A pushing construction method of a steel box girder

Abstract

This invention discloses a method for jacking construction of steel box girders, comprising: ① constructing the substructure of the bridge and erecting an assembly platform; ② assembling the first box unit and jacking it; ③ after the first box unit reaches the predetermined position, installing a longitudinal sliding rail on its top plate; ④ jacking the second box unit on the assembly platform, moving it onto the sliding rail, and pulling it forward to the predetermined position; then, using a positioning device to jack the second box unit laterally, and then lowering it into place; ⑤ following step four, sequentially jacking, shifting, and lowering the remaining box units; ⑥ after all box units are in place, performing transverse system connections; ⑦ constructing the bridge deck system, dismantling all temporary facilities, and completing the entire bridge construction. This invention can reduce the size of the assembly platform, reduce the weight and difficulty of a single jacking operation, and has the advantages of small temporary facility size, high construction efficiency, and low cost of temporary measures.

Description

Technical Field

[0001] This invention relates to the field of bridge engineering construction technology, specifically to a method for jacking construction of large-span steel box girders, which is particularly suitable for steel box girder bridges with transverse multi-cell cross-sections. Background Technology

[0002] Due to their small footprint and ability to effectively solve traffic bottlenecks and improve traffic efficiency, the demand for long-span bridges is increasing. Conventional construction often requires the erection of a large number of temporary support structures and the use of heavy hoisting equipment. However, for bridges crossing rivers, valleys, or intersections where it is inconvenient to erect supports under the bridge, the incremental launching method is often used. This method involves using hydraulic launching equipment to push the steel box girder longitudinally from the assembly platform on one side of the bridge abutment to the designed position on the opposite bank.

[0003] For steel box girders, especially large-section multi-cell steel box girders, traditional jacking construction typically treats the entire girder as a single unit. However, this method has several drawbacks: First, jacking requires installing a considerable length of steel guide beam at the front end to reduce cantilever bending moment. The guide beam itself consumes a large amount of steel, and its installation and dismantling are complex and costly. Second, during jacking, the rear assembly platform needs to cover the entire bridge width, resulting in massive temporary supports, demanding high-level foundation treatment, and consequently increasing project costs and time. Finally, the large weight of the entire steel box girder places extremely stringent requirements on the load-bearing capacity and synchronous control precision of the jacking equipment (such as jacks and temporary piers), leading to significant construction risks and control challenges.

[0004] Therefore, there is an urgent need for a method for launching multi-compartment steel box girders that can reduce temporary facilities, lower construction difficulty, and improve work efficiency. Summary of the Invention

[0005] This invention aims to overcome the shortcomings of existing technologies and provide a method for segmented jacking construction of multi-compartment steel box girders. This method, by breaking down the multi-compartment cross-section into smaller sections and jacking each section sequentially into place, fundamentally avoids the use of a front guide beam, significantly reduces the size of the assembly platform, lowers the weight of a single jacking operation and the construction difficulty, and exhibits significant economic and safety advantages.

[0006] To achieve the above objectives, the present invention can adopt the following technical solutions: The jacking construction method for steel box girders described in this invention is suitable for steel box girders formed by connecting multiple box cell units through transverse systems, and is characterized by comprising the following steps: The first step is to erect an assembly platform at the abutment or the designated starting pier after the construction of the bridge substructure is completed. The second step is to assemble the first compartment unit on the assembly platform and start the jacking device to jack it up; during the jacking process, assemble the second compartment unit and temporarily connect it with the compartment unit in front, so that the two compartment units move forward synchronously. The third step is to install a longitudinal bridge sliding track on the top plate after the first compartment unit reaches the predetermined position. The fourth step is to lift the second box unit on the assembly platform and install the bottom sliding shoe. Then, move the second box unit to the sliding track and slide it forward using the horizontal traction device until it reaches the predetermined position. Remove the bottom sliding shoe of the second box unit, then move the second box unit laterally using the positioning device, and then lower the beam to place it in place. Fifth, following the steps in step four, perform longitudinal bridge-direction jacking, transverse bridge-direction displacement, and beam placement operations on the remaining assembled box cell units. Step 6: After all the compartment units are in place, make lateral connections so that they can share the load. The seventh step involves paving the bridge deck, installing crash barriers, and other bridge deck system construction. Finally, all temporary facilities are removed to complete the entire bridge construction.

[0007] Preferably, the width of the assembly platform is greater than the width of the container unit, and the width difference between the assembly platform and the container unit is 1~2m.

[0008] Preferably, the jacking device in step two is set on the assembly platform and includes a jacking slide system and a walking jacking device.

[0009] Preferably, the sliding track in step three is set on both sides of the top plate of the first compartment unit, including temporary brackets welded to the top plate. The temporary brackets are arranged in two rows at intervals along the longitudinal bridge direction. The temporary brackets are welded to the steel profiles on the top covered with stainless steel plates. The upper surface of the stainless steel plates is uniformly coated with silicone grease.

[0010] Preferably, in step four, the second box unit is lifted by a large-tonnage jack set on the assembly platform. The horizontal traction device is a continuous jack set at the end of the first box unit or on the target pier. The positioning device is a three-dimensional jack, which is installed next to the permanent support or temporary support at the top of the target pier.

[0011] Preferably, the transverse connection in step six includes welding the longitudinal butt joint of the top plate between adjacent compartment units, and fastening the crossbeams on the outer side of the web of adjacent compartment units with high-strength bolts.

[0012] The length of a single box unit in the steel box girder is 50~100m, and the bridge composed of steel box girders is a simply supported or continuous beam structure.

[0013] The steel box girder jacking construction method provided by this invention divides the transverse multi-box steel girder into multiple single-box jackings. First, one box is jacked into place, and then the already jacked steel girder is used as a support to quickly jack the remaining box chambers into place. This avoids the disadvantage of large-scale guide beams and jacking assembly platforms in traditional steel girder jacking construction. It has the advantages of small-scale temporary facilities and low cost. Secondly, because the jacking unit is small, the construction operation is convenient, the construction efficiency is high, and it is easy to quickly erect the steel girder.

[0014] Compared with the prior art, the present invention has the following significant advantages: (1) Completely eliminate the front guide beam: Since the heavy multi-compartment structure is decomposed into light single-compartment units and pushed, the root bending moment under the maximum cantilever state is greatly reduced, and there is no need to set up a long and heavy guide beam, saving about 30% of steel and construction time.

[0015] (2) Significantly reduce the size of the assembly platform: The assembly platform only needs to meet the width of a single compartment unit. Compared with a full-width platform, the temporary support, foundation and floor space are reduced by about 50%, which is especially suitable for narrow construction sites.

[0016] (3) Reduce the difficulty and risk of jacking construction: The single-cell unit is lightweight, has low requirements for the jacking equipment capacity, the jacking process is easier to control, the local stress of the structure is smaller, and the safety is significantly improved.

[0017] (4) Achieve efficient assembly line operation: Form a parallel assembly line of "rear assembly, front jacking, and middle sliding positioning", with less interference between each process, smoother construction organization, and an overall efficiency improvement of about 25%.

[0018] (5) Strong environmental adaptability: It is particularly suitable for engineering scenarios such as crossing busy traffic lines, deep valleys, and wide rivers where it is impossible to build large-scale temporary supports, and has outstanding social and economic benefits. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the steel box girder after the completion of construction of this invention.

[0020] Figures 2a-2h This is a construction step diagram of the present invention.

[0021] Figure 3 yes Figure 2a , Figure 2b Cross-sectional view.

[0022] Figure 4 yes Figure 2c , Figure 2d Cross-sectional view.

[0023] Figure 5 yes Figure 2e Cross-sectional view.

[0024] Figure 6 yes Figure 2f , Figure 2g Cross-sectional view. Detailed Implementation

[0025] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. These embodiments are implemented based on the technical solution of the present invention, and detailed implementation methods and specific construction processes are given. However, the scope of protection of the present invention is not limited to the following embodiments.

[0026] A simply supported steel box girder highway bridge spanning a canal has a main span of 60m, and its cross-section is as follows: Figure 1 As shown, the structure consists of three equal-width box girder units, with the first unit B1, the second unit B2, and the third unit B3 laterally connected by inter-box beams and the bridge deck. During the main span construction, the steel box girder jacking construction method described in this invention is employed, specifically including the following steps: The first step is to complete the construction of the bridge substructure, followed by the erection of assembly platform 1 at the designated starting pier (see...). Figure 2a , Figure 3 Since the steel box girder is a transversely assembled structure, the width of the assembled platform 1 can be greatly reduced compared to a conventional platform, only 1 to 2 meters larger than the width of the box unit. This saves on platform floor space and platform cost.

[0027] The second step involves reinforcing the foundation of assembly platform 1 and assembling the first compartment unit B1 on assembly platform 1. Following this, the jacking operation is commenced. Specifically, this includes installing a jacking slide system and a walking-type jacking device on assembly platform 1, wherein the jacking reaction seat of the walking-type jacking device is installed on the PTFE sliding plate at the bottom of the first compartment unit B1. Once the above work is complete, the jacking device is activated to push the first compartment unit B1 forward out of assembly platform 1 (see...). Figure 2a , Figure 3 ).

[0028] While the first box-cell unit B1 is being jacked up, the second box-cell unit B2 is being assembled on assembly platform 1 and temporarily connected to the web and bottom plate of the front box-cell unit. This allows the two box-cell units to move forward synchronously until the first box-cell unit B1 reaches its predetermined position and is completely positioned on the temporary support of the target pier (see...). Figure 2b , Figure 3 ); To enhance the stability of the steel box girder during placement, temporary supports M were erected on the inner sides of the predetermined starting pier and the target pier, respectively.

[0029] Thirdly, after the first compartment unit B1 is in place, install the longitudinal bridge-oriented sliding track 2 on its top plate (see...). Figure 2c , Figure 4 The aforementioned sliding track 2 is located on both sides of the top plate of the first compartment unit B1, including temporary brackets arranged in two rows. Each row of temporary brackets is spaced apart and welded to the top plate. The top of the temporary brackets is fitted with steel as the sliding main beam. The top surface of the main beam is fully covered and fixed with a 3mm thick stainless steel plate. Then, silicone grease is evenly applied to the surface of the stainless steel plate.

[0030] Fourth, using the large-tonnage jacks 3 on the assembly platform 1, the assembled second compartment unit B2 is lifted as a whole, and a sliding shoe with a PTFE plate is installed at its bottom. Then, the second compartment unit B2 is moved and lowered onto the sliding track 2 on top of the first compartment unit B1 (see...). Figure 2c , Figure 4 ).

[0031] Two continuous jacks are installed on the crossbeam at the end of the first compartment unit B1 furthest from the assembly platform 1 as a horizontal traction device. The steel strands of the continuous jacks are connected to the second compartment unit B2, allowing it to slide smoothly forward along the sliding track 2 on the top of the first compartment unit B1 until the longitudinal projection position of the second compartment unit B2 matches the design (see...). Figure 2d , Figure 4 ).

[0032] A three-dimensional hydraulic jack is placed next to the permanent support at the top of the target pier as a positioning device, and the bottom slipper of the second box-cell unit B2 is removed. The horizontal hydraulic cylinder of the three-dimensional hydraulic jack is operated to precisely move the second box-cell unit B2 laterally to the designed bridge position. Then, the vertical hydraulic cylinder of the three-dimensional hydraulic jack is used to slowly lower the beam, placing the second box-cell unit B2 onto the permanent support, and temporarily limiting its position with steel wedges (see...). Figure 2e , Figure 5 ).

[0033] Fifth, following step four, perform longitudinal bridge jacking, transverse bridge displacement, and beam placement operations on the third box cell unit B3 (see...). Figure 2f , Figure 6 If the steel box girder consists of more than three box cell units, then follow step four to perform longitudinal bridge jacking, transverse bridge displacement, and girder placement work on the remaining box cell units.

[0034] Step 6: After all the compartment units are in place, perform transverse system connections to ensure they share the load. This includes welding the longitudinal butt joints 4 of the top plates between adjacent compartment units, and fastening the transverse beams on the outer side of the web plates of adjacent compartment units with high-strength bolts 5 (see...). Figure 2f , Figure 6 ).

[0035] Step 7: Carry out bridge deck paving (6), crash barrier (7), and other bridge deck system construction, and finally dismantle all temporary facilities (see...). Figure 1 ), and completed the construction of the entire bridge.

[0036] The steel beam jacking construction method described in this invention is suitable for simply supported beams or continuous beams with a main span of 50-100m. It addresses situations where it is inconvenient to erect scaffolding under the bridge, such as when the main span crosses rivers, valleys, or intersecting roads. By designing the main span box girder into multiple transversely connected box units, each box unit is jacked separately, thereby reducing the size of the assembly platform, lowering the weight of a single jacking operation, and reducing construction difficulty. It has advantages such as small temporary facility size, high construction efficiency, and low cost of temporary measures, and has broad application prospects in the construction of steel beams crossing rivers, valleys, and intersecting roads.

[0037] It should be noted that in the description of this invention, terms such as "front," "rear," "left," "right," "vertical," "horizontal," "inner," and "outer" indicating orientation or positional relationships are based on the orientation or positional relationships shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

Claims

1. A method for jacking construction of a steel box girder, suitable for steel box girders formed by connecting multiple box cell units through transverse systems, characterized in that, Includes the following steps: The first step is to erect an assembly platform at the abutment or the designated starting pier after the construction of the bridge substructure is completed. The second step is to assemble the first compartment unit on the assembly platform and start the jacking device to jack it up; during the jacking process, assemble the second compartment unit and temporarily connect it with the compartment unit in front, so that the two compartment units move forward synchronously. The third step is to install a longitudinal bridge sliding track on the top plate after the first compartment unit reaches the predetermined position. The fourth step is to lift the second box unit on the assembly platform and install the bottom sliding shoe. Then, move the second box unit to the sliding track and slide it forward using the horizontal traction device until it reaches the predetermined position. Remove the bottom sliding shoe of the second box unit, then use the positioning device to lift the second box unit to move it laterally, and then perform the beam lowering operation to put it in place. Fifth, following the steps in step four, perform longitudinal bridge-direction jacking, transverse bridge-direction displacement, and beam placement operations on the remaining assembled box cell units. Step 6: After all the compartment units are in place, make lateral connections so that they can share the load. The seventh step involves paving the bridge deck, installing crash barriers, and other bridge deck system construction. Finally, all temporary facilities are removed to complete the entire bridge construction.

2. The method for jacking construction of steel box girders according to claim 1, characterized in that: The width of the assembly platform is greater than the width of the container unit, and the width difference between the assembly platform and the container unit is 1~2m.

3. The method for jacking steel box girders according to claim 1, characterized in that: The jacking device in step two is set on the assembly platform and includes a jacking slide system and a walking jacking device.

4. The method for jacking steel box girders according to claim 1, characterized in that: The sliding track in step three is set on both sides of the top plate of the first compartment unit, including temporary brackets welded to the top plate. The temporary brackets are arranged in two rows at intervals along the longitudinal bridge direction. The temporary brackets are welded to the steel profiles on the top covered with stainless steel plates. The upper surface of the stainless steel plates is uniformly coated with silicone grease.

5. The method for jacking steel box girders according to claim 1, characterized in that: In step four, the second box unit is lifted using a large-tonnage jack set on the assembly platform. The horizontal traction device is a continuous jack set at the end of the first box unit or on the target pier. The positioning device is a three-dimensional jack, which is installed next to the permanent support or temporary support at the top of the target pier.

6. The method for jacking steel box girders according to claim 1, characterized in that: The transverse connection in step six includes welding the longitudinal butt joint of the top plate between adjacent compartment units, and fastening the crossbeams on the outer side of the web of adjacent compartment units with high-strength bolts.

7. The method for jacking construction of steel box girders according to claim 1, characterized in that: The length of a single box unit in the steel box girder is 50~100m, and the bridge composed of steel box girders is a simply supported or continuous beam structure.

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