A prefabricated box girder construction method of railway bridge

Abstract

The present application relates to the technical field of railway bridge construction, and particularly relates to a prefabricated box girder construction method for railway bridge, wherein, step S1, a bridge erecting machine is carried to a tunnel opening construction position, step S2, the bridge erecting machine is carried on a beam carrying vehicle, and a walking type is adopted to pass through the tunnel; step S3, after a front supporting leg of the bridge erecting machine walks out of the tunnel opening, the front supporting leg is turned down and supported on a cushion stone, step S4, a rear supporting leg is rotated backward again to leave a beam feeding channel, step S5, a front beam lifting vehicle and a rear beam lifting vehicle are moved to a beam taking position along a machine arm, and the box girder is lifted and moved forward synchronously to above a waiting hole position; step S6, the front beam lifting vehicle and the rear beam lifting vehicle are synchronously lowered to place the box girder on a support, and support grouting is performed; the rear supporting leg is rotated backward to greatly reduce the external size in the carrying state, and in combination with a walking type self-walking process, the bridge erecting machine can safely pass through the tunnel without disassembly, so that time and cost are significantly saved.

Description

Technical Field

[0001] This invention belongs to the technical field of railway bridge construction, specifically relating to a method for constructing precast box girders for railway bridges. Background Technology

[0002] Precast box girders are widely used in railway bridge construction due to their advantages such as controllable quality and high construction efficiency. Precast box girders are typically erected using bridge-building machines. However, when the bridge line needs to cross tunnels, especially when the tunnel exit is directly adjacent to the bridge, the construction difficulty increases significantly.

[0003] In existing technologies, bridge erecting machines are large in length and have fixed dimensions, making it difficult for them to pass directly through tunnels. Typically, the machine needs to be disassembled, its components transported to the tunnel exit, and then reassembled. This process is time-consuming, costly, and the repeated disassembly and reassembly significantly impacts the equipment's accuracy and structural safety.

[0004] Therefore, there is a need to provide an improved technical solution that addresses the shortcomings of the existing technology. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art. This invention provides a method for constructing precast box girders for railway bridges.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A method for constructing precast box girders for railway bridges, using a bridge erecting machine, which includes a boom, guide beam, front leg, middle leg, rear leg, front beam lifting trolley, and rear beam lifting trolley, includes the following steps: Step S1, transport the bridge erecting machine to the construction position at the tunnel entrance and adjust the bridge erecting machine to the beam erection state; Step S2: The entire bridge erecting machine is loaded onto the beam transport vehicle. The rear outriggers of the bridge erecting machine are rotated and raised to reduce the size of the transported machine. The beam transport vehicle carries the bridge erecting machine through the tunnel in a walking manner. The relative movement between the front outriggers, middle outriggers and the machine arm allows the bridge erecting machine to travel to the position of the hole to be erected. Step S3: After the front outrigger of the bridge erecting machine exits the tunnel entrance, it flips down and is supported on the pad stone. The guide beam is supported by the front outrigger and the middle outrigger, and is rigidly connected and fixed to the already constructed box girder and the pad stone respectively. Step S4: The girder transport vehicle carries the box girder to the tail of the bridge erecting machine. The rear support leg rotates and tilts backward again to make room for the girder feeding channel. The girder transport vehicle pushes the box girder to the guide beam and is supported by the support wheel set set at the rear of the guide beam or the bridge erecting machine, which rolls on the already constructed box girder to form a stable girder feeding channel. Step S5: The front and rear beam trolleys move along the boom to the beam-picking position, lift the box girder, and then move forward synchronously to the position above the mounting hole. Step S6: The front and rear beam trolleys simultaneously lower the box girder, place it on the support, and grout the support. Step S7: Repeat steps S4-S6 to erect beams sequentially along one line of the bridge.

[0007] Preferably, the steps for the bridge erecting machine to pass through the tunnel include: Step S201: The rear outrigger is raised and supported on the constructed box girder by the middle and front outriggers. The boom of the bridge erecting machine is slid forward a set distance by the front and rear gantry cranes. The front and rear gantry cranes move backward to the tail of the boom in sync. Step S202: After the boom moves forward to the position, the rear outrigger is flipped down to support the beam transport vehicle or the already constructed box girder. The middle outrigger is retracted and driven by the rear lifting beam trolley to slide forward along the bottom track of the boom to the position. Then the middle outrigger is extended and supported on the already constructed box girder by the hydraulic cylinder and locked. Step S203: After the middle outrigger provides stable support, the front outrigger is retracted and driven forward along the front end track of the boom by the front crane trolley. Step S204: Repeat steps S201-S203 until the tunnel is passed.

[0008] Preferably, in step S1, when the beam transport vehicle carries the box girder through the tunnel, a distance sensor is installed at the flange plate position of the box girder along the transport direction. The distance sensor is connected to the travel limit control system of the beam transport vehicle. When the distance between the outer edge of the flange plate and the tunnel lining is less than a preset threshold, the system automatically issues a stop command.

[0009] Preferably, in step S6, the bearing grouting adopts gravity grouting method, and the grouting bucket is set at a height of 1 meter from the top surface of the box girder on the front leg of the bridge erecting machine, and the non-shrink grouting material is injected by gravity height difference.

[0010] Preferably, the pad stone is provided with an anchor bolt corresponding to the support, the support is provided with a positioning hole corresponding to the anchor bolt, and the anchor bolt is provided with an adjusting nut corresponding to the positioning hole. A grouting template with corresponding supports is provided on the pad stone. The grouting template is provided with a vibrating rib that runs horizontally through it, and one end of the vibrating rib is connected to a vibrating motor.

[0011] Preferably, the two vibrating ribs are arranged in a cross shape, and the template has assembly holes for the corresponding vibrating ribs, with rubber sleeves for the corresponding vibrating ribs on the assembly holes.

[0012] Preferably, in step S7, when erecting the bridge abutment from the third to the last span beam, sleepers or steel pads of different heights are added under the front support leg or guide beam corresponding to the front support leg position, the columns and roller support mechanisms of the front and middle support legs are disassembled or folded, and the support position of the rear support leg is adjusted, so as to complete the erection of the third to the last span, the second to the last span, and the last span beam in sequence.

[0013] Preferably, after one section of the bridge is erected, the beam transport vehicle carrying the bridge erecting machine turns around; When turning around, the front of the bridge erecting machine is supported on the beam transport vehicle by the front outriggers, and the middle outriggers are used as the turning point. The beam transport vehicle pushes the boom to make a circular motion to achieve the turning around.

[0014] Preferably, the bearing is installed on the bottom surface of the box girder. Before installation, the bridge design drawings are reviewed to determine the bearing type and installation position. After the bearing is installed at the bottom of the box girder, the connecting bolts between the bearing and the beam are tightened. The gap between the bearing and the pre-embedded steel plate at the bottom of the beam is filled by grouting. After the top plate of the bearing is firmly connected to the box girder, the height difference at the four corners of the bearing is checked.

[0015] Beneficial effects: By rotating and tilting the rear outriggers backward, the overall dimensions during transport are significantly reduced. Combined with the walking-type self-propelled technology, the entire bridge erecting machine can safely pass through tunnels without disassembly, significantly saving time and costs. Through secondary rearward movement of the rear outriggers and the assistance of support wheel sets, a stable and unobstructed beam feeding channel is constructed within the limited space at the tunnel entrance, solving the rear-end interference problem of conventional bridge erecting machines and improving beam feeding efficiency. Attached Figure Description

[0016] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. Wherein: Figure 1 This is a construction schematic diagram of the bridge erecting machine in a specific embodiment provided by the present invention; Figure 2 This is a simplified structural diagram of the infusion template provided in a specific embodiment of the present invention.

[0017] In the diagram: 1. Box girder; 2. Pier to be erected; 3. Crane boom; 4. Guide beam; 5. Front beam lifting trolley; 6. Rear beam lifting trolley; 7. Front outrigger; 8. Middle outrigger; 9. Rear outrigger; 10. Beam transport vehicle; 11. Pouring formwork; 12. Vibrating reinforcement. Detailed Implementation

[0018] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.

[0019] In the description of this invention, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," and "bottom," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and do not require the invention to be constructed and operated in a specific orientation; therefore, they should not be construed as limitations on the invention. The terms "connected" and "linked" used in this invention should be interpreted broadly. For example, they can refer to a fixed connection or a detachable connection; they can refer to a direct connection or an indirect connection through intermediate components. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0020] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other.

[0021] like Figure 1 As shown, a method for constructing precast box girders for railway bridges is described. The construction is carried out using a bridge erecting machine, which includes a boom 3, guide beam 4, front outrigger 7, middle outrigger 8, rear outrigger 9, front beam lifting trolley 5, and rear beam lifting trolley 6, as well as a hydraulic and electrical system. During span crossing operations, the machine achieves self-propelled movement through the relative motion of each outrigger and the boom 3, eliminating the need for track laying. During beam feeding, the rear outrigger 9 automatically rotates and tilts backward, clearing a path for the beam transport vehicle 10, and, in conjunction with the rigid connection of the guide beam 4 and the rolling support of the support wheel set, achieves stable beam feeding. When the beam transport vehicle 10 carries the box girder 1 through a tunnel, it automatically stops to prevent collisions by linking a distance sensor installed on the flange plate of the box girder 1 with the travel limit switch. The beam lowering is controlled synchronously by a PLC and the support reaction force is adjusted to ensure installation accuracy.

[0022] In this embodiment, the construction method of precast box girder for railway bridge includes the following steps: Step S1, transport the bridge erecting machine to the preset construction position at the tunnel entrance, conduct comprehensive debugging and calibration of the outriggers, boom 3, beam lifting trolley, hydraulic system and control system of the bridge erecting machine, adjust the overall posture of the bridge erecting machine, so that each component of the bridge erecting machine is in a stable state ready for beam erection, and ensure that the subsequent tunnel crossing and beam erection operations are carried out accurately.

[0023] In step S2, the entire bridge erecting machine is loaded onto the beam transport vehicle 10. The rear outrigger 9 is rotated and tilted backward by the bridge erecting machine control system, which greatly reduces the overall size of the bridge erecting machine and makes it suitable for the narrow passage space of the tunnel. The beam transport vehicle 10 carries the bridge erecting machine and walks through the tunnel in a low-speed walking mode. By utilizing the adaptive relative movement between the front outrigger 7, the middle outrigger 8 and the boom 3, the entire bridge erecting machine can move autonomously and smoothly until it reaches the front of the bridge span to be erected.

[0024] Step S3: After the front outrigger 7 of the bridge erecting machine has completely exited the tunnel entrance, control the front outrigger 7 to flip down so that it is precisely supported on the top surface of the pad stone. Adjust the posture of the guide beam 4 so that the guide beam 4 is positioned by the double support of the front outrigger 7 and the middle outrigger 8. Then, the two ends of the guide beam 4 are respectively connected to the box girder 1 and the pad stone that have been constructed using rigid connectors to eliminate equipment shaking deviation and build a stable foundation structure for the bridge erecting operation.

[0025] In step S4, the girder transport vehicle 10 carries the box girder 1 smoothly to the working area at the rear of the bridge erecting machine. The rear support leg 9 of the bridge erecting machine is then rotated and tilted backward to completely clear the feeding channel and avoid the obstruction and interference of the rear support leg 9 on the movement of the box girder 1. The two girder transport vehicles 10 push the box girder 1 at a uniform speed, so that the box girder 1 moves smoothly in the horizontal direction above the guide beam 4. At the same time, relying on the support wheel set set on the guide beam 4 or the rear of the bridge erecting machine, the box girder 1 rolls and is supported on the already constructed box girder, which greatly reduces the feeding friction resistance and forms a stable and safe feeding channel.

[0026] In step S5, the front lifting beam trolley 5 and the rear lifting beam trolley 6 of the bridge erecting machine are precisely moved along the track of the boom 3 to the position for picking up the box girder 1. The lifting equipment is firmly connected to the preset lifting point of the box girder 1, and the box girder 1 is lifted up at a uniform speed and smoothly. After the lifting is completed, the front lifting beam trolley 5 and the rear lifting beam trolley 6 move forward synchronously and at the same speed, transporting the box girder 1 to the top of the span of the pier 2 to be erected, and accurately aligning it.

[0027] In step S6, the front beam-lifting trolley 5 and the rear beam-lifting trolley 6 descend slowly and synchronously to complete the lowering operation of box girder 1, accurately placing box girder 1 in the preset position of the pier support. After the girder is in place, gravity grouting is used to carry out the support grouting construction. The grouting bucket is fixed at the position of the front outrigger 7 of the bridge erecting machine, and the bottom surface of the grouting bucket is kept at a constant height of 1 meter from the top surface of box girder 1. Using the fixed gravity height difference, non-shrink grout is evenly poured from the perimeter of the support and between the pouring template 11 to ensure that the grout is fully filled and without gaps. After the grout has cured to the designed strength, the pouring template is removed to complete the support fixing operation.

[0028] Step S7: Repeat the beam feeding, beam lifting, beam lowering, and grouting procedures from steps S4 to S6, and complete the erection of box girders 1 at each standard span along the single line of the bridge. Furthermore, when erecting the beams from the third to last span of the bridge abutment, in response to the limited construction space and support height deviation at the last span, sleepers or steel pads of different specifications and heights are added under the front support leg 7 or guide beam 4 at the corresponding position of the front support leg 7. At the same time, the columns and roller mechanisms of the front support leg 7 and the middle support leg 8 are disassembled or folded to adaptively adjust the support height and support position of the rear support leg, and the erection of the beams of the third to last span, the second to last span, and the last span is completed in sequence with precision.

[0029] After one section of the bridge is erected, the bridge erecting machine is transported back to the beam yard by the beam transport vehicle 10 for turning around. During the turning operation, the front of the bridge erecting machine is stably supported on the top surface of the beam transport vehicle 10 by the front outrigger 7, and the middle outrigger 8 is used as the pivot point. The beam transport vehicle 10 smoothly pushes the boom 3 to make a circular rotation movement. Without the assistance of large hoisting equipment, the entire bridge erecting machine can be turned around quickly, preparing for the subsequent beam erection operation of another section.

[0030] In this embodiment, in step S1, when the beam transport vehicle 10 carries the box girder 1 through the tunnel, distance sensors are symmetrically installed on both sides of the flange plate of the box girder 1 along the beam transport direction. The distance sensors are electrically connected to the travel limit control system of the beam transport vehicle 10 to monitor the distance between the outer edge of the flange plate of the box girder 1 and the inner wall of the tunnel lining in real time. When the monitored distance is less than the system's preset safety threshold, the control system immediately triggers an alarm signal and automatically issues an emergency stop command to prevent the box girder 1 from colliding or scraping with the tunnel lining.

[0031] In an optional embodiment, the steps for the bridge erecting machine to pass through the tunnel include: Step S201, controlling the rear outrigger 9 of the bridge erecting machine to tilt up, and being stably supported on the beam surface of the completed box girder 1 by only the middle outrigger 8 and the front outrigger 7. The boom 3 of the bridge erecting machine is driven forward by the power of the front lifting beam trolley 5 and the rear lifting beam trolley 6 to slide forward a preset safe distance. After the sliding is completed, the front lifting beam trolley 5 and the rear lifting beam trolley 6 are controlled to move backward synchronously and return to the tail position of the boom 3, completing the first round of attitude adjustment.

[0032] In step S202, after the boom 3 moves forward precisely into position, the rear outrigger 9 is flipped down and stably supported on the top surface of the beam transport vehicle 10 or the already constructed box girder. Then, the middle outrigger 8 is retracted and moved forward along the dedicated track at the bottom of the boom 3 to the designated work position by the rear lifting beam trolley 6. After sliding into position, the hydraulic cylinder of the middle outrigger 8 is extended, so that the middle outrigger 8 is tightly supported on the already constructed box girder and mechanically locked to ensure the stability of the support structure.

[0033] In step S203, after the middle support leg 8 is stably supported and the force is up to standard, the front support leg 7 is retracted and pulled up. The front support leg 7 is then driven forward along the front rail of the boom 3 by the front crane 5 to match the overall progress of the bridge erecting machine.

[0034] Step S204: Repeat the posture adjustment, outrigger repositioning, and sliding travel procedures from steps S201 to S203. Through multiple rounds of cyclical progressive walking, the entire bridge erecting machine can smoothly pass through the tunnel without disassembling the main structure of the bridge erecting machine.

[0035] In another optional embodiment, the bearing construction adopts a pre-installation process. Before the box girder 1 leaves the factory, the bridge design drawings are reviewed to accurately verify the bearing model, specifications, installation coordinates and elevation parameters. The bearing is pre-installed and fixed on the bottom surface of the box girder 1, and the connecting bolts between the bearing and the beam are tightened. The gap between the bearing and the pre-embedded steel plate at the bottom of the beam is filled and compacted by high-pressure grouting. After the top plate of the bearing is firmly connected to the beam of the box girder 1, the height difference of the four corners of the bearing is accurately checked and calibrated to ensure that the bearing installation accuracy meets the standards.

[0036] In this embodiment, anchor bolts matching the support are pre-installed above the pad stone. Positioning holes corresponding to the anchor bolts are opened on the bottom surface of the support. Adjustable nuts with adjustable height are fitted on the anchor bolts, allowing for precise fine-tuning of the support's installation level and elevation. Simultaneously, a square grouting template 11 matching the support's shape is installed on the pad stone. The grouting template 11 has horizontally arranged cross-shaped vibration ribs 12. Figure 2 As shown. One end of the vibratory rib 12 is connected to a vibratory motor, which eliminates air bubbles inside the grout through mechanical vibration and improves the density of the grout. The template has an assembly hole adapted to the vibratory rib 12. The assembly hole is fitted with a rubber sleeve, which can effectively reduce shock and seal to prevent grout leakage. The two vibratory ribs 12 have a height difference to avoid mutual interference. After the grouting is completed, the end of the vibratory rib 12 can be cut off or left on the bridge pier.

[0037] After lowering the beam and initially adjusting the level of the support, the square template is placed around the support, with its bottom flange tightly against the surface of the pad stone, and temporarily fixed with expansion bolts. Then, the vibration motor is started, causing the vibrating rib 12 to generate high-frequency micro-amplitude vibration. This vibration is buffered by the rubber sleeve and transmitted to the side wall of the template, and further acts on the grout in the grouting chamber.

[0038] Preferably, the square template is made of high-strength steel or aluminum alloy, and is a topless and bottomless rectangular frame. Its inner contour dimensions are slightly larger than the plane dimensions of the support base plate (e.g., 3-5 cm larger on each side), and its height is 50-150 mm. It is used to enclose a closed grouting chamber above the pad stone. The four side edges of the template are bent outward to form horizontal flanges, and multiple positioning holes are opened on the flanges. The template can be temporarily fixed to the surface of the pad stone by expansion bolts or steel nails to prevent the template from shifting or floating during grouting. The four inner corners of the template are preferably rounded to reduce dead zones in grout flow.

[0039] On two sets of opposite sidewalls of the square template, horizontally penetrating assembly holes are respectively provided. The central axes of the two assembly holes are perpendicular to each other in the horizontal plane and are distributed in a cross shape. A metal vibrating rib 12 (e.g., round or square steel) is inserted into each assembly hole, and both ends of the vibrating rib 12 extend beyond the sidewall of the template by a certain length (e.g., 100-200mm). The vibrating rib 12 can slide freely axially within the assembly hole.

[0040] To isolate the vibratory rib 12 from direct rigid contact with the template sidewall and avoid metal impact noise and wear, a rubber sleeve is embedded in the assembly hole. This rubber sleeve is an elastic cylindrical structure; its inner wall is interference-fitted with the outer wall of the vibratory rib 12, and its outer wall is tightly fitted with the inner wall of the assembly hole. Both ends of the rubber sleeve are also provided with annular flanges, which respectively fit against the inner and outer surfaces of the template sidewall, serving as limiting and sealing functions. One end of the vibratory rib 12 (preferably the non-interfering ends of two vibratory ribs 12) is detachably connected to a high-frequency vibration motor via a quick clamp or threaded coupling. This vibration motor is pneumatic or electric, with an operating frequency range of 50Hz-200Hz and adjustable excitation force.

[0041] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention shall be within the scope of protection of the pending claims of the present invention.

Claims

1. A method for constructing precast box girders for railway bridges, characterized in that, Construction is carried out using a bridge erecting machine, which includes a boom, guide beam, front outrigger, middle outrigger, rear outrigger, front beam lifting trolley, and rear beam lifting trolley. The steps are as follows: Step S1, transport the bridge erecting machine to the construction position at the tunnel entrance and adjust the bridge erecting machine to the state ready for beam erection. Step S2: The entire bridge erecting machine is loaded onto the beam transport vehicle. The rear outriggers of the bridge erecting machine are rotated and raised to reduce the size of the transported machine. The beam transport vehicle carries the bridge erecting machine through the tunnel in a walking manner. Through the relative movement between the front outriggers, middle outriggers and the machine arm, the bridge erecting machine moves to the position of the hole to be erected. Step S3: After the front outrigger of the bridge erecting machine exits the tunnel entrance, it flips down and is supported on the pad stone. The guide beam is supported by the front outrigger and the middle outrigger, and is rigidly connected and fixed to the already constructed box girder and the pad stone respectively. Step S4: The beam transport vehicle carries the box girder to be constructed to the tail of the bridge erecting machine. The rear support leg rotates and tilts backward again to make room for the beam feeding channel. The beam transport vehicle pushes the box girder to the guide beam and rolls on the constructed box girder through the support wheel group set at the rear of the guide beam or the bridge erecting machine to form a stable beam feeding channel. Step S5: The front and rear beam trolleys move along the boom to the beam-picking position, lift the box girder, and then move forward synchronously to the position above the mounting hole. Step S6: The front and rear beam trolleys simultaneously lower the box girder, place it on the support, and grout the support. Step S7: Repeat steps S4-S6 to erect beams sequentially along one line of the bridge.

2. The construction method for precast box girders of railway bridges according to claim 1, characterized in that, The steps for a bridge erecting machine to pass through a tunnel include: Step S201: The rear outrigger is raised and supported on the constructed box girder by the middle and front outriggers. The boom of the bridge erecting machine is slid forward a set distance by the front and rear gantry cranes. The front and rear gantry cranes move backward to the tail of the boom in sync. Step S202: After the boom moves forward to the position, the rear outrigger is flipped down to support the beam transport vehicle or the already constructed box girder. The middle outrigger is retracted and driven by the rear lifting beam trolley to slide forward along the bottom track of the boom to the position. Then the middle outrigger is extended and supported on the already constructed box girder by the hydraulic cylinder and locked. Step S203: After the middle outrigger provides stable support, the front outrigger is retracted and driven forward along the front end track of the boom by the front crane trolley. Step S204: Repeat steps S201-S203 until the tunnel is passed.

3. The construction method for precast box girders of railway bridges according to claim 1, characterized in that, In step S1, when the beam transport vehicle carries the box girder through the tunnel, a distance sensor is installed at the flange plate position of the box girder along the transport direction. The distance sensor is connected to the travel limit control system of the beam transport vehicle. When the distance between the outer edge of the flange plate and the tunnel lining is less than a preset threshold, the system automatically issues a stop command.

4. The construction method for precast box girders of railway bridges according to claim 1, characterized in that, In step S6, the bearing grouting adopts gravity grouting method. The grouting bucket is set at a height of 1 meter from the top surface of the box girder on the front leg of the bridge erecting machine. The non-shrink grouting material is injected by gravity height difference.

5. The construction method for precast box girders of railway bridges according to claim 4, characterized in that, An anchor bolt corresponding to the support is provided above the pad stone, and a positioning hole corresponding to the anchor bolt is provided below the support. An adjusting nut corresponding to the positioning hole is provided on the anchor bolt. A grouting template with corresponding supports is provided on the pad stone. The grouting template is provided with a vibrating rib that runs horizontally through it, and one end of the vibrating rib is connected to a vibrating motor.

6. The construction method for precast box girders of railway bridges according to claim 5, characterized in that, There are two vibrating ribs, which are arranged in a cross shape. The template has assembly holes for the corresponding vibrating ribs, and rubber sleeves for the corresponding vibrating ribs are installed in the assembly holes.

7. The construction method for precast box girders of railway bridges according to claim 1, characterized in that, In step S7, when erecting the bridge abutment from the third to the last span, sleepers or steel pads of different heights are added under the front support leg or guide beam corresponding to the front support leg position. The columns and roller support mechanisms of the front and middle support legs are disassembled or folded over, and the support position of the rear support leg is adjusted. The erection of the third to the last span, the second to the last span, and the last span beam is completed in sequence.

8. The construction method for precast box girders of railway bridges according to claim 7, characterized in that, After one section of the bridge is erected, the beam transport vehicle carrying the bridge erecting machine turns around. When turning around, the front of the bridge erecting machine is supported on the beam transport vehicle by the front outriggers, and the middle outriggers are used as the turning point. The beam transport vehicle pushes the boom to make a circular motion to achieve the turning around.

9. The construction method for precast box girders of railway bridges according to claim 1, characterized in that, Before installation, the bridge design drawings are reviewed to determine the type and location of the bearings. After the bearings are installed at the bottom of the box girder, the connecting bolts between the bearings and the box girder are tightened. The gap between the bearings and the pre-embedded steel plates at the bottom of the girder is filled by grouting. After the bearings are firmly connected to the box girder, the height difference at the four corners of the bearings is checked.

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