A construction method for strengthening a bridge by in-situ active underpinning applicable to navigable waters

Abstract

The present application discloses a construction method for in-situ active replacement and reinforcement of a bridge applicable to navigable waters. By constructing a peripheral cofferdam, all the original bridge piers at the intersection of the tunnel extension direction and the bridge extension direction are enclosed within the peripheral cofferdam, the water inside the cofferdam is drained, and preparations are made for in-situ active replacement construction; then a replacement raft foundation and a replacement circular bridge pier are newly built. The replacement circular bridge pier is arranged around the periphery of the original bridge pier to expand the diameter of the original bridge pier. The replacement circular bridge piers corresponding to each original bridge pier are all arranged above the replacement raft foundation, and the replacement raft foundation plays a supporting role for the replacement circular bridge pier; a space is reserved between the top of the replacement circular bridge pier and the bottom of the bridge body, and a jack with a self-locking function is installed at the reserved space. The jack pre-lifts the end beam position at the bottom of the bridge body. When the bridge pile foundation settles during the construction stage, the height position of the bridge body is adjusted through the jack. The present application has the effect of reducing the occupation of the river channel by the replacement system.

Description

Technical Field

[0001] This application relates to the field of bridge pile foundation underpinning construction, and in particular to a method for in-situ active underpinning bridge reinforcement construction applicable to navigable waters. Background Art

[0002] During the construction of shield tunnels, there will be cases where the tunnel passes under an old bridge. The bridge piles hinder the excavation of the shield machine tunnel. Then, it is necessary to cut off the bottom of the bridge piles. To avoid the settlement of the bridge during the construction process, it is necessary to carry out pile foundation underpinning for the bridge. By driving piles on both sides of the bridge and building an underpinning system to meet the bearing capacity requirements of the bridge.

[0003] However, in the construction environment of narrow navigable waters, the conventional underpinning system occupies a wide range of space, affecting normal navigation. Therefore, there is still room for improvement. Summary of the Invention

[0004] In order to reduce the occupation of the river channel by the underpinning system, this application provides a method for in-situ active underpinning bridge reinforcement construction applicable to navigable waters.

[0005] A method for in-situ active underpinning bridge reinforcement construction provided by this application adopts the following technical solutions:

[0006] A method for in-situ active underpinning bridge reinforcement construction applicable to navigable waters includes the following steps:

[0007] S1: Preliminary preparation: Carry out the construction of the peripheral cofferdam, enclose all the original bridge piles at the intersection of the tunnel extension direction and the bridge extension direction within the peripheral cofferdam, drain the water inside the cofferdam, and prepare for the in-situ active underpinning construction.

[0008] S2: In-situ active underpinning construction: Build a new underpinning raft foundation and an underpinning circular bridge pier. The underpinning circular bridge pier is arranged around the outer periphery of the original bridge pile to expand the diameter of the original bridge pile. Each underpinning circular bridge pier corresponding to the original bridge pile is arranged above the underpinning raft foundation, and the underpinning raft foundation plays a supporting role for the underpinning circular bridge pier; both the underpinning raft foundation and the underpinning circular bridge pier can move relative to the original bridge pile; Leave a space between the top of the underpinning circular bridge pier and the bottom of the bridge body, install a jack with a self-locking function at the reserved space, and the jack pre-lifts the end beam position at the bottom of the bridge body. When the bridge pile foundation settles during the construction stage, the height position of the bridge body is adjusted through the jack.

[0009] By adopting the above technical solutions, the underpinning raft foundation and the underpinning circular bridge pier play a supporting role for the bridge body, achieving the purpose of in-situ active underpinning, reducing the occupation of the river channel by the underpinning system, which is conducive to normal navigation. At the same time, both the underpinning raft foundation and the underpinning circular bridge pier can be displaced relative to the original bridge piles. During the construction process, when the original bridge piles settle, the underpinning raft foundation and the underpinning circular bridge pier can provide supporting force for the bridge body through the preloading of the jacks and can be adjusted in time through the jacks, which is beneficial to reducing the impact of shield construction on the bridge body.

[0010] Preferably, in the step S1, after the steel pipe piles of the peripheral cofferdam are driven and the water inside the peripheral cofferdam is drained, steel pipe piles are respectively driven around several original bridge piles to be cut, and an inner cofferdam is formed around the original bridge piles to be cut. The top position of the inner cofferdam is lower than the top position of the peripheral cofferdam; in the step S2, the underpinning foundation pit is excavated inside the inner cofferdam, and the underpinning raft foundation and the underpinning circular bridge pier are constructed at the underpinning foundation pit.

[0011] When actively underpinning the original bridge piles on the inner side of the bridge body under the construction conditions of three bridges, due to the limitation of the clearance under the bridge, it is not easy to drive the steel pipe piles of the cofferdam. By adopting the above technical solutions, all the original bridge piles are enclosed by the peripheral cofferdam first, and then the water inside the peripheral cofferdam is pumped dry to reduce the clearance limitation under the bridge. Then, a local inner cofferdam is constructed around the original bridge piles to be cut, and then the underpinning foundation pit is excavated for the construction of the underpinning raft foundation and the underpinning circular bridge pier.

[0012] Preferably, before the construction of the underpinning raft foundation in the step S2, the bottom of the underpinning foundation pit is reinforced by jet grouting to strengthen the supporting effect of the bottom of the underpinning foundation pit on the underpinning raft foundation.

[0013] By adopting the above technical solutions, it is beneficial to improve the supporting effect of the bottom of the underpinning foundation pit on the underpinning raft foundation.

[0014] Preferably, in the step S2, before installing the jacks, concrete pads are first poured at the bottom of the end beam, and the top of the jacks is jacked against the bottom of the concrete pads.

[0015] By adopting the above technical solutions, the concrete pads play a protective role for the end beam of the bridge body, which is beneficial to improving problems such as cracking of the end beam of the bridge body caused by preloading and adjustment of the jacks.

[0016] Preferably, in the step S2, the original bridge piles and the concrete pads are connected by planting steel bars.

[0017] By adopting the above technical solutions, it is beneficial to improve the connection between the concrete pads and the original bridge piles.

[0018] Preferably, during the construction of the underpinning raft foundation and the underpinning circular bridge pier in S2, a layer of foam board is first wrapped around the outer periphery of the original bridge pile to separate the original bridge pile from the cast-in-place structures of the newly built underpinning raft foundation and the underpinning circular bridge pier.

[0019] By adopting the above technical solution, it is ensured that there is no adhesion between the concrete of the original bridge pile and the cast-in-place structure, so as to ensure that the original bridge pile and the completed outer structure can move relative to each other, so that the newly built underpinning raft foundation and the underpinning circular bridge pier do not undergo synchronous settlement with the original bridge pile, facilitating the adjustment operation using a jack.

[0020] Preferably, after the in-situ active underpinning construction in S2 and the tunnel shield excavation construction are completed, the jacks are filled and cast in the reserved space between the concrete cushion plate and the underpinning circular pier, and the underpinning circular pier, the original bridge pile and the concrete cushion plate form an integral body.

[0021] By adopting the above technical solution, the underpinning circular pier and the underpinning raft foundation become the permanent supporting structures of the bridge, which is beneficial to improving the stability of the bridge body. Description of the Drawings

[0022] Figure 1 is the plan view of the pile foundation underpinning in the in-situ active underpinning bridge reinforcement construction method applicable to navigable waters disclosed in the embodiment of the present application.

[0023] Figure 2 is Figure 1 the cross-sectional view in the A-A direction in

[0024] Description of the reference numerals: 1, peripheral cofferdam; 2, inner cofferdam; 3, original bridge pile; 4, tunnel shield excavation direction; 5, bridge body; 51, end beam; 52, concrete cushion plate; 6, underpinning circular bridge pier; 7, underpinning raft foundation; 8, jet grouting pile foundation; 81, cushion layer; 9, jack. Detailed Description of the Embodiment

[0025] The following is a further detailed description of the present application in combination with the attached Figure 1-2 drawings.

[0026] The embodiment of the present application discloses an in-situ active underpinning bridge reinforcement construction method applicable to navigable waters. An in-situ active underpinning bridge reinforcement construction method applicable to navigable waters includes the following steps:

[0027] S1: Preliminary preparation: Construct the peripheral cofferdam 1 to enclose all the original bridge piles 3 at the intersection of the tunnel shield excavation direction 4 and the bridge extension direction within the peripheral cofferdam 1, drain the water inside the peripheral cofferdam 1, and build a temporary access road to meet the needs of subsequent construction machinery transportation, material transportation, personnel passage, etc.

[0028] Due to the active jacking construction of the original bridge piles 3 inside the bridge body 5 under three bridge construction conditions, restricted by the under-bridge clearance, it is not easy to drive the cofferdam steel pipe piles. Therefore, after driving the steel pipe piles of the peripheral cofferdam 1 and dewatering the water inside the peripheral cofferdam 1, steel pipe piles are respectively driven around several original bridge piles 3 to be cut off, and an inner cofferdam 2 is formed around the original bridge piles 3 to be cut off. The steel sheet piles of the inner cofferdam 2 are driven by the screen method. First, use a crane to lift the steel sheet piles to the pile driving point for pile driving. Among them, the top position of the inner cofferdam 2 is lower than the top position of the peripheral cofferdam 1. The inner cofferdam 2 is supported by type III Larssen steel sheet piles, and the length of the steel sheet piles is 9m. Prepare for in-situ active jacking construction.

[0029] S2: In-situ active jacking construction: First, carry out the excavation construction of the jacking foundation pit inside the inner cofferdam 2, and set a steel section support inside the foundation pit. The excavation depth of the jacking foundation pit is 4.9m, and the under-bridge clearance of the jacking foundation pit is about 14m x 9m. Then, carry out the construction of the jacking raft foundation 7 and the jacking circular bridge pier 6 at the jacking foundation pit.

[0030] Before constructing the jacking raft foundation 7, first carry out the reinforcement construction of the jet grouting pile foundation 8 at the bottom of the jacking foundation pit to strengthen the supporting effect of the bottom of the jacking foundation pit on the jacking raft foundation 7, and then lay a C20 plain concrete cushion 81 on the jet grouting pile foundation 8.

[0031] The formwork for pouring the jacking raft foundation 7 is made of bamboo plywood. The lower structure reinforcement system uses the temporary foundation pit steel sheet piles as the external formwork support body, and the formwork is reinforced between the steel sheet piles and the structure body; the upper structure reinforcement system uses 50mm x 100mm square wood secondary ribs with a spacing of 300mm + 48mm x 3.5mm steel pipe main ribs with a spacing of 600mm + a14 tie bolts, and finally uses 48mm x 3.5mm steel pipes + jack supports for diagonal bracing with a spacing of 1200mm.

[0032] The formwork for pouring the jacking raft foundation 7 is made of bamboo plywood. The jacking circular bridge pier 6 is surrounded outside the original bridge pile 3 to expand the diameter of the original bridge pile 3. The jacking circular bridge piers 6 corresponding to each original bridge pile 3 are all arranged above the jacking raft foundation 7, and the jacking raft foundation 7 plays a supporting role for the jacking circular bridge pier 6.

[0033] Among them, during the construction of the jacking raft foundation 7 and the jacking circular bridge pier 6, a layer of foam board needs to be covered outside the original bridge pile 3 to separate the original bridge pile 3 from the cast-in-place structures of the newly built jacking raft foundation 7 and the jacking circular bridge pier 6. To ensure that both the jacking raft foundation 7 and the jacking circular bridge pier 6 can move relative to the original bridge pile 3. In addition, for the case where there are tie beams between some adjacent original bridge piles 3, it is necessary to ensure that there is a gap between the tie beam and the cast-in-place structure of the jacking circular bridge pier 6, and the size of the gap should meet the requirement that the jacking circular bridge pier 6 and the original bridge pile 3 can move relative to each other when the height of the bridge body 5 is adjusted by the jack 9.

[0034] Then, a concrete cushion plate 52 is poured at the bottom of the end beam 51 at the lower end of the bridge body 5, and the original bridge pile 3 is connected to the concrete cushion plate 52 by post-inserted bars. A space is reserved between the top of the replacement ring-shaped pier 6 and the concrete cushion plate 52 at the bottom of the bridge body 5, and a jack 9 with a self-locking function is installed at the reserved space. The jack 9 pre-lifts the concrete cushion plate 52 at the position of the end beam 51 at the bottom of the bridge body 5. The purpose of the pre-lifting is to eliminate the adverse effects of the deformation of the replacement new pile on the replacement system, prevent the settlement of the original bridge pile 3 driven by the settlement of the top of the replacement new pile, and test the bearing capacity of the replacement beam replacement system. And when the bridge pile foundation settles during the construction stage, the height position of the bridge body 5 is adjusted by the jack 9.

[0035] Finally, after the in-situ active replacement construction and the tunnel shield excavation construction are completed, the jack 9 is filled and poured into the reserved space between the concrete cushion plate 52 and the replacement ring-shaped pier 6. The replacement ring-shaped pier 6, the original bridge pile 3, and the concrete cushion plate 52 form an integral body, making the replacement ring-shaped pier and the replacement raft foundation 7 the permanent supporting structure of the bridge, which is beneficial to improving the stability of the bridge body.

[0036] The above are all the preferred embodiments of the present application, and the protection scope of the present application is not limited accordingly. Therefore, all equivalent changes made according to the structure, shape, and principle of the present application shall be covered within the protection scope of the present application.

Claims

1. A construction method for in-situ active underpinning and strengthening of bridges applicable to navigable waters, characterized in that: It includes the following steps: S1: Preliminary preparation: Conduct the construction of the peripheral cofferdam to enclose all the original bridge piles at the intersection of the tunnel shield excavation direction and the bridge extension direction within the peripheral cofferdam, drain the water inside the cofferdam, and prepare for the in-situ active underpinning construction; S2: In-situ active underpinning construction: Construct a new underpinning raft foundation and an underpinning annular bridge pier. The underpinning annular bridge pier is arranged around the outer periphery of the original bridge pile to expand the diameter of the original bridge pile. The underpinning annular bridge piers corresponding to each original bridge pile are all arranged above the underpinning raft foundation, and the underpinning raft foundation plays a supporting role for the underpinning annular bridge pier; Both the underpinning raft foundation and the underpinning annular bridge pier can be displaced relative to the original bridge pile; Leave a space between the top of the underpinning annular bridge pier and the bottom of the bridge body. Install a jack with a self-locking function at the reserved space. The jack pre-lifts the end beam position at the bottom of the bridge body. When the bridge pile foundation settles during the construction stage, adjust the height position of the bridge body through the jack.

2. The in-situ active underpinning bridge strengthening construction method applicable to navigable waters according to claim 1, characterized in that: In the step S1, after the steel pipe piles of the peripheral cofferdam are driven and the water inside the peripheral cofferdam is drained, drive steel pipe piles around the outer periphery of several original bridge piles to be cut, and form an inner cofferdam around the outer periphery of the original bridge piles to be cut. The top position of the inner cofferdam is lower than the top position of the peripheral cofferdam; In the step S2, conduct the excavation construction of the underpinning foundation pit inside the inner cofferdam, and construct the underpinning raft foundation and the underpinning annular bridge pier at the underpinning foundation pit.

3. A construction method for in-situ active underpinning bridge reinforcement applicable to navigable waters according to claim 2, characterized in that: Before the construction of the underpinning raft foundation in the step S2, conduct the reinforcement construction of the jet grouting pile foundation at the bottom of the underpinning foundation pit to strengthen the supporting effect of the bottom of the underpinning foundation pit on the underpinning raft foundation.

4. A construction method for strengthening a bridge by in-situ active underpinning applicable to navigable waters according to claim 3, characterized in that: In the step S2, before installing the jack, first pour a concrete cushion at the bottom of the end beam, and the top of the jack abuts against the bottom of the concrete cushion.

5. A construction method for in-situ active underpinning bridge reinforcement applicable to navigable waters, as claimed in claim 4, wherein: In the step S2, connect the original bridge pile and the concrete cushion by planting steel bars.

6. The in-situ active underpinning bridge strengthening construction method applicable to navigable waters according to claim 1, wherein: In the construction of the underpinning raft foundation and the underpinning annular bridge pier in the step S2, first cover a layer of foam board on the outer periphery of the original bridge pile to separate the original bridge pile from the cast-in-place structures of the newly built underpinning raft foundation and the underpinning annular bridge pier.

7. A method for strengthening the construction of an in-situ active replacement bridge applicable to navigable waters according to claim 4, characterized in that: After the completion of the in-situ active underpinning construction in the step S2 and the completion of the tunnel shield excavation construction, fill and pour the jack into the reserved space between the concrete cushion and the underpinning annular pier together, and the underpinning annular pier, the original bridge pile and the concrete cushion form an integral body.

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