Multi-unit multi-span bridge synchronous pushing device and method

Abstract

The application discloses a kind of multi-connection multi-span bridge synchronous pushing device and method, including base plate, the downside of base plate is equipped with several lifting legs, the upside of base plate is equipped with mutually parallel first slide, second slide and third slide, first slide is equipped with first lifting mechanism, second slide is equipped with second lifting mechanism, third slide is equipped with third lifting mechanism;The upside of base plate is fixedly provided with mounting seat, mounting seat is connected with first flat pushing drive oil cylinder, second flat pushing drive oil cylinder and third flat pushing drive oil cylinder;The first lifting mechanism and the third lifting mechanism are synchronous lifting, the first lifting mechanism and the second lifting mechanism are alternately lifted;The first flat pushing drive oil cylinder and the third flat pushing drive oil cylinder are synchronous extension and contraction, the first flat pushing drive oil cylinder and the second flat pushing drive oil cylinder are alternately extended and contracted;The application is fast in construction speed, bridge is transported smoothly, solve the problem of difficult to adapt to bridge slope section.

Description

Technical Field

[0001] This invention relates to the field of bridge jacking equipment technology, specifically to a synchronous jacking device and method for multi-span bridges. Background Technology

[0002] The incremental launching method involves setting up a prefabrication yard behind the abutments along the bridge axis, and installing steel guide beams, temporary piers, sliding tracks, and horizontal jacks for force application. Specifically, prefabricated concrete beam segments are connected by longitudinal prestressed tendons, and the beams are then pushed (pushed) out segment by segment. The next segment is then poured on a narrower prefabrication platform, and this repeated cycle is called the incremental launching method. The incremental launching method is an application of the steel bridge dragging method's erection principle; the difference lies in the sliding and force application devices.

[0003] The jacking device is a key piece of equipment used in the jacking method. These devices are concentrated on the abutments or piers near the main beam prefabrication yard, with sliding supports installed at each forward support point. There are two types of jacking devices: one uses horizontal jacks to apply a jacking force to the prefabricated beam through traction steel rods on both sides of the box girder; the other uses a combination of horizontal and vertical jacks to push the prefabricated beam forward. In China, the tie-rod type jacking scheme is more commonly used. At each pier, a pair of hydraulic through-type horizontal jacks are installed. Each side's jack uses one or two φ25 mm high-strength threaded steel bars. The front end of the jack is fixed to the head of the horizontal jacking piston rod via a conical wedge block, and the other end is connected to the box girder using a specially designed anchor, fixing plate, or other connector. The horizontal jacks are fixed to a specially designed platform on the pier body, and a sliding plate and slider are installed under the beam. When the horizontal jacks apply jacking force, they drive the box girder to slide forward on the track.

[0004] The shortcomings of the existing technology are: (1) Some bridges have a slope section at the contact point between the lower side and the pier, and the current jacking device is difficult to adapt to bridges with slope sections and large vertical curvature; (2) The bridge is repeatedly raised and lowered during the jacking process, which requires a lot of temporary constraints, the tensioning process is complicated, and the internal stress of the bridge is large; (3) As the bridge length increases, the construction progress is slow. Summary of the Invention

[0005] The purpose of this invention is to address the problems existing in the prior art by providing a synchronous jacking device and method for multi-span bridges, which enables fast construction, stable bridge transportation, and solves the problem of difficulty in adapting to bridge slope sections.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A synchronous jacking device for multi-span bridges includes a base plate. The lower side of the base plate has several lifting legs. The upper side of the base plate has three parallel sliding tracks: a first sliding track, a second sliding track, and a third sliding track. A first lifting mechanism is located within the first sliding track, a second lifting mechanism within the second sliding track, and a third lifting mechanism within the third sliding track. A mounting base is fixedly mounted on the upper side of the base plate. The mounting base is connected to a first horizontal pushing drive cylinder, a second horizontal pushing drive cylinder, and a third horizontal pushing drive cylinder. The first horizontal pushing drive cylinder is connected to the first lifting mechanism, the second horizontal pushing drive cylinder is connected to the second lifting mechanism, and the third horizontal pushing drive cylinder is connected to the third lifting mechanism. The first and third lifting mechanisms move up and down synchronously, and alternately. The first and third horizontal pushing drive cylinders extend and retract synchronously, and alternately extend and retract.

[0008] The first lifting mechanism, the second lifting mechanism and the third lifting mechanism each include two slide blocks connected in series. One slide block is connected to the telescopic rod of the corresponding horizontal push drive cylinder. The two slide blocks are arranged sequentially along the corresponding slide rails. Each slide block is connected to a lifting cylinder. Each lifting cylinder is hinged to a push plate.

[0009] A horizontal adjustment cylinder is provided between each pair of slide blocks.

[0010] Both slides of the second lifting mechanism are shell structures with openings at the top. The bottom of the lifting cylinder slides against the inner wall of the bottom of the shell structure. A correction cylinder is provided on one side of each slide. The correction cylinder is set perpendicular to the second slide rail. The telescopic rod of the correction cylinder passes through the shell of the slide and abuts against one side of the lifting cylinder.

[0011] The push plate includes a movable plate and a fixed plate stacked on top of each other. The movable plate has a concave surface on its lower side and a convex surface on its upper side. The movable plate has a recessed groove in the middle and a strip-shaped through groove at the bottom of the recessed groove. Bolts pass through the strip-shaped through groove and are connected to the fixed plate.

[0012] Four parallel limiting plates are fixedly provided on the upper side of the substrate, and the four limiting plates form the first slide, the second slide and the third slide respectively between each other; the first push drive cylinder, the second push drive cylinder and the third push drive cylinder are all located at the same end of the corresponding slide.

[0013] It includes a laser ranging device, which is fixedly mounted at the first end of the substrate.

[0014] A method for synchronous jacking of bridges includes the following steps:

[0015] S1. Several fixed piles are pre-set along the bridge-building direction, and a jacking device is placed on each fixed pile, and the second jacking mechanism is in the jacking state;

[0016] S2. Hoist the bridge box girder to the top of several fixed piles of the first section, and then lower it to the bottom of the bridge box girder to contact the jacking device.

[0017] S3. Each of the aforementioned jacking devices operates synchronously. First, the second horizontal push drive cylinder pushes the second lifting mechanism to move along the second slide rail. The second lifting mechanism drives the bridge box girder to move a predetermined distance. The first lifting mechanism and the third lifting mechanism rise synchronously to be level with the second lifting mechanism. Then, the second lifting mechanism descends and retracts. The first lifting mechanism and the third lifting mechanism drive the bridge box girder to move another predetermined distance. This cycle repeats, allowing the bridge box girder to move forward smoothly.

[0018] The bottom of the bridge box girder is provided with a variable slope section. When the jacking device is in the variable slope section, the lifting cylinders arranged at the front and rear change the extension amount according to the slope, so that the jacking plate abuts against the bottom of the bridge. When the distance between the base plate and the bottom of the beam increases or decreases beyond a predetermined value, the corresponding jacking device rises or falls synchronously by a predetermined distance, and the lifting cylinder extends or retracts by the same distance.

[0019] When the junction of the slope-changing section of the bridge box girder is displaced to the head end of a jacking device, all jacking devices stop synchronously. If the second jacking mechanism is in a retracted state at this time, the distance between the two jacking cylinders of the second jacking mechanism is adjusted so that the jacking plate avoids the junction of the slope-changing section.

[0020] If the first and third lifting mechanisms are in the retracted state, adjust the distance between the two lifting cylinders of the first and third lifting mechanisms respectively so that the jacking plate avoids the junction of the slope section.

[0021] Compared with the prior art, the beneficial effects of the present invention are:

[0022] 1. By setting up a second jacking mechanism to alternately push with the first and third jacking mechanisms, the bridge box girder is always in the forward transportation process. Compared with the existing technology that uses a set of jacking mechanisms, it saves the retraction waiting time, speeds up the transportation speed of the bridge box girder, and solves the problem of slow construction speed and long time consumption of the traditional jacking scheme when erecting long bridges.

[0023] 2. By setting up a second lifting mechanism to alternately push the first and third lifting mechanisms, the bridge box girder is always transported on the same horizontal plane. Compared with the existing technology that uses a set of lifting mechanisms, this avoids the problems of frequent up and down bumping of the bridge box girder, repeated high stress, large beam height, many temporary constraints, and complicated tensioning process.

[0024] 3. By setting several lifting legs on the lower side of the base plate, the jacking device can change the height of the base plate according to the distance between it and the bottom of the bridge box girder when it encounters the slope section on the lower side of the bridge box girder, so that the jacking device can pass through the slope section of the bridge box girder smoothly; and while the lifting legs move, the jacking mechanism moves in the opposite direction at the same time, so that the jacking mechanism always maintains support for the bridge box girder, which is convenient to operate, reduces complicated manual on-site operations, improves safety, and has a low cost.

[0025] 4. By placing the first lifting mechanism and the third lifting mechanism on both sides of the second lifting mechanism, and arranging the first lifting mechanism, the second lifting mechanism and the third lifting mechanism in a horizontal parallel arrangement, the overall space occupied is small. The first lifting mechanism is located in the middle of the substrate, so that the substrate is subjected to uniform force regardless of whether the first lifting mechanism or the first and third lifting mechanisms are pushing, thus avoiding lateral displacement due to unbalanced force on both sides of the pushing device.

[0026] 5. By setting two lifting cylinders in each lifting mechanism, the lifting height of the two lifting cylinders can be changed according to the slope when the bridge box girder changes slope. This makes the contact between the jacking plate and the bottom of the beam more stable, avoiding the need to place triangular pads on the jacking plate in the existing technology. The operation is simpler, the applicability is better, and the safety is improved.

[0027] 6. A horizontal adjustment cylinder is provided between each pair of sliding blocks. When the junction of the slope section of the bridge box girder is displaced to the head end of a jacking device, the distance between the two jacking cylinders of the jacking mechanism in the retracted state is adjusted so that the jacking plate of the jacking mechanism can avoid the junction of the slope section during the next jacking, thus avoiding unstable contact between the jacking plate and the bottom of the beam. Attached Figure Description

[0028] Figure 1 This is a perspective view of the pushing device of the present invention;

[0029] Figure 2 This is a perspective view of the pushing device of the present invention;

[0030] Figure 3 This is a diagram showing the usage state of the jacking device of the present invention;

[0031] Figure 4 This is a schematic diagram of the jacking device of the present invention passing through the slope section of the bridge box girder;

[0032] Figure 5 This is a schematic diagram of the jacking device of the present invention passing through the slope section of the bridge box girder;

[0033] Figure 6 This is a schematic diagram of the structure of the push plate of the present invention;

[0034] In the diagram: 1. Base plate; 2. Lifting support leg; 3. First slide rail; 4. Second slide rail; 5. Third slide rail; 6. Mounting base; 7. First horizontal push drive cylinder; 8. Second horizontal push drive cylinder; 9. Third horizontal push drive cylinder; 10. Slide seat; 11. Lifting cylinder; 13. Horizontal push adjustment cylinder; 14. Correction cylinder; 15. Push plate; 16. Movable plate; 17. Fixed plate; 18. Sink; 19. Strip through groove; 20. Limiting plate. Detailed Implementation

[0035] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] In the description of this invention, it should be noted that the terms "upper", "lower", "left", "right", "top", "bottom", "inner", "outer", "horizontal", "vertical", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, 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 limiting this invention.

[0037] like Figures 1 to 6 As shown, a synchronous jacking device for multi-span bridges includes a base plate 1. The lower side of the base plate 1 is provided with several lifting legs 2. The upper side of the base plate 1 is provided with a first slide rail 3, a second slide rail 4, and a third slide rail 5 that are parallel to each other. A first lifting mechanism is provided in the first slide rail 3, a second lifting mechanism in the second slide rail 4, and a third lifting mechanism in the third slide rail 5. A mounting base 6 is fixedly provided on the upper side of the base plate 1. The mounting base 6 is connected to a first horizontal push drive cylinder 7, a second horizontal push drive cylinder 8, and a third horizontal push drive cylinder 9. The first horizontal push drive cylinder 7 is connected to the first lifting mechanism, the second horizontal push drive cylinder 8 is connected to the second lifting mechanism, and the third horizontal push drive cylinder 9 is connected to the third lifting mechanism. The first and third lifting mechanisms move up and down synchronously, and alternately. The first and third horizontal push drive cylinders 7 and 9 extend and retract synchronously, and alternately extend and retract.

[0038] After the bottom of the bridge box girder contacts the jacking device, each jacking device moves synchronously. First, the second horizontal push drive cylinder 8 pushes the second lifting mechanism to move along the second slide rail 4. The second lifting mechanism drives the bridge box girder to move a predetermined distance. The first lifting mechanism and the third lifting mechanism rise synchronously to be level with the second lifting mechanism. Then the second lifting mechanism descends and retracts. The first lifting mechanism and the third lifting mechanism drive the bridge box girder to move another predetermined distance. This cycle repeats, allowing the bridge box girder to move forward smoothly.

[0039] By setting up a second lifting mechanism to alternately push the bridge box girder with the first and third lifting mechanisms, the bridge box girder is always in the process of forward transportation. Compared with the existing technology that uses a set of lifting mechanisms, this saves the retraction waiting time, speeds up the transportation of the bridge box girder, and solves the problem of slow construction speed and long time consumption of the traditional jacking scheme when erecting long bridges.

[0040] By setting up a second lifting mechanism to alternately push the first and third lifting mechanisms, the bridge box girder is always transported on the same horizontal plane. Compared with the existing technology that uses a set of lifting mechanisms, this avoids the problems of frequent up-and-down bumping of the bridge box girder, repeated high stress, large beam height, many temporary constraints, and complicated tensioning procedures.

[0041] By providing several lifting legs 2 on the lower side of the base plate 1, the jacking device can change the height of the base plate 1 according to the distance between it and the bottom of the bridge box girder when it encounters the slope section on the lower side of the bridge box girder, so that the jacking device can pass through the slope section of the bridge box girder smoothly; and while the lifting legs 2 move, the jacking mechanism moves in the opposite direction at the same time, so that the jacking mechanism always maintains support for the bridge box girder, which is convenient to operate, reduces complicated manual on-site operations, improves safety, and has a low cost.

[0042] By placing the first lifting mechanism and the third lifting mechanism on both sides of the second lifting mechanism, and arranging the first lifting mechanism, the second lifting mechanism and the third lifting mechanism in a horizontal parallel arrangement, the overall space occupied is small. The first lifting mechanism is located in the middle of the substrate. Whether the first lifting mechanism or the first and third lifting mechanisms are pushing, the substrate 1 is subjected to uniform force, avoiding lateral displacement due to unbalanced force on both sides of the pushing device.

[0043] In one specific embodiment, the first, second, and third lifting mechanisms each include two interconnected slide blocks 10. One slide block 10 is connected to the telescopic rod of a corresponding horizontal push drive cylinder. The two slide blocks 10 are arranged sequentially along corresponding slide tracks. Each slide block 10 is connected to a lifting cylinder 11, and each lifting cylinder 11 is hinged to a push plate 15. By setting two lifting cylinders 11 in each lifting mechanism, the lifting height of the two lifting cylinders 11 can be changed according to the slope when the bridge box girder changes slope. This makes the contact between the push plate 15 and the bottom of the beam more stable, avoiding the need to place a triangular pad on the push plate 15 in the prior art. The operation is simpler, the applicability is better, and the safety is improved.

[0044] Preferably, the sum of the areas of the jacking plates 15 of the first lifting mechanism and the third lifting mechanism is equal to the area of ​​the jacking plate 15 of the second lifting mechanism, so that the bottom of the beam is in force balance.

[0045] In one specific embodiment, a horizontal adjustment cylinder 13 is provided between every two sliding blocks 10. When the junction of the slope transition section of the bridge box girder is displaced to the head end of a jacking device, the distance between the two jacking cylinders of the jacking mechanism in the retracted state is adjusted so that the jacking plate 15 of the jacking mechanism can avoid the junction of the slope transition section during the next jacking, thus preventing unstable contact between the jacking plate 12 and the bottom of the beam.

[0046] In one specific embodiment, both slide blocks 10 of the second lifting mechanism are open-top shell structures, and the bottom of the lifting cylinder 11 slides against the inner bottom wall of the shell structure. A correction cylinder 14 is provided on one side of each of the two slide blocks 10. The correction cylinder 14 is perpendicular to the second slide rail 4, and its extension rod passes through the shell of the slide block 10 and abuts against one side of the lifting cylinder 11. By providing the correction cylinder 14, the transport direction of the bridge box girder can be finely adjusted to prevent deviation.

[0047] In a specific embodiment, such as Figure 6 As shown, the push plate 15 includes a movable plate 16 and a fixed plate 17 stacked vertically. The lower side of the movable plate 16 has a concave surface, and the upper side of the fixed plate 17 has a convex surface. The middle of the movable plate 16 has a recessed groove 18, and the bottom of the recessed groove 18 has a strip-shaped through groove 19. Bolts pass through the strip-shaped through groove 19 to connect with the fixed plate 17. The movable plate 16 rotates relative to the fixed plate 17, thereby changing its angle to adapt to the slope of the beam bottom. By setting the concave and convex surfaces to contact each other, the contact area between the movable plate 16 and the fixed plate 17 is large when rotating, making the force on the movable plate 16 more balanced compared to other hinged methods.

[0048] In one specific embodiment, four parallel limiting plates 20 are fixedly provided on the upper side of the substrate 1. The four limiting plates 20 are arranged in pairs to form the first slide rail 3, the second slide rail 4, and the third slide rail 5, respectively. The first horizontal push drive cylinder 7, the second horizontal push drive cylinder 8, and the third horizontal push drive cylinder 9 are all located at the same end of the corresponding slide rail. By using the four limiting plates 20 to divide the slide rail into three slide rails, the three slide rails can share a single smooth surface, which facilitates installation, increases integration, and reduces the overall space occupied by the device.

[0049] In one specific embodiment, a laser ranging device is included, which is fixedly mounted at the head end of the base plate 1. The laser ranging device detects the distance between the base plate 1 and the bottom of the beam. When the distance is less than a preset value, it indicates that an uphill section has been encountered; when the distance is greater than the preset value, it indicates that a downhill section has been encountered. A signal is then sent to stop the jacking operation, which facilitates the adjustment of the distance between the lifting cylinders.

[0050] The present invention also provides a method for synchronous jacking of bridges, comprising the following steps:

[0051] S1. Several fixed piles are pre-set along the bridge-building direction, and a jacking device is placed on each fixed pile, and the second jacking mechanism is in the jacking state;

[0052] S2. Hoist the bridge box girder to the top of several fixed piles of the first section, and then lower it to the bottom of the bridge box girder to contact the jacking device.

[0053] S3. Each of the aforementioned jacking devices operates synchronously. First, the second horizontal push drive cylinder pushes the second lifting mechanism to move along the second slide rail. The second lifting mechanism drives the bridge box girder to move a predetermined distance. The first lifting mechanism and the third lifting mechanism rise synchronously to be level with the second lifting mechanism. Then, the second lifting mechanism descends and retracts. The first lifting mechanism and the third lifting mechanism drive the bridge box girder to move another predetermined distance. This cycle repeats, allowing the bridge box girder to move forward smoothly.

[0054] like Figure 4 and Figure 5 As shown, the bottom of the bridge box girder is provided with a variable slope section. When the jacking device is in the variable slope section, the lifting cylinders arranged at the front and rear change the extension amount according to the slope, so that the corresponding two jacking plates adapt to the slope of the bottom of the bridge. When the distance between the base plate and the bottom of the beam increases or decreases beyond a predetermined value, the corresponding jacking device rises or falls synchronously by a predetermined distance, and the lifting cylinders in the extended state extend or retract by the same distance.

[0055] When the junction of the slope-changing section of the bridge box girder is displaced to the head end of a jacking device, all jacking devices stop synchronously. If the second jacking mechanism is in a retracted state at this time, the distance between the two jacking cylinders of the second jacking mechanism is adjusted so that the jacking plate avoids the junction of the slope-changing section.

[0056] If the first and third lifting mechanisms are in the retracted state, adjust the distance between the two lifting cylinders of the first and third lifting mechanisms respectively so that the jacking plate avoids the junction of the slope section.

[0057] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A synchronous jacking device for multi-span, multi-connected bridges, characterized in that, The system includes a base plate (1), with several lifting legs (2) on its lower side. The upper side of the base plate (1) is provided with a first slide rail (3), a second slide rail (4), and a third slide rail (5) that are parallel to each other. A first lifting mechanism is provided in the first slide rail (3), a second lifting mechanism is provided in the second slide rail (4), and a third lifting mechanism is provided in the third slide rail (5). A mounting base (6) is fixedly provided on the upper side of the base plate (1), and the mounting base (6) is connected to a first horizontal push drive cylinder (7), a second horizontal push drive cylinder (8), and a third horizontal push drive cylinder (9). The third horizontal push drive cylinder (9) is connected to the third lifting mechanism, the first horizontal push drive cylinder (7) is connected to the first lifting mechanism, the second horizontal push drive cylinder (8) is connected to the second lifting mechanism, and the third horizontal push drive cylinder (9) is connected to the third lifting mechanism; the first lifting mechanism and the third lifting mechanism move up and down synchronously, and the first lifting mechanism and the second lifting mechanism move up and down alternately; the first horizontal push drive cylinder (7) and the third horizontal push drive cylinder (9) extend and retract synchronously, and the first horizontal push drive cylinder (7) and the second horizontal push drive cylinder (8) extend and retract alternately; The first lifting mechanism, the second lifting mechanism and the third lifting mechanism each include two slide blocks (10) connected in series. The two slide blocks (10) are arranged in sequence along the corresponding slide rails. One of the slide blocks (10) is connected to the telescopic rod of the corresponding flat push drive cylinder. Each slide block (10) is connected to a lifting cylinder (11). Each lifting cylinder (11) is hinged to a push plate (15). A horizontal adjustment cylinder (13) is provided between each pair of said slides (10).

2. The synchronous jacking device for multi-span bridges according to claim 1, characterized in that, The two slides (10) of the second lifting mechanism are both shell structures with openings at the top. The bottom of the lifting cylinder (11) slides against the inner wall of the bottom of the shell structure. A correction cylinder (14) is provided on one side of each of the two slides (10). The correction cylinder (14) is perpendicular to the second slide rail (4). The telescopic rod of the correction cylinder (14) passes through the shell of the slide (10) and abuts against one side of the lifting cylinder (11).

3. The synchronous jacking device for multi-span bridges according to claim 1, characterized in that, The push plate (15) includes a movable plate (16) and a fixed plate (17) stacked on top of each other. The lower side of the movable plate (16) is provided with a concave surface, and the upper side of the fixed plate (17) is provided with a convex surface. The middle part of the movable plate (16) is provided with a recessed groove (18), and the bottom of the recessed groove (18) is provided with a strip-shaped through groove (19). Bolts pass through the strip-shaped through groove (19) and connect to the fixed plate (17).

4. The synchronous jacking device for multi-span bridges according to claim 1, characterized in that, Four parallel limiting plates (20) are fixedly provided on the upper side of the substrate (1). The four limiting plates (20) form the first slide (3), the second slide (4) and the third slide (5) respectively between each other. The first flat push drive cylinder (7), the second flat push drive cylinder (8) and the third flat push drive cylinder (9) are all located at the same end of the corresponding slide.

5. The synchronous jacking device for multi-span bridges according to claim 1, characterized in that, It includes a laser ranging device, which is fixedly disposed at the head end of the substrate (1).

6. The bridge synchronous jacking method according to any one of claims 1 to 5, characterized in that, Includes the following steps: S1. Several fixed piles are pre-set along the bridge-building direction, and a jacking device is placed on each fixed pile, and the second jacking mechanism is in the jacking state; S2. Hoist the bridge box girder to the top of several fixed piles of the first section, and then lower it to the bottom of the bridge box girder to contact the jacking device. S3. Each of the aforementioned jacking devices operates synchronously. First, the second horizontal push drive cylinder (8) pushes the second jacking mechanism to move along the second slide (4). The second jacking mechanism drives the bridge box girder to move a predetermined distance. The first jacking mechanism and the third jacking mechanism rise synchronously to be level with the second jacking mechanism. Then, the second jacking mechanism descends and retracts. The first jacking mechanism and the third jacking mechanism drive the bridge box girder to move a predetermined distance again. This cycle repeats, allowing the bridge box girder to move forward smoothly.

7. The bridge synchronous jacking method according to claim 6, characterized in that, The bottom of the bridge box girder is provided with a slope section. When the jacking device is in the slope section, the lifting cylinders (11) arranged at the front and rear change the extension amount according to the slope. When the distance between the base plate and the bottom of the beam increases or decreases beyond a predetermined value, the corresponding jacking device will rise or fall a predetermined distance simultaneously, and the lifting cylinders (11) in the extended state will extend or retract by the same distance.

8. The bridge synchronous jacking method according to claim 7, characterized in that, When the junction of the slope section of the bridge box girder is displaced to the head end of a jacking device, all jacking devices stop synchronously. If the second jacking mechanism is in a retracted state at this time, the distance between the two jacking cylinders (11) of the second jacking mechanism is adjusted so that the jacking plate (15) avoids the junction of the slope section. If the first lifting mechanism and the third lifting mechanism are in the retracted state, the distance between the two lifting cylinders of the first lifting mechanism and the third lifting mechanism is adjusted respectively so that the jacking plate (15) avoids the junction of the slope section.

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