Steel box girder multi-point continuous pushing construction method

Abstract

The application provides a steel box girder multi-point continuous pushing construction method, which comprises the following steps: S1, erecting a temporary pier; S2, erecting an assembling platform; S3, installing pushing equipment and vertical jacks; S4, assembling a steel box girder; S5, pushing the steel box girder; S6, repeating step S5; and S7, falling the girder. The separate pushing of the pushing equipment and the vertical jacks is clear in stress and simple in structure, reduces the girder falling height, guarantees the stability of the whole during the construction process, overcomes the difficulties of the bridge site being a river channel, a valley, a complex terrain and the like, especially in the areas with high requirements for environmental protection and water system protection, the "off-site assembly and whole pushing" construction can better show its superiority, can effectively reduce the temporary land occupation during the construction, protect the local environment, and is favorable for the construction organization, shortens the construction period, and can greatly reduce the construction cost.

Description

Technical Field

[0001] This invention relates to the field of bridge construction, and in particular to a method for multi-point continuous jacking construction of steel box girders. Background Technology

[0002] my country's highway bridge construction has evolved from plains to mountainous and hilly areas, and from general rivers and lakes to major rivers. Bridge structures have primarily been beam bridges and arch bridges, developing towards longer spans, deeper water, newer structures, and prefabricated construction. Steel box girder bridges, as an important bridge structure type, play a crucial role in transportation construction. Their precise design, convenient manufacturing, and excellent durability make them an essential component of modern transportation infrastructure. In the future, with technological advancements and accumulated experience, the performance and quality of steel box girder bridges will be further improved, providing safer and more convenient bridge access for people's travel.

[0003] There are many methods for constructing steel box girder bridges, and incremental launching is one of them, which aligns with the trend of energy conservation, environmental protection, intelligence, and efficiency in bridge construction. In existing incremental launching construction methods, patent document CN111395164B discloses a steel box girder incremental launching structure for bridge construction. Each temporary pier has two columns, and each pier has two support columns for supporting the steel box girder. An incremental launching component is installed between the two support columns on each pier. Patent document CN114606871B discloses a method for jacking steel beams with variable height sections for long-span bridges. It involves setting up a front jacking support in front of a permanent pier, a rear jacking support behind the permanent pier, and a temporary jacking support between the permanent pier and the rear jacking support. The elevations of the front and rear jacking supports correspond to the bottom elevation of the steel beam after jacking, while the elevation of the temporary jacking support is based on the condition that the bottom elevation of the steel beam is higher than the elevation of the permanent pier during jacking. Walking machines are installed on the front, rear, and temporary jacking supports. However, the temporary pier structures in both prior art are complex and economical, and they cannot meet the requirements for lowering the steel box girder when its cross-section is inclined. Therefore, a multi-point continuous jacking construction method for steel box girders is proposed to solve these problems. Summary of the Invention

[0004] The main objective of this invention is to provide a multi-point continuous jacking construction method for steel box girders, which solves the problems of temporary pier structures in the prior art, which are relatively complex and economical, and cannot meet the requirements of lowering steel box girders with inclined cross-sections.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a method for multi-point continuous jacking construction of steel box girders, the method comprising: S1. Erect temporary piers. In the jacking construction area, erect several temporary piers between every two permanent piers according to the design requirements. S2. Erect an assembly platform. An assembly platform is erected between the two permanent piers at the starting end of the jacking construction area. The assembly platform is connected to the temporary pier at the starting end. S3. Install jacking equipment and vertical jacks. Install jacking equipment symmetrically on the top of the temporary piers located in the assembly platform, and install jacking equipment and vertical jacks symmetrically on the top of the remaining temporary piers and each permanent pier located in the jacking construction area. S4. Assemble the steel box girder. Transport the processed steel box girder to the construction site and hoist the first section of the steel box girder onto the assembly platform. Then assemble the steel guide beam at the front end of the first section of the steel box girder. S5. Pushing the steel box girder: Using the pushing equipment, the assembled steel box girder and steel guide beam are pushed forward. The pushing distance can meet the assembly space of the steel box girder in the next process. S6. Repeat step S5 until all the steel box girders in the jacking construction area are assembled and jacked to the design position. S7. Lowering the beam: Using jacking equipment and vertical jacks in conjunction with pad blocks, the beam lowering posture of the steel box girder is adjusted, and the supports are installed for lowering. In the preferred embodiment, the initial temporary pier consists of four upright steel pipes and two steel crossbeams placed between the four upright steel pipes. The remaining temporary piers consist of two symmetrically arranged support piers, each of which consists of four upright steel pipes and three steel crossbeams placed between the four upright steel pipes. The temporary pier located outside the assembly platform is equipped with a reinforcement support frame at its bottom. The reinforcement support frame includes a support platform at the bottom of the temporary pier and two sets of reinforcement columns symmetrically arranged at the bottom of the support platform, with three reinforcement columns in each set.

[0006] In the preferred embodiment, the assembly platform can install up to three steel box girders simultaneously; The assembly platform consists of independent platforms set on both sides of the initial temporary pier. Each independent platform includes two symmetrically arranged support steel frames, a support truss set on top of the support steel frames, an adjustment pipe set on top of the support truss, and an interconnecting passage between the two support steel frames. In the preferred embodiment, in step S4, when the head and tail of the overall steel box girder structure in the jacking construction area are both irregular structures with variable cross sections, a local steel beam reinforcement structure is set at its bottom. The local steel beam reinforcement structure consists of two independent support structures symmetrically set at its bottom. The independent support structure includes two symmetrically set heightened steel frames, a connecting steel beam set between the bottom of the two heightened steel frames, and a widened steel frame set outside the two heightened steel frames. In the preferred embodiment, the specific installation method of the support in step S7 is as follows: by placing pads on the alternating jacking equipment and vertical jacks, the steel box girder is jacked to the design height, the jacking equipment is removed and supported by vertical jacks, pads are placed at the original jacking equipment location, and the steel box girder is lowered onto the pads. Then, the support is installed on the pad stone of the permanent pier, and the support and pad stone are grouted. After the grout has solidified, the steel box girder is lifted by vertical jacks, the pads are removed, and the steel box girder is lowered onto the support. Finally, the vertical jacks are removed. When the cross-section of the steel box girder needs to be inclined after it is lowered, the jacking equipment on one side and the vertical jacks are used alternately to lift one side of the steel box girder, making it inclined. The jacking equipment is used to precisely adjust the position and posture of the steel box girder. The jacking equipment is then removed and supported by the vertical jacks. A pad is placed at the original location of the jacking equipment, and the steel box girder is lowered onto the pad. Then, a support is installed on the pad stone of the permanent pier, and grouting is performed on the support and pad stone. After the grout has solidified, the steel box girder is lifted by the vertical jacks, the pad is removed, and the steel box girder is lowered onto the support. Finally, the vertical jacks are removed. In the preferred embodiment, the top of the permanent pier is also equipped with a support sliding installation device located on the side of the pad stone; The support sliding installation device includes a box with an open top, two limiting sliding rods and a hydraulic push cylinder disposed in the box, a sliding feeding assembly slidably disposed outside the limiting sliding rods and connected to the output shaft of the hydraulic push cylinder, and a fixed plate disposed outside the box. The sliding feeding assembly includes a vertical plate with through holes adapted to the limiting sliding rods. The front side of the vertical plate is provided with two support arms for supporting the support, and the top of each support arm is provided with a limiting abutment block. In the preferred embodiment, the specific installation method of the support is as follows: before the jacking of the steel box girder begins, the sliding installation device of the support and the support are hoisted onto the beam system, and a groove adapted to the support arm is reserved on the pad stone. After the jacking equipment is removed, the sliding feeding assembly is pushed by the hydraulic push cylinder to slide on the two limit sliding rods, and the upright plate is sent into the groove. The support is then sent onto the pad stone, and the support and the pad stone are fixed with bolts. The upright plate is then pulled out of the groove by the hydraulic push cylinder. Finally, the support, pad stone and groove are grouted. In the preferred embodiment, a number of rotatable first ball bearings are provided on the inner wall surface of the perforation, and a number of linearly arranged second ball bearings are provided on the bottom of the vertical plate. In the preferred embodiment, when pushing the steel box girder in step S5, the web of the steel box girder must always be kept within ±50mm of the pushing center axis.

[0007] In the preferred embodiment, a visual inspection device for detecting the offset of the steel box girder is also included; The visual inspection device includes a binocular vision camera, with L-shaped frames symmetrically arranged on both sides of the binocular vision camera. The L-shaped frames are located at the center of the two cameras of the binocular vision camera. A transparent plate is bolted to the top of the two L-shaped frames, and a baseline is set at the center of the transparent plate. Mounting plates for fixing are also set on both sides of the binocular vision camera. The method for measuring the offset of the steel box girder is as follows: A visual inspection device is installed linearly at the top of the beam system of the permanent pier, and the baseline on the visual inspection device is aligned with the center axis of the bottom of the web of the steel box girder. After the steel box girder is assembled and positioned in step S4, the measurement line is measured at the center axis of the bottom of its web. During the jacking process, the positional relationship between the baseline and the measurement line is captured by a binocular visual camera, and the deviation value is measured in real time using the visual inspection device. This invention provides a multi-point continuous jacking construction method for steel box girders. By employing separate jacking equipment and vertical jacks, the method ensures clear force distribution, simplifies the structure, reduces the girder lowering height, and guarantees overall stability during construction. It overcomes difficulties such as bridge sites located in rivers, valleys, and complex terrain. Especially in areas with high requirements for environmental and water system protection, the "displaced assembly, integral jacking" construction method demonstrates its superiority. It effectively reduces temporary land occupation during construction, protects the local environment, facilitates construction organization, shortens the construction period, and significantly reduces construction costs. The assembly site is centralized, facilitating component assembly during construction, reducing the use of reusable materials, improving construction efficiency, and making it easier to control construction quality. Furthermore, it has a wide range of applications, suitable for both land construction with minimal terrain undulations and water construction with minimal hydrological changes, and exhibits strong adaptability to variable-width cross-sections of steel box girders. Attached Figure Description

[0008] The present invention will be further described below with reference to the accompanying drawings and embodiments: Figure 1 This is a schematic diagram of the overall pushing structure of the present invention; Figure 2 This is a cross-sectional structural diagram of the first temporary pier at the starting end of this invention; Figure 3 This is a cross-sectional structural diagram of the second temporary pier at the starting end of the present invention; Figure 4 This is a cross-sectional structural diagram of the temporary pier outside the assembly platform of this invention; Figure 5 This is a cross-sectional structural diagram of the assembly platform of the present invention; Figure 6 This is a cross-sectional structural diagram of the permanent pier of the present invention; Figure 7 This is a side view of the partial reinforcement structure of the steel beam of the present invention; Figure 8 This is a cross-sectional structural diagram of the partially reinforced steel beam structure of the present invention; Figure 9 This is a schematic diagram of the first part of the pushing process of the present invention; Figure 10 This is a schematic diagram of the second part of the pushing process of the present invention; Figure 11 This is a schematic diagram of the top-pushing process in the third part of this invention; Figure 12 This is a schematic diagram of the inclined beam dropping process in the first part of the present invention; Figure 13 This is a schematic diagram of the inclined beam dropping process in the second part of the present invention; Figure 14 This is a structural diagram of the sliding mounting device for the support of the present invention; Figure 15 This is a structural diagram of the support sliding installation device and the support connection of the present invention; Figure 16 This is a schematic diagram of the support installation structure of the present invention; Figure 17 This is a structural diagram of the sliding feeding component of the present invention; Figure 18 This is a front view of the sliding feeding assembly structure of the present invention; Figure 19 This is a top view of the sliding feeding assembly structure of the present invention; Figure 20 This is a structural diagram of the visual inspection device of the present invention; In the diagram: Permanent pier 1; Temporary pier 2; Assembly platform 3; Supporting steel frame 301; Supporting truss 302; Interchange passage 303; Adjusting pipe 304; Steel box girder 4; Steel guide beam 5; Partial reinforcement structure of steel beam 6; Heightened steel frame 601; Connecting steel beam 602; Widened steel frame 603; Jacking equipment 7; Vertical jack 8; Support sliding installation device 9; Box body 91; Limiting sliding rod 92; Hydraulic push cylinder 93; Sliding feeding assembly 94; Vertical plate 940; Perforation 941; Support arm 942; Limiting contact block 943; First ball bearing 944; Second ball bearing 945; Fixing plate 95; Support 10; Pad block 11; Pad stone 12; Groove 13; Visual inspection device 14; Binocular vision camera 141; Mounting plate 142; L-shaped frame 143; Baseline 144; Transparent plate 145. Detailed Implementation

[0009] Example 1 like Figure 1-13 As shown, a multi-point continuous jacking construction method for steel box girders includes: S1. Erect temporary piers 2. In the jacking construction area, erect several temporary piers 2 between every two permanent piers 1 according to the design requirements. S2. Erect the assembly platform 3. Erect the assembly platform 3 between the two permanent piers 1 at the starting end of the jacking construction area. The assembly platform 3 is connected to the temporary pier 2 at the starting end. S3. Install the jacking equipment 7 and the vertical jacks 8. The jacking equipment 7 is symmetrically installed on the top of the temporary pier 2 located in the assembly platform 3, and the jacking equipment 7 and the vertical jacks 8 are symmetrically installed on the top of the remaining temporary piers 2 and each permanent pier 1 located in the jacking construction area. In this embodiment, two jacking equipment 7 are set on the top of the temporary pier 2 located in the assembly platform 3, and four jacking equipment 7 and eight vertical jacks 8 are set on the remaining temporary piers 2. Two jacking equipment 7 and two vertical jacks 8 are set on the top of the permanent pier 1. S4. Assemble the steel box girder 4. Transport the processed steel box girder 4 to the construction site and hoist the first section of steel box girder 4 onto the assembly platform 3. Then assemble the steel guide beam 5 at the front end of the first section of steel box girder 4. S5. Push the steel box girder 4 forward. Use the pushing equipment 7 to push the assembled steel box girder 4 and steel guide beam 5 forward. The pushing distance can meet the assembly space of the steel box girder 4 in the next process. S6. Repeat step S5 until all the steel box girder 4 in the jacking construction area is assembled and jacked to the design position. S7. Lowering the beam: Using the jacking device 7 and the vertical jack 8 in conjunction with the pad block 11, the lowering posture of the steel box girder 4 is adjusted, and the support 10 is installed for lowering the beam.

[0010] This method employs two separate jacking devices: a jacking device 7 and a vertical jack 8. This reduces the beam lowering height, ensuring overall stability during construction. It also greatly simplifies the structure of temporary piers, effectively reducing temporary land occupation during construction, protecting the local environment, facilitating construction organization, shortening the construction period, and significantly reducing construction costs. Furthermore, during the jacking process, the steel box girder 4 can be temporarily supported by the vertical jack 8, allowing the jacking device 7 to precisely adjust the position of the steel box girder 4.

[0011] It should be noted that the guide beam connecting section is an I-shaped to box-shaped structure, while the remaining sections of the guide beam are I-shaped straight web structures, divided into 7 sections. The web and upper flange at the section of the guide beam are bolted together. The bottom plate of the guide beam is first butt-welded on site, and then reinforced with a plate. The middle crossbeam is connected to the main beam of the guide beam by a pin shaft. The root of the guide beam is fully welded to the steel-concrete composite section. The foremost end is the upper pier end, which is stepped with the connecting section thereafter. During dismantling, the guide beam is dismantled after the last temporary pier has passed through the section joint. A 30m space is reserved between the last temporary pier and the preceding structure for guide beam dismantling.

[0012] In addition, the jacking device 7 in this embodiment is a walking jacking device, which mainly includes a sliding surface structure, an upper sliding structure, a lower support structure, a support cylinder, a lateral adjustment cylinder and a jacking cylinder. It achieves combined and sequential actions through computer control and hydraulic drive to meet construction requirements. It is a conventional technical means in jacking construction, so it will not be described in detail here.

[0013] In the preferred embodiment, the initial temporary pier 2 consists of four upright steel pipes and two steel crossbeams set between the four upright steel pipes. The remaining temporary piers 2 consist of two symmetrically arranged support piers, each of which consists of four upright steel pipes and three steel crossbeams set between the four upright steel pipes. Among them, a reinforcement support frame is set at the bottom of the temporary pier 2 located outside the assembly platform 3. The reinforcement support frame includes a support platform set at the bottom of the temporary pier 2, and two sets of reinforcement columns symmetrically set at the bottom of the support platform, with three reinforcement columns in each set.

[0014] It should be noted that the purpose of setting up the temporary pier 2 is to reasonably and effectively reduce the material used for the temporary pier 2 without affecting the support, thereby reducing construction costs. Because the two temporary piers 2 at the initial end are subjected to less force under the influence of the assembly platform 3, they can be directly subjected to single pile force. The temporary pier 2 at the rear is subjected to greater force, so the form of three reinforced columns supporting two column steel pipes is adopted, which can effectively reduce the single pile bearing force. In the preferred embodiment, the assembly platform 3 can simultaneously install up to three steel box girders 4, ensuring sufficient space to complete the installation of multiple steel box girders 4; The assembly platform 3 consists of independent platforms set on both sides of the initial temporary pier 2. Each independent platform includes two symmetrically arranged support steel frames 301, a support truss 302 set on top of the support steel frames 301, an adjustment pipe 304 set on top of the support truss 302, and an interconnection channel 303 set between the two support steel frames 301. By setting adjustment pipes 304 at different heights, the height difference caused by the inclined design of the steel box girder 4 can be accommodated. The number of interconnection channels 303 is not less than two, which facilitates the movement of construction personnel. In the preferred embodiment, in step S4, when both the head and tail of the overall steel box girder structure in the jacking construction area are irregularly shaped structures with variable cross-sections, a local steel beam reinforcement structure 6 is installed at its bottom. The local steel beam reinforcement structure 6 consists of two symmetrically arranged independent support structures 61 at its bottom. Each independent support structure 61 includes two symmetrically arranged heightened steel frames 601, a connecting steel beam 602 positioned between the bottoms of the two heightened steel frames 601, and a widened steel frame 603 positioned outside the two heightened steel frames 601. The local steel beam reinforcement structure 6 ensures a smooth bottom surface for the variable cross-section, guaranteeing a normal connection between the guide beam and the head of the steel beam, and ensuring normal load-bearing capacity during the jacking of the tail of the steel beam. The steel beam reinforcement is temporary and needs to be removed after the jacking is completed, without affecting the lowering of the steel beam and the installation of permanent supports.

[0015] In the preferred embodiment, the specific installation method of the support 10 in step S7 is as follows: by placing pad blocks 11 on the alternating jacking device 7 and the vertical jack 8, the steel box girder 4 is jacked to the design height. The jacking device 7 is removed and supported by the vertical jack 8. The pad blocks 11 are placed at the original jacking device 7 and the steel box girder 4 is lowered onto the pad blocks 11. Then, the support 10 is installed on the pad stone 12 of the permanent pier 1. The support 10 and the pad stone 12 are then grouted. After the grout has solidified, the steel box girder 4 is lifted by the vertical jack 8. Then, the pad blocks 11 are removed and the steel box girder 4 is lowered onto the support 10. Finally, the vertical jack 8 is removed. When the cross-section of the steel box girder 4 needs to be inclined after it is lowered, the jacking device 7 on one side and the vertical jack 8 are used alternately to lift one side of the steel box girder 4, so that the steel box girder 4 is inclined. The jacking device 7 is used to precisely adjust the position and posture of the steel box girder 4. The jacking device 7 is then removed and the vertical jack 8 is used for support. A pad block 11 is placed at the original location of the jacking device 7, and the steel box girder 4 is lowered onto the pad block 11. Then, the support 10 is installed on the pad stone 12 of the permanent pier 1, and the support 10 and the pad stone 12 are grouted. After the grout has solidified, the vertical jack 8 is used to lift the steel box girder 4. Then, the pad block 11 is removed, and the steel box girder 4 is lowered onto the support 10. Finally, the vertical jack 8 is removed. In this method, the alternating lifting between the jacking device 7 and the vertical jack 8 can more precisely adjust the lowering progress of the steel box girder 4, and at the same time, it can meet the requirements of inclined lowering according to the design. This effectively reduces the temporary land occupation for construction and lowers the construction cost in areas with complex terrain such as river channels and valleys.

[0016] Example 2 Further explanation in conjunction with Example 1, such as Figure 14-19 As shown in the structure, in order to improve the installation efficiency of the support 10, the top of the permanent pier 1 is also provided with a support sliding installation device 9 located on the side of the pad stone 12. The support 10 can be installed quickly through the support sliding installation device 9. The sliding mounting device 9 for the support includes a box 91 with an open top, two limiting sliding rods 92 disposed in the box 91 and a hydraulic push cylinder 93, a sliding feeding assembly 94 slidably disposed outside the limiting sliding rods 92 and connected to the output shaft of the hydraulic push cylinder 93, and a fixing plate 95 disposed outside the box 91. The fixing plate 95 has holes for fixing. The sliding feeding assembly 94 includes a vertical plate 940 with through holes 941 adapted to the limiting sliding rods 92. The front side of the vertical plate 940 has two support arms 942 for supporting the support 10. The top of each support arm 942 is provided with a limiting abutment block 943. In use, the sliding feeding assembly 94 can slide on the two limiting sliding rods 92 by the hydraulic push cylinder 93, thereby pushing the two support arms 942. The limiting abutment block 943 on the support arm 942 is used to limit the placement position of the support 10, so that the support 10 can be quickly sent to the pad stone 12 in a narrow space.

[0017] The specific installation method of the support 10 is as follows: Before the jacking of the steel box girder 4 begins, the support sliding installation device 9 and the support 10 are hoisted onto the beam system, and a groove 13 adapted to the support arm 942 is reserved on the pad stone 12. After the jacking equipment 7 is removed, the hydraulic push cylinder 93 is used to push the sliding feeding component 94 to slide on the two limit sliding rods 92, sending the upright plate 940 into the groove 13 and the support 10 onto the pad stone 12. The support 10 and the pad stone 12 are fixed with bolts. The hydraulic push cylinder 93 is used to pull the upright plate 940 out of the groove 13. Finally, the support 10, the pad stone 12 and the groove 13 are grouted.

[0018] In the preferred embodiment, a number of rotatable first balls 944 are provided on the inner wall surface of the perforation 941, and a number of linearly arranged second balls 945 are provided on the bottom of the vertical plate 940. The balls can effectively reduce the friction of the sliding feeding assembly 94 when it moves. Example 3 Further explanation in conjunction with Examples 1 and 2, such as Figure 20 As shown in the structure, when pushing the steel box girder 4 in step S5, the web of the steel box girder 4 must always be kept within ±50mm of the pushing center axis.

[0019] In the preferred embodiment, in order to quickly measure the offset of the steel box girder 4, this embodiment also includes a visual inspection device 14 for detecting the offset of the steel box girder 4; The visual inspection device 14 includes a binocular vision camera 141. L-shaped frames 143 are symmetrically arranged on both sides of the binocular vision camera 141. The L-shaped frames 143 are located at the center of the two cameras of the binocular vision camera 141. A transparent plate 145 is bolted to the top of the two L-shaped frames 143. A baseline 144 is set at the center of the transparent plate 145. Mounting plates 142 for fixing are also provided on both sides of the binocular vision camera 141. The method for measuring the offset of the steel box girder 4 is as follows: A visual inspection device 14 is installed linearly at the top of the beam system of the permanent pier 1, and the baseline 144 on the visual inspection device 14 is aligned with the center axis of the bottom of the web of the steel box girder 4. After the steel box girder 4 is assembled and positioned in step S4, the measurement line is measured at the center axis of the bottom of its web. During the jacking process, the positional relationship between the baseline 144 and the measurement line is captured by a binocular visual camera 141, and the deviation value is measured in real time using the visual inspection device.

[0020] The specific method for measuring the deviation is as follows: the parallax of the left and right cameras of the binocular vision camera 141 is used to obtain the depth information of the baseline 144 and the measurement line. Image processing techniques such as edge detection and line fitting algorithms are used to extract the pixel coordinates of the standard line and the target line in the image. The extracted pixel coordinates of the standard line and the target line are mapped to three-dimensional space through camera calibration parameters. The positional difference between the two in the actual space is calculated, that is, the lateral and longitudinal deviations between them are obtained. Finally, high-precision measurement is achieved through error analysis and correction. This is a conventional technique in the field of visual measurement and a mature existing technology, so it will not be described in detail here.

[0021] The above embodiments are merely preferred technical solutions of the present invention and should not be considered as limitations on the present invention. The scope of protection of the present invention should be limited to the technical solutions described in the claims, including equivalent substitutions of the technical features described in the claims. That is, equivalent substitutions and improvements within this scope are also within the scope of protection of the present invention.

Claims

1. A method for multi-point continuous jacking construction of steel box girders, characterized by: The method includes: S1. Erect temporary piers (2). In the jacking construction area, erect several temporary piers (2) between every two permanent piers (1) according to the design requirements. S2. Erect an assembly platform (3). Erect an assembly platform (3) between two permanent piers (1) at the beginning of the jacking construction area. The assembly platform (3) is connected to the temporary pier (2) at the beginning. S3. Install the jacking equipment (7) and vertical jacks (8). Install the jacking equipment (7) symmetrically on the top of the temporary pier (2) located in the assembly platform (3) in the horizontal direction. Install the jacking equipment (7) and vertical jacks (8) symmetrically on the top of the remaining temporary piers (2) and each permanent pier (1) located in the jacking construction area in the horizontal direction. S4. Assemble the steel box girder (4). Transport the finished steel box girder (4) to the construction site and hoist the first section of the steel box girder (4) onto the assembly platform (3). Then assemble the steel guide beam (5) at the front end of the first section of the steel box girder (4). S5. Push the steel box girder (4). Use the pushing equipment (7) to push the assembled steel box girder (4) and steel guide beam (5) forward. The pushing distance can meet the assembly space of the steel box girder (4) in the next process. S6. Repeat step S5 until all the steel box girders (4) in the jacking construction area are assembled and jacked to the design position; S7. Lowering the beam: Using the jacking equipment (7) and vertical jacks (8) in conjunction with the pads (11) to alternately lift the steel box girder (4), adjust the lowering posture of the beam, and install the support (10) to lower the beam.

2. The multi-point continuous jacking construction method for steel box girders according to claim 1, characterized in that: The initial temporary pier (2) consists of four steel pipe columns and two steel beams set between the four steel pipe columns. The remaining temporary piers (2) consist of two piers symmetrically set in the transverse direction of the bridge. The piers consist of four steel pipe columns and three steel beams set between the four steel pipe columns. Among them, a reinforcement support frame is provided at the bottom of the temporary pier (2) located outside the assembly platform (3). The reinforcement support frame includes a support platform set at the bottom of the temporary pier (2) and two sets of reinforcement columns symmetrically set at the bottom of the support platform in the transverse direction of the bridge. Each set of reinforcement columns has three columns.

3. The multi-point continuous jacking construction method for steel box girders according to claim 1, characterized in that: The assembly platform (3) can simultaneously install up to three steel box girders (4); The assembly platform (3) consists of independent platforms set on both sides of the initial end temporary pier (2). The independent platforms include two support steel frames (301) symmetrically arranged in the transverse direction of the bridge, a support truss (302) set on the top of the support steel frame (301), an adjustment pipe (304) set on the top of the support truss (302), and an interconnection channel (303) set between the two support steel frames (301).

4. The multi-point continuous jacking construction method for steel box girders according to claim 1, characterized in that: in In step S4, when the head and tail of the overall steel box girder structure in the jacking construction area are both irregular structures with variable cross sections, a steel beam local reinforcement structure (6) is set at its bottom. The steel beam local reinforcement structure (6) consists of two independent support structures (61) symmetrically set at its bottom in the transverse direction. The independent support structure (61) includes two heightened steel frames (601) symmetrically set in the transverse direction, a connecting steel beam (602) set between the bottom of the two heightened steel frames (601), and a widened steel frame (603) set outside the two heightened steel frames (601).

5. The multi-point continuous jacking construction method for steel box girders according to claim 1, characterized in that: The specific installation method of the support (10) in step S7 is as follows: by placing pads (11) on the alternating jacking device (7) and vertical jack (8), the steel box girder (4) is jacked to the design height, the jacking device (7) is removed and supported by the vertical jack (8), pads (11) are placed at the original jacking device (7), and the steel box girder (4) is lowered onto the pads (11), and then the support (10) is installed on the pad stone (12) of the permanent pier (1), and then the support (10) and pad stone (12) are grouted. After the grout has solidified, the steel box girder (4) is lifted by the vertical jack (8), then the pads (11) are removed, and the steel box girder (4) is lowered onto the support (10), and finally the vertical jack (8) is removed. When the cross section of the steel box girder (4) needs to be inclined after it is lowered, the jacking device (7) on one side and the vertical jack (8) are used alternately to lift one side of the steel box girder (4) so ​​that the steel box girder (4) is inclined. The jacking device (7) is used to precisely adjust the position and posture of the steel box girder (4). The jacking device (7) is removed and the vertical jack (8) is used for support. A pad (11) is placed at the original jacking device (7) and the steel box girder (4) is lowered onto the pad (11). Then, a support (10) is installed on the pad stone (12) of the permanent pier (1) and the support (10) and pad stone (12) are grouted. After the grout has solidified, the vertical jack (8) is used to lift the steel box girder (4). Then the pad (11) is removed and the steel box girder (4) is lowered onto the support (10). Finally, the vertical jack (8) is removed.

6. The multi-point continuous jacking construction method for steel box girders according to claim 5, characterized in that: The top of the permanent pier (1) is also equipped with a support sliding installation device (9) located on the side of the pad stone (12). The support sliding installation device (9) includes a box (91) with an open top, two limiting sliding rods (92) and a hydraulic push cylinder (93) disposed in the box (91), a sliding feeding assembly (94) slidably disposed outside the limiting sliding rods (92) and connected to the output shaft of the hydraulic push cylinder (93), and a fixing plate (95) disposed outside the box (91). The sliding feeding assembly (94) includes a vertical plate (940), which has a through hole (941) adapted to the limiting sliding rods (92). The front side of the vertical plate (940) is provided with two support arms (942) for receiving the support (10), and the top of each of the two support arms (942) is provided with a limiting abutment block (943).

7. The multi-point continuous jacking construction method for steel box girders according to claim 6, characterized in that: The specific installation method of the support (10) is as follows: Before the jacking of the steel box girder (4) begins, the support sliding installation device (9) and the support (10) are hoisted onto the tie beam of the permanent pier (1), and a groove (13) adapted to the support arm (942) is reserved on the pad stone (12). After the jacking equipment (7) is removed, the sliding feeding component (94) is pushed by the hydraulic push cylinder (93) to slide on the two limit sliding rods (92), and the upright plate (940) is sent into the groove (13), and the support (10) is sent onto the pad stone (12). The support (10) and the pad stone (12) are fixed with bolts. The upright plate (940) is pulled out from the groove (13) by the hydraulic push cylinder (93). Finally, the support (10), the pad stone (12) and the groove (13) are grouted.

8. The multi-point continuous jacking construction method for steel box girders according to claim 7, characterized in that: Several rotatable first ball bearings (944) are provided on the inner wall surface of the perforation (941), and several linearly arranged second ball bearings (945) are provided on the bottom of the upright plate (940).

9. The multi-point continuous jacking construction method for steel box girders according to claim 1, characterized in that: in When pushing the steel box girder (4) in step S5, the web of the steel box girder (4) must always be kept within ±50mm of the pushing center axis.

10. The multi-point continuous jacking construction method for steel box girders according to claim 9, characterized in that: It also includes a visual inspection device (14) for detecting the offset of the steel box girder (4); The visual inspection device (14) includes a binocular vision camera (141). L-shaped frames (143) are symmetrically arranged on both sides of the binocular vision camera (141). The L-shaped frames (143) are located at the center of the two cameras of the binocular vision camera (141). A transparent plate (145) is bolted to the top of the two L-shaped frames (143). A baseline (144) is set at the center of the transparent plate (145). Mounting plates (142) for fixing are also provided on both sides of the binocular vision camera (141). The method for measuring the offset of the steel box girder (4) is as follows: a visual inspection device (14) is installed linearly at the top of the tie beam of the permanent pier (1), and the baseline (144) on the visual inspection device (14) is aligned with the center axis of the bottom of the web of the steel box girder (4). After the steel box girder (4) is assembled and positioned in step S4, the line is measured at the center axis of the bottom of its web. During the jacking process, the positional relationship between the baseline (144) and the measurement line is captured by a binocular visual camera (141), and the deviation value is measured in real time using the visual inspection device (14).

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