Construction method of steel box girder overpassing subway line

Abstract

The present application belongs to the field of bridge construction technology, and discloses a steel box girder construction method for overpassing a subway line. When the steel box girder overpasses the subway line, multiple steel box girders are sequentially welded in the assembling area. Then, during the window period of the subway line, the combined box girder is hoisted and erected on the supporting base. A connecting structure is arranged between the girder member and the combined box girder, so as to temporarily fix the combined box girder. Then, during the next window period of the subway line, the connecting structure is disassembled, the combined box girder is hoisted to directly above the construction interval section, and the two ends of the combined box girder are erected on the supports of the constructed bridge on both sides of the construction interval section. Finally, the combined box girder is welded with the girder member of the constructed bridge. The steel box girder construction method for overpassing the subway line section of the bridge can avoid affecting the normal operation of the subway line and damaging the operating equipment due to the falling of welding slag, and has strong safety.

Description

Technical Field

[0001] This invention relates to the field of bridge construction technology, and in particular to a method for constructing a steel box girder that crosses a subway line. Background Technology

[0002] Steel box girders are steel beams welded or bolted together to form a closed hollow box-shaped cross-section. They have advantages such as light weight, low foundation cost, high torsional stiffness, and excellent seismic performance, and are widely used in urban elevated bridges and interchange ramps. With the development of urban three-dimensional transportation networks, a large number of newly built elevated or interchange bridges need to cross over existing operating subway lines.

[0003] Currently, when a bridge crosses an existing operational subway line, the usual practice is to control the hoisting equipment to lift multiple steel box girders segment by segment directly above the subway line, and then weld the segments sequentially. Alternatively, the multiple steel box girders of the crossing section can be welded into a single box girder on the ground, and then the hoisting equipment can be used to lift and install the single box girder during the subway's non-operational hours. However, both of these construction methods have drawbacks. The first method will affect the normal operation of the subway line, and the welding work at high altitudes is susceptible to poor weld quality due to external factors such as temperature and wind speed. Furthermore, the welding slag and other debris generated during the welding process can easily fall onto the subway's overhead contact system, tracks, and other operating equipment, posing a significant risk of damage. While the second method can avoid damage to the subway's operating equipment from welding slag, the single box girder is large in size and weight, and the entire hoisting, positioning, and adjustment process is time-consuming. The hoisting and installation time may exceed the subway's effective nighttime maintenance window, thus affecting the subway line's operation. Summary of the Invention

[0004] The purpose of this invention is to provide a construction method for steel box girders that cross subway lines, which can avoid affecting the normal operation of the subway lines and prevent welding slag from falling and damaging operating equipment, thus having strong safety.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A construction method for a steel box girder crossing a subway line is provided, including the following steps: S1. Determine the section of the bridge that crosses the subway line and designate this section as a construction section. Both ends of the construction section are horizontally offset from the subway line. Both ends of the construction section have other sections of the bridge already constructed. Calculate and determine the number of steel box girders required for the construction section. S2. Based on the distribution of the subway lines and the section distribution of the bridges that have been constructed, the construction site is divided into an assembly area and a hoisting area. S3. Arrange the hoisting equipment in the hoisting area, and install multiple support devices at intervals in the assembly area. The support devices are adjustable in vertical height. S4. Control the hoisting equipment to hoist any of the steel box girders and place the bottom of the steel box girder on at least two of the supporting devices. Adjust the vertical height of the two supporting devices according to the camber of the bottom of the steel box girder and the position of the two supporting devices so that the upper surface of the steel box girder is arranged in the horizontal direction. S5. Repeat step S4 and place the newly erected steel box girder on one side of the previous steel box girder until all the steel box girders are arranged. Weld any two adjacent steel box girders to connect all the steel box girders into a composite box girder. S6. Multiple support bases are spaced apart on the beam members of the bridge section that has been constructed on any side of the construction section, and the vertical height of the multiple support bases is set according to the camber of the bottom of the composite box girder. S7. During the maintenance window of the subway line, control the hoisting equipment to vertically lift the composite box girder to a first preset height, and hoist and erect the composite box girder on multiple support bases so that the upper surface of the composite box girder is arranged in the horizontal direction; S8. A connecting structure is provided between the beam member and the composite box girder to fix the composite box girder; S9. During the maintenance window of the next subway line, disassemble the connecting structure, control the hoisting equipment to hoist the composite box girder to the top of the construction section, and place both ends of the composite box girder on the supports of the constructed bridge on both sides of the construction section. S10. Weld the two ends of the composite box girder to the beam components of the bridge that have been constructed on both sides.

[0006] Optionally, step S10 specifically includes the following steps: S101. Protective components are respectively installed below both ends of the combined box girder, and the protective components are directly opposite the ends of the combined box girder for receiving debris. S102. Weld the two ends of the composite box girder to the beam components of the bridge that have been constructed on both sides.

[0007] Optionally, after step S2 is executed and before step S3 is executed, step S30 is executed, which specifically includes the following steps: S301. Determine the model of the hoisting equipment based on the number of steel box girders, and construct multiple foundation reinforcement piles in the stratum of the hoisting area to ensure that the bearing capacity of the foundation in the hoisting area meets the load-bearing requirements of the hoisting equipment. S302. Set the projection areas of the assembly area, the hoisting area and the construction section as warning areas, and set up warning and restraining elements along the circumference of the warning areas.

[0008] Optionally, the support device includes a support base, a top support mechanism, and multiple support rods. The support base is stacked on the ground, and the housing of the top support mechanism is installed on the support base. The output end of the top support mechanism can extend and retract vertically and can abut against the steel box girder. The multiple support rods are respectively disposed on both sides of the top support mechanism. The two ends of each support rod are connected to the support base and the housing of the top support mechanism, respectively. The support rods on both sides of the top support mechanism extend upward at an angle along the side closest to each other.

[0009] Optionally, step S4 specifically includes the following steps: S41. Control the hoisting equipment to hoist any of the steel box girders, and place the bottom of the steel box girder on the top support mechanism of at least two of the supporting devices; S42. Based on the camber of the bottom of the steel box girder and the positions of the two support devices, control the output end of the top support mechanism to extend or retract, so that the top support mechanism drives the steel box girder to move vertically until the upper surface of the steel box girder is laid out horizontally.

[0010] Optionally, multiple supporting and reinforcing frames are spaced apart below the beam members of the constructed bridge section, and the upper end of each supporting and reinforcing frame abuts against the beam member. After step S5 and before step S6, step S60 is carried out, which specifically includes the following steps: S601. Calculate the bearing capacity of the beam members of the constructed bridge section, and determine the number of the supporting and reinforcing frames below the beam members based on the bearing capacity and the weight of the composite box girder. S602. Install multiple supporting and reinforcing frames at intervals below the beam components.

[0011] Optionally, the connection structure includes a tension member and multiple connecting plates, and step S8 specifically includes the following steps: S81. Multiple connecting plates are disposed on both sides of the composite box girder. Multiple connecting plates on each side of the composite box girder are spaced apart along the length direction of the composite box girder. The two ends of each connecting plate are welded to the composite box girder and the beam component, respectively. S82. The two ends of the composite box girder are provided with the traction member, and the traction member is wrapped around the composite box girder and the beam component and tied and fixed.

[0012] Optionally, the first preset height is greater than the vertical height of the contact wire of the subway line, and the difference between the two is greater than or equal to 3m.

[0013] Optionally, step S9 specifically includes the following steps: S91. During the maintenance window of the next subway line, disassemble the connecting structure, control the hoisting equipment to vertically lift the composite box girder to the second preset height, and move it horizontally along the composite box girder to directly above the construction section. S92. Along the vertically downward composite box girder, the two ends of the composite box girder are respectively erected on the supports of the constructed bridge on both sides of the construction section, and the actual elevation of the composite box girder is detected by measuring equipment; S93. Compare and determine whether the difference between the actual elevation and the design elevation of the composite box girder is greater than or equal to the control error value. If yes, proceed to S10; otherwise, proceed to S94. S94. Control the hoisting equipment to adjust the position of the composite box girder until the measuring equipment detects that the difference between the actual elevation and the design elevation of the composite box girder is less than the control error value, and then execute S10.

[0014] Optionally, the second preset height is greater than the design elevation of the combined box girder, and the difference between the two is greater than or equal to 50cm, and the control error value is 2mm.

[0015] The beneficial effects of this invention are: This invention provides a construction method for steel box girders crossing subway lines. When constructing steel box girders for bridge sections crossing subway lines, multiple steel box girders are welded and spliced ​​in the ground assembly area. Then, during the subway line's maintenance window, the welded composite box girder is hoisted and erected on multiple support bases. A connecting structure is set between the beam components and the composite box girder to temporarily fix the composite box girder, allowing it to be stably placed on the already constructed bridge section. Then, during the next subway line's maintenance window, the connecting structure is disassembled, and the composite box girder is hoisted directly above the construction section, with both ends erected on the supports of the already constructed bridge on both sides of the construction section. Finally, the composite box girder is welded to the beam components of the already constructed bridge.

[0016] By welding multiple steel box girders in the ground assembly area, welding of the steel box girders at high altitudes is eliminated, preventing environmental factors from affecting welding quality and avoiding welding slag from falling onto the subway line's operating equipment, thus ensuring strong safety. The integrated composite box girder is hoisted and installed in two stages, avoiding the disruption to normal subway line operations caused by long single hoisting times. Given that both ends of the construction section are horizontally offset from the subway line, and the composite box girder faces the construction section with its ends supported by existing bridge supports on both sides of the construction section, the horizontal offset distribution of the composite box girder from the subway line ensures that welding slag from the composite box girder and beam components will not affect the subway line's operating equipment. Attached Figure Description

[0017] Figure 1 This is a flowchart of the construction method for a steel box girder crossing a subway line provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of the hoisting equipment provided in this embodiment of the invention when the combined box girder is separated from the supporting device; Figure 3 This is a schematic diagram of the structure of the hoisting equipment provided in this embodiment of the invention when hoisting the combined box girder to the support base.

[0018] In the picture: 1. Subway lines; 2. Construction section; 3. Bridges; 31. Beam components; 4. Lifting equipment; 5. Support device; 51. Support base; 52. Top support mechanism; 53. Support rod; 6. Composite box girder; 7. Support base; 8. Support and reinforce the frame. Detailed Implementation

[0019] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0020] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0021] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0022] In the description of this embodiment, the terms "upper," "lower," "left," and "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not 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 the present invention. In addition, the terms "first" and "second" are used only for distinction in description and have no special meaning.

[0023] This embodiment provides a construction method for steel box girders crossing subway lines, such as... Figures 1 to 3 As shown, the method of constructing the steel box girder of bridge 3 over the section of subway line 1 can avoid affecting the normal operation of subway line 1 and prevent welding slag from falling and damaging the operating equipment, thus having strong safety.

[0024] The construction method for steel box girders crossing subway lines includes the following steps: S1, see also Figures 1 to 3 As shown, the section of bridge 3 that crosses subway line 1 is determined and this section is designated as construction section 2. Both ends of construction section 2 are horizontally offset from subway line 1. Both ends of construction section 2 have other sections of bridge 3 already constructed. The number of steel box girders required for construction section 2 is calculated and determined. S2, see also Figure 1 As shown, based on the distribution of subway line 1 and the section distribution of the already constructed bridge 3, the construction site is divided into an assembly area and a hoisting area. S3, see also Figure 1 As shown, the hoisting equipment 4 is arranged in the hoisting area, and multiple support devices 5 are installed at intervals in the assembly area. The vertical height of the support devices 5 is adjustable. S4, see also Figure 1 As shown, the hoisting equipment 4 is controlled to hoist any steel box girder and the bottom of the steel box girder is placed on at least two support devices 5. According to the camber of the bottom of the steel box girder and the position of the two support devices 5, the vertical height of the two support devices 5 is adjusted so that the upper surface of the steel box girder is arranged in the horizontal direction. S5, see also Figure 1 As shown, repeat step S4 and place the newly erected steel box girder on one side of the previous steel box girder until all steel box girders are arranged. Weld any two adjacent steel box girders to connect all the steel box girders into a composite box girder 6. S6, see also Figure 1 and Figure 3 As shown, multiple support bases 7 are spaced apart on the beam members 31 of the constructed bridge section 3 on either side of the construction section 2. The vertical height of the multiple support bases 7 is set according to the camber of the bottom of the composite box girder 6. S7, see also Figures 1 to 3 As shown, during the maintenance window of subway line 1, the hoisting equipment 4 is controlled to vertically lift the composite box girder 6 to the first preset height, and the composite box girder 6 is hoisted and erected on multiple support bases 7 so that the upper surface of the composite box girder 6 is arranged in the horizontal direction. S8, see also Figure 1 As shown, a connecting structure is provided between the beam member 31 and the composite box girder 6 to fix the composite box girder 6; S9, see also Figure 1 As shown, during the maintenance window of the next subway line 1, the connecting structure is disassembled, the hoisting equipment 4 is controlled to hoist the composite box girder 6 to the top of the construction section 2, and the two ends of the composite box girder 6 are respectively erected on the supports of the existing bridge 3 on both sides of the construction section 2. S10, see below Figure 1 As shown, the two ends of the composite box girder 6 are welded to the beam components 31 of the bridge 3 that have been constructed on both sides.

[0025] When the steel box girder of Bridge 3 crosses the section of Metro Line 1, multiple steel box girders are welded and spliced ​​in the assembly area on the ground. Then, during the maintenance window of Metro Line 1, the welded composite box girder 6 is hoisted and erected on multiple support bases 7. A connecting structure is set between the beam component 31 and the composite box girder 6 to temporarily fix the composite box girder 6 so that it can be stably placed on the already constructed section of Bridge 3. Then, during the next maintenance window of Metro Line 1, the connecting structure is disassembled, the composite box girder 6 is hoisted to the top of the construction section 2 and its two ends are erected on the supports of the already constructed Bridge 3 on both sides of the construction section 2. Finally, the composite box girder 6 is welded to the beam component 31 of the already constructed Bridge 3.

[0026] By welding multiple steel box girders in the assembly area on the ground, welding of the steel box girders at high altitudes is eliminated, preventing environmental factors from affecting the welding quality and avoiding welding slag from falling onto the operating equipment of Metro Line 1, thus ensuring strong safety. The integrated composite box girder 6 is hoisted and installed in two stages, avoiding the impact of long single hoisting times on the normal operation of Metro Line 1. It is known that both ends of the construction section 2 are horizontally offset from Metro Line 1, and the composite box girder 6 is directly opposite the construction section 2, with its two ends respectively erected on the supports of the existing bridge 3 on both sides of the construction section 2. Therefore, the two ends of the composite box girder 6 are horizontally offset from Metro Line 1, so the welding slag from welding the composite box girder 6 and the beam component 31 will not affect the operating equipment of Metro Line 1.

[0027] For example, the first preset height is greater than the vertical height of the overhead contact line of subway line 1, and the difference between the two is greater than or equal to 3m.

[0028] In this embodiment, the difference between the first preset height and the vertical height of the contact wire is 3m. In other embodiments, the difference may be set to a value greater than 3m, and this is not limited here.

[0029] It should be noted that the hoisting equipment 4 includes a crawler crane, and there are 3 support bases 7. The required number of steel box girders is determined by the span of the construction section 2 and the length of the steel box girders.

[0030] In this embodiment, two support devices 5 are correspondingly provided for each steel box girder, and the two support devices 5 are respectively located at both ends of the steel box girder. In other embodiments, more than two support devices 5 may be provided at intervals at the bottom of each steel box girder, depending on actual needs; this is not limited here.

[0031] Optionally, step S10 specifically includes the following steps: S101. Protective components are installed below both ends of the composite box girder 6, with the protective components facing the ends of the composite box girder 6, for receiving debris. S102. Weld the two ends of the composite box girder 6 to the beam components 31 of the bridge 3 already constructed on both sides.

[0032] By installing a protective component directly below the end of the composite box girder 6, it can be used to withstand the welding generated during the welding process of the composite box girder 6 and the beam component 31, which can further enhance the protective effect, fully prevent welding slag from falling onto the operating equipment of the subway line 1, and improve the safety of construction.

[0033] For example, protective devices include fire-catching hoods, fire blankets, etc.

[0034] Optionally, step S30 is executed after step S2 and before step S3. Step S30 specifically includes the following steps: S301. Determine the model of hoisting equipment 4 based on the number of steel box girders, and construct multiple foundation reinforcement piles in the stratum of the hoisting area to ensure that the bearing capacity of the foundation in the hoisting area meets the load-bearing requirements of hoisting equipment 4. S302. Set the projection areas of the assembly area, hoisting area and construction section 2 as warning areas, and set up warning and restriction components along the circumference of the warning areas.

[0035] By constructing multiple foundation reinforcement piles in the stratum of the hoisting area, the bearing capacity of the foundation in the hoisting area can be improved, the soil strength and compressibility characteristics can be enhanced, the large local concentrated loads generated by the four legs of the hoisting equipment during the hoisting operation can be resisted, the foundation settlement and uneven differential deformation can be suppressed, the lateral extrusion of the soil can be prevented, and the tilting and instability of the hoisting equipment can be avoided. At the same time, it can also suppress the transmission of additional stratum deformation caused by the hoisting load to the surrounding area, reduce the disturbance to the adjacent existing operating subway structure, and ensure the safety of the hoisting operation of the large-tonnage steel box girder and the subway operation. In addition, setting up a warning zone and setting up warning and restriction elements around the perimeter of the warning zone can delineate the dangerous hoisting operation area, isolate irrelevant personnel and non-operational equipment from the risk range of falling objects and component swinging during the hoisting of the steel box girder, prevent personnel from accidentally entering the hoisting danger zone and causing injury from falling objects or collisions, achieve physical warning separation of the operation area, facilitate on-site safety management, and ensure the personal safety of hoisting construction personnel and surrounding passers-by.

[0036] It should be noted that the required number of foundation reinforcement piles is determined by factors such as the actual conditions of the construction site, the geological conditions and bearing capacity of the foundation in the hoisting area, and the model of hoisting equipment 4.

[0037] Optionally, see Figure 2As shown, the support device 5 includes a support base 51, a top support mechanism 52, and multiple support rods 53. The support base 51 is stacked on the ground, and the housing of the top support mechanism 52 is mounted on the support base 51. The output end of the top support mechanism 52 can extend and retract vertically, and the output end of the top support mechanism 52 can abut against the steel box girder. Multiple support rods 53 are distributed on both sides of the top support mechanism 52, and the two ends of each support rod 53 are connected to the support base 51 and the housing of the top support mechanism 52, respectively. The support rods 53 on both sides of the top support mechanism 52 extend upward at an angle along the side closest to each other. By setting up the support base 51, a flat installation foundation can be provided for the top support mechanism 52. The multiple support rods 53 on both sides of the top support mechanism 52 can provide support for the top support mechanism 52, ensuring the stability of the top support mechanism 52 and helping to ensure stable support for the steel box girder.

[0038] For example, the supporting mechanism 52 includes a hydraulic jack.

[0039] In this embodiment, step S4 specifically includes the following steps: S41. Control the hoisting equipment 4 to hoist any steel box girder and place the bottom of the steel box girder on the top support mechanism 52 of at least two support devices 5; S42. Based on the camber of the bottom of the steel box girder and the positions of the two support devices 5, control the extension or retraction of the output end of the top support mechanism 52 so that the top support mechanism 52 drives the steel box girder to move vertically until the upper surface of the steel box girder is laid out horizontally.

[0040] Optionally, see Figure 3 As shown, multiple supporting and reinforcing frames 8 are spaced apart below the beam members 31 of the constructed bridge section 3, and the upper end of each supporting and reinforcing frame 8 abuts against the beam member 31. After step S5 and before step S6, step S60 is performed. Step S60 specifically includes the following steps: S601. Calculate the bearing capacity of the beam member 31 of the constructed bridge section 3, and determine the number of supporting and reinforcing frames 8 under the beam member 31 based on the bearing capacity and the weight of the composite box girder 6. S602. Multiple support and reinforcement frames 8 are installed at intervals below the beam component 31.

[0041] By setting up the support and reinforcement frame 8, a vertical reinforcement support can be formed for the beam component 31, which can share the temporary concentrated load transferred to the beam component 31 during the hoisting and positioning stage of the composite box girder 6, reduce the bending stress generated by the temporary hoisting load on the beam component 31, reduce the deflection deformation of the composite box girder 6, and avoid cracking damage to the beam component 31. At the same time, it can resist the impact load and lateral force generated during the placement and adjustment process of the composite box girder 6, restrain the lateral displacement of the beam component 31, prevent the beam component 31 from exceeding the stress limit, protect the structural safety of the beam component 31, and also provide stress guarantee for the temporary placement and positioning adjustment of the composite box girder 6, thereby improving the construction safety of the overall structure during the hoisting and positioning stage.

[0042] For example, two supporting and reinforcing frames 8 are provided under the beam member 31 of the bridge section 3 that has been constructed on either side. In other embodiments, other numbers of supporting and reinforcing frames 8 may be provided under the beam member 31 on each side as needed, which is not limited here.

[0043] Optionally, the connection structure includes a tension member and multiple connecting plates. Step S8 specifically includes the following steps: S81. Multiple connecting plates are disposed on both sides of the composite box girder 6. Multiple connecting plates on each side of the composite box girder 6 are spaced apart along the length of the composite box girder 6. The two ends of each connecting plate are welded to the composite box girder 6 and the beam member 31, respectively. S82. Both ends of the composite box girder 6 are equipped with tie members, which are wrapped around the composite box girder 6 and the beam component 31 and tied and fixed.

[0044] By setting up tie members and connecting plates, the composite box girder 6 can be provided with double constraint fixation, ensuring that the composite box girder 6 can be stably installed on the already constructed bridge section 3 during the interval between the two subway skylights, ensuring the installation stability of the composite box girder 6 and preventing safety accidents caused by its rolling.

[0045] For example, the tensioning element includes a guy rope.

[0046] Optionally, step S9 specifically includes the following steps: S91. During the maintenance window of the next subway line 1, disassemble the connecting structure, control the hoisting equipment 4 to lift the combined box girder 6 vertically to the second preset height, and move it horizontally along the combined box girder 6 to directly above the construction section 2. S92. Along the vertically downward composite box girder 6, both ends of the composite box girder 6 are respectively erected on the supports of the existing bridge 3 on both sides of the construction section 2, and the actual elevation of the composite box girder 6 is detected by measuring equipment. S93. Compare and determine whether the difference between the actual elevation and the design elevation of the composite box girder 6 is greater than or equal to the control error value. If yes, proceed to S10; otherwise, proceed to S94. S94. Control the hoisting equipment 4 to adjust the position of the composite box girder 6 until the measuring equipment detects that the difference between the actual elevation and the design elevation of the composite box girder 6 is less than the control error value, and then execute S10.

[0047] For example, the measuring equipment includes a total station, the second preset height is greater than the design elevation of the composite box girder 6, and the difference between the two is greater than or equal to 50cm, with a control error value of 2mm.

[0048] In this embodiment, the difference between the second preset height and the design elevation of the composite box girder 6 is 50cm. In other embodiments, the difference may be set to a value greater than 50cm, and this is not limited here.

[0049] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art will be able to make various obvious changes, readjustments, and substitutions without departing from the scope of protection of the present invention. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A construction method for a steel box girder crossing a subway line, characterized in that, Includes the following steps: S1. Determine the section of the bridge that crosses the subway line and designate this section as a construction section. Both ends of the construction section are horizontally offset from the subway line. Both ends of the construction section have other sections of the bridge already constructed. Calculate and determine the number of steel box girders required for the construction section. S2. Based on the distribution of the subway lines and the section distribution of the bridges that have been constructed, the construction site is divided into an assembly area and a hoisting area. S3. Arrange the hoisting equipment in the hoisting area, and install multiple support devices at intervals in the assembly area. The support devices are adjustable in vertical height. S4. Control the hoisting equipment to hoist any of the steel box girders and place the bottom of the steel box girder on at least two of the supporting devices. Adjust the vertical height of the two supporting devices according to the camber of the bottom of the steel box girder and the position of the two supporting devices so that the upper surface of the steel box girder is arranged in the horizontal direction. S5. Repeat step S4 and place the newly erected steel box girder on one side of the previous steel box girder until all the steel box girders are arranged. Weld any two adjacent steel box girders to connect all the steel box girders into a composite box girder. S6. Multiple support bases are spaced apart on the beam members of the bridge section that has been constructed on any side of the construction section, and the vertical height of the multiple support bases is set according to the camber of the bottom of the composite box girder. S7. During the maintenance window of the subway line, control the hoisting equipment to vertically lift the composite box girder to a first preset height, and hoist and erect the composite box girder on multiple support bases so that the upper surface of the composite box girder is arranged in the horizontal direction; S8. A connecting structure is provided between the beam member and the composite box girder to fix the composite box girder; S9. During the maintenance window of the next subway line, disassemble the connecting structure, control the hoisting equipment to hoist the composite box girder to the top of the construction section, and place both ends of the composite box girder on the supports of the constructed bridge on both sides of the construction section. S10. Weld the two ends of the composite box girder to the beam components of the bridge that have been constructed on both sides.

2. The construction method for steel box girders crossing subway lines according to claim 1, characterized in that, Step S10 specifically includes the following steps: S101. Protective components are respectively installed below both ends of the combined box girder, and the protective components are directly opposite the ends of the combined box girder for receiving debris. S102. Weld the two ends of the composite box girder to the beam components of the bridge that have been constructed on both sides.

3. The construction method for steel box girders crossing subway lines according to claim 1, characterized in that, After step S2 is executed and before step S3 is executed, step S30 is executed, which specifically includes the following steps: S301. Determine the model of the hoisting equipment based on the number of steel box girders, and construct multiple foundation reinforcement piles in the stratum of the hoisting area to ensure that the bearing capacity of the foundation in the hoisting area meets the load-bearing requirements of the hoisting equipment. S302. Set the projection areas of the assembly area, the hoisting area and the construction section as warning areas, and set up warning and limiting members along the circumference of the warning areas.

4. The construction method for steel box girders crossing subway lines according to claim 1, characterized in that, The support device includes a support base, a top support mechanism, and multiple support rods. The support base is stacked on the ground, and the housing of the top support mechanism is installed on the support base. The output end of the top support mechanism can extend and retract vertically and can abut against the steel box girder. The multiple support rods are respectively located on both sides of the top support mechanism. The two ends of each support rod are connected to the support base and the housing of the top support mechanism, respectively. The support rods on both sides of the top support mechanism extend upward at an angle along the side closest to each other.

5. The construction method for steel box girders crossing subway lines according to claim 4, characterized in that, Step S4 specifically includes the following steps: S41. Control the hoisting equipment to hoist any of the steel box girders, and place the bottom of the steel box girder on the top support mechanism of at least two of the supporting devices; S42. Based on the camber of the bottom of the steel box girder and the positions of the two support devices, control the output end of the top support mechanism to extend or retract, so that the top support mechanism drives the steel box girder to move vertically until the upper surface of the steel box girder is laid out horizontally.

6. The construction method for steel box girders crossing subway lines according to claim 1, characterized in that, In the constructed bridge section, multiple supporting and reinforcing frames are spaced apart below the beam members, and the upper end of each supporting and reinforcing frame abuts against the beam member. After step S5 and before step S6, step S60 is carried out, which specifically includes the following steps: S601. Calculate the bearing capacity of the beam members of the constructed bridge section, and determine the number of the supporting and reinforcing frames below the beam members based on the bearing capacity and the weight of the composite box girder. S602. Install multiple supporting and reinforcing frames at intervals below the beam components.

7. The construction method for steel box girders crossing subway lines according to claim 1, characterized in that, The connection structure includes a tension member and multiple connecting plates, and step S8 specifically includes the following steps: S81. Multiple connecting plates are disposed on both sides of the composite box girder. Multiple connecting plates on each side of the composite box girder are spaced apart along the length direction of the composite box girder. The two ends of each connecting plate are welded to the composite box girder and the beam component, respectively. S82. The two ends of the composite box girder are provided with the traction member, and the traction member is wrapped around the composite box girder and the beam component and tied and fixed.

8. The construction method for steel box girders crossing subway lines according to claim 1, characterized in that, The first preset height is greater than the vertical height of the contact wire of the subway line, and the difference between the two is greater than or equal to 3m.

9. The construction method for steel box girders crossing subway lines according to claim 1, characterized in that, Step S9 specifically includes the following steps: S91. During the maintenance window of the next subway line, disassemble the connecting structure, control the hoisting equipment to vertically lift the composite box girder to the second preset height, and move it horizontally along the composite box girder to directly above the construction section. S92. Along the vertically downward composite box girder, the two ends of the composite box girder are respectively erected on the supports of the constructed bridge on both sides of the construction section, and the actual elevation of the composite box girder is detected by measuring equipment; S93. Compare and determine whether the difference between the actual elevation and the design elevation of the composite box girder is greater than or equal to the control error value. If yes, proceed to S10; otherwise, proceed to S94. S94. Control the hoisting equipment to adjust the position of the composite box girder until the measuring equipment detects that the difference between the actual elevation and the design elevation of the composite box girder is less than the control error value, and then execute S10.

10. The construction method for a steel box girder crossing a subway line according to claim 9, characterized in that, The second preset height is greater than the design elevation of the combined box girder, and the difference between the two is greater than or equal to 50cm, and the control error value is 2mm.

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