A synchronous demolition and construction method for in-situ reconstruction of low tower cable-stayed bridges

Abstract

The present invention relates to a construction method for synchronous demolition and construction of in-situ reconstruction of a low tower cable-stayed bridge. Before the demolition of the old bridge, new bridge main girder assembly brackets are respectively erected on both sides of each old bridge tower along the longitudinal direction of the river. While demolishing the old bridge, a floating crane is used to assemble the new bridge main girder from the far end to the main tower direction on the new bridge main girder assembly brackets. After the demolition of the old bridge main tower and the bearing platform, the new bridge bearing platform is constructed in-situ, and a slewing turntable is installed on the new bearing platform. The new main tower of the bridge is constructed on the new bearing platform, and the new main tower is supported on the turntable. The stay cables between the main tower and the main girder are connected and tensioned. The new bridge main girder assembly brackets are unloaded, so that the vertical force of the new bridge is supported by the turntable. The new bridge main girder is slewed into place, and the mid-span closure segment and the side-span closure segment are installed to complete the in-situ reconstruction construction of the cable-stayed bridge. The present invention can realize the synchronous construction of the demolition of the old bridge and the in-situ reconstruction of the new bridge, thereby greatly shortening the construction period and reducing the time occupying the main navigation channel.

Description

Technical Field

[0001] The present invention belongs to the field of bridge construction, and relates to the construction of demolishing and reconstructing an old bridge in-situ, specifically to a synchronous construction method for demolishing and reconstructing a cable-stayed bridge in-situ. Background Art

[0002] After an old concrete beam cable-stayed bridge has been in operation for a certain number of years, various damages will inevitably occur to its structure. When it still cannot meet the requirements for safe operation after repair, it needs to be demolished and reconstructed. Given that the service life of concrete beams is relatively short and the construction difficulty is relatively large, steel truss beams are generally used for the main girder of the newly built cable-stayed bridge.

[0003] The conventional idea for demolition and reconstruction is: first demolish the old bridge → clean the site → then build the new bridge. However, the construction period is long. In the case where the river under the bridge is a navigable channel, the occupation time of the waterway is long, which has a great impact on the normal navigation of the river. Summary of the Invention

[0004] The purpose of the present invention is to provide a synchronous construction method for demolishing and reconstructing a low tower cable-stayed bridge in-situ to shorten the construction period and reduce the impact on river navigation in view of the above problems.

[0005] The technical solution of the present invention is as follows:

[0006] A synchronous construction method for demolishing and reconstructing a low tower cable-stayed bridge in-situ, the cable-stayed bridge is of a double-tower structure, including a main span and two side spans. The main girder of the old bridge is of a concrete continuous beam structure, and the main girder of the new bridge adopts a steel truss beam. It is characterized by including the following steps:

[0007] (1) On the outer sides of the two side spans of the old bridge, construct steel trestles as temporary passageways for construction personnel from both banks towards the river respectively; longitudinally along the river, erect assembly supports for the main girder of the new bridge on both sides of each bridge tower of the old bridge, and at the same time erect side span supports under the cast-in-place sections of the side spans of the old bridge.

[0008] (2) Use a deck crane to release the closure section of the main span of the old bridge; use a floating crane to release the closure section of the side span of the old bridge, and at the same time demolish the cast-in-place section of the side span of the old bridge.

[0009] (3) Use a deck crane to symmetrically demolish the main girder segments of the main span and side spans of the old bridge, and remove the corresponding stay cables. At the same time, use a floating crane to assemble the main girder of the new bridge on the assembly support of the new bridge from the far end towards the main tower. Assemble a side span main girder on the assembly support on one side of each main tower, and assemble half of the main span main girder on the assembly support on the other side. The main girder of the new bridge above the main tower cap is not assembled first, leaving space for the demolition of the old cap and the construction of the new cap.

[0010] (4) After the demolition of the main girder of the old bridge is completed, install a tower crane on the main tower cap of the old bridge, and use the tower crane to demolish the main tower of the old bridge; after the demolition of the main tower of the old bridge, remove the tower crane.

[0011] (5) Demolish the old bridge cap, construct a new bridge cap in situ, and install a horizontal rotation turntable on the new cap.

[0012] (7) Install a tower crane on the new cap, and use the tower crane to construct the main tower of the new bridge. The new main tower is supported on the said turntable.

[0013] (8) Use the tower crane to install all the stay cables on the new main tower, and then demolish the tower crane; use a floating crane to assemble the remaining main girders of the new bridge and complete the permanent connection between the main girder and the main tower; connect all the stay cables to the steel truss girder and tension them; unload the formwork support of the new bridge main girder, and conduct system conversion. The vertical force of the new bridge is supported by the turntable.

[0014] (9) Rotate the new bridge main girder into place and lock the turntable.

[0015] (10) Use a floating crane to install the mid-span closure segment and the side-span closure segment to complete the in-situ reconstruction construction of the cable-stayed bridge.

[0016] The present invention is applicable to the in-situ demolition and reconstruction construction of a low tower cable-stayed bridge. While demolishing the old bridge, the main girders of the new cable-stayed bridge are assembled longitudinally along the river on both sides of the tower position. After the old tower cap and tower column are demolished, a new cap is constructed in situ, a turntable is installed on the cap, the cable tower of the new bridge is constructed on the turntable, the stay cable connection between the cable tower and the main girder is completed, then the new bridge main girder is rotated into place, and finally the new bridge main girder is closed to complete the construction of the new bridge. Since there is no conflict between the old bridge demolition construction and the new bridge main girder assembly position, the demolition and construction can be carried out simultaneously, which can greatly shorten the construction period and reduce the time occupying the main navigation channel. Brief Description of the Drawings

[0017] Figure 1 is the construction flow chart of the present invention;

[0018] Figure 2 is the side view along the bridge direction of the trestle, side-span support and new bridge main girder assembly support erected;

[0019] Figure 3 is the plane structure schematic diagram of the trestle, side-span support and new bridge main girder assembly support erected;

[0020] Figure 4 is the side view state schematic diagram of demolishing the mid-span closure segment, side-span closure segment and side-span cast-in-place segment of the old bridge;

[0021] Figure 5 is the side view of demolishing the old bridge main girder and simultaneously assembling the new bridge main girder;

[0022] Figure 6 is the plane state schematic diagram of demolishing the old bridge main girder and simultaneously assembling the new bridge main girder;

[0023] Figure 7 is the state schematic diagram of the tower crane demolishing the old bridge main tower.

[0024] Figure 8 It is a side view structure schematic diagram after the construction of the new bridge main tower caisson is completed;

[0025] Figure 9 It is a plan view structure schematic diagram after the construction of the new bridge main tower caisson is completed;

[0026] Figure 10 It is a state schematic diagram of the tower crane constructing the new bridge main tower;

[0027] Figure 11 It is a longitudinal side view of the new bridge main tower and the new bridge main beam connected by stay cables;

[0028] Figure 12 It is a plan view structure schematic diagram of the new bridge main tower and the new bridge main beam connected by stay cables;

[0029] Figure 13 It is a longitudinal side view along the river of the new bridge main beam and the new bridge main tower connected by stay cables;

[0030] Figure 14 It is a state schematic diagram during the horizontal rotation process of the new bridge main beam;

[0031] Figure 15 It is a top view state schematic diagram after the new bridge main beam is horizontally rotated in place;

[0032] Figure 16 It is a side view state schematic diagram after the new bridge main beam is horizontally rotated in place;

[0033] Figure 17 It is a side view state schematic diagram of the state when the new bridge construction is completed. Specific implementation manners

[0034] The method of the present invention is described below through a specific embodiment. In this embodiment, a cable-stayed bridge spanning a navigable river is a double-tower structure, including a main span and two side spans. Due to structural aging and inability to be completely repaired, it is necessary to demolish and reconstruct a new cable-stayed bridge in situ. The old bridge main beam is a concrete continuous beam structure, and the new bridge main beam adopts a steel truss beam. To shorten the construction period and reduce the impact time on river navigation, the method of the present invention is used for construction, and the construction process is as Figure 1 shown, and the specific construction method is as follows:

[0035] (1) As Figure 2 、 Figure 3 shown, on the outer sides of the two side spans of the old bridge, steel trestles 1 are constructed from both banks towards the river as temporary passages for construction equipment and personnel; new bridge main beam assembly brackets 3 are respectively erected on both sides of each old bridge main tower 2 along the longitudinal direction of the river; side span brackets 4 are erected below the side span cast-in-place section of the old bridge for temporarily supporting the side span cast-in-place section when the side span closure section of the old bridge is demolished;

[0036] (2) As Figure 4 shown, use the deck crane 5 to release the closure segment of the main span of the old bridge; use the floating crane 6 to release the closure segment of the side span of the old bridge, and at the same time demolish the cast-in-place segment of the side span of the old bridge;

[0037] (3) As Figure 5 、 Figure 6 shown, use the deck crane 5 to symmetrically demolish the main span and side span main girders 7 of the old bridge in segments, and demolish the corresponding stay cables 8 of the old bridge. At the same time, use the floating crane 6 to assemble the new bridge main girder 9 on the new bridge main girder erection bracket 3 from the far end towards the main tower. Assemble one side span main girder on the erection bracket on one side of each main tower, and assemble half of the main span main girder on the erection bracket on the other side. Do not assemble the new bridge main girder above the main tower cap first, leaving space for the demolition of the old cap and the construction of the new cap;

[0038] (4) As Figure 7 shown, after the demolition of the old bridge main girder is completed, install a tower crane 11 on the old bridge main tower cap 10, and use the tower crane 11 to demolish the old bridge main tower 2; after the demolition of the old bridge main tower, demolish the tower crane;

[0039] (5) As Figure 8 、 Figure 9 shown, demolish the old bridge cap, then construct the new bridge cap 12 in place, and install a slewing turntable 13 in the middle of the top of the new cap 12;

[0040] (7) As Figure 10 shown, install a tower crane 11 on the new cap 12, and use the tower crane to construct the new bridge main tower 14. The bottom of the new bridge main tower 14 is supported on the turntable 13 on the cap; use the tower crane to install all the new bridge stay cables 15 on the new main tower 14, and then demolish the tower crane;

[0041] (8) As Figure 11 、 Figure 12 、 Figure 13 shown, use the floating crane to assemble the remaining new bridge main girder 9, that is, the new bridge main girder above the cap, and complete the permanent connection between the new main girder 9 and the new main tower 14; connect and tension all the new stay cables 15 to the new main girder 9; unload the new bridge main girder erection bracket, so that the top height of the main girder erection bracket 3 is reduced and separated from the new bridge main girder 9, realizing the system conversion, and the vertical force of the new bridge is supported by the turntable 13;

[0042] (9) As Figure 14 、 Figure 15 、 Figure 16 shown, use the traction device to traction the new bridge main girder for slewing. When the new bridge main girder 9 slews, the main tower 14 rotates together. After the new bridge main girder 9 is slewed in place, lock the turntable 13;

[0043] (10) As Figure 17As shown in the figure, a floating crane is used to install the mid-span closure segment 16 and the side-span closure segment 17 of the new bridge, completing the in-situ reconstruction construction of the cable-stayed bridge.

Claims

1. A method for synchronous demolition and construction of an in-situ reconstructed low tower cable-stayed bridge. The cable-stayed bridge has a double-tower structure, including a main span and two side spans. The main beam of the old bridge is a concrete continuous beam structure, and the main beam of the new bridge uses a steel truss beam; it is characterized in that, It includes the following steps: (1) On the outer sides of the two side spans of the old bridge, construct steel trestles from both banks towards the river as temporary passageways for construction workers; longitudinally along the river, erect new bridge main girder assembly supports on both sides of each old bridge tower, and at the same time, erect side span supports under the cast-in-place sections of the old bridge side spans; (2) Use a deck crane to release the closure section of the main span of the old bridge; use a floating crane to release the closure section of the side span of the old bridge, and at the same time, demolish the cast-in-place section of the old bridge side span; (3) Use a deck crane to symmetrically demolish the main span and side span main girder segments of the old bridge, and demolish the corresponding stay cables. At the same time, use a floating crane to assemble the new bridge main girder on the new bridge main girder assembly support from the far end towards the main tower. Assemble one side span main girder on the assembly support on one side of each main tower, and assemble half of the main span main girder on the assembly support on the other side. The new bridge main girder above the main tower cap is not assembled first, leaving space for the demolition of the old cap and the construction of the new cap; (4) After the demolition of the old bridge main girder is completed, install a tower crane on the old bridge main tower cap, and use the tower crane to demolish the old bridge main tower; after the demolition of the old bridge main tower, demolish the tower crane; (5) Demolish the old bridge cap, construct a new bridge cap in-situ, and install a slewing turntable on the new cap; (7) Install a tower crane on the new cap, and use the tower crane to construct the new bridge main tower. The new main tower is supported on the said turntable; (8) Use the tower crane to install all the stay cables on the new main tower, and then demolish the tower crane; use a floating crane to assemble the remaining main girder of the new bridge and complete the permanent connection between the main girder and the main tower; connect all the stay cables to the steel truss girder and tension them; unload the new bridge main girder assembly support and perform system conversion. The vertical force of the new bridge is supported by the turntable; (9) Rotate the new bridge main girder into place and lock the turntable; (10) Use a floating crane to install the mid-span closure section and the side span closure section to complete the in-situ reconstruction construction of the cable-stayed bridge.

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