Variable-cross-section suspended pouring box girder assembly type support and locking assembly construction method of variable-cross-section suspended pouring box girder assembly type support

Abstract

The invention discloses a variable cross-section suspended pouring box girder spliced support and a locking and splicing construction method thereof, and relates to the field of bridge construction, the variable cross-section suspended pouring box girder spliced support comprises a support composed of a plurality of standard knots, a top knot, a sand bucket, I-shaped steel and a box girder, the plurality of standard knots are fixedly connected through hexagon bolts and nuts, and a screwing mechanism used for screwing the nuts. The screwing mechanism is composed of an L-shaped abutting plate and an L-shaped movable plate, an L-shaped driving cavity is formed in the movable plate, cylindrical containing blocks are arranged on the two sides of the driving cavity, a mounting groove is formed in the bottom wall of the corner of the driving cavity, a transmission assembly used for driving the two containing blocks to rotate is arranged in the mounting groove, and a rotating assembly connected with the transmission assembly is arranged on one side of the transmission assembly. The rotating assembly is used for controlling the transmission assembly to move. A constructor does not need to manually tighten the nuts one by one, the manual operation time and labor consumption are reduced, the construction difficulty and danger are reduced, the construction period is greatly shortened, and the construction efficiency is improved.

Description

Technical Field

[0001] The present invention mainly relates to the technical field of bridge construction, and specifically relates to a segmentally variable cross-section cantilever casting box girder assembled bracket and its locking and assembling construction method. Background Technique

[0002] The segmentally variable cross-section cantilever casting box girder assembled bracket is widely used in the field of bridge construction, especially suitable for the construction of variable cross-section continuous box girders and variable cross-section cantilever box girders, etc. When large bridges require cantilever casting operations, this bracket plays an important role as a temporary structure support. It can support the loads of formwork and concrete pouring, and is composed of a plurality of standard sections of steel pipe structures and a top section, and can be adjusted according to the specific construction requirements.

[0003] The existing splicing method is to fix a standard section to the bearing platform with anchor bolts, stack standard sections in sequence above, so that the sleeves are in corresponding contact, then insert bolts from above into the two sleeves, and then screw nuts onto the threaded ends of the bolts from below to connect the two standard sections and ensure the firmness of the connection.

[0004] Although the above technology can ensure the firmness and stability of the connection during the assembly construction process, during high-altitude operations, construction workers must tighten the nuts one by one, which not only consumes time and labor, but also increases the construction difficulty and danger. In addition, the process of tightening the nuts one by one is extremely time-consuming and will greatly extend the construction period. Summary of the Invention

[0005] Based on this, the purpose of the present invention is to provide a segmentally variable cross-section cantilever casting box girder assembled bracket and its locking and assembling construction method to solve the technical problems raised in the above background technique.

[0006] To achieve the above purpose, the present invention provides the following technical solutions: A segmentally variable cross-section cantilever casting box girder assembled bracket, including a bracket composed of a plurality of standard sections, a top section, sand barrels, I-beams and box girders. The plurality of standard sections are fixedly connected by hexagon bolts and nuts, and a tightening mechanism for tightening the nuts. Each standard section is composed of four vertical steel pipes. Two adjacent outer walls at the top and bottom of each steel pipe are welded with sleeves. The tightening mechanism is composed of an L-shaped abutting plate and an L-shaped movable plate. The abutting plate and the movable plate are connected by a telescopic rod. Two symmetrically arranged card slots matching the hexagon bolts are opened on both sides of the lower surface of the abutting plate; An L-shaped driving cavity is opened inside the movable plate. Cylindrical placement blocks are arranged on both sides of the driving cavity. An installation groove is opened on the bottom wall at the corner of the driving cavity. A transmission component for driving the two placement blocks to rotate is arranged in the installation groove. A rotating component is connected to one side of the transmission component, and the rotating component is used to control the movement of the transmission component.

[0007] Specifically, hexagonal grooves matching the nuts are formed at the tops of the two placement blocks, and grooves are formed at the inner bottom wall of the driving cavity at the positions of the hexagonal grooves.

[0008] Specifically, the transmission assembly includes a rotating shaft, the top end of the rotating shaft is rotatably connected to the inner top wall of the driving cavity, a sprocket is fixedly sleeved on the top of the rotating shaft in sequence, inner channel teeth are arranged on the outer walls of the two placement blocks, the two inner channel teeth are respectively in the same horizontal plane as the two sprockets, and the two sprockets are respectively in transmission connection with the inner channel teeth through transmission chains.

[0009] Specifically, the bottom end of the rotating shaft is rotatably connected to the inner bottom wall of the installation groove, a meshing gear is fixedly sleeved on the outer wall of the bottom of the rotating shaft, the diameter of the meshing gear is larger than the diameters of the two sprockets, and through grooves communicating with the driving cavity are formed on the inner walls of the two sides of the movable plate close to the steel pipe.

[0010] Specifically, the rotation assembly includes a vertical shaft, the vertical shaft is located on one side of the rotating shaft, a driving gear is fixedly sleeved on the outer wall of the vertical shaft, the driving gear is matched with the meshing gear in diameter, the driving gear is in meshing connection with the meshing gear, and the top end of the vertical shaft is rotatably connected to the inner top wall of the installation groove.

[0011] Specifically, the bottom end of the vertical shaft penetrates through the installation groove and extends to the outside of the movable plate, a rotating block is arranged below the movable plate, the bottom end of the vertical shaft is fixedly connected to the upper surface of the rotating block, and a slot matching the electric screwdriver is formed on the lower surface of the rotating block.

[0012] Specifically, the four steel pipes are connected by a plurality of horizontal and inclined square pipes, and fixing blocks are welded on the outer walls of the bottoms of each steel pipe on one side above the sleeve, a receiving groove is formed on one side of each fixing block close to the abutting plate, a horizontal threaded rod is arranged in the receiving groove, a locking block is sleeved on the threaded rod, and one end of the threaded rod penetrates through the receiving groove and extends to the outside of the fixing block and is fixedly connected with a rotating handle.

[0013] Specifically, the outer wall of the locking block is in contact with the groove wall of the receiving groove and is in sliding connection, locking grooves are formed on the outer walls of both ends of the abutting plate, the sizes of the locking grooves are the same as the size of the receiving groove, and the locking block is matched with the locking groove.

[0014] Specifically, top plates are welded on the sides of the abutting plates away from the steel pipes, ear plates are welded on the sides of the movable plates away from the steel pipes, the telescopic rods are fixed on the lower surfaces of the top plates by screws, and the telescopic ends of the telescopic rods are fixedly connected to the upper surfaces of the ear plates by screws.

[0015] According to the above technical solution, a locking and assembling construction method for a variable cross-section cantilever-cast box girder assembling support is also provided, including the following steps: Step 1: Assembly. Place a standard section on the bearing platform by a tower crane and fix it with anchor bolts. Then stack and butt the remaining standard sections in sequence, making the sleeves of each other in contact. Next, insert hexagon bolts into the two contacting sleeves. At this time, place the abutting plate and the movable plate on the outer wall of the steel pipe, and fix the abutting plate with a locking block, so that the card slot is sleeved on the top end of the hexagon bolt, and place two nuts in the hexagon groove; Step 2: Tightening and fixing. Insert the end of an electric screwdriver into the rotating block, start the electric screwdriver, the rotating block drives the driving gear to rotate through the vertical shaft, the driving gear controls the rotation of the rotating shaft through the meshing gear, and the rotating shaft controls the rotation of the two placing blocks respectively through two sprockets and a transmission chain. When rotating, the construction worker pushes the movable plate upward, so that the placed nuts are tightened on the threaded end of the hexagon bolt. Finally, loosen the locking block, install the tightening mechanism on another steel pipe, and repeat the above operation; Step 3: Overall construction. After fixing multiple standard sections in sequence, fix the top section on the topmost standard section with bolts, then fix the sand bucket, and fix the I-beam on the top of the sand bucket. Finally, assemble and fix the box girder on the I-beam, thus completing the assembly of the entire support; Step 4: Preloading. Lift sandbags into the box girder and stack them according to the predetermined position and sequence until the settlement and deformation of the support reach a stable state and meet the design requirements, and then unload.

[0016] In summary, the present invention mainly has the following beneficial effects: By inserting the electric screwdriver into the slot of the rotating block and starting it, the power is transmitted to the rotating shaft, driving the sprocket to rotate, and making the placing block rotate, so as to realize the automatic tightening of the nut. The construction worker does not need to manually tighten the nuts one by one, reducing the manual operation time and labor consumption, reducing the construction difficulty and danger, greatly shortening the construction period, and improving the construction efficiency; And the telescopic rod design of the tightening mechanism enables the adjustable distance between the movable plate and the abutting plate. Cooperating with the rotatable placing block, it can adapt to the tightening requirements of hexagon bolts with different lengths, enhancing the versatility and stability of the support. At the same time, it can also ensure that the tightening torques of multiple nuts are consistent, avoiding stress concentration caused by individual nuts being too loose or too tight, thereby improving the stability and load-bearing capacity of the entire structure. Brief Description of the Drawings

[0017] Figure 1 It is a schematic diagram of the support of the present invention; Figure 2 It is a schematic diagram of the splicing of standard sections of the present invention; Figure 3 It is a positive axonometric schematic diagram of a single standard section of the present invention; Figure 4 Isometric sectional view of the fixed block of the present invention; Figure 5 Isometric view of the tightening mechanism of the present invention; Figure 6 Oblique isometric view of the tightening mechanism of the present invention; Figure 7 Oblique isometric sectional view of the movable plate of the present invention; Figure 8 Bottom view of the movable plate of the present invention; Figure 9 Schematic diagram of the structure of the transmission component and the rotating component of the present invention; Figure 10 Flow chart of the method steps of the present invention.

[0018] Description of the drawings: 1. Bracket; 101. Standard section; 102. Top section; 1021. Sand bucket; 103. I-beam; 104. Box girder; 2. Steel pipe; 201. Sleeve; 202. Fixed block; 2021. Receiving groove; 2022. Rotating handle; 2023. Threaded rod; 2024. Locking block; 3. Tightening mechanism; 4. Contact plate; 401. Locking groove; 402. Top plate; 403. Telescopic rod; 5. Movable plate; 501. Ear plate; 502. Driving cavity; 5021. Through groove; 5022. Groove; 503. Placing block; 5031. Hexagonal groove; 5032. Inner toothed; 504. Installation groove; 6. Transmission component; 601. Rotating shaft; 602. Sprocket; 6021. Transmission chain; 6022. Meshing gear; 7. Rotating component; 701. Vertical shaft; 702. Driving gear; 703. Rotating block; 8. Hexagonal bolt; 801. Nut. Detailed implementation manners

[0019] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. The embodiments described below by referring to the accompanying drawings are exemplary and are only used to explain the present invention and should not be construed as limiting the present invention.

[0020] Next, the embodiments of the present invention will be described according to the overall structure of the present invention. Embodiment

[0021] Please refer to Figure 1-7As shown in the figure, a segmentally variable cross-section cast-in-place box girder assembled support includes a support 1 composed of a plurality of standard sections 101, a top section 102, sand barrels 1021, I-beams 103, and a box girder 104. The plurality of standard sections 101 are fixedly connected by hexagon head bolts 8 and nuts 801, and a tightening mechanism 3 is used to tighten the nuts 801. Each standard section 101 is composed of four vertical steel pipes 2. At the top and bottom of each steel pipe 2, sleeves 201 are welded to two adjacent outer walls. The four steel pipes 2 are connected by a number of horizontal and inclined square pipes. At one side above the sleeve 201 on the bottom outer wall of each steel pipe 2, a fixing block 202 is welded. On one side of each fixing block 202 close to the abutting plate 4, a receiving groove 2021 is provided. A horizontal threaded rod 2023 is provided in the receiving groove 2021. A locking block 2024 is sleeved on the threaded rod 2023. One end of the threaded rod 2023 penetrates through the receiving groove 2021 and extends outside the fixing block 202 and is fixedly connected to a turning handle 2022. The outer wall of the locking block 2024 is in contact with the groove wall of the receiving groove 2021 and is slidably connected. Locking grooves 401 are provided on both outer walls at the two ends of the abutting plate 4. The sizes of the locking grooves 401 are the same as those of the receiving grooves 2021. The locking block 2024 is matched with the locking groove 401; The tightening mechanism 3 is composed of an L-shaped abutting plate 4 and an L-shaped movable plate 5. The abutting plate 4 and the movable plate 5 are connected by a telescopic rod 403. On the side of the abutting plate 4 away from the steel pipe 2, a top plate 402 is welded. On the side of the movable plate 5 away from the steel pipe 2, an ear plate 501 is welded. The telescopic rod 403 is fixed to the lower surface of the top plate 402 by screws. The telescopic end of the telescopic rod 403 is fixedly connected to the upper surface of the ear plate 501 by screws. On both sides of the lower surface of the abutting plate 4, card slots matching the hexagon head bolts 8 are symmetrically provided. An L-shaped driving cavity 502 is provided inside the movable plate 5. On both sides of the driving cavity 502, cylindrical placing blocks 503 are provided. At the top of the two placing blocks 503, hexagon slots 5031 matching the nuts 801 are provided. At the position of the hexagon slot 5031 on the inner bottom wall of the driving cavity 502, a groove 5022 is provided. At the bottom wall of the corner of the driving cavity 502, a mounting groove 504 is provided. A transmission component 6 for driving the two placing blocks 503 to rotate is provided in the mounting groove 504. A rotating component 7 is connected to one side of the transmission component 6. The rotating component 7 is used to control the movement of the transmission component 6.

[0022] When the bracket 1 needs to be assembled, the construction workers first place a standard section 101 on the designated foundation platform by a crane and fix it with anchor bolts. Then, the remaining standard sections 101 are stacked and docked in sequence, so that the sleeves 201 of each other are in contact. Insert the hexagon bolt 8 into the two contacting sleeves 201. At this time, abut the L surfaces of the abutting plate 4 and the movable plate 5 against the outer wall of the steel pipe 2 and move them, so that the card slot on the lower surface of the abutting plate 4 is sleeved on the top end of the hexagon bolt 8. At this time, the end of the abutting plate 4 is located at the fixed block 202. Then manually rotate the rotary handle 2022, and the rotary handle 2022 drives the threaded rod 2023 to rotate, so that the locking block 2024 moves along the receiving groove 2021 following the rotation of the threaded rod 2023. The end of the locking block 2024 moves out of the receiving groove 2021 and inserts into the locking groove 401 to complete the fixation of the abutting plate 4; Next, the construction workers place two nuts 801 in the hexagonal groove 5031. Through the cooperation of an electric screwdriver and the rotating assembly 7, the transmission assembly 6 can be driven to move. The transmission assembly 6 drives the placing block 503 to rotate, realizing the automatic screwing of the nut 801 with the threaded end of the hexagon bolt 8. Thus, the construction workers do not need to manually tighten the nuts 801 one by one, reducing the manual operation time and labor consumption, lowering the construction difficulty and danger, significantly shortening the construction period, and improving the construction efficiency; After the multiple standard sections 101 are tightly assembled in the above manner, the top section 102 is fixed on the uppermost standard section 101 by bolts, then the sand bucket 1021 is fixed, and the I-beam 103 is fixed at the top of the sand bucket 1021. Finally, the box girder 104 is assembled and fixed on the I-beam 103, thus completing the assembly of the entire bracket 1.

[0023] Please refer to Figure 6-9 As shown in the figure, the transmission assembly 6 includes a rotating shaft 601. The top end of the rotating shaft 601 is rotatably connected to the inner top wall of the driving cavity 502. A sprocket 602 is sequentially and fixedly sleeved on the top of the rotating shaft 601. Inner channel teeth 5032 are provided on the outer walls of the two placing blocks 503. The two inner channel teeth 5032 are respectively in the same horizontal plane as the two sprockets 602. The two sprockets 602 are respectively in transmission connection with the inner channel teeth 5032 through transmission chains 6021. The bottom end of the rotating shaft 601 is rotatably connected to the inner bottom wall of the installation groove 504. A meshing gear 6022 is fixedly sleeved on the outer wall of the bottom of the rotating shaft 601. The diameter of the meshing gear 6022 is larger than the diameters of the two sprockets 602. Through grooves 5021 communicating with the driving cavity 502 are opened on both inner walls of the movable plate 5 close to the steel pipe 2. Lubricating oil can be added to the inner channel teeth 5032 and the transmission chains 6021 through the through grooves 5021. Among them, balls are embedded at the end of the placing block 503 and are in contact with the inner bottom wall of the driving cavity 502, which can ensure the rotation effect and reduce friction. The rotating assembly 7 includes a vertical shaft 701. The vertical shaft 701 is located on one side of the rotating shaft 601. A driving gear 702 is fixedly sleeved on the outer wall of the vertical shaft 701. The driving gear 702 is matched with the meshing gear 6022 in diameter. The driving gear 702 is meshed and connected with the meshing gear 6022. The top end of the vertical shaft 701 is rotatably connected to the inner top wall of the installation groove 504. The bottom end of the vertical shaft 701 passes through the installation groove 504 and extends to the outside of the movable plate 5. A rotating block 703 is arranged below the movable plate 5. The bottom end of the vertical shaft 701 is fixedly connected to the upper surface of the rotating block 703. A slot matching the electric screwdriver is opened on the lower surface of the rotating block 703.

[0024] When tightening the nut 801, the construction worker inserts the end of the electric screwdriver into the slot of the rotating block 703, controls the rotation of the rotating block 703 through the electric screwdriver. The rotating block 703 drives the driving gear 702 to rotate through the vertical shaft 701. The driving gear 702 drives the meshing gear 6022 to rotate. The meshing gear 6022 drives the rotating shaft 601 passing through it to rotate, and then controls the rotation of the two sprockets 602. The two sprockets 602 respectively control the rotation of the placed block 503 connected through the transmission chain 6021 and the inner track teeth 5032, so that the placed block 503 drives the nut 801 placed inside to rotate. At this time, the construction worker pushes the rotating block 703 upward, and pushes the movable plate 5 upward through the vertical shaft 701. Cooperating with the rotating nut 801 can make it screw into the threaded end of the hexagonal bolt 8 to complete the tightening operation. And through the telescopic rod 403, the distance between the movable plate 5 and the abutting plate 4 can be adjusted. Cooperating with the rotatable placed block 503 to meet the tightening requirements of hexagonal bolts 8 with different lengths, enhancing the versatility and stability of the bracket 1. At the same time, it can also ensure that the tightening torques of multiple nuts 801 are consistent, avoiding stress concentration caused by individual nuts 801 being too loose or too tight, thereby improving the stability and load-bearing capacity of the entire structure.

[0025] Please refer to Figure 1-10 As shown in the figure, according to the above embodiments, a locking and assembling construction method for a variable cross-section cantilever casting box girder assembling bracket will also be provided, including the following steps: Step 1: Assembly. Place a standard section 101 on the bearing platform through a tower crane and fix it with anchor bolts. Then stack and butt the remaining standard sections 101 in sequence so that their sleeves 201 are in contact. Then insert the hexagonal bolt 8 into the two contacting sleeves 201. At this time, place the abutting plate 4 and the movable plate 5 on the outer wall of the steel pipe 2, and fix the abutting plate 4 through the locking block 2024 so that the clamping groove is sleeved on the top end of the hexagonal bolt 8. Place two nuts 801 in the hexagonal groove 5031. Step 2: Tighten and fix. Insert the end of the electric screwdriver into the rotating block 703. Start the electric screwdriver. The rotating block 703 drives the driving gear 702 to rotate through the vertical shaft 701. The driving gear 702 controls the rotation of the rotating shaft 601 through the meshing gear 6022. The rotating shaft 601 controls the rotation of the two placing blocks 503 through the two sprockets 602 and the transmission chain 6021 respectively. During rotation, the construction worker pushes the movable plate 5 upward, so that the placed nut 801 is tightened on the threaded end of the hexagonal bolt 8. Finally, loosen the locking block 2024, install the tightening mechanism 3 on another steel pipe 2, and repeat the above operation; Step 3: Overall erection. After fixing multiple standard sections 101 in sequence, fix the top section 102 on the uppermost standard section 101 with bolts, then fix the sand bucket 1021, and fix the I-beam 103 on the top of the sand bucket 1021. Finally, assemble and fix the box girder 104 on the I-beam 103, thereby completing the assembly of the entire support 1; Step 4: Preloading. Lift the sandbags into the box girder 104 and stack them according to the predetermined positions and sequences until the settlement and deformation of the support 1 reach a stable state and meet the design requirements, and then unload.

[0026] The working principle of the present invention is as follows: When it is necessary to assemble the support 1, the construction worker first places a standard section 101 on the designated foundation by a crane and fixes it with an anchor bolt, and then stacks and docks the remaining standard sections 101 in sequence so that the sleeves 201 of each other are in contact. Insert the hexagonal bolt 8 into the two contacting sleeves 201. At this time, abut the L surfaces of the abutting plate 4 and the movable plate 5 against the outer wall of the steel pipe 2 and move them so that the card slot on the lower surface of the abutting plate 4 is sleeved on the top end of the hexagonal bolt 8. At this time, the end of the abutting plate 4 is located at the fixing block 202. Then manually rotate the rotating handle 2022. The rotating handle 2022 drives the threaded rod 2023 to rotate, so that the locking block 2024 moves along the receiving groove 2021 following the rotation of the threaded rod 2023. The end of the locking block 2024 moves out of the receiving groove 2021 and inserts into the locking groove 401 to complete the fixation of the abutting plate 4; Next, the construction workers place two nuts 801 in the hexagonal groove 5031, insert the end of the electric screwdriver into the slot of the rotating block 703, control the rotation of the rotating block 703 through the electric screwdriver. The rotating block 703 drives the driving gear 702 to rotate through the vertical shaft 701. The driving gear 702 drives the engaged meshing gear 6022 to rotate. The meshing gear 6022 drives the penetrated rotating shaft 601 to rotate, thereby controlling the rotation of the two sprockets 602. The two sprockets 602 respectively control the rotation of the connected placement block 503 through the transmission chain 6021 and the inner track teeth 5032, so that the placement block 503 drives the internally placed nut 801 to rotate. At this time, the construction worker pushes the rotating block 703 upward, and pushes the movable plate 5 upward through the vertical shaft 701. Cooperating with the rotating nut 801 can make it screw onto the threaded end of the hexagonal bolt 8 to complete the tightening operation. After fastening and assembling between multiple standard sections 101 in the above manner, the top section 102 is fixed to the uppermost standard section 101 by bolts, then the sand bucket 1021 is fixed, and the I-beam 103 is fixed to the top of the sand bucket 1021. Finally, the box girder 104 is assembled and fixed on the I-beam 103, thereby completing the assembly of the entire bracket 1.

[0027] Although the embodiments of the present invention have been shown and described, the specific embodiments are only explanations of the present invention and are not limitations of the invention. The described specific features, structures, materials or characteristics can be combined in a suitable manner in any one or more embodiments or examples. After reading this specification, those skilled in the art can make modifications, substitutions and variations that do not make creative contributions to the embodiments according to needs, but as long as they are within the scope of the claims of the present invention, they are protected by the patent law.

Claims

1. A segmentally variable cast-in-situ box girder assembled support, comprising a support (1) composed of a plurality of standard sections (101), a top section (102), sand barrels (1021), I-beams (103) and a box girder (104), wherein the plurality of standard sections (101) are fixedly connected by hexagon bolts (8) and nuts (801), and a tightening mechanism (3) for tightening the nuts (801), characterized in that, Each of the standard sections (101) is composed of four vertical steel pipes (2). Sleeve pipes (201) are welded to two adjacent outer walls at the top and bottom of each steel pipe (2). The tightening mechanism (3) is composed of an L-shaped abutting plate (4) and an L-shaped movable plate (5). The abutting plate (4) and the movable plate (5) are connected by a telescopic rod (403). Slots matching the hexagon bolts (8) are symmetrically formed on both sides of the lower surface of the abutting plate (4). An L-shaped driving cavity (502) is formed inside the movable plate (5). Cylindrical placing blocks (503) are arranged on both sides of the driving cavity (502). An installation groove (504) is formed in the bottom wall at the corner of the driving cavity (502). A transmission component (6) for driving the rotation of the two placing blocks (503) is arranged in the installation groove (504). A rotating component (7) is connected to one side of the transmission component (6). The rotating component (7) is used to control the movement of the transmission component (6).

2. The assembled bracket for variable cross-section cantilever-cast box girder according to claim 1, wherein, Hexagonal grooves (5031) matching the nuts (801) are formed at the tops of the two placing blocks (503). A groove (5022) is formed in the inner bottom wall of the driving cavity (502) at the position of the hexagonal groove (5031).

3. The assembled bracket for variable cross-section cantilever casting box girder according to claim 1, characterized in that, The transmission component (6) includes a rotating shaft (601). The top end of the rotating shaft (601) is rotatably connected to the inner top wall of the driving cavity (502). A sprocket (602) is sequentially and fixedly sleeved on the top of the rotating shaft (601). Inner channel teeth (5032) are arranged on the outer walls of the two placing blocks (503). The two inner channel teeth (5032) are in the same horizontal plane as the two sprockets (602) respectively. The two sprockets (602) are respectively in transmission connection with the inner channel teeth (5032) through transmission chains (6021).

4. The assembled support for variable cross-section cantilever casting box girder according to claim 3, characterized in that The bottom end of the rotating shaft (601) is rotatably connected to the inner bottom wall of the installation groove (504). A meshing gear (6022) is fixedly sleeved on the outer wall of the bottom of the rotating shaft (601). The diameter of the meshing gear (6022) is larger than the diameters of the two sprockets (602). Through grooves (5021) communicating with the driving cavity (502) are formed on both inner walls of the movable plate (5) close to the steel pipe (2).

5. The assembled bracket for variable cross-section cantilever casting box girder according to claim 4, characterized in that, The rotating component (7) includes a vertical shaft (701). The vertical shaft (701) is located on one side of the rotating shaft (601). A driving gear (702) is fixedly sleeved on the outer wall of the vertical shaft (701). The driving gear (702) matches the diameter of the meshing gear (6022). The driving gear (702) is in meshing connection with the meshing gear (6022). The top end of the vertical shaft (701) is rotatably connected to the inner top wall of the installation groove (504).

6. The assembled bracket for variable cross-section cantilever casting box girder according to claim 5, characterized in that, The bottom end of the vertical shaft (701) passes through the installation groove (504) and extends to the outside of the movable plate (5). A rotating block (703) is arranged below the movable plate (5). The bottom end of the vertical shaft (701) is fixedly connected to the upper surface of the rotating block (703). A slot matching an electric screwdriver is formed on the lower surface of the rotating block (703).

7. A segmental casting variable cross-section box girder assembled support according to claim 1, characterized in that, The four steel pipes (2) are connected by a number of horizontal and inclined square pipes. A fixing block (202) is welded on one side above the sleeve (201) on the outer wall of the bottom of each steel pipe (2). A receiving groove (2021) is formed on one side of each fixing block (202) close to the abutting plate (4). A horizontal threaded rod (2023) is arranged in the receiving groove (2021). A locking block (2024) is sleeved on the threaded rod (2023). One end of the threaded rod (2023) penetrates through the receiving groove (2021) and extends to the outside of the fixing block (202) and is fixedly connected with a rotating handle (2022).

8. The assembled support for variable cross-section cantilever casting box girder according to claim 7, characterized in that, The outer wall of the locking block (2024) is in contact with the groove wall of the receiving groove (2021) and is in sliding connection. Locking grooves (401) are formed on the outer walls at both ends of the abutting plate (4). The sizes of the locking grooves (401) are the same as those of the receiving grooves (2021). The locking block (2024) is matched with the locking grooves (401).

9. The assembled support for variable cross-section cantilever cast box girder according to claim 1, characterized in that, A top plate (402) is welded on one side of the abutting plate (4) away from the steel pipe (2). An ear plate (501) is welded on one side of the movable plate (5) away from the steel pipe (2). The telescopic rod (403) is fixed on the lower surface of the top plate (402) by screws. The telescopic end of the telescopic rod (403) is fixedly connected with the upper surface of the ear plate (501) by screws.

10. A locking and assembling construction method for a variable cross-section cast-in-place box girder assembled support according to any one of claims 1-9, characterized in that, It includes the following steps: Step 1, assembly: Place a standard section (101) on the foundation platform by a tower crane and fix it with anchor bolts. Then stack and butt the remaining standard sections (101) in sequence so that the sleeves (201) of each other are in contact. Then insert the hexagonal bolts (8) into the two contacting sleeves (201). At this time, place the abutting plate (4) and the movable plate (5) on the outer wall of the steel pipe (2) required, and fix the abutting plate (4) by the locking block (2024) so that the clamping groove is sleeved on the top end of the hexagonal bolt (8). Place two nuts (801) in the hexagonal groove (5031). Step 2, tightening and fixing: Insert the end of an electric screwdriver into the rotating block (703). Start the electric screwdriver. The rotating block (703) drives the driving gear (702) to rotate through the vertical shaft (701). The driving gear (702) controls the rotation of the rotating shaft (601) through the meshing gear (6022). The rotating shaft (601) controls the rotation of the two placing blocks (503) respectively through two sprockets (602) and a transmission chain (6021). When rotating, the construction worker pushes the movable plate (5) upward, so that the placed nuts (801) are tightened on the threaded end of the hexagonal bolt (8). Finally, loosen the locking block (2024), install the tightening mechanism (3) on another steel pipe (2), and repeat the above operation. Step 3: Overall erection. After fixing multiple standard sections (101) in sequence, fix the top section (102) to the topmost standard section (101) with bolts, then fix the sand bucket (1021), and fix the I-beam (103) at the top of the sand bucket (1021). Finally, assemble and fix the box girder (104) on the I-beam (103), thereby completing the erection of the entire support (1). Step 4: Preloading. Hoist sandbags into the box girder (104) and stack them according to the predetermined positions and sequences until the settlement and deformation of the support (1) reach a stable state and meet the design requirements, and then unload the sandbags.

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