Construction method for jacking large-span frame bridge based on composite girder reinforcement of existing railway line

Abstract

The present application relates to the field of business line railway jacking construction technology, and specifically discloses a large-span frame bridge jacking construction method based on combined temporary beam reinforcement of existing railway line, which comprises frame bridge prefabrication and back beam construction, track stress dissipation, temporary support pier installation, steel sleeper beam installation, longitudinal beam installation, artificial hole digging pile construction, horizontal lifting beam installation, excavation jacking, combined temporary beam removal and line recovery. After the temporary support pier is used to erect the combined temporary beam, artificial hole digging pile and horizontal lifting beam installation can be carried out, the track beam digging pile technology is cancelled, the safety risk is reduced, and the construction period is saved. When the artificial hole digging pile is constructed, a construction channel is excavated under the railway line, which can reduce the number of personnel entering the railway line, ensure the railway operation and personal safety, and continuously construct when the train arrives, thereby improving the construction efficiency.

Description

Technical Field

[0001] This invention belongs to the field of railway operating line construction technology, specifically relating to a method for jacking construction of large-span frame bridges based on the reinforcement of existing railway lines with combined temporary beams. Background Technology

[0002] With the rapid development of my country's economy, urban transportation is inevitably becoming more convenient. The number of new and expanded railway underpass jacking projects is increasing, and the traditional small-span frame bridges no longer meet the needs of urban development. Now, continuous large-span frame bridges are becoming the inevitable choice for transportation development. Various construction methods for large-span frame bridge jacking have emerged, adapting to local conditions. The use of continuous combined temporary beam track reinforcement technology has solved the construction challenges of large-span frame bridges crossing multiple railway tracks. At the same time, this method offers rapid construction speed, significantly reducing the time lost due to slow train travel and minimizing the impact on railway operations. The practical application of this technology has yielded good results, achieving significant social and economic benefits and possessing considerable potential for widespread application. Summary of the Invention

[0003] To address the shortcomings of current technologies, this invention provides a method for jacking construction of large-span frame bridges based on the reinforcement of existing railway lines using combined temporary beams. This continuous combined temporary beam reinforcement technology solves the construction challenges of large-span frame bridges crossing multiple railway tracks. Furthermore, this method offers rapid construction speed, significantly reducing the time lost due to slow train travel and minimizing impact on railway operations.

[0004] To achieve the above objectives, the present invention adopts the following solution:

[0005] The method for constructing a large-span frame bridge by jacking up an existing railway line using a composite temporary beam reinforcement system includes the following steps:

[0006] S1. Precast frame bridge and back beam construction: including foundation pit protection construction, pilot tunnel excavation, sliding plate construction, sliding layer construction, frame bridge, and back beam construction;

[0007] S2. Track stress release: Stress release is achieved by using the skylight to release the stress on the seamless steel rail. The rail is cut according to the pre-measured position, and the connecting plates and fasteners are connected to achieve the required stress.

[0008] S3. Temporary support installation: Temporary supports are arranged using a combination of steel and wood, with a uniform spacing of 11m.

[0009] S4. Steel sleeper beam installation: The steel sleeper beam is installed within the skylight point;

[0010] S5. Longitudinal beam installation: When the horizontal hoisting distance of the longitudinal beam installation is less than 20m, a new type of 200t folding arm crane shall be used for erection. Before installation, the beam shall be placed in place outside the track in advance and connected with equal strength at 24m or 36m intervals, and then placed parallel to the outside of the track. When the horizontal hoisting distance of the longitudinal beam installation is greater than 20m, a rail crane shall be used for erection.

[0011] S6. Construction of manually excavated bored piles: including manual tunnel excavation and manual excavation of bored piles;

[0012] S7. Installation of horizontal lifting beams: Each set of horizontal lifting beams adopts two H70 type double web I-beams in double splicing. The joints of the two horizontal lifting beams should be staggered by no less than 2m. The joints are connected with steel plates and high-strength bolts.

[0013] S8. Excavation and jacking: including trial jacking, equipment debugging; formal jacking; track reinforcement during jacking; and correction of deviation during frame bridge jacking.

[0014] S9. Demolition of the combined temporary beam and restoration of the line: After the jacking is completed, the backfill behind the abutment is all done with concrete; the reinforcement and demolition of the combined temporary beam follows the principle of "installation before demolition, and near before far"; after the line is restored, the main line is tamped with a large machine to complete the step speed increase, and the changes in line settlement are observed during the step speed increase period and ballast is added as needed.

[0015] Furthermore, the specific construction of the foundation pit protection in S1 is as follows: the foundation pit protection construction is carried out according to the geological survey, and steel sheet piles, high-pressure jet grouting piles and manually excavated piles are used for protection; before excavation, the excavated area is dewatered, and the dewatering height is 1 to 2m from the bottom of the frame;

[0016] Pit excavation: excavate in layers, leaving 10-15cm of undisturbed soil at the base, which is then manually cleaned and compacted to ensure that the bearing capacity of the base meets the design requirements;

[0017] Slide board construction: The slide board consists of anchor beams, slide boards, guide piers and sliding layers. The anchor beams are excavated and trimmed manually, and the concrete at the anchor beam positions is ensured to be dense.

[0018] Construction of the sliding layer: After the initial setting of the sliding concrete, the plastic sheeting, lubricant, talcum powder, and top layer of plastic sheeting are laid manually in sequence.

[0019] Construction of the frame bridge and its back beam: The main construction of the frame bridge is divided into two steps. The first step is to complete the binding of the pre-embedded steel bars of the bottom slab and vertical walls and to complete the concrete pouring of the bottom slab. The second step is to complete the binding of all remaining steel bars of the vertical walls, the corner beams and the top slab and to complete the concrete construction of the main frame bridge.

[0020] Furthermore, the torque of the bolt joints of the S2 clamping plate is not less than that of grade 10.9, reaching 700-1100 N·m, and the torque of the fasteners reaches 80-150 N·m.

[0021] Furthermore, for seamless track cutting in S2, the rail gap should be reserved at 8mm and should not exceed 10mm. The rail temperature before and after cutting should be recorded during the operation. After cutting, the on-site technical supervisor should determine the permanent treatment plan based on the on-site cutting situation to facilitate the restoration of the track for future rail matching and welding operations.

[0022] After the clamping plates are installed, jumper wires must be installed. Insulated jumper wires must be used within the steel temporary beam area to prevent short circuits in the track and the occurrence of red light accidents during subsequent construction.

[0023] Furthermore, the bottom area of ​​the temporary support in S3 should be no less than 1.2m × 1.2m.

[0024] Furthermore, before installing the steel sleeper beams in S4, the ballast is bagged and stacked on-site to prevent track deformation and to avoid disturbing the existing ballast under the sleepers during construction.

[0025] When inserting the sleeper beam, the sleeper beam must be kept balanced to avoid impacting the rail; when installing the fasteners, all fasteners on one side of the track should be used.

[0026] Insulating fasteners are used on one side, while steel fasteners are used on the other side to ensure good track insulation and prevent the red light strip from affecting train operation.

[0027] Furthermore, the excavation of the artificial passage in S6 is specifically as follows: a working passage with a width of 3m and a height of 2.5 to 3m is excavated under the combined temporary beam. The passage is excavated and supported at the same time. The excavation slope is adjusted according to the soil conditions to maintain the stability of the slope. For every 3m of excavation, I-beam gantry frames or steel pipe frames and bamboo plywood are used for support.

[0028] Furthermore, the specific details of the manually excavated bored piles in S6 are as follows: the vertical transport frame adopts a lifting steel frame as the load-bearing structure, equipped with a slow-speed winch for lifting; horizontal slag removal is carried out using a conveyor belt in conjunction with mechanical transport; the steel guard arm is 50cm high per section, and after each section of the pile hole is excavated, a section of steel casing is installed, with a 10cm gap between the upper and lower steel casings, which are bolted together to form a whole, and the outside of the casing is filled with self-mixed concrete; the steel cage is installed in sections inside the hole, and the vertical main reinforcement is connected by mechanical sleeves; all pile foundation concrete is poured using a ground pump; when filling the core of the bored piles between two lines, the ground pump pipe is inserted through the gap between the sleepers, with the upper end of the pump pipe 10cm lower than the bottom of the rail, and insulating material is laid on the upper part of the pump pipe; protection is set up during pouring, and work is stopped when a train passes; the top 4-6m section of the pile body is poured and vibrated in layers to ensure the quality of concrete pouring.

[0029] Furthermore, the installation of the transverse lifting beam in S7 includes:

[0030] S71. Temporary support installation: When installing temporary supports, corresponding to the installation position of the horizontal lifting beam, place a stack of sleepers on the platform outside the passage, with the same height as the support pile, and place a sliding trolley or roller on top. The number of supports shall not be less than 2, and the supports shall be arranged at a 5m interval between supports and between supports and support piles.

[0031] S72, Placement of the horizontal lifting beam: Use a crane to temporarily lift the horizontal lifting beam onto the temporary support and the outer support pile, and use a tensioner to reinforce it. Place a chain hoist at the far end of the horizontal lifting beam and fix the other end to the existing support pile or anti-slip pile. Multiple horizontal lifting beams are spliced ​​and installed in stages. Stretch the steel beam horizontally to the installation position. Place a sliding trolley temporarily between the top of the support pile and the horizontal lifting beam.

[0032] S73. Reinforcement of the Horizontal Lifting Beam: After the horizontal lifting beam is in place, use U-bolts to fix it under the combined temporary beam. Before fixing, ensure the existing rails above the horizontal lifting beam are insulated and protected, then tighten the U-bolts. At the same time, use jacks to lift the horizontal lifting beam 5mm, and place temporary supports and steel plates between the horizontal lifting beam and the support piles. After the supports are installed, remove the jacks to complete the reinforcement of the horizontal lifting beam.

[0033] S74. Inspection and Acceptance: During the reinforcement of the crossbeam, the elevation of the track is strictly controlled. The elevation of the bottom surface of the rail is measured in real time using a tape measure to ensure the geometric dimensions of the track. After the reinforcement is completed, the elevation of the bottom surface of the rail is checked and confirmed with the cooperating personnel to complete the acceptance of this process.

[0034] Furthermore, S8 specifically includes the following steps:

[0035] S81. Trial jacking and equipment debugging: The trial jacking work continues until the bridge body is jacked. There are dedicated personnel at each observation point to pay attention to changes at any time. After the pump is started, the pump must be stopped and observed whenever the oil pressure rises by 5-10 MPa. If any abnormality is found, it should be dealt with in time. When the jack piston begins to extend and the jacking column is pressed tight, the pump should be stopped immediately. After checking that there are no abnormalities in all parts, the pump can be restarted until the box body starts.

[0036] S82. Formal jacking: According to the distribution of the track and fulcrum piles, excavate and jack in sections. Before each jacking, check the hydraulic system, jacking iron installation and backing condition.

[0037] During jacking, follow the jacking progress. Each jacking advance is less than 1m or 80% of the jacking stroke. After the box body advances, the jacking piston returns to its original position. Add the jacking iron in the neutral position to prepare for the next jacking. Repeat this cycle.

[0038] When the jacking reaches the vicinity of the support piles, the top surface of the box girder is reinforced with sleeper stacks, and the sliding trolley is fixed with wedge-shaped sleepers. This row of support piles can only be removed when the line is confirmed to be completely stable and reliable. Before removal, the pads on the support piles should be removed. The lower part of the support piles should be removed to 5-10cm below the bottom surface of the box girder bottom plate. Then, backfill and compact with crushed stone and soil. The sliding plate is poured at the same time as each pile is broken. The bearing capacity of the sliding plate must meet the bearing capacity requirements. The sliding plate is poured with C45 early strength concrete.

[0039] Different specifications of jacking blocks or jacking columns should be replaced or replenished as needed according to the jacking length. The placement of jacking blocks or jacking columns must be aligned with the axis of the jacking plate and perpendicular to the crossbeam. Each row of jacking blocks and jacking columns must be in a straight line with the jacks. To ensure the stability of the jacking columns under pressure, a fixed crossbeam is installed every 4m. The crossbeam and the jacking column are firmly connected with bolts. Before jacking, jacking blocks and jacking columns of different specifications and sizes are arranged and combined. They are added or replaced according to each jacking stroke. The installation of jacking columns and crossbeams is carried out using a truck crane.

[0040] S83. Reinforcement of the line during the jacking process: Before the jacking begins, the pre-embedded pull rings on the bridge top are connected to the horizontal lifting beams with chain hoists and steel wire ropes. During the jacking, a dedicated person is responsible for tightening the chain hoists and keeping the pulling speed synchronized with the forward speed of the box culvert top to prevent damage to the line during the jacking.

[0041] A sliding trolley is installed under the crossbeam at the top of the culvert to transfer the track load and reduce the jacking resistance during jacking. When the remote guard reports that a train has emerged, the jacking work is stopped immediately, the sliding trolley is fixed with wooden wedges, and the crossbeam is supported by a stack of sleepers to stabilize the track.

[0042] During the jacking process, the railway displacement and settlement and the geometric dimensions of the track are closely monitored. The track is inspected and the fastening bolts are checked after each train passes during the jacking process. If any non-compliance is found, it is repaired immediately.

[0043] The final allowable error for jacking culverts is: centerline error <20cm, elevation error <1% of jacking distance, deviation from the standard height <15cm, deviation from the standard height <20cm;

[0044] S84. Frame bridge jacking correction: Adjustment of box girder directional deviation, following the principle of adjustment as jacking progresses, with measurement and correction performed after each jacking operation;

[0045] When the box body deviates in direction during the empty roof stage, a dedicated person can replace the rolling wedge plates between the left and right sides and the direction pier using the direction pier; alternatively, a jack can be installed on the outside of the side wall to correct the direction during the empty roof stage.

[0046] Increase or decrease the jacking force on one side: that is, open or close the valve of one side of the jack to increase or decrease the jacking force.

[0047] Adjust by alternately operating the two high-pressure oil pumps: if it deviates to the left, operate the left high-pressure oil pump; if it deviates to the right, operate the right high-pressure oil pump.

[0048] Adjusting with the back top iron: When adding or replacing the top iron, wed the top iron on one side tightly according to the deviation, and wed the top iron on the other side loosely or leave a gap. Explore and grasp the regularity when adjusting, and pay attention to the changes caused by uneven force on the box body.

[0049] In front of the cutting feet on both the left and right sides, the direction can be adjusted by over-digging on one side and under-digging or not digging on the other side.

[0050] A lateral support is added to the front of the box body for adjustment. One end of the support is supported on the side wall, and the other end is supported on the excavation surface. When jacking, it forces the box body to adjust to the side being jacked.

[0051] Furthermore, S9 specifically includes the following steps:

[0052] When reinforcing and dismantling the combined temporary beam line, the ballast should be bagged in advance and stacked on both sides of the line. During the construction "window", the horizontal beams should be dismantled first, and the gaps between the horizontal beams should be filled with ballast and compacted. Then the longitudinal beams should be dismantled. Then the horizontal beams should be removed at "6 times the length of 1". At the same time, the position of the horizontal beams should be filled with ballast and compacted until the dismantling is completed.

[0053] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0054] 1. After the temporary support piers are used to erect the combined temporary beams, manual excavation of bored piles and installation of crossbeams can be carried out, eliminating the need for the track-mounted beam excavation process, reducing safety risks, and saving construction time. When constructing manually excavated bored piles, excavating a construction passage under the railway line can reduce the number of times personnel enter the railway line, ensuring railway operation and personal safety. At the same time, construction can continue when trains arrive, improving construction efficiency.

[0055] 2. The longitudinal beams do not require the installation of a new type of 200t large-tonnage folding boom crane. Compared with the traditional railcar beam erection, the folding boom crane beam erection operation is more flexible and convenient. At the same time, it can erect beams across railway lines, and two lines can be constructed simultaneously within a closed window, which greatly speeds up the beam erection speed and saves costs.

[0056] 3. The combined temporary beam structure is reasonably designed and easy to use. There is a connection point every 10cm between the longitudinal beam and the steel sleeper beam. Unless there are special circumstances, the existing sleeper spacing will not be adjusted. Only the steel sleeper beam spacing will be adjusted to reduce the impact on the stability of the existing track bed.

[0057] 4. This method uses a combination of H20 type steel sleeper beams, I115 type longitudinal beams, and H70 type double-web I-beam transverse lifting beams to reinforce the line. The longitudinal beams are connected by rigid plates and high-strength bolts, which can theoretically be extended indefinitely without pre-camber, keeping the line smooth. Support piles and transverse lifting beams are reasonably added according to different spans, resulting in small line deformation and stable overall structure. It is superior to the D-type temporary beam and the longitudinal and transverse lifting beam method of the suspended rail, and meets the technical requirements for overhead lines with a span of more than 24m.

[0058] 5. The I115 type longitudinal beam has a single length of 12m, is lightweight, and easy to erect. When the horizontal hoisting distance across the railway line is less than 20m, a new type of 200t folding arm crane can be used to erect a 36m long longitudinal beam (3 beams spliced ​​together, weighing less than 15t) across the track, which is safe and fast. When the horizontal hoisting distance is greater than 20m, a rail crane is used to erect a 24m longitudinal beam (2 beams spliced ​​together, weighing less than 10t), solving the problem of exceeding the hoisting distance limit. During longitudinal erection, only the track is closed, and there is no need to shut down the contact wire. The height limit can be controlled within 4.1m above the rail top, which meets the safety clearance of the contact wire and the requirements of the China State Railway Group to prohibit the hoisting and erection of temporary beams across the contact wire. Attached Figure Description

[0059] Figure 1 This is a flowchart of the method;

[0060] Figure 2 This is a plan view of the temporary support piers;

[0061] Figure 3 This is a schematic diagram of the artificial passageway structure;

[0062] Figure 4 This is a schematic diagram showing the distribution of tracks and fulcrum piles. Detailed Implementation

[0063] The present invention will be further described in conjunction with specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined in this application.

[0064] This invention discloses a method for jacking a large-span frame bridge using a composite temporary beam to reinforce an existing railway line. The method begins with preparation for construction on an operational line, determining the reinforcement scheme based on site conditions. According to construction drawings and meeting minutes, a comprehensive construction plan is prepared and approved, a safety agreement is signed, and construction permits are obtained promptly. Simultaneously, monthly specific jacking construction plans are prepared and submitted to the railway bureau according to relevant requirements. Construction then commences, specifically including the following steps:

[0065] S1, Precasting of frame bridge and construction of back beams

[0066] Foundation pit protection construction: Foundation pit protection construction is carried out according to the geological survey, and steel sheet piles, high-pressure jet grouting piles, and manually excavated bored piles are commonly used. Before excavation, the excavated area is dewatered, and the dewatering height should be 1-2m from the bottom of the frame.

[0067] Pit excavation: excavate in layers, leaving 10-15cm of undisturbed soil at the base, which is then manually cleaned and compacted to ensure that the bearing capacity of the base meets the design requirements.

[0068] Slide bed construction: The slide bed consists of anchor beams, slide bed plates, guide piers, and a sliding layer. Anchor beams are constructed by manually excavating and trimming the foundation trench, ensuring the concrete at the anchor beam location is dense.

[0069] Construction of the sliding layer: After the initial setting of the sliding concrete, the plastic sheet, lubricant, talcum powder and top layer of plastic sheet are laid manually in sequence.

[0070] Construction of the frame bridge and its back beam: The main construction of the frame bridge is divided into two steps. The first step is to complete the binding of the pre-embedded steel bars of the bottom slab and vertical walls and to complete the concrete pouring of the bottom slab. The second step is to complete the binding of all remaining steel bars of the vertical walls, the corner beams and the top slab and to complete the concrete construction of the main frame bridge.

[0071] The back beam is the provider of the counter-thrust force during the jacking process. It must have sufficient strength and stability, and its construction process is the same as that of the reinforced concrete main structure.

[0072] S2, Track Stress Release

[0073] To prevent stress concentration in the overhead rails, which could cause track deformation and rail bulging, the seamless rails are stress-relievingly released using skylights. They are then cut at pre-measured locations, and the connecting plates and fasteners are brought to the required stress levels. The bolt joint torque of the plates is no less than that of grade 10.9 bolts, reaching 700–1100 N·m, and the torque of the fasteners reaches 80–150 N·m.

[0074] For seamless track cutting, the rail gap should be reserved at 8mm and should not exceed 10mm. The rail temperature before and after cutting should be recorded during the operation. After cutting, the on-site technical supervisor should determine the permanent treatment plan based on the on-site cutting situation to facilitate the restoration of the track for future rail matching and welding operations.

[0075] After the clamping plates are installed, jumper wires must be installed. Insulated jumper wires must be used within the steel temporary beam area to prevent short circuits in the track and the occurrence of red light accidents during subsequent construction.

[0076] S3, Temporary support installation

[0077] Temporary supports shall be constructed using a combination of steel and wood, with a base area of ​​not less than 1.2m × 1.2m. The allowable bearing capacity of the foundation at the temporary supports shall be 150kPa to meet design requirements. The spacing of the temporary supports should be sufficient to allow for the excavation of the passageway and the installation of the crossbeams after the erection of the combined temporary beams. The spacing can be adjusted appropriately, generally arranged evenly at 11m intervals. A penetration test shall be conducted on the existing roadbed before construction to verify the bearing capacity of the foundation. The plan layout of the temporary supports is shown below. Figure 2 As shown.

[0078] S4. Steel sleeper beam installation

[0079] The installation of steel sleeper beams must be completed within the track maintenance window. The standard spacing between concrete sleepers on the track is 60cm, and square sleepers are generally not required. Before installing the steel sleeper beams, the ballast should be bagged and stacked on the spot to prevent track deformation. During construction, the existing ballast under the sleepers should be disturbed as little as possible, which is the key to ensuring track stability.

[0080] When inserting the sleeper beam, the sleeper beam must be kept balanced to avoid impacting the rail; the key points for fastener installation are that all fasteners on one side of the track should be insulated, while all fasteners on the other side should be steel, to ensure good track insulation and prevent the red light strip from affecting train operation.

[0081] During construction, the line condition will be tracked and measured in a timely manner, and any problems will be resolved promptly to ensure that the line remains in good condition and prevent delays or accidents. After the line is opened, the speed limit will be 45 km / h for the subsequent jacking construction, and the slow construction will end when the line is restored.

[0082] S5, Longitudinal beam installation

[0083] When the horizontal hoisting distance for longitudinal beam installation is less than 20m, a new type of 200t folding boom crane is used for erection. Before installation, the crane is pre-positioned outside the track, connected in equal lengths of 24m or 36m, and placed parallel to the track outside for easy hoisting during track maintenance windows. Using the new 200t folding boom crane for longitudinal beam hoisting operations offers convenient access to the site, and its horizontal lifting performance meets the construction requirements of this project. It can lift 15t and 36m longitudinal beams when the horizontal boom extends 20m, reducing the number of beam erections, saving track maintenance windows, and at a lower cost than rail-mounted cranes.

[0084] The lifting operation area must be free from any influencing factors. The crane platform should be 3m below the rail top elevation to ensure a safe distance between the lifting height and the contact wire during crane operation. The platform should be set with a 0-degree slope, the geological conditions should be good, and the ground should be leveled and compacted in advance.

[0085] The longitudinal beam is composed of multiple 12m temporary beams connected by equal strength. A 24m or 36m composite beam will be selected based on the actual site conditions. Before lifting, the longitudinal beam is placed along the track direction. A trial lift is conducted to determine the lifting points and center of gravity of the longitudinal beam. The beam is suspended at four points using four 1m long steel wire ropes. The lifting points should ideally be less than 1m above the beam, and the lifting angle of the steel wire ropes should be less than 60°. Maintaining the beam's balance during lifting is crucial. Two guy wires are fixed at each end to prevent instability during lifting and intrusion into the contact wire safety clearance.

[0086] After the longitudinal beams are in place, install bolts to connect the steel beams, adjust the bolt hole positions of the longitudinal and transverse beams, and align the connecting bolts as you adjust; after the connecting bolts are aligned, tighten the previously loose steel sleeper beams and fasteners; assign a specialist to inspect all fasteners, check for omissions and fill any gaps, and reinforce any loose fasteners.

[0087] After all installations are completed, the length of the track at both ends of the combined temporary beam shall be extended by no less than 50m. Manual operation shall be used to ensure the track is smooth and to prevent the track geometry from exceeding the limit and affecting driving safety.

[0088] The construction supervisor and equipment management personnel re-inspected the reinforcement of the longitudinal beams and the geometric dimensions of the track. Electrical personnel confirmed the insulation of the track circuits. Once the conditions for releasing trains were met, both parties signed off. The first train was limited to a speed of 35 km / h (passenger trains were prohibited from passing), and thereafter the original speed limit of 45 km / h was restored. The first three trains after opening underwent a track inspection, followed by inspections every 4 hours. The track direction, level, gauge, and insulation were checked and recorded, and any deviations in geometric dimensions were promptly rectified.

[0089] When the horizontal hoisting distance of the longitudinal beam installation is greater than 20m, a rail crane is used for erection. This method is suitable for use in stations or for jacking beams on four or more tracks. The longitudinal beams are inverted onto the rail crane from the nearest dedicated line or freight yard in advance. During the track maintenance window, the traction locomotive pulls the beams to the installation site for hoisting operations. Due to railway transportation restrictions, the length of each set of longitudinal beams shall not exceed 24m. The installation method is similar to that of the boom crane and will not be described in this method.

[0090] S6. Construction of manually excavated bored piles

[0091] 1. Excavation of artificial passage

[0092] like Figure 3 As shown, a working passage, 3m wide and 2.5-3m high, is excavated below the combined temporary working beam. The passage is excavated and supported simultaneously, with the slope adjusted according to soil conditions to maintain stability. Every 3m of excavation, an I-beam gantry frame or steel pipe frame and bamboo plywood are used for support. Excavation without support is strictly prohibited.

[0093] 2. Manually excavated bored piles

[0094] Due to height restrictions, manual excavation of bored piles is carried out using specific equipment, and different wall reinforcement measures are adopted according to different geological conditions to ensure safety.

[0095] The vertical transport frame uses a lifting steel frame as its load-bearing structure and is equipped with a slow-speed winch for hoisting. The support frame is 2-2.5m high. An electric hoist is installed on the vertical transport frame to lift slag, and horizontal slag is discharged using a conveyor belt in conjunction with mechanical transport.

[0096] Excavation is carried out using a 60-80cm wide belt conveyor, with centralized mechanical cleaning outside the channel. The hole spacing is greater than 5m, allowing for parallel construction of multiple holes.

[0097] The steel casing is 50cm high per section. After the excavation of each section of the pile hole is completed, a section of steel casing is installed. A 10cm gap is reserved between the upper and lower steel casings. They are connected by bolts to form a whole. The outside of the casing is filled with self-mixed concrete.

[0098] Due to height restrictions, the steel cage is installed in sections inside the hole, and the vertical main reinforcement bars are connected by mechanical sleeves.

[0099] All pile foundation concrete is poured using a ground pump, which does not affect train operation. When filling the core of the bored piles between the two tracks, the ground pump pipe is inserted through the gap between the sleepers, with the upper end of the pump pipe 10cm below the bottom of the rail. Insulation material is laid on the upper part of the pump pipe to prevent short circuits in the track. Protective measures are in place during the pouring process, and work is stopped when a train passes.

[0100] The top 4-6m section of the pile body is poured and vibrated in layers to ensure the quality of the concrete pouring.

[0101] S7, installation of crossbeams

[0102] Each set of horizontal lifting beams adopts a double-jointed combination of two H70 type double-web I-beams. The joints of the two horizontal lifting beams should be staggered by no less than 2m. The joints are connected with steel plates and high-strength bolts, resulting in high structural stability.

[0103] S71, Temporary support installation

[0104] Corresponding to the installation position of the horizontal lifting beam, stacks of sleepers are arranged on the platform outside the passage, with the same height as the fulcrum piles, and a sliding trolley or roller is placed on top. There are no less than 2 piers, and the piers are arranged with a 5m interval between each other and between each pier and the fulcrum pile.

[0105] S72, Placement of the horizontal lifting beam

[0106] Using a crane, the horizontal lifting beam is temporarily hoisted onto temporary supports and outer fulcrum piles, and reinforced with tensioners to prevent slippage. A chain hoist is installed at the far end of the horizontal lifting beam, and the other end is fixed to the existing fulcrum pile or anti-slip pile. Multiple horizontal lifting beams are spliced ​​and installed in stages for each section. The steel beams are horizontally stretched to the installation position. A sliding trolley is temporarily placed between the top of the fulcrum pile and the horizontal lifting beam to reduce frictional resistance and facilitate displacement adjustment. The sliding device is removed after the adjustment is in place.

[0107] S73, Reinforcement of the transverse lifting beam in place

[0108] After the horizontal lifting beam is in place, it is fixed to the bottom of the combined temporary beam using U-bolts. Before fixing, the existing steel rails above the horizontal lifting beam must be insulated and protected, and then the U-bolts are tightened. At the same time, the horizontal lifting beam is lifted by 5mm using jacks, and temporary supports and steel plates are placed between the horizontal lifting beam and the support piles. After the supports are installed, the jacks are removed, and the reinforcement of the horizontal lifting beam is completed.

[0109] S74. Inspection and Acceptance

[0110] During the reinforcement process, the track elevation is strictly controlled. The elevation of the bottom surface of the rail is measured in real time using a measuring tape to ensure the geometric dimensions of the track. After the reinforcement is completed, the elevation of the bottom surface of the rail is checked and confirmed with the cooperating personnel to complete the acceptance of this process.

[0111] S8, Excavation and jacking

[0112] S81, Trial jacking, equipment debugging

[0113] The test jacking work continues until the bridge body is jacked. Each observation point is staffed with a designated person to monitor changes at all times. After the pump is started, it must be stopped and observed whenever the oil pressure rises by 5-10 MPa. Any abnormalities should be dealt with promptly. When the jack piston begins to extend and the jacking column (jacking iron) is tightened, the pump should be stopped immediately. After checking that there are no abnormalities in any part, the pump can be restarted until the gearbox body starts moving.

[0114] S82, Formal Tack

[0115] Based on the distribution of the track and fulcrum piles, excavation and jacking are carried out in sections, such as... Figure 4 As shown.

[0116] Before each jacking operation, the hydraulic system, jacking iron installation, and backing condition should be checked. During jacking, follow the jacking progress, jacking less than 1m or 80% of the jacking iron's stroke each time. After the box girder advances, the jacking iron piston returns to its original position, and the jacking iron is added at the neutral point, ready for the next jacking operation. This cycle is repeated. When jacking reaches the vicinity of the support piles, the top surface of the box girder's horizontal lifting beam is reinforced with sleeper stacks, and the sliding trolley is fixed with wedge-shaped sleepers. Only after confirming that the track is completely stable and reliable can this row of support piles be removed. Before removal, remove the padding wood on the support piles. The lower part of the support piles should be removed to 5-10cm below the bottom surface of the box girder's bottom plate. Then, backfill and compact with crushed stone and soil. Simultaneously with each pile breaking, the sliding plate is poured. The sliding plate's bearing capacity must meet the requirements. The sliding plate is poured with C45 early-strength concrete.

[0117] Different specifications of jacking blocks or jacking columns should be replaced or replenished as needed according to the jacking length. The placement of jacking blocks or jacking columns must be aligned with the axis of the jacking plate and perpendicular to the crossbeam. Each row of jacking blocks and jacking columns must be in a straight line with the jacks. To ensure the stability of the jacking columns under pressure, a fixed crossbeam is installed every 4m. The crossbeam and the jacking column are firmly connected with bolts. Before jacking, jacking blocks and jacking columns of different specifications and sizes are arranged and combined. They are added or replaced according to each jacking stroke. The installation of jacking columns and crossbeams is carried out using a truck crane.

[0118] S83, Reinforcement of the track during the jacking process

[0119] Before starting the jacking, the pre-embedded pull ring (φ22 round steel) on the top of the bridge is connected to the cross beam with a chain hoist wire rope. During the jacking, a dedicated person is responsible for tightening the chain hoist, and the pulling speed is synchronized with the forward speed of the box culvert top to prevent damage to the track during the jacking.

[0120] A sliding trolley is installed under the crossbeam at the top of the culvert to transfer the track load and reduce jacking resistance during jacking. When the remote safety officer reports the appearance of a train, the jacking work is immediately stopped, the sliding trolley is fixed with wooden wedges, and the crossbeam is supported by stacks of sleepers to stabilize the track.

[0121] During the jacking process, the railway displacement and settlement and the geometric dimensions of the track are closely monitored. The track is inspected and the fastening bolts are checked after each train passes by. If any discrepancies are found, they are repaired immediately.

[0122] The final allowable error for jacking culverts is: centerline error <20cm, elevation error <1% of jacking distance, deviation from the standard height <15cm, and deviation from the standard height <20cm.

[0123] S84, Frame Bridge Jacking Correction

[0124] The principle of adjusting the directional deviation of the box body is to adjust it as it is being pushed forward. Each time the pick is pushed forward, a measurement is taken and a correction is made.

[0125] When the box body deviates in direction during the empty roof stage, a dedicated person can replace the rolling wedge plates between the left and right sides and the direction pier using the direction pier; alternatively, a jack can be installed on the outside of the side wall to correct the direction during the empty roof stage.

[0126] Increase or decrease the jacking force on one side: that is, open or close the valve of one side of the jack to increase or decrease the jacking force.

[0127] Adjust by alternately operating the two high-pressure oil pumps: if it deviates to the left, operate the left high-pressure oil pump; if it deviates to the right, operate the right high-pressure oil pump.

[0128] Adjusting with the back support (post): When adding or replacing the support, wed the support on one side tightly according to the deviation, and wed the support on the other side loosely or leave a gap. Explore and master the regularity during adjustment, and pay attention to the changes caused by uneven force on the box body.

[0129] In front of the cutting feet on both sides, the direction can be adjusted by over-digging on one side and under-digging or not digging on the other side.

[0130] A lateral support is added to the front of the box body for adjustment. One end of the support is supported on the side wall, and the other end is supported on the excavation surface, forcing it to adjust to the side being pushed during jacking.

[0131] S9, dismantling of combined temporary beams and restoration of power lines.

[0132] To ensure the stability of the roadbed between the frame bridge and the roadbed transition section, after the jacking is completed, all backfilling behind the abutment is done with concrete, which reduces the subsequent roadbed settlement and the number of subsequent line maintenance and repairs, in line with the latest technical requirements of China State Railway Group for railway jacking construction.

[0133] When reinforcing and dismantling the combined temporary beam line, the principle of "install first, then dismantle; near first, then far" should be followed. When restoring the line, ballast should be bagged in advance and stacked on both sides of the line. During the construction "window", the horizontal beams should be dismantled first, and the gaps between the horizontal beams should be filled with ballast and compacted. Then the longitudinal beams should be dismantled. Then the horizontal beams should be removed according to the "6-removal-1" method. At the same time, the positions of the horizontal beams should be filled with ballast and compacted until the dismantling is completed.

[0134] After the line is restored, the main line must be tamped with heavy machinery to complete the step speed increase. During the step speed increase period, the changes in line settlement should be monitored and ballast should be added as needed to ensure the stability of the line.

[0135] The principle of this construction is as follows:

[0136] First, temporary supports and steel sleeper beams are installed on both sides of the track, directly below the longitudinal beams, according to design requirements. Multiple sets of I115 longitudinal beams are then erected using a folding boom crane or rail crane. After the longitudinal beams are connected and secured to the steel sleeper beams, the longitudinal beams are lifted using the temporary supports. All track loads are transferred to the temporary supports via the steel sleeper beams and longitudinal beams, thus separating the track from the roadbed and ballast, completing the temporary overhead track protection system.

[0137] The construction process of excavating piles for the track-locking beams is eliminated. Under the overhead protection of the combined temporary beams, the excavation of the passage under the track, the construction of manually excavated support piles, and the installation of the transverse lifting beams are carried out in sequence. When crossing multiple tracks, the construction personnel no longer need to cross the track and can complete the work directly under the combined temporary beams. After the support piles reach the required strength, the transverse lifting beams are installed. The transverse lifting beams and longitudinal beams are connected by the support piles to completely suspend the track. The temporary supports will no longer be effective, thus completing the overhead protection system for the excavated and jacked track.

[0138] Then, the excavation and jacking operation is carried out. First, the external jacking of the track is completed. After the frame bridge is pushed to below the end of the transverse lifting beam, a sliding support point is set below the corresponding transverse lifting beam on the frame bridge. Then, the excavation and jacking continue. When the jacking distance is 1m from the first row of support piles, the support point of the transverse lifting beam is reinforced above the frame bridge. Pulleys, rollers and fixed support points are set up to transfer the force of the first row of support piles to the top of the frame bridge. The support points are quickly adjusted into place according to the track elevation to ensure the safe and timely passage of trains. Then the first row of support piles can be removed and the excavation and jacking continues to the second row of support piles. This cycle is repeated until the frame bridge is jacked into place.

[0139] Finally, construction work was carried out, including backfilling the abutment with concrete, backfilling the ballast, installing the wing-shaped wall, restoring the railway line, and dismantling the combined temporary beams.

Claims

1. A method for jacking construction of a large-span frame bridge based on the reinforcement of existing railway lines using composite temporary beams, characterized in that... Includes the following steps: S1. Precast frame bridge and back beam construction: including foundation pit protection construction, pilot tunnel excavation, sliding plate construction, sliding layer construction, frame bridge, and back beam construction; S2. Track stress release: Stress release is achieved by using the skylight to release the stress on the seamless steel rail. The rail is cut according to the pre-measured position, and the connecting plates and fasteners are connected to achieve the required stress. S3. Installation of the first temporary support: The first temporary support is made of a combination of steel and wood, and is evenly arranged at a spacing of 11m. S4. Steel sleeper beam installation: The steel sleeper beam is installed within the skylight point; S5. Longitudinal beam installation: When the horizontal hoisting distance of the longitudinal beam installation is less than 20m, a 200t folding arm crane shall be used for erection. Before installation, the beam shall be placed in place outside the track in advance and connected with equal strength at 24m or 36m intervals, and then placed parallel to the outside of the track. When the horizontal hoisting distance of the longitudinal beam installation is greater than 20m, a rail crane shall be used for erection. S6. Construction of manually excavated bored piles: This includes the excavation of manual passageways and the construction of manually excavated bored piles. When constructing manually excavated bored piles, manual passageways are excavated under the railway line to reduce the number of times personnel enter the railway line, ensuring railway operation and personal safety. At the same time, continuous construction is possible when trains arrive, improving construction efficiency. S7. Installation of horizontal lifting beams: Each set of horizontal lifting beams adopts two H70 type double web I-beams in double splicing. The joints of the two horizontal lifting beams should be staggered by no less than 2m. The joints are connected with steel plates and high-strength bolts. S8. Excavation and jacking: including trial jacking, equipment debugging; formal jacking; Track reinforcement during jacking; deviation correction during frame bridge jacking; S9. Demolition of the combined temporary beam and restoration of the line: After the jacking is completed, the backfill behind the abutment is all filled with concrete; the reinforcement and demolition of the combined temporary beam follows the principle of "installation before demolition, and near before far"; after the line is restored, the main line is tamped with a large machine to complete the step speed increase, and the changes in line settlement are observed during the step speed increase period and ballast is added as needed. Specifically, the excavation of the artificial passage in S6 is as follows: a working passage with a width of 3m and a height of 2.5 to 3m is excavated under the combined temporary beam. The passage is excavated and supported at the same time. The slope of the excavation is adjusted according to the soil conditions to maintain the stability of the slope. For every 3m of excavation, I-beam gantry frames or steel pipe frames and bamboo plywood are used for support. The installation of the crossbeam in S7 includes: S71. Installation of the second temporary support: When installing the second temporary support, the sleeper stacks are arranged on the platform outside the passage at the same height as the support piles, corresponding to the installation position of the horizontal lifting beam. A sliding trolley or roller is placed on top of the sleeper stacks. There are no less than 2 second temporary supports. The second temporary supports are arranged at a 5m interval from each other and from the support piles. S72, Placement of horizontal lifting beam: Use a crane to temporarily lift the horizontal lifting beam onto the temporary support and the outer support pile, and use a tensioner to reinforce it. Place a chain hoist at the far end of the horizontal lifting beam and fix the other end to the existing support pile or anti-slip pile. Multiple horizontal lifting beams are spliced ​​and installed in stages. Stretch the steel beam horizontally to the installation position. Place a sliding trolley temporarily between the top of the support pile and the horizontal lifting beam. S73. Reinforcement of the horizontal lifting beam: After the horizontal lifting beam is in place, use U-bolts to fix it under the combined temporary beam. Before fixing, the existing steel rail above the horizontal lifting beam should be insulated and protected, and then the U-bolts should be tightened. At the same time, use jacks to lift the horizontal lifting beam by 5mm, and place temporary supports and steel plates between the horizontal lifting beam and the support piles. After the supports are installed, remove the jacks to complete the reinforcement of the horizontal lifting beam. S74. Inspection and Acceptance: During the reinforcement of the crossbeam, the elevation of the track is strictly controlled. The elevation of the bottom surface of the rail is measured in real time using a tape measure to ensure the geometric dimensions of the track. After the reinforcement is completed, the elevation of the bottom surface of the rail is checked and confirmed with the cooperating personnel to complete the acceptance of this process. S8 specifically includes the following steps: S81. Trial jacking and equipment debugging: The trial jacking work continues until the bridge body is jacked. There are dedicated personnel at each observation point to pay attention to changes at any time. After the pump is started, the pump must be stopped and observed whenever the oil pressure rises by 5-10 MPa. If any abnormality is found, it should be dealt with in time. When the jack piston begins to extend and the jacking column is pressed tight, the pump should be stopped immediately. After checking that there are no abnormalities in all parts, the pump can be restarted until the box body starts. S82. Formal jacking: According to the distribution of the track and fulcrum piles, excavate and jack in sections. Before each jacking, check the hydraulic system, jacking iron installation and backing condition. During jacking, follow the jacking progress. Each jacking advance is less than 1m or 80% of the jacking stroke. After the box body advances, the jacking piston returns to its original position. Add the jacking iron in the neutral position to prepare for the next jacking. Repeat this cycle. When the jacking reaches the vicinity of the support piles, the top surface of the box girder is reinforced with sleeper stacks, and the sliding trolley is fixed with wedge-shaped sleepers. This row of support piles can only be removed when the line is confirmed to be completely stable and reliable. Before removal, the pads on the support piles should be removed. The lower part of the support piles should be removed to 5-10cm below the bottom surface of the box girder bottom plate. Then, backfill and compact with crushed stone and soil. The sliding plate is poured at the same time as each pile is broken. The bearing capacity of the sliding plate must meet the bearing capacity requirements. The sliding plate is poured with C45 early strength concrete. Different specifications of jacking irons or jacking columns should be replaced or replenished as needed according to the jacking length. The jacking irons or jacking columns must be placed in a straight line with the axis of the jacking plate and perpendicular to the crossbeam. Each row of jacking irons and jacking columns should be in a straight line with the jack. To ensure the stability of the jacking columns under pressure, a fixed crossbeam should be installed every 4m. The crossbeam and the jacking column should be firmly connected with bolts. Before jacking, jacking irons and jacking columns of different specifications and sizes should be arranged and combined. They should be added or replaced according to each jacking stroke. The installation of jacking columns and crossbeams should be carried out by a truck crane. S83. Reinforcement of the line during the jacking process: Before the jacking begins, the pre-embedded pull rings on the bridge top are connected to the horizontal lifting beams with chain hoists and steel wire ropes. During the jacking, a dedicated person is responsible for tightening the chain hoists and keeping the pulling speed synchronized with the forward speed of the box culvert top to prevent damage to the line during the jacking. A sliding trolley is installed under the crossbeam at the top of the culvert to transfer the track load and reduce the jacking resistance during jacking. When the remote guard reports that a train has emerged, the jacking work is stopped immediately, the sliding trolley is fixed with wooden wedges, and the crossbeam is supported by a stack of sleepers to stabilize the track. During the jacking process, the railway displacement and settlement and the geometric dimensions of the track are closely monitored. The track is inspected and the fastening bolts are checked after each train passes during the jacking process. If any non-compliance is found, it is repaired immediately. The final allowable error for jacking culverts is: centerline error <20cm, elevation error <1% of jacking distance, deviation from the standard height <15cm, deviation from the standard height <20cm; S84. Frame bridge jacking correction: Adjustment of box girder directional deviation, following the principle of adjustment as jacking progresses, with measurement and correction performed after each jacking operation; When the box body deviates in direction during the empty roof stage, a special person is assigned to replace the rolling wedge plates between the left and right sides and the direction pier using the direction pier; or a jack is set up on the outside of the side wall to correct the direction during the empty roof stage. Increase or decrease the jacking force on one side: that is, open or close the valve of one side of the jack to increase or decrease the jacking force. Adjust by alternately operating the two high-pressure oil pumps: if it deviates to the left, operate the left high-pressure oil pump; if it deviates to the right, operate the right high-pressure oil pump. Adjusting with the back top iron: When adding or replacing the top iron, wed the top iron on one side tightly according to the deviation, and wed the top iron on the other side loosely or leave a gap. Explore and grasp the regularity when adjusting, and pay attention to the changes caused by uneven force on the box body. To adjust the direction, over-dig on one side and under-dig or not dig at all on the other side in front of the cutting feet on both sides. A lateral support is added to the front of the box body for adjustment. One end of the support is supported on the side wall, and the other end is supported on the excavation surface. When jacking, it forces the box body to adjust to the side being jacked.

2. The method for jacking construction of a large-span frame bridge based on the reinforcement of existing railway lines using composite temporary beams as described in claim 1, characterized in that, The specific construction of foundation pit protection in S1 is as follows: foundation pit protection construction is carried out according to the geological survey, and steel sheet piles, high-pressure jet grouting piles and manually excavated piles are used for protection; before excavation, the excavated area is dewatered, and the dewatering height is 1-2m from the bottom of the frame. Pit excavation: excavate in layers, leaving 10-15cm of undisturbed soil at the base, which is then manually cleaned and compacted to ensure that the bearing capacity of the base meets the design requirements; Slide board construction: The slide board consists of anchor beams, slide boards, guide piers and sliding layers. The anchor beams are excavated and trimmed manually, and the concrete at the anchor beam positions is ensured to be dense. Construction of the sliding layer: After the initial setting of the sliding concrete, the plastic sheeting, lubricant, talcum powder, and top layer of plastic sheeting are laid manually in sequence. Construction of the frame bridge and its back beam: The main construction of the frame bridge is divided into two steps. The first step is to complete the binding of the pre-embedded steel bars of the bottom slab and vertical walls and to complete the concrete pouring of the bottom slab. The second step is to complete the binding of all remaining steel bars of the vertical walls, the corner beams and the top slab and to complete the concrete construction of the main frame bridge.

3. The method for jacking construction of a large-span frame bridge based on the reinforcement of existing railway lines using composite temporary beams, as described in claim 1, is characterized in that... In S2, the bolt joint torque of the clamp plate shall not be lower than that of grade 10.9, reaching 700-1100 N·m, and the torque of the fastener shall reach 80-150 N·m.

4. The method for jacking construction of a large-span frame bridge based on the reinforcement of existing railway lines using composite temporary beams, as described in claim 1, is characterized in that... For seamless track cutting in S2, the rail gap should be reserved at 8mm and should not exceed 10mm. The rail temperature before and after cutting should be recorded during the operation. After cutting, the on-site technical supervisor should determine the permanent treatment plan based on the on-site cutting situation to facilitate the restoration of the track for future rail matching and welding operations. After the clamping plates are installed, jumper wires must be installed. Insulated jumper wires must be used within the steel temporary beam area to prevent short circuits in the track and the occurrence of red light accidents during subsequent construction.

5. The method for jacking construction of a large-span frame bridge based on the reinforcement of existing railway lines using composite temporary beams as described in claim 1, characterized in that... The bottom area of ​​the first temporary support in S3 should be no less than 1.2m × 1.2m.

6. The method for jacking construction of a large-span frame bridge based on the reinforcement of an existing railway line using a composite temporary beam, as described in claim 1, is characterized in that... Before installing the S4 medium steel sleeper beams, the ballast should be bagged and stacked on the spot to prevent the track from deforming. During construction, the ballast under the existing sleepers should not be disturbed. When inserting the sleeper beam, the sleeper beam must be kept balanced to avoid impacting the rail; when installing the fasteners, all fasteners on one side of the track should be used. Insulating fasteners are used on one side, while steel fasteners are used on the other side to ensure good track insulation and prevent the red light strip from affecting train operation.

7. The method for jacking construction of a large-span frame bridge based on the reinforcement of an existing railway line using a combined temporary beam, as described in claim 1, is characterized in that... The specific details of manually excavated bored piles in S6 are as follows: The vertical transport frame uses a lifting steel frame as the load-bearing structure, equipped with a slow-speed winch for lifting; horizontal slag removal uses a conveyor belt in conjunction with mechanical transport; the steel protective arm is 50cm high per section. After each section of the pile hole is excavated, a section of steel casing is installed, with a 10cm gap between the upper and lower casings, connected by bolts to form a whole; the outside of the casing is filled tightly with self-mixed concrete; the reinforcing cage is installed in sections inside the hole, with the vertical main reinforcement connected by mechanical sleeves; all pile foundation concrete is poured using a ground pump; when filling the core of bored piles between two lines, the ground pump pipe is inserted through the sleeper gap, with the upper end of the pump pipe 10cm lower than the bottom of the rail, and insulating material is laid on the upper part of the pump pipe; protection measures are in place during pouring, and work is stopped when a train passes; the top 4-6m section of the pile body is poured and vibrated in layers to ensure the quality of the concrete pouring.

8. The method for jacking construction of a large-span frame bridge based on the reinforcement of existing railway lines using composite temporary beams as described in claim 1, characterized in that... S9 specifically includes the following steps: When reinforcing and dismantling the combined temporary beam line, the ballast should be bagged in advance and stacked on both sides of the line. During the construction "window", the horizontal beams should be dismantled first, and the gaps between the horizontal beams should be filled with ballast and compacted. Then the longitudinal beams should be dismantled. Then the horizontal beams should be removed according to the "6-1-6" rule, and the positions of the horizontal beams should be filled with ballast and compacted until the dismantling is completed.

Images