been transported to the area under the bridge.

[0026] Figure 9 This is a side view of the steel arch frame structure.

[0027] Figure 10 This is a schematic diagram of the cross-sectional structure of the steel arch frame;

[0028] Figure 11 A schematic diagram showing the status of a bridge deck crane hoisting a steel arch frame;

[0029] Figure 12 This is a schematic diagram of the steel arch frame being installed on the rotating slide along the bridge direction;

[0030] Figure 13 This is a schematic diagram of the steel arch frame installed on the rotating slide in the transverse direction;

[0031] Figure 14 This is a schematic diagram showing the state of a steel arch frame supporting a single main span superstructure;

[0032] Figure 15 This is a schematic diagram of the rotation method of the main span superstructure. Detailed Implementation

[0033] Figure 1 This is the overall construction flowchart of the present invention, and the specific construction method is as follows:

[0034] Step 1: As Figure 2 , Figure 3 As shown, the first step is to remove the main beam flange 3 within the range from the first stay cable 2 closest to the main tower 1 to the tower body, in order to provide space for the installation and operation of the bridge deck crane.

[0035] In order to improve the local bearing capacity of the main girder at the root of the main tower, the main girder 4 box chamber after removing the main girder flange can be filled with plain concrete 5.

[0036] As shown in Figure 4 , Figure 5 , after removing the main girder flange, the bridge deck crane track 6 is laid on both sides of the top surface of the main girder 4, and a bridge deck crane 7 is arranged on both sides of the main tower transversely, and the two ends of the bridge deck crane 7 are cantilevered to extend outside the bridge on both sides; the two bridge deck cranes 7 can move along the bridge deck crane track 6.

[0037] When laying the bridge deck crane track, in order to ensure the bearing capacity of the bridge deck crane track, the bridge deck crane track can be laid along the main girder web.

[0038] Step two: as shown in Figure 4 , Figure 5 , a sliding rail foundation 10 is arranged around the main pier 9 on the main pier cap 8, and a ring-shaped rotating body sliding rail 11 is installed on the sliding rail foundation 10;

[0039] The sliding rail foundation can be poured with reinforced concrete, and the bottom of the sliding rail foundation is fixed with the cap by the way of planting reinforcement on the surface of the cap. The sliding rail foundation should be higher than the highest water level, and the cross section of the sliding rail foundation 10 is a concentric circular ring with the main pier.

[0040] When constructing the sliding rail foundation, the construction can be carried out when the lowest water level is lower than the top surface of the cap; if the lowest water level is higher than the cap, a water retaining cofferdam needs to be arranged outside the cap.

[0041] The sliding rail foundation can be constructed synchronously with step one.

[0042] The rotating body sliding rail 11 is welded by steel plates and fixed on the sliding rail foundation. The planar structure of the rotating body sliding rail 11 is a concentric circular ring as shown in Figure 6 , and the cross section of the rotating body sliding rail 11 is arranged as U-shaped as shown in Figure 7 . In order to reduce the friction of the rotating body sliding rail, a Teflon sliding plate can be laid in the rotating body sliding rail.

[0043] Step three: as shown in Figure 8 , two pre-processed steel arches 12 are transported to the main pier transversely on both sides of the bridge by two transport ships.

[0044] The steel arch is used to provide support for load conversion on the bridge, and is pre-processed in the factory. As shown in Figure 9 , Figure 10 , the steel arch 12 adopts a steel box concrete structure, and the top plate 121, the bottom plate 122 and the two side plates 123 are all welded by steel plates to form the outer shell of the steel structure, and the steel arch is filled with concrete.

[0045] To ensure the load bearing capacity of the steel arch, stiffeners 124 are welded to the inner sides of the top plate, bottom plate and two side plates of the steel arch; further, a prestressed structure is arranged in the steel arch, before pouring the concrete, a corrugated pipe is arranged in the steel arch along the axial direction, a prestressed tendon is arranged in the corrugated pipe, and the prestressed tendon is tensioned after the concrete is poured.

[0046] To avoid the stress deformation of the steel arch and ensure its load bearing capacity, a pull rod 125 is arranged between the two arch feet of the steel arch. The pull rod is arranged in four, is made of 40Cr steel material with a diameter of 200 mm, and is fixed by nuts at both ends. To improve the stress bearing capacity of the pull rod at the arch foot of the steel arch, horizontal and vertical steel pipe meshes are arranged in the concrete of the arch foot.

[0047] Step four: as shown in Figure 11 , Figure 12 , the two steel arches 12 are lifted by the bridge crane 7, the two bridge cranes move along the bridge crane track to the main tower, the two steel arches are symmetrically placed on the swivel slide rail 11, and the two arch feet of each steel arch are supported in the swivel slide rail 11.

[0048] To facilitate the connection of the bridge crane and the steel arch, two triangular hangers 13 are welded to the two ends of the steel arch 12 when the bridge crane lifts the steel arch, and the bridge crane 7 lifts the steel arch 12 by connecting the triangular hangers 13.

[0049] Step five: as shown in Figure 13 , 14 , after the steel arch 12 is lifted, the bridge crane and the bridge crane track are removed; a connecting wall piece 14 is arranged between the steel arch 12 and the main pier 9 to improve the lateral stability of the steel arch; a steel wedge 15 is inserted between the top surface of the steel arch 12 and the bottom surface of the main beam 4, and the steel wedge is tightly pressed against the bottom surface of the main beam.

[0050] The steel wedge 15 can be a steel plate with a slope, which is inserted between the steel arch and the main beam and closely contacts the bottom surface of the beam.

[0051] Step six: the closure section of the main span and the side span of the cable-stayed bridge is released, and the main span forms a T structure;

[0052] Step seven: the main pier 9 of the cable-stayed bridge is cut along the plane parallel to the swivel slide rail by a rope saw, so that the dead load of the entire upper structure of the main span of the cable-stayed bridge is supported by the main pier 9 and the steel arch 12, and is converted to be supported by the steel arch 12 alone, and the load bearing system conversion is completed.

[0053] Step eight: the entire upper structure of the main span of the cable-stayed bridge is pulled to rotate a certain angle along the swivel slide rail to avoid the main navigation channel under the bridge. As Figure 15As shown, the steel arch 12 slides along the rotation track 11, carrying the main span upper structure, and rotates together. After the rotation is completed, the main span of the cable-stayed bridge is removed in sections and transported away by the transport ship. Since the main channel is released, the river navigation is not affected during the bridge removal process.

Claims

1. A method for dismantling a tower cable-stayed bridge swivel, characterized in that, The method comprises the following steps: Step one: remove the first cable from the main tower to the main beam flange in the range, lay the bridge crane track on both sides of the main beam top surface, set a bridge crane on both sides of the main tower transversely, and extend the two ends of the bridge crane to the outside of the bridge respectively; the two bridge cranes can move along the bridge crane track; Step two: set a circular sliding rail foundation concentric with the main pier on the main pier cap, and install a ring-shaped rotating sliding rail on the sliding rail foundation; Step three: transport two pre-processed steel arches to the main pier transversely on both sides of the bridge by two transport ships respectively; Step four: use the bridge crane to lift the two steel arches, and move the two bridge cranes along the bridge crane track to the main tower respectively, and place the two steel arches symmetrically on the rotating sliding rail; the two arch feet of each steel arch are supported on the rotating sliding rail; Step five: remove the bridge crane and the bridge crane track; set a connecting wall between the steel arch and the main pier to improve the lateral stability of the steel arch; insert a steel wedge between the top surface of the steel arch and the bottom surface of the main beam, and the steel wedge is in close contact with the bottom surface of the main beam; Step six: remove the closure section of the main span and the side span of the cable-stayed bridge, and form a T-shaped structure of the main span; Step seven: cut the main pier of the cable-stayed bridge along the plane parallel to the rotating sliding rail by using a rope saw, so that the dead load of the entire upper structure of the main span of the cable-stayed bridge is supported by the pier and the steel arch, and then is converted to be supported by the steel arch alone; Step eight: rotate the entire upper structure of the main span of the cable-stayed bridge along the rotating sliding rail by a certain angle to avoid the main channel below the bridge, and then remove the main span of the cable-stayed bridge section by section.

2. The method according to claim 1, wherein: In step one, the main beam box chamber removed from the main beam flange is filled with plain concrete to improve the local bearing capacity of the main beam at the root of the main tower.

3. The method according to claim 1, wherein: The bridge crane track on the top surface of the main beam is laid along the web of the main beam.

4. The method of claim 1, wherein: The sliding rail foundation is made of reinforced concrete, the bottom of the sliding rail foundation is fixed with the cap by the way of planting reinforcing steel bars on the surface of the cap, the sliding rail foundation is higher than the highest water level, and the cross section of the sliding rail foundation is circular.

5. The method of claim 1, wherein: When the sliding rail foundation is constructed on the cap, a steel cofferdam is arranged around the cap to pour and construct the sliding rail foundation when the water level is higher than the top surface of the cap.

6. The method of claim 1, wherein: The rotating sliding rail is made of steel plates and is fixed on the sliding rail foundation, the cross section of the rotating sliding rail is U-shaped, and four fluorine sliding plates are laid in the sliding rail.

7. The method of claim 1, wherein: The steel arch is a steel box concrete structure, the shell of the steel arch includes a top plate, a bottom plate and two side plates, which are all made of steel plates by welding, the steel arch is filled with concrete, and the two arch feet of the steel arch are pulled by a pull rod.

8. The method according to claim 7, wherein: The inside of the top plate, the bottom plate and the two side plates of the steel arch are all welded with stiffening ribs, corrugated pipes are arranged in the steel arch along the axial direction, pre-stressed steel bars are arranged in the corrugated pipes and are pre-tensioned.

9. The method of claim 1, wherein: When the bridge crane lifts the steel arch, two triangular hangers are welded at the two ends of the steel arch respectively, and the bridge crane lifts the steel arch through the triangular hangers.

10. The method of claim 1, wherein: The steel wedge is a steel plate with an inclined slope, which is inserted between the steel arch and the main beam and is in close contact with the beam bottom.

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