Secondary girder lifting erection method and equipment for large box girder

Abstract

The invention provides a large box girder secondary girder lifting erection method and equipment thereof.The method comprises the following steps that S1, a front support is supported at the top of a pier, and a supporting block is arranged on the side face of the front support; s2, the crown block moves to be close to the front support and the middle support for supporting, the rear support is folded upwards, and the beam transporting vehicle carries the beam to enter; s3, the rear support recovers the support, and the middle support is folded upwards; s4, the crown block lifts the beam and then moves in place; s5, the box girder is put down, one end of the box girder is arranged at the top of the supporting block, and the other end is arranged at the top of the installed box girder; s6, the girder transporting vehicle is driven out, and the bridge erecting machine moves by one pier position; s7, the crown block lifts the beam for the second time, and the supporting block is moved away; s8, the crown block moves the box girder and then puts down the box girder; and S9, the steps S1 to S8 are repeated until all box girders are installed. Installation of the large box girder is completed in a secondary girder lifting mode, operation is easy, the construction efficiency is higher, and the construction period is shortened; the method is suitable for complex and special box girder erection scenes needing cantilever welding and the like, the construction difficulty is lowered, and rapid erection of the box girder is more convenient.

Description

Technical Field

[0001] The present invention relates to the technical field of large box girder erection, and particularly to a method and equipment for secondary lifting and erection of large box girders. Background Art

[0002] Urban reconstruction and expansion is an activity of reforming and expanding existing areas, facilities, etc. in the city, which is a process of continuous self-renewal in urban development, including beam bridge erection projects; the so-called beam bridge erection project is the process of installing box girders according to the expected route during the reconstruction and expansion process.

[0003] With the development of bridge construction technology, the span of the whole steel box girder bridge is getting larger and larger, up to 53m at most, and the width is large, reaching 34.5m, the weight reaches 1100t, the bridge deck span reaches 50m, and the cantilever of the steel box girder end is installed deep at the pier top.

[0004] The existing methods often use highway bridge erection machines or railway box girder bridge erection machines for erection. However, in the actual construction process, using traditional construction methods, due to the too long length of the box girder, large stress, high cost, and when the steel beam moves forward, the outriggers cannot be opened, which cannot meet the requirements of beam erection; although the railway bridge erection machine can erect 1000t railway box girders, the width is small, it uses trough-shaped outriggers, the outriggers are too wide and heavy, and the supporting beams on both sides of the trough are cantilevered deep outside the bridge, affecting traffic; and during the erection of some box girders, their construction requirements are different, such as the need for cantilever welding. At this time, the box girder extends out of the pier top, and the outriggers cannot stand, so the construction cannot be completed. Summary of the Invention

[0005] The main purpose of the present invention is to provide a method and equipment for secondary lifting and erection of large box girders, so as to solve the problems of difficult erection of large box girders and low construction efficiency.

[0006] To solve the above technical problems, the technical solution adopted by the present invention is: A method for secondary lifting and erection of large box girders, comprising the following steps: S1. The front support is supported on the top of the pier, and a support block is arranged on the side of the front support; S2. The overhead crane moves close to the front support, the middle support is supported, the rear support is folded upward, and the beam transport vehicle carries the beam and enters; S3. The rear support resumes support, and the middle support is folded upward; S4. The overhead crane lifts the beam, and then moves, driving one end of the box girder to move above the support block; S5. Lower the box girder, one end of the box girder is placed on the top of the support block, and the other end is placed on the top of the already installed box girder; S6. The beam transport vehicle drives out, and the bridge erection machine moves one pier position; S7. The overhead crane lifts the beam for the second time, and removes the support block; S8. The overhead crane moves the box girder and then lowers it, connecting one end of the box girder to the already installed box girder and placing the other end on top of the pier. S9. Repeat S1 - S8 until all box girders are installed.

[0007] In the preferred solution, there is one front support and three overhead cranes. Among them, two overhead cranes are used for transporting the box girder, and a support block is connected under the other overhead crane. The height of the support block is the same as that of the box girder.

[0008] In the preferred solution, S6 includes the following steps: S611. The middle support resumes support, the rear support folds upward, and the beam transporter drives out. S612. The rear support resumes support, and the middle support is lifted. S613. The trolley at the bottom of the rear support moves, driving the beam transporter to move one pier position. There are leg pulleys between the main beam of the beam transporter and the front support for relative sliding between the main beam and the front support. S614. The middle support resumes support, the front support cancels support, and moves along the main beam to the position above the next pier through the leg pulleys. S615. The front support completes support, and the middle support folds upward.

[0009] In the preferred solution, S7 includes the following steps: S711. Use two overhead cranes to lift the box girder for the second time, and the box girder is lifted. S712. Use the other overhead crane to lift the support block. S713. Move the support block to the position above the next pier and lower it, placing it on the side of the front support.

[0010] In the preferred solution, there are two front supports and two overhead cranes. Among them, two overhead cranes are used for transporting the box girder. One of the front supports is used for supporting and connecting the support block, and the other front support is used for temporary support. The front support connecting the support block is close to the already installed box girder. S8 also includes the following steps: S81. The middle support resumes support, and the front support without the installed support block moves away from the pier. S82. The front support with the installed support block supports on top of the pier.

[0011] In the preferred solution, S6 includes the following steps: S621. The middle support resumes support, the rear support folds upward, and the beam transporter drives out. S622. The rear support resumes support, and the middle support is lifted. S623. The rear support bottom trolley moves, driving the beam transporter to move one pier position. There are leg pulleys between the main beam and the front support of the beam transporter for relative sliding between the main beam and the front support. S624. The front support without the support block moves above the next pier and then supports on the top of the pier.

[0012] In the preferred solution, S7 includes the following steps: S721. Use two overhead cranes to lift the box girder for the second time, and the box girder is lifted. S722. The front support with the support block installed moves above the next pier. The front support with the support block installed supports on the top of the pier. Or The front support with the support block installed does not support on the top of the pier temporarily.

[0013] The large box girder second-lifting erection equipment includes a main beam. There are several overhead cranes on the top of the main beam, and the overhead cranes are slidably connected to the main beam. There are rear supports, middle supports and front supports below the main beam. The rear supports and the middle supports are rotatably connected to the main beam. The front support is arranged on the top of the pier, and there is a support block on the side of the front support.

[0014] In the preferred solution, there is a front support and a spare front support. The spare front support has the same structure as the front support, and the support block is fixedly connected to the front support. Or There is a spare overhead crane. The support block is connected to the spare overhead crane, and the support block only contacts the front support. The rear support includes a first support seat fixed to the main beam. The first support seat is hinged to a first support arm through a first hinge. Both the first support seat and the first support arm are provided with first connecting frames on the side. The first connecting frames between the first support seat and the first support arm are connected by a first hydraulic cylinder, and the connection modes at both ends of the first hydraulic cylinder are hinged. The bottom of the first support arm is provided with a fixed seat, and there is a fixed plate on the side of the fixed seat. The fixed plate is provided with several second hydraulic cylinders. The output ends of the second hydraulic cylinders are provided with movable frames, and the bottoms of the movable frames are provided with rollers. The middle support includes a second support seat fixed to the main beam. The second support seat is hinged to a second support arm through a second hinge. Both the second support seat and the second support arm are provided with second connecting frames on the side. The second connecting frames between the second support seat and the second support arm are connected by a third hydraulic cylinder, and the connection modes at both ends of the third hydraulic cylinder are hinged. The bottom end of the second support arm is provided with a telescopic support column. The front support includes a connecting seat, and the top of the connecting seat is slidably connected to the main beam through a support leg pulley; The bottom of the connecting seat is provided with support legs, and the support legs are arranged on the top of the bridge pier.

[0015] In a preferred embodiment, the support block includes a fixed block and a fixed sleeve connected to the front support; The fixed block is located on the side of the front support, and the fixed sleeve is fixedly sleeved on the outside of the front support; Several guide rings are provided on the outer peripheral surface of the fixed sleeve, and the guide rings are rotatably connected to a movable sleeve; The movable sleeve is provided with a connecting rod, and the connecting rod is provided with a backing plate; The backing plates are stacked on the top of the fixed block.

[0016] The present invention provides a method and equipment for erecting large box girders by secondary beam lifting. By adopting the above solutions, the following beneficial effects are achieved: 1. The installation of large box girders is completed by the method of secondary beam lifting, with simple operation, higher construction efficiency, and shorter construction period.

[0017] 2. It is suitable for complex and special box girder erection scenarios such as cantilever welding, reducing the construction difficulty and facilitating the rapid erection of box girders.

[0018] 3. During the erection process, the external space occupation is small, so it will not affect the existing traffic use.

[0019] 4. Through the cooperation of various erection structures for the erection of box girders, it can adapt to different erection requirements and construction conditions, with more convenient operation and better adaptability.

[0020] 5. It can adjust the height of the support block according to needs to adapt to different box girders, with better adaptability. Brief Description of the Drawings

[0021] The following further describes the present invention in conjunction with the drawings and embodiments: Figure 1 It is a schematic structural diagram when the box girder of the present invention is transported in; Figure 2 It is a schematic structural diagram when the box girder of the present invention is lifted for the first time and then lowered; Figure 3 It is a schematic structural diagram when the beam transport vehicle drives out; Figure 4 It is a schematic structural diagram after the main beam of the present invention is moved; Figure 5 It is a schematic structural diagram when the box girder of the present invention is lifted for the second time; Figure 6 It is a schematic structural diagram after the erection of one section of the box girder of the present invention is completed; Figure 7 It is a schematic structural diagram when waiting for the next section of the box girder to be transported in; Figure 8 It is a schematic structural diagram of the rear support of the present invention; Figure 9 It is a schematic structural diagram of the middle support of the present invention; Figure 10 It is a schematic structural diagram of the front support of the present invention; Figure 11 It is a schematic structural diagram of an embodiment of the present invention using only one front support; Figure 12 It is a schematic structural diagram of the fixing block of the present invention.

[0022] In the figure: pier 101, box girder 102, main beam 2, overhead crane 201, rear support 3, first support seat 301, first support arm 302, first hinge 303, first connecting frame 304, first hydraulic cylinder 305, fixed seat 306, fixed plate 307, second hydraulic cylinder 308, movable frame 309, roller 310, middle support 4, second support seat 401, second support arm 402, second hinge 403, second connecting frame 404, third hydraulic cylinder 405, telescopic support column 406, front support 5, spare front support 501, connecting seat 502, leg pulley 503, leg 504, support block 6, fixing block 601, fixing sleeve 602, guide ring 603, movable sleeve 604, connecting rod 605, backing plate 606. Specific Embodiments

[0023] Embodiment 1: As Figures 1-7 shown, in the present application, the main beam 2 and the overhead crane 201 of the bridge erecting machine preferably adopt the structures of existing bridge erecting machines; The method for erecting large box girders by double-lifting the girders includes the following steps: S1. The front support is supported on the top of the pier, and a support block is arranged on the side of the front support; In this embodiment, there are two front supports and two overhead cranes; among them, the two overhead cranes are used for transporting girders; One of the front supports is used for supporting and connecting the support block, and the other front support is used for temporary support; The front support connecting the support block is close to the already installed box girder.

[0024] S2. As Figure 1 shown, the overhead crane of the bridge erecting machine is moved to a position close to the front support by an existing method, and the middle support is made to complete the support, and the rear support is folded upward; Then the girder carrier vehicle enters with the girder on its back, and the girder carrier vehicle adopts the commonly used box girder carrier vehicle in the prior art; S3. As Figure 2 shown, the rear support resumes the support, and the middle support is folded upward; S4. The overhead crane moves along the main girder to above the box girder in the existing manner, then lifts the girder. After the lifting is completed, it moves along the main girder and moves one end of the box girder to above the support block. S5. Then lower the box girder so that one end of the box girder is placed on the top of the support block and the other end is placed on the top of the already installed box girder to complete the first lifting and lowering of the girder. S6. As shown in Figure 3 and 4 , the beam carrier drives out and the bridge erecting machine moves one pier position. Specifically, it includes the following steps: S621. The middle support resumes support and the rear support folds upward. The beam carrier drives out and goes to the box girder storage area to install a new box girder. S622. The rear support resumes support, lower the trolley and the middle support lifts. S623. The trolley at the bottom of the rear support moves. The trolley at the bottom of the rear support is a common moving trolley of the existing bridge erecting machine and is controlled and moved in the existing manner to drive the beam carrier to move one pier position. There is a leg pulley between the main girder and the front support of the beam carrier for relative sliding between the main girder and the front support. The leg pulley is the leg pulley used for connecting the main girder and the leg of the existing bridge erecting machine, so it will not be elaborated here. During the movement, the overhead crane moves to a position close to the rear support.

[0025] During this process, the front support for installing the support block always supports on the top of the pier.

[0026] S624. The front support without the support block moves above the next pier and then supports on the top of the pier, showing the state as shown in Figure 4 .

[0027] S7. The overhead crane lifts the girder for the second time and removes the support block. Specifically, it includes the following steps: S721. As shown in Figure 5 , use two overhead cranes to lift the girder for the second time and lift the box girder. S722. The front support for installing the support block moves above the next pier. As needed, the front support for installing the support block supports on the top of the pier or the front support for installing the support block is selected not to support on the top of the pier temporarily.

[0028] S8. As shown in Figure 6 and 7 , the overhead crane moves the box girder and then lowers the box girder so that one end of the box girder is connected to the already installed box girder and the other end is placed on the top of the pier. After installation: S81. The overhead crane cancels the connection with the box girder, the middle support resumes support, and the front support without the support block moves away from the pier. S82. The front support for installing the support block supports on the top of the pier.

[0029] S9. Repeat S1 - S8 until all box girders are installed.

[0030] Through the above erection method, the sequential erection of large - scale box girders can be completed quickly, and it can meet special erection requirements such as cantilever welding of large - scale box girders, reduce the construction difficulty, have better adaptability and higher efficiency.

[0031] Embodiment 2: As Figure 11 shown, the method for erecting large - scale box girders for the second time includes the following steps: S1. The front support is supported on the top of the pier, and support blocks are arranged on the side of the front support; There is one front support and three overhead cranes; Among them, two overhead cranes are used for transporting girders, and a support block is connected below the other overhead crane; The height of the support block is the same as the height of the box girder.

[0032] S2. The overhead crane of the bridge - erecting machine moves to a position close to the front support through the existing method, and makes the middle support complete the support, and the rear support folds upward; Then the girder - carrying vehicle enters while carrying the girder. The girder - carrying vehicle adopts the commonly used existing box - girder - carrying vehicle; S3. The rear support resumes support, and the middle support folds upward; S4. The overhead crane moves along the main girder to above the box girder through the existing method, and then lifts the girder. After the girder - lifting is completed, it moves along the main girder and moves one end of the box girder to above the support block; S5. Then lower the box girder so that one end of the box girder is placed on the top of the support block and the other end is placed on the top of the already - installed box girder to complete the first girder - lifting and girder - placing; S6. The girder - carrying vehicle drives out, and the bridge - erecting machine moves one pier position. Specifically, it includes the following steps: S611. The middle support resumes support, and the rear support folds upward; The girder - carrying vehicle drives out and goes to the box - girder storage area to install a new box girder; S612. The rear support resumes support, lower the trolley, and lift the middle support; S613. The trolley at the bottom of the rear support moves. The trolley at the bottom of the rear support is the commonly used moving trolley of the existing bridge - erecting machine, and it is controlled and moved through the existing method to drive the girder - carrying vehicle to move one pier position; There are leg pulleys between the main girder and the front support of the girder - carrying vehicle for relative sliding between the main girder and the front support; the leg pulleys are the leg pulleys used for connecting the main girder and the legs of the existing bridge - erecting machine, so they will not be elaborated here; During the movement, the overhead crane moves to a position close to the rear support; During this process, the front support is always supported on the top of the pier, and the support block is located on the top of the pier.

[0033] S614. The middle support resumes supporting, the front support cancels the support, and then the front support moves along the main beam to above the next pier through the leg pulley.

[0034] In this embodiment, the middle support is a telescopic leg that can support the top of box girders at different heights. S615. The front support completes the support, and the middle support folds upward.

[0035] S7. The overhead crane lifts the beam for the second time and removes the support block. Specifically, it includes the following steps: S711. Use two overhead cranes to lift the beam for the second time to lift the box girder. S712. Use another overhead crane to lift the support block. S713. Move the support block to above the next pier and lower it to the side of the front support. S8. The overhead crane moves the box girder and then lowers the box girder so that one end of the box girder is connected to the already installed box girder and the other end is placed on the top of the pier. After installation, the overhead crane cancels the connection with the box girder, and the middle support resumes supporting; in the state as Figure 11 shown.

[0036] S9. Repeat S1 - S8 until all box girders are installed.

[0037] Through the above erection method, the sequential erection of large box girders can be completed quickly, and it can meet special erection requirements such as the cantilever welding of large box girders, reduce the construction difficulty, have better adaptability, and higher efficiency.

[0038] Embodiment 3: As Figures 1-12 shown, the large box girder secondary beam lifting and erection equipment includes a main beam 2. A plurality of overhead cranes 201 are provided on the top of the main beam 2, and the overhead cranes 201 are slidably connected to the main beam 2; the overhead cranes 201 are used to lift, move and lower the box girder 102; the box girder 102 refers to the box girder to be installed and erected; the overhead cranes 201 and the main beam 2 are the common structures and connection methods of existing bridge erecting machines, and the overhead cranes 201 move, connect and hoist the box girder 102 in the existing way, such as steel rope connection, so it will not be elaborated here. Below the main beam 2, there are a rear support 3, a middle support 4 and a front support 5; the rear support 3 and the middle support 4 are rotatably connected to the main beam 2; the front support 5 is connected to the pier 101 through a support frame.

[0039] During use, the box girder 102 is lifted, moved and placed by the overhead crane 201, and the overall erection of the box girder 102 and the movement of the bridge erecting machine are completed through the cooperation of the rear support 3, the middle support 4 and the front support 5.

[0040] Further, the rear support 3 includes a first support base 301 fixed to the main beam 2. The first support base 301 is hinged to a first support arm 302 through a first hinge 303. The first hinge 303 is an existing hinge structure. First connection frames 304 are provided on the sides of both the first support base 301 and the first support arm 302. The first connection frames 304 of the first support base 301 and the first support arm 302 are connected by a first hydraulic cylinder 305. The connection modes at both ends of the first hydraulic cylinder 305 are hinge connections. A fixed seat 306 is provided at the bottom of the first support arm 302, and a fixed plate 307 is provided on the side of the fixed seat 306. A number of second hydraulic cylinders 308 are provided on the fixed plate 307. The first hydraulic cylinder 305 and the second hydraulic cylinders 308 are fixed hydraulic cylinders commonly used in existing bridge erection machines, and the hydraulic system is driven, controlled, and connected in an existing manner. The output end of the second hydraulic cylinder 308 is provided with a movable frame 309. A roller 310 is provided at the bottom of the movable frame 309. The roller 310 is a roller with a driving structure, such as a roller mechanism with a motor, or a hub motor is directly used, or a trolley mechanism used in the legs of existing bridge erection machines. During use, the driving structure (such as motor drive) of the roller 310 drives the roller 310 to rotate, so that the roller 310 can move along the box girder.

[0041] During use, by starting the first hydraulic cylinder 305, it can be telescoped, thereby driving the first support arm 302 to rotate relative to the first support base 301 through the first hinge 303. When the first support arm 302 rotates downward, the support is completed, and when the first support arm 302 rotates upward, the rear support 3 is retracted. When the first support arm 302 is in a vertical state, start the second hydraulic cylinder 308 to make it extend, which can drive the movable frame 309 and the roller 310 to move downward until the roller 310 abuts against the box girder and the fixed seat 306 is lifted by 1 - 10 cm. Then, by rotating the roller 310, it can move along the box girder, thereby driving the rear support 3 and the main beam 2 to move along the box girder.

[0042] Further, the middle support 4 includes a second support base 401 fixed to the main beam 2. The second support base 401 is hinged to a second support arm 402 through a second hinge 403. The second hinge 403 adopts an existing hinge structure. Second connecting frames 404 are provided on the sides of both the second support base 401 and the second support arm 402. The second connecting frames 404 of the second support base 401 and the second support arm 402 are connected by a third hydraulic cylinder 405. The connection modes at both ends of the third hydraulic cylinder 405 are hinge connections. The third hydraulic cylinder 405 is a commonly used hydraulic cylinder for existing bridge erecting machines and is connected, controlled, and connected to the hydraulic system in an existing manner. A telescopic support column 406 is provided at the bottom of the second support arm 402. The telescopic support column 406 is slidably connected to the second support arm 402. The second support arm 402 is provided with a hydraulic cylinder for driving the telescopic support column 406 to slide relative to the second support arm 402. The hydraulic cylinder is a commonly used hydraulic cylinder for existing bridge erecting machines and is connected, controlled, and connected to the hydraulic system in an existing manner. By driving the telescopic support column 406 to expand and contract through the hydraulic cylinder, after the telescopic support column 406 contracts, the middle support 4 becomes shorter and can support on the top of the box girder placed after the first beam lifting. After the telescopic support column 406 extends, it can support on the top of the box girder after installation.

[0043] During use, by starting the third hydraulic cylinder 405, it can be telescoped, thereby driving the second support arm 402 to rotate relative to the second support base 401 through the second hinge 403. When the second support arm 402 rotates downwards, the support is completed. When the second support arm 402 rotates upwards, the retraction of the middle support 4 is completed. The operation is simple and it can meet different fixed use requirements. When this embodiment is used in Embodiment 1, a front support 5 and a spare front support 501 are provided. The spare front support 501 has the same structure as the front support 5. The support block 6 is fixedly connected to the front support 5.

[0044] Further, the front support 5 includes a connection seat 502. The top of the connection seat 502 is slidably connected to the main beam 2 through a leg pulley 503. The leg pulley 503 is a commonly used leg pulley structure for existing bridge erecting machines and is connected and controlled to move in an existing manner.

[0045] A leg 504 is provided at the bottom of the connection seat 502. The leg 504 is arranged on the top of the bridge pier.

[0046] In a further embodiment, the support block 6 includes a fixing block 601 and a fixing sleeve 602 connected to the front support 5; the fixing block 601 is located on the side of the front support 5, and the fixing sleeve 602 is fixedly sleeved outside the front support 5; a plurality of guide rings 603 are provided on the outer peripheral surface of the fixing sleeve 602, and a movable sleeve 604 is rotatably connected to the guide rings 603; a connecting rod 605 is provided on the movable sleeve 604, and a backing plate 606 is provided on the connecting rod 605; the backing plates 606 are stacked on the top of the fixing block 601. During use, according to the actual height requirement of the support block 6, rotate the backing plate 606 so that it rotates around the guide ring 603 through the movable sleeve 604, so that the backing plate 606 rotates to the top of the fixing block 601 or rotates away. Thus, according to the combination of the fixing block 601 and different numbers of backing plates 606, the height of the support block 6 can be adjusted to adapt to different fixed erection requirements, with simple operation and better adaptability.

[0047] When this embodiment is used in Embodiment 2, a spare overhead crane 7 is provided, the support block 6 is connected to the spare overhead crane, and the support block 6 only contacts the front support 5.

[0048] The above embodiments are only the preferred technical solutions of the present invention and should not be regarded as limitations on the present invention. The protection scope of the present invention should be the technical solutions recorded in the claims, including equivalent replacement solutions of the technical features in the technical solutions recorded in the claims. That is, equivalent replacement improvements within this scope are also within the protection scope of the present invention.

Claims

1. Method for secondary beam lifting and erection of large box girders, characterized in that: It includes the following steps: S1. The front support is supported on the top of the pier, and support blocks are arranged on the side of the front support; S2. The overhead crane moves close to the front support, the middle support is supported, the rear support is folded upward, and the girder carrier enters with the beam on its back; S3. The rear support resumes support, and the middle support is folded upward; S4. The overhead crane lifts the beam, then moves and moves one end of the box girder above the support block; S5. Lower the box girder, place one end of the box girder on the top of the support block, and the other end on the top of the already installed box girder; S6. The girder carrier drives out, and the bridge erecting machine moves one pier position; S7. The overhead crane lifts the beam for the second time and removes the support block; S8. The overhead crane moves the box girder, then lowers the box girder to connect one end of the box girder with the already installed box girder, and the other end is placed on the top of the pier; S9. Repeat S1 - S8 until all box girders are installed.

2. The method for secondary beam lifting and erection of large box girders according to claim 1, characterized in that: There is one front support and three overhead cranes; Among them, two overhead cranes are used for transporting beams, and a support block is connected below the other overhead crane; The height of the support block is the same as the height of the box girder.

3. The method for secondary beam lifting and erection of large box girders according to claim 2, wherein: In S6, it includes the following steps: S611. The middle support resumes support, the rear support is folded upward, and the girder carrier drives out; S612. The rear support resumes support, and the middle support is lifted; S613. The trolley at the bottom of the rear support moves to drive the girder carrier to move one pier position; There are leg pulleys between the main girder of the girder carrier and the front support for relative sliding between the main girder and the front support; S614. The middle support resumes support, the front support cancels support, and moves to above the next pier along the main girder through the leg pulleys; S615. The front support completes support, and the middle support is folded upward.

4. The method for secondary beam lifting and erection of large box girders according to claim 2, characterized in that: at In S7, it includes the following steps: S711. Use two overhead cranes to lift the beam for the second time, and the box girder is lifted; S712. Use the other overhead crane to lift the support block; S713. Move the support block to above the next pier and lower it to be placed on the side of the front support.

5. The method for the secondary beam lifting and erection of a large box girder according to claim 1, characterized in that: There are two front supports and two overhead cranes; Among them, two overhead cranes are used for transporting beams; One of the front supports is used for support and connection of the support block, and the other front support is used for temporary support; The front support connecting the support block is close to the already installed box girder.

6. The method for erecting a large box girder by secondary beam lifting according to claim 5, characterized in that: at In S6, it includes the following steps: S621. The middle support resumes support, the rear support is folded upward, and the girder carrier drives out; S622. The rear support resumes support, and the middle support is lifted; S623. The trolley at the bottom of the rear support moves to drive the girder carrier to move one pier position; There are leg pulleys between the main girder of the girder carrier and the front support for relative sliding between the main girder and the front support; S624. The front support without the support block moves to above the next pier and then is supported on the top of the pier.

7. The method for second-time beam lifting and erection of large box girders according to claim 5, characterized in that: at In S7, it includes the following steps: S721. Use two overhead cranes to lift the beam for the second time, and the box girder is lifted; S722. The front support with the support block moves to above the next pier; The front support with the support block is supported on the top of the pier; Or The front support with the support block is not temporarily supported on the top of the pier; In S8, it also includes the following steps: S81. The middle support resumes support, and the front support without the support block moves away from the pier; S82. The front support with the support block is supported on the top of the pier.

8. Erection equipment for the large box girder secondary beam lifting and erection method according to any one of claims 1-7, characterized in that: It includes a main girder (2), and several overhead cranes (201) are arranged on the top of the main girder (2), and the overhead cranes (201) are slidably connected with the main girder (2); Below the main girder (2), there are a rear support (3), a middle support (4) and a front support (5); The rear support (3) and the middle support (4) are rotatably connected to the main beam (2). The front support (5) is arranged on the top of the pier (101), and a support block (6) is arranged on the side of the front support (5).

9. The large box girder secondary beam lifting and erection equipment according to claim 8, characterized in that: There are a front support (5) and a spare front support (501). The spare front support (501) has the same structure as the front support (5), and the support block (6) is fixedly connected to the front support (5). Or There is a spare overhead crane (7). The support block (6) is connected to the spare overhead crane, and the support block (6) only contacts the front support (5). The rear support (3) includes a first support seat (301) fixed to the main beam (2). The first support seat (301) is hinged to a first support arm (302) through a first hinge (303). First connection frames (304) are arranged on the sides of both the first support seat (301) and the first support arm (302). The first connection frames (304) of the first support seat (301) and the first support arm (302) are connected by a first hydraulic cylinder (305). The connection modes at both ends of the first hydraulic cylinder (305) are hinge connections. A fixed seat (306) is arranged at the bottom of the first support arm (302), and a fixed plate (307) is arranged on the side of the fixed seat (306). A number of second hydraulic cylinders (308) are arranged on the fixed plate (307). The output end of the second hydraulic cylinder (308) is provided with a movable frame (309), and a roller (310) is arranged at the bottom of the movable frame (309). The middle support (4) includes a second support seat (401) fixed to the main beam (2). The second support seat (401) is hinged to a second support arm (402) through a second hinge (403). Second connection frames (404) are arranged on the sides of both the second support seat (401) and the second support arm (402). The second connection frames (404) of the second support seat (401) and the second support arm (402) are connected by a third hydraulic cylinder (405). The connection modes at both ends of the third hydraulic cylinder (405) are hinge connections. A telescopic support column (406) is arranged at the bottom end of the second support arm (402). The front support (5) includes a connection seat (502). The top of the connection seat (502) is slidably connected to the main beam (2) through a leg pulley (503). The bottom of the connection seat (502) is provided with a leg (504), and the leg (504) is arranged on the top of the pier.

10. The large box girder secondary beam lifting and erection equipment according to any one of claims 8 or 9, characterized in that: The support block (6) includes a fixed block (601) and a fixed sleeve (602) connected to the front support (5). The fixed block (601) is located on the side of the front support (5), and the fixed sleeve (602) is fixedly sleeved outside the front support (5). A number of guide rings (603) are arranged on the outer peripheral surface of the fixed sleeve (602), and a movable sleeve (604) is rotatably connected to the guide rings (603). The movable sleeve (604) is provided with a connecting rod (605), and a backing plate (606) is arranged on the connecting rod (605). The backing plates (606) are stacked on the top of the fixed block (601).

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