Temporary steel beam removing device and removing method for beam of restricted environment swivel bridge pier

Abstract

The application belongs to the technical field of bridge construction, and particularly relates to a limited environment swivel bridge pier beam temporary steel cross beam dismantling device and dismantling method. The device comprises a bearing support assembly, which comprises a door-shaped frame fixed above a reserved tension hole of a bridge beam body, a traction driving element, which is a hand-operated hoist suspended on the door-shaped frame, an anchoring and pulling assembly, which comprises a 5-hole flat anchor suspended at the lower end of the hand-operated hoist, two groups of 12-hole round anchors, which are respectively upper and lower anchoring elements, the upper anchoring element being arranged on the top surface of the bridge beam body and directly below the 5-hole flat anchor, and the lower anchoring element being arranged below the H-shaped steel cross beam to be dismantled, steel strands, which are arranged in the 5-hole flat anchor and the two groups of 12-hole round anchors, an extrusion sleeve, and the extrusion sleeve being anchored at the lower end of the steel strands to form anchoring and limiting with the H-shaped steel cross beam to be dismantled.

Description

Technical Field

[0001] This invention belongs to the field of bridge construction technology, specifically a device and method for dismantling temporary steel crossbeams of bridge piers in confined environments. Background Technology

[0002] The initial purpose of the temporary pier-beam consolidation design is threefold: first, to ensure the overturning stability of the beam during construction; second, to limit the horizontal displacement and rotation of the beam to ensure the accuracy of the construction alignment; and third, to temporarily consolidate the pier-beam into a monolithic structure, placing it in a statically determinate and safe state during the cantilever construction phase. After construction, the temporary pier-beam consolidation H-beams need to be dismantled and lowered. Existing methods for dismantling and lowering similar temporary pier-beam consolidation H-beams include: ① Dual-crane synchronous lowering method: using two cranes to hang the beam at both ends and lower it synchronously and smoothly; ② Single-crane midpoint lowering method: using one crane to hang the beam at the middle point and lower it slowly and uniformly; ③ Segmented dismantling and lifting method: cutting the beam into several small segments and lifting them away from the work area segment by segment. However, the above construction methods have the following problems: ① They require two cranes and a professional team to work in close coordination. If they lose control at the same time, it can easily lead to uneven stress on the beam, tearing of the lifting points, or impact on the pier structure, resulting in significant safety risks. The investment of two equipment doubles the rental and labor costs, and it has high requirements for the space and bearing capacity of the construction site, making it difficult to apply in narrow sites such as densely packed piers or mountainous areas. At the same time, the stress pattern of the lifting points at both ends can easily lead to the downward deformation of the middle section of the long-span beam, which, combined with weld defects or corrosion risks, may aggravate structural damage. The high requirements for the professionalism of the operating team also further increase the time cost and operational risks. ② Using the midpoint as the lifting point will cause the two ends of the crossbeam to sag due to their own weight, creating a stress state of "tension at the midpoint and compression at both ends". Large-span, heavy crossbeams are prone to permanent bending, flange deformation, or weld cracking. The crossbeam in the air is easily affected by wind and lowering speed, making it difficult to accurately control the landing point. It may collide with the pier structure and cause damage, and may also cause the lifting rope to wear off or become unhooked. In addition, this method is only applicable to short-span, light-weight crossbeams, with a very narrow scope of application. It is also prone to tilting during lowering, requiring high-altitude assistance to straighten it, further increasing the operational risks and difficulty. ③ The high-temperature sparks and vibrations generated by high-altitude cutting operations can easily ignite surrounding facilities, damage pier and beam concrete or embedded components, and may also cause micro-damage to the original structure, resulting in high subsequent repair costs; the additional cutting, cleaning, and segmented hoisting processes significantly reduce construction efficiency and extend the construction period, and repeated hoisting also increases the probability of operational errors; the cutting accuracy and segmentation rationality are difficult to control, and uneven cuts or improper segmentation positions can easily lead to stress concentration and falling risks in small segments, and the steel slag and scrap iron generated by cutting require special cleaning, increasing environmental protection and on-site management pressure. Summary of the Invention

[0003] To address the aforementioned problems, this invention provides a device and method for dismantling temporary steel crossbeams of bridge piers in confined environments.

[0004] This invention adopts the following technical solution: a device for dismantling temporary steel crossbeams of bridge piers in confined environments, comprising: The load-bearing support assembly includes: A portal frame, which is fixed above the reserved tensioning hole of the bridge beam; A traction drive unit, wherein the traction drive unit is a hand chain hoist, and the hand chain hoist is suspended on the U-shaped frame; Anchoring and lifting assembly, the anchoring and lifting assembly comprising: A 5-hole flat anchor, which is suspended from the lower end of the hand chain hoist; Two sets of 12-hole round anchors, namely upper anchor and lower anchor, are provided. The upper anchor is located on the top surface of the bridge beam and directly below the 5-hole flat anchor, and the lower anchor is located below the H-beam to be removed. The steel strand is threaded along its entire length through a 5-hole flat anchor and two sets of 12-hole round anchors; Extrusion sleeve; the extrusion sleeve is anchored to the lower end of the steel strand and is used to form an anchoring limit with the H-beam to be removed.

[0005] In some embodiments, the portal frame is made of 14H steel welded together. The portal frame is arranged around the pre-reserved tension hole in the beam and is fixed to the beam by welding or bolts.

[0006] In some embodiments, the hand chain hoist is suspended from the midpoint of the crossbar of the U-shaped frame by a wire rope loop, and the 5-hole flat anchor is suspended from the lower hook of the hand chain hoist by a wire rope loop; both ends of the wire rope loop are fastened by compression sleeves.

[0007] In some embodiments, an arc-shaped iron plate is fixed to the bottom of the 5-hole flat anchor. The arc-shaped iron plate covers the connection between the 5-hole flat anchor and the wire rope loop to protect the wire rope loop from wear during stress.

[0008] In some embodiments, the steel strand is As15.2 steel strand. Two parallel steel strands are provided in a single set of dismantling device. Both steel strands are threaded through the corresponding holes of the 5-hole flat anchor and the two sets of 12-hole round anchors. The upper end of the steel strand is reserved with a spare length to meet the lowering stroke of the crossbeam.

[0009] A method for dismantling the temporary fixed four-section H-beam crossbeam of a rotating bridge pier includes the following steps: S1: After the construction of the bridge closure section and the conversion of the load-bearing system are completed and accepted, the four H-beams to be demolished will be cut and separated from the beam body using a concrete wire saw. S2: At the upper part of the bridge beam, at both ends of the crossbeam to be demolished, a set of demolition devices as described in claim 1 are respectively installed. The crossbeam to be demolished is anchored to the two sets of demolition devices by steel strands, and the steel strands are pre-tightened. S3: By operating the hand-operated hoists of the two sets of demolition devices simultaneously, the anchoring force state of the 5-hole flat anchor and the upper anchor fastener is switched in a cyclical manner, and the beam to be demolished is gradually and smoothly lowered to the ground. S4: Disassemble each of the four H-beams lowered to the ground and transport them to the designated material storage area to complete the dismantling operation.

[0010] In some embodiments, in step S2, the two sets of dismantling devices are respectively arranged at both ends of the beam to be dismantled, at a distance of 2m from the ends. The anchoring and pre-tightening in step S2 specifically includes: S21: Weld a portal frame around the pre-reserved tension hole in the beam, erect a steel pipe scaffold as an operating platform, and fix the portal frame to the top surface of the beam. S22: Connect the U-shaped frame and the 5-hole flat anchor at the top and bottom ends of the hand chain hoist using wire rope loops; S23: The steel strand is sequentially threaded through 5 flat anchor holes, upper anchor, pre-reserved tensioning hole in the beam, crossbeam to be removed, and lower anchor. An extrusion sleeve is installed at the bottom of the steel strand to complete the anchoring. S24: Operate the hand-operated hoist to pre-tighten the steel strand, adjust the force of the two sets of dismantling devices, and make the beam to be dismantled evenly stressed.

[0011] In some embodiments, step S3 includes: S31: Tighten the clamps of the 5-hole flat anchor, loosen the clamps of the upper anchor, and let the hand chain hoist bear the full load of the beam to be removed. S32: Simultaneously operate the two sets of hand chain hoists of the dismantling device to drive the crossbeam to descend at a uniform speed. Stop the operation when the hand chain hoist reaches the maximum stroke, and tighten the clamps of the upper anchor to lock the position of the steel strand and the crossbeam. S33: Loosen the clamp of the 5-hole flat anchor and reverse the operation of the hand chain hoist to restore its working stroke; S34: Repeat steps S31 to S33 until the beam is lowered smoothly to the ground.

[0012] In some embodiments, during the lowering operation in step S3, a total station is used to monitor the lowering height of both ends of the beam to be dismantled in real time, and the lowering height difference between the two ends of the beam is controlled to not exceed 5mm.

[0013] In some embodiments, the demolition method is applied to restricted construction environments such as railway operating line slopes, dense pier areas, and narrow mountain sites; during the lowering operation, the operation is suspended and the position of the crossbeam is locked when a railway train passes by, and all outdoor operations are stopped when encountering strong winds of level 5 or above, heavy rain, or thunderstorms.

[0014] Compared with the prior art, the present invention has the following beneficial effects: 1. The double-end symmetrical anchoring lifting and alternating anchor locking lowering process avoids risks such as beam deformation, hook falling, and structural collision; it eliminates the need for high-altitude segmented cutting, thus eliminating the risk of fire and beam structural damage, and is suitable for the stringent safety control requirements of restricted environments such as railway operating lines.

[0015] 2. Relying on the structural support of the bridge beams themselves, no large hoisting equipment is required on site. There are no special requirements for the construction site space or ground bearing capacity. It is perfectly suited to restricted environments such as railway operating line slopes, dense pier areas, and narrow mountain sites. It can cover the dismantling of temporary steel beams of different specifications.

[0016] 3. With real-time monitoring using a total station, the accuracy of the crossbeam lowering can be precisely controlled, ensuring a smooth lowering of the crossbeam throughout the process and avoiding collision damage to the main structure of the bridge; the use of wire saw cutting and separation results in no vibration or impact, effectively protecting the integrity of the pre-embedded components and steel components of the beam. Attached Figure Description

[0017] Figure 1 Schematic diagram of the temporary steel crossbeam dismantling device for a bridge pier in a confined environment; Figure 2 Schematic diagram of the temporary steel crossbeam dismantling device for a bridge pier in a confined environment; Detailed Implementation To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are some embodiments of the present invention, but 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.

[0018] like Figure 1-2As shown, a temporary steel crossbeam removal device for a bridge pier in a confined environment includes: a load-bearing support assembly, which includes: a portal frame 1 fixed above a pre-reserved tensioning hole in the bridge beam; a traction drive unit, which is a hand-operated hoist 2 suspended from the portal frame 1; and an anchoring and lifting assembly, which includes: a 5-hole flat anchor 3 suspended from the hand-operated hoist. The lower end of 2; two sets of 12-hole round anchors 4, the two sets of 12-hole round anchors 4 are respectively the upper anchor and the lower anchor. The upper anchor is set on the top surface of the bridge beam and directly below the 5-hole flat anchor 3. The lower anchor is set below the H-shaped steel beam to be removed; steel strand 5, the steel strand 5 is inserted through the 5-hole flat anchor and the two sets of 12-hole round anchors; extrusion sleeve 6; the extrusion sleeve 6 is anchored to the lower end of the steel strand 5 and is used to form an anchorage limit with the H-shaped steel beam to be removed.

[0019] Specifically, the portal frame 1 is made of 14H steel welded together. The portal frame 1 is arranged with the pre-reserved tension hole in the beam as the center. The portal frame 1 is fixed to the beam by welding or bolts.

[0020] Specifically, the hand chain hoist 2 is suspended from the midpoint of the crossbar of the U-shaped frame 1 by a wire rope loop, and the 5-hole flat anchor 3 is suspended from the hook at the lower end of the hand chain hoist 2 by a wire rope loop; both ends of the wire rope loop are fastened by compression sleeves.

[0021] Specifically, an arc-shaped iron plate is fixed to the bottom of the 5-hole flat anchor 3. The arc-shaped iron plate covers the connection between the 5-hole flat anchor 3 and the wire rope loop, and is used to protect the wire rope loop from wear during the stress process.

[0022] Specifically, the steel strand 5 is an As15.2 steel strand. Two parallel steel strands 5 are installed in a single set of dismantling devices. Both steel strands 5 are threaded through the corresponding holes of the 5-hole flat anchor 3 and the two sets of 12-hole round anchors 4. The upper end of the steel strand 5 is reserved with a spare length to meet the lowering stroke of the crossbeam.

[0023] A method for dismantling the temporary fixed four-section H-beam crossbeam of a rotating bridge pier, implemented using a temporary steel crossbeam dismantling device for rotating bridge piers in a confined environment, includes the following steps: S1: After the construction of the bridge closure section and the conversion of the load-bearing system are completed and accepted, the four H-beams to be demolished will be cut and separated from the beam body using a concrete wire saw. S2: At the upper part of the bridge beam, at both ends of the crossbeam to be demolished, a set of demolition devices as described in claim 1 are respectively installed. The crossbeam to be demolished is anchored to the two sets of demolition devices by steel strands, and the steel strands are pre-tightened. S3: By operating the hand-operated hoists of the two sets of demolition devices simultaneously, the anchoring force state of the 5-hole flat anchor and the upper anchor fastener is switched in a cyclical manner, and the beam to be demolished is gradually and smoothly lowered to the ground. S4: Disassemble each of the four H-beams lowered to the ground and transport them to the designated material storage area to complete the dismantling operation.

[0024] Specifically, in step S2, the two sets of dismantling devices are respectively positioned at both ends of the beam to be dismantled, 2m from the ends. The anchoring and pre-tightening in step S2 specifically includes: S21: Weld a portal frame 1 with the pre-reserved tension hole in the beam as the center, erect a steel pipe scaffold as an operating platform, and fix the portal frame 1 to the top surface of the beam; S22: Connect the gate-shaped frame 1 and the 5-hole flat anchor 3 to the upper and lower ends of the hand chain hoist 2 respectively by steel wire rope loops; S23: Insert the steel strand 5 sequentially through 5 flat anchor holes, upper anchor, pre-reserved tension hole in the beam, crossbeam to be removed, and lower anchor. Install the extrusion sleeve at the bottom of the steel strand 5 to complete the anchoring. S24: Operate the hand chain hoist 2 to put the steel strand in a pre-tightened state, adjust the force of the two sets of dismantling devices, and make the beam to be dismantled evenly stressed.

[0025] Specifically, step S3 includes: S31: Tighten the clamp of the 5-hole flat anchor 3, loosen the clamp of the upper anchor, so that the hand chain hoist 2 can bear the full load of the beam to be removed. S32: Simultaneously operate the two sets of hand chain hoists 2 of the dismantling device, drive the crossbeam to descend at a uniform speed, stop the operation when the hand chain hoist 2 reaches the maximum stroke, and tighten the clamps of the upper anchor to lock the position of the steel strand and the crossbeam. S33: Loosen the clamp of the 5-hole flat anchor 3 and reverse the operation of the hand chain hoist 2 to restore its working stroke; S34: Repeat steps S31 to S33 until the beam is lowered smoothly to the ground.

[0026] Specifically, during the lowering operation in step S3, a total station is used to monitor the lowering height of both ends of the beam to be dismantled in real time, and the lowering height difference between the two ends of the beam is controlled to not exceed 5mm.

[0027] The demolition method is applicable to restricted construction environments such as railway operating line slopes, dense pier areas, and narrow mountain sites. During the lowering operation, the operation is suspended and the position of the crossbeam is locked when a railway train passes by. All outdoor operations are suspended in the event of strong winds of level 5 or above, heavy rain, or thunderstorms. Specific implementation examples: Construction preparation 1. Review the bridge construction design drawings, prepare a special construction plan, and conduct safety and technical briefings for project technicians, site managers and workers, focusing on training them on the operational requirements of key aspects such as equipment installation, synchronous lowering, and monitoring and control.

[0029] 2. Entrust a qualified unit to verify and inspect the core equipment and materials such as hand chain hoists, anchorages, and steel strands; set up construction safety protection facilities in advance, delineate the safety protection zone of the railway operating line, and set up warning signs.

[0030] 3. Prepare sufficient 14H steel, steel pipe scaffolding, steel strands, anchors and other materials according to construction needs, and ensure that the equipment and materials are intact.

[0031] beam cutting and separation After the bridge closure section construction and load-bearing system conversion are completed and accepted, diamond wire saws are horizontally installed at the positions of the four H-beam crossbeams and the bottom concrete pad of the main beam. During the cutting process, the sawing speed and cutting force are strictly controlled to maintain stable and continuous operation, so as to achieve a complete and flat separation between the crossbeam and the beam body, and minimize the damage of vibration to the beam concrete and embedded components. After the cutting is completed, the debris on the section is cleaned, the integrity of the main beam is checked, and it is confirmed that there are no quality defects such as cracks or deformation.

[0032] Beam anchorage position 1. Take two AS15.2 steel strands, install the appropriate special extrusion sleeves at the ends and anchor them. Thread the steel strands sequentially through the 12-hole round anchor below the steel beam, the reserved hole in the steel beam, the reserved channel in the beam, and the 12-hole round anchor above the beam, and finally thread them through the 5-hole flat anchor system.

[0033] 2. Straighten and straighten the steel strands, and use high-strength clamps to anchor the steel strands to the 12-hole round anchors above the beam, so that the steel beam is firmly fixed to the bottom of the beam and the anchoring is secure.

[0034] 3. Install and anchor the 5-hole flat anchor clamp assembly. Apply pre-tension to the steel strand system using a hand-operated hoist and chain hoist. Simultaneously adjust the position and force distribution of each connecting component to ensure uniform force distribution and structural stability of the entire device, achieving optimal operating conditions.

[0035] Steel column removal 1. Set up a warning line in the construction area. The lifting vehicle enters the site and sends the workers to the top of the steel column at a position of 1m. The diamond wire saw is set up at a 45° angle. At the same time, the wire rope is wrapped around the steel column and welded with steel bars to fix it to prevent slippage. Then it is hung on the hook of the folding arm crane.

[0036] 2. Evacuate personnel, start the wire saw, and slowly cut the steel column. The person in charge pays close attention and directs the folding boom crane to slowly tighten the boom until the steel column is completely cut through. The folding boom crane then lifts the column to the ground.

[0037] 3. The lifting vehicle will transport the worker to the middle of the remaining steel column, wrap the steel wire rope around the steel column and weld the steel bars to fix it to prevent slippage, and then hang it on the hook of the folding arm crane.

[0038] 4. Install a wire saw at the base of the steel column. After personnel have evacuated, start the wire saw and slowly cut the steel column. The person in charge should pay close attention and direct the folding boom crane to slowly tighten the boom until the steel column is completely cut through. Then, lift the folding boom crane to the ground.

[0039] 5. Dismantle the steel columns one by one using this method. After all the columns have been dismantled, lower the crossbeams.

[0040] The crossbeam is gradually lowered. 1. Tighten the 5-hole flat anchor clamps on the top of the beam and loosen the 12-hole round anchor clamps to ensure that the hand-operated hoist fully bears the entire load of the steel beam; arrange for a dedicated person to thoroughly inspect all key connection parts and confirm that there is no looseness and the clamps are secure before proceeding with the lowering operation.

[0041] 2. Two experienced operators should be positioned at opposite ends of the steel beam to coordinate the operation of the chain hoist to lower the beam smoothly, slowly, and evenly. When the beam reaches the maximum stroke of the chain hoist, the operation must be stopped immediately, and the 12-hole round anchor clips above the beam surface must be tightened quickly to effectively lock the steel strand and ensure the safety and reliability of the lowering process.

[0042] 3. After tightening the 12-hole round anchor clamps, the operator must loosen the 5-hole flat anchor clamps, then reverse the chain hoist to restore its effective working stroke; subsequently, tighten the 5-hole flat anchor clamps again and loosen the 12-hole round anchor clamps above the beam surface to prepare for the next stage of lowering. Repeat this process, gradually lowering the beam until it finally lands smoothly.

[0043] 4. Throughout the entire lowering operation, surveyors must use a high-precision total station to continuously monitor the lowering height of both ends of the crossbeam in real time to ensure that the height difference between the two ends is within the allowable range, thereby ensuring the safety of the entire lowering process.

[0044] Disassembly and transportation of crossbeams After the crossbeams are placed on the ground, the high-strength bolt connections and welded parts between the four H-beams are disassembled one by one in the predetermined order. Violent disassembly is strictly prohibited to prevent deformation and damage to the steel. The disassembled steel is then lifted smoothly by a truck crane and transported to a designated site. It is then neatly stacked according to specifications and models, and rust prevention and protection measures are taken to ensure that the materials can be recycled.

[0045] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A device for dismantling temporary steel crossbeams of a bridge pier in a confined environment, characterized in that, include: The load-bearing support assembly includes: A portal frame (1) is fixed above the reserved tensioning hole of the bridge beam; The traction drive component is a hand chain hoist (2), which is suspended on the U-shaped frame (1); Anchoring and lifting assembly, the anchoring and lifting assembly comprising: A 5-hole flat anchor (3) is suspended from the lower end of a hand-operated hoist (2); Two sets of 12-hole round anchors (4) are upper anchors and lower anchors, respectively. The upper anchors are set on the top surface of the bridge beam and directly below the 5-hole flat anchors (3). The lower anchors are set below the H-beam to be removed. The steel strand (5) is threaded through a 5-hole flat anchor and two sets of 12-hole round anchors along its length. Extrusion sleeve (6); the extrusion sleeve (6) is anchored to the lower end of the steel strand (5) and is used to form an anchoring limit with the H-beam to be dismantled.

2. The temporary steel crossbeam removal device for a confined environment rotating bridge pier as described in claim 1, characterized in that, The portal frame (1) is made of 14H steel welded together. The portal frame (1) is arranged with the pre-reserved tension hole of the beam as the center. The portal frame (1) is fixed to the beam by welding or bolting.

3. The temporary steel crossbeam removal device for a confined environment rotating bridge pier as described in claim 1, characterized in that, The hand chain hoist (2) is suspended at the midpoint of the crossbar of the U-shaped frame (1) by a wire rope loop, and the 5-hole flat anchor (3) is suspended at the lower hook of the hand chain hoist (2) by a wire rope loop; both ends of the wire rope loop are fastened by compression sleeves.

4. The temporary steel crossbeam removal device for a confined environment rotating bridge pier as described in claim 1, characterized in that, The bottom of the 5-hole flat anchor (3) is fixed with an arc-shaped iron plate, which covers the connection between the 5-hole flat anchor (3) and the wire rope loop to protect the wire rope loop from wear during the stress process.

5. The temporary steel crossbeam removal device for a confined environment rotating bridge pier as described in claim 1, characterized in that, The steel strand (5) is an As15.2 steel strand. Two parallel steel strands (5) are installed in a single set of dismantling device. Both steel strands (5) are threaded through the corresponding holes of the 5-hole flat anchor (3) and the two sets of 12-hole round anchors (4). The upper end of the steel strand (5) is reserved with a spare length to meet the lowering stroke of the crossbeam.

6. A method for dismantling the temporary fixed four-section H-beam crossbeam of a rotating bridge pier, characterized in that, The implementation of the temporary steel crossbeam removal device for the confined environment rotating bridge pier as described in claims 1-5 includes the following steps: S1: After the construction of the bridge closure section and the conversion of the load-bearing system are completed and accepted, the four H-beams to be demolished will be cut and separated from the beam body using a concrete wire saw. S2: At the upper part of the bridge beam, at both ends of the crossbeam to be demolished, a set of demolition devices as described in claim 1 are respectively installed. The crossbeam to be demolished is anchored to the two sets of demolition devices by steel strands, and the steel strands are pre-tightened. S3: By operating the hand-operated hoists of the two sets of demolition devices simultaneously, the anchoring force state of the 5-hole flat anchor and the upper anchor fastener is switched in a cyclical manner, and the beam to be demolished is gradually and smoothly lowered to the ground. S4: Disassemble each of the four H-beams lowered to the ground and transport them to the designated material storage area to complete the dismantling operation.

7. The method for dismantling the temporary fixed four-section H-beam crossbeam of the rotating bridge pier according to claim 6, characterized in that, In step S2, the two sets of dismantling devices are respectively positioned at both ends of the beam to be dismantled, 2m from the ends. The anchoring and pre-tightening in step S2 specifically includes: S21: Weld a portal frame (1) around the pre-reserved tension hole in the beam, erect a steel pipe scaffold as an operating platform, and fix the portal frame (1) to the top surface of the beam; S22: Connect the gate-shaped frame (1) and the 5-hole flat anchor (3) at the top and bottom ends of the hand chain hoist (2) respectively through steel wire rope loops; S23: Insert the steel strand (5) sequentially with 5 flat anchors, upper anchors, pre-reserved tensioning holes in the beam, beams to be removed, and lower anchors, and install a compression sleeve at the bottom of the steel strand (5) to complete the anchoring. S24: Operate the hand chain hoist (2) to put the steel strand in a pre-tightened state, adjust the force of the two sets of dismantling devices, and make the beam to be dismantled uniformly stressed.

8. The method for dismantling the temporary fixed four-section H-beam crossbeam of the rotating bridge pier according to claim 6, characterized in that, Step S3 includes: S31: Tighten the clamp of the 5-hole flat anchor (3), loosen the clamp of the upper anchor, so that the hand chain hoist (2) can bear the full load of the beam to be removed. S32: Simultaneously operate the two sets of dismantling devices' hand chain hoists (2) to drive the crossbeam to descend at a uniform speed. Stop the operation when the hand chain hoist (2) reaches its maximum stroke, and tighten the clamps of the upper anchor to lock the position of the steel strand and the crossbeam. S33: Loosen the clamp of the 5-hole flat anchor (3) and reverse the operation of the hand chain hoist (2) to restore its working stroke; S34: Repeat steps S31 to S33 until the beam is lowered smoothly to the ground.

9. The method for dismantling the temporary fixed four-section H-beam crossbeam of the rotating bridge pier according to claim 6, characterized in that, During the lowering operation in step S3, a total station is used to monitor the lowering height of both ends of the beam to be dismantled in real time, and the lowering height difference between the two ends of the beam is controlled to not exceed 5mm.

10. The method for dismantling the temporary fixed four-section H-beam crossbeam of the rotating bridge pier according to claim 6, characterized in that, The demolition method is applicable to restricted construction environments such as railway operating line slopes, dense pier areas, and narrow mountain sites. During the lowering operation, the operation is suspended and the position of the crossbeam is locked when a railway train passes by. All outdoor operations are stopped in the event of strong winds of level 5 or above, heavy rain, or thunderstorms.

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