A jacking construction method for a shallow passenger tunnel adjacent to an existing line

Abstract

The application discloses a kind of shallow passenger tunnel jacking construction methods near existing line, comprising the following construction steps: (1) operating line reinforcement: tunnel both sides construction hole pile, hole pile reaches design strength after cutting off existing slope shoulder, in turn construction crown beam, cross brace;Sectional interval groove is excavated and is made to retaining wall, retaining wall single section length is about 4m, longitudinal reinforcement is welded connection.Adopting hole pile, crown beam, cross brace, sectional retaining wall combination forms complete operating line reinforcement system, can effectively prevent tunnel jacking process frame both sides and top roadbed filling collapse, stabilizes existing roadbed and line structure.Small crushing equipment is simultaneously used to remove slope, shoulder structure, with real-time monitoring, dynamic control line state of whole process professional line worker, avoids the disturbance of large area excavation, large equipment operation to shallow existing railway, reduces roadbed settlement, line deformation and other hidden dangers.

Description

Technical Field

[0001] This invention relates to the field of existing railway line construction technology, and in particular to a method for jacking construction of shallow-buried passenger tunnels near existing railway lines. Background Technology

[0002] With the continuous improvement of the railway transportation network and the increasing transportation pressure on existing railway hubs, in order to optimize the pedestrian passage system in station areas, eliminate safety hazards at railway level crossings, and achieve separation of pedestrians and vehicles, a large number of existing railway lines need to add or renovate underpass passenger tunnel projects. The traditional jacking method has the following problems: large jacking distance, difficulty in controlling direction and elevation, limited space inside the foundation pit, inability for large equipment to enter, shallow burial depth of existing passenger tunnels, and easy impact on existing railways during excavation. Summary of the Invention

[0003] The purpose of this invention is to solve the problems of traditional jacking methods mentioned in the background art, such as large jacking distance, difficulty in controlling direction and elevation, limited internal space of the foundation pit, inability of large equipment to enter, shallow burial depth of existing passenger tunnels, and easy impact on existing railways during excavation.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: A method for constructing a shallow-buried passenger tunnel near an existing railway line by jacking, comprising the following construction steps: (1) Reinforcement of the operating line: bored piles are constructed on both sides of the tunnel. After the bored piles reach the design strength, the existing slope protection shoulder is removed and the cap beam and cross bracing are constructed in sequence. The retaining wall is constructed by excavating trenches in sections. The length of each section of the retaining wall is about 4m. The longitudinal steel bars are connected by welding. The lap length of the steel bars is reserved and the lap position is staggered. The line is restored after the retaining wall is completed. (2) Remove existing frame slope protection and shoulder: After the reinforcement of the operating line is completed, use a small breaker to remove the frame beam and shoulder within the jacking range, and excavate the soil inside the protective pile to the end of the existing passenger tunnel; throughout the construction process, arrange professional line workers to observe, inspect and record the status of the railway line in real time, and deal with line safety hazards in a timely manner. (3) Construction of sliding plate and guide pier: First, a 20cm thick layer of crushed stone is compacted in the foundation, and then a 20cm thick C25 reinforced concrete sliding plate is poured; a 30cm×45cm ground anchor beam with the same length as the tunnel floor is set every 3m under the sliding plate, and the ground anchor beam is poured integrally with the sliding plate; the sliding plate uses a 2m×2m grid to embed Φ16 steel bar heads, and the leveling is done at points during concrete pouring to control the elevation of the sliding plate surface. After the concrete has initially set, a ≤2cm thick M10 cement mortar is applied to the surface, and a 1:3 machine oil talcum powder lubricating layer is applied to the top surface. A plastic sheet isolation layer is laid in front of the precast tunnel; the elevation deviation of the top surface of the sliding plate is controlled to be +20~-30mm, the unevenness within a 2m length does not exceed 3mm, and the overall flatness is ≤5mm; concrete guide piers are poured on both sides of the sliding plate, and a 10cm gap is reserved between the guide piers and the edge of the tunnel frame. (4) Precast passenger tunnel frame: The total station is used for positioning to make the center line of the tunnel frame, the center line of the bottom plate, and the center line of the jacking bridge coincide; steel formwork is used in combination with wooden formwork, Φ16 tie rods are used in combination with back ribs for reinforcement, the top plate is made of 1.5cm high-strength bamboo plywood, the longitudinal 10×10cm square timber distribution beams are spaced at 20cm, and the transverse 10×10cm square timber distribution beams are spaced at 90cm; the support is Φ60 reinforced disc buckle steel pipe support, the top of the steel pipe is set with adjusting screw rods to adjust the height, and the support can be removed after the top plate concrete reaches 100% of the design strength; the frame culvert is poured in two stages, the first stage is the bottom plate and the ribs, and the second stage is the side walls and the top plate; the concrete is poured in layers and symmetrically on the left and right, with a height difference of no more than 50cm, and plastic sheeting is used for covering and watering after pouring; when precasting the box body concrete, the soil above the box bottom is pressed into the box bottom at the front end of the box bottom to enhance its bearing capacity and prevent the bow slope from collapsing; (5) Jacking construction: The tunnel frame is jacked up in one step using the jacking method; hydraulic jacks are arranged at equal intervals, and various specifications of jacking irons and jacking columns are set up. The axis of the jacking irons and jacking columns is consistent with the jacking force axis, and the support surface is in close contact; then the equipment is debugged and graded test jacking is carried out. After normal operation, the formal jacking operation is carried out. After each jacking stroke is completed, the jacks are returned to their original positions, the matching jacking irons are replaced and crossbeams are set up. The axis and elevation of the box body are observed simultaneously. If the box body deviates, the jacking force is increased or decreased on one side, the oil pump is turned on in sections, the jacking irons on one side are wedged, and the horizontal support is added to the front end of the box body for correction; at the junction of the new and old tunnels, the existing reserved waterstop grooves and pre-embedded bolts are used to install Ω-shaped detachable waterstops. The construction joints are filled with sealant to achieve first-level waterproofing. (6) Backfilling construction: After the jacking is completed, the back, guide pier, roadbed retaining wall and retaining pile cap beam should be removed, and then the gap between the jacking section and the existing railway roadbed should be backfilled with foamed lightweight soil.

[0005] Preferably, during the trial jacking operation, once the jack piston begins to extend and the jacking column (jacking iron) is pressed down, the jacking should be stopped immediately. After checking the condition of each part and finding no abnormalities, the pump can be restarted until the tank body starts.

[0006] Preferably, the ground anchor beams are constructed using a direct trenching and pouring process during the installation of the sliding plate, eliminating the need for additional support formwork.

[0007] Preferably, during the precast casting process of the tunnel, the wall formwork is reinforced with tie rods and double Φ48 steel pipe clips.

[0008] Preferably, the elevation of the tunnel floor observation markers is observed daily during the jacking process, and the axis and elevation monitoring data of the box girder are fully recorded after each jacking section is completed.

[0009] Compared with the prior art, the present invention has the following beneficial effects: A complete reinforcement system for the operational railway line is formed by combining bored piles, capping beams, cross bracing, and segmented retaining walls. This effectively prevents the collapse of the subgrade fill material on both sides and the top of the frame during tunnel jacking, stabilizing the existing subgrade and track structure. Simultaneously, small-scale crushing equipment is used to remove the slope protection and shoulder structures, while professional track workers monitor and dynamically manage the track status throughout the process. This avoids disturbance to the shallowly buried existing railway caused by large-scale excavation and heavy equipment operations, reducing potential hazards such as subgrade settlement and track deformation.

[0010] A composite sliding plate structure combining a crushed stone layer and C25 reinforced concrete is employed, along with integrated ground anchor beams to enhance the overall integrity and stability of the sliding plate. Leveling is achieved through precise positioning with grid-like steel reinforcement heads and high-precision mortar finishing, strictly controlling the elevation and flatness deviations of the sliding plate to provide a flat and stable working base for the caisson jacking. Simultaneously, applying a lubricating layer of machine oil and talcum powder and laying a plastic sheeting isolation layer significantly reduces the friction and starting resistance during caisson jacking, preventing jamming and displacement. Furthermore, guide blocks are installed on both sides of the sliding plate, with pre-set gaps to precisely constrain the caisson's trajectory. Combined with a pre-positioning method using three overlapping lines, the positioning accuracy of the tunnel frame prefabrication and jacking is guaranteed from the foundation level, solving the industry challenge of controlling the jacking direction and elevation in traditional processes.

[0011] This process employs miniaturized construction equipment, direct excavation and casting of ground anchor beams, and on-site prefabrication of the frame, eliminating the need for large support formwork and construction equipment, making it suitable for confined pit working environments. The tunnel frame utilizes a reinforced system of disc-lock steel pipe supports, high-strength bamboo plywood, and square timber distribution beams. Combined with layered symmetrical casting, segmented molding, and water curing techniques, it effectively ensures the density and molding quality of the box structure. Attached Figure Description

[0012] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0014] Figure 2 This is a schematic diagram of the present invention.

[0015] Figure 3 This is a schematic diagram of the present invention. Detailed Implementation

[0016] The present invention will now be described in further detail with reference to the accompanying drawings.

[0017] The following description is intended to disclose the invention so that those skilled in the art can implement it. The preferred embodiments described below are merely examples, and other obvious modifications will be apparent to those skilled in the art. The basic principles of the invention defined in the following description can be used in other embodiments, modifications, improvements, equivalents, and other technical solutions that do not depart from the spirit and scope of the invention.

[0018] Those skilled in the art should understand that, in the disclosure of this invention, the terms "longitudinal," "lateral," "upper," "lower," "left," "right," "front," "rear," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or position based on the orientation or positional relationship shown in the accompanying drawings. They are merely simplified descriptions for the convenience of describing this invention and do not indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the above terms should not be construed as limitations on this invention.

[0019] It is understood that the term "a" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of an element can be one, while in another embodiment, the number of the element can be multiple, and the term "a" should not be understood as a limitation on the number.

[0020] Please see Figures 1-3 A method for constructing a shallow-buried passenger tunnel near an existing railway line by jacking, comprising the following construction steps: (1) Reinforcement of the operating line: Before the tunnel jacking construction, in order to prevent the collapse of the fill material on both sides of the frame and the top of the roadbed during the jacking process, bored piles are constructed on both sides of the tunnel. After the bored piles reach the design strength, the existing slope protection shoulder is removed, and the cap beam and cross brace are constructed in sequence. After the strength reaches the requirements, the middle section is excavated at intervals to construct the retaining wall. The length of a single section of the retaining wall is about 4m, that is, the retaining wall is completed in two stages. The longitudinal steel bars are connected by welding, and the lap length of the steel bars is reserved and the lap position is staggered. After the retaining wall construction is completed, the line is restored.

[0021] (2) Remove existing frame slope protection and shoulder: After the reinforcement of the operating line is completed, use a small breaker to remove the frame beam and shoulder within the jacking range, and excavate the soil inside the protective pile to the end of the existing passenger tunnel; the excavation is carried out in one excavation form, and professional line workers are arranged to observe, inspect and record the status of the railway line in real time throughout the construction process, and deal with line safety hazards in a timely manner.

[0022] (3) Construction of sliding plate and guide pier: First, a 20cm thick layer of crushed stone is compacted in the foundation, and then a 20cm thick C25 reinforced concrete sliding plate is poured; a 30cm×45cm ground anchor beam with the same length as the tunnel floor is set every 3m under the sliding plate, and the ground anchor beam is poured integrally with the sliding plate; the sliding plate uses a 2m×2m grid to embed Φ16 steel bar ends, and the leveling is done at points during concrete pouring to control the elevation of the sliding plate surface. After the concrete has initially set, a layer of M10 cement mortar with a thickness of ≤2cm is applied to the surface, and the top surface is coated with 1:3 machine oil talcum powder for lubrication. To reduce jacking friction, a plastic sheet isolation layer is laid before the precast tunnel to prevent the frame base plate from sticking to the slide plate and reduce starting resistance. The elevation deviation of the top surface of the slide plate is controlled to be +20 to -30 mm, the unevenness within a 2m length does not exceed 3 mm, and the overall flatness is ≤5 mm. During the construction of the slide plate, the ground anchor beam adopts the direct trenching and pouring process, without the need for additional support formwork. In order to control the accurate direction of the precast frame before it is jacked into the soil, concrete guide piers are poured on both sides of the slide plate, and a 10cm gap is reserved between the guide piers and the edge of the tunnel frame.

[0023] (4) Precast passenger tunnel frame: Using a total station for positioning, ensure that the center line of the tunnel frame, the center line of the bottom slab, and the center line of the jacking bridge coincide; precast reinforced concrete tunnel frame on the lubrication isolation layer of the working pit bottom slab, using steel formwork with wooden formwork, Φ16 tie rods with back ribs for reinforcement, the top slab uses 1.5cm high-strength bamboo plywood, the longitudinal 10×10cm square timber distribution beams are spaced 20cm apart with a span of 90cm, the transverse 10×10cm square timber distribution beams are spaced 90cm apart with a span of 90cm; the support uses Φ60 reinforced disc-type steel pipe support, with adjusting screws at the top of the steel pipes to adjust the height, and the top slab concrete can only be used after it reaches 100% of the design strength. Remove the supports; the culvert body is poured in two stages: the first stage is for the bottom slab and ribs, and the second stage is for the side walls and top slab; the concrete is poured in layers, symmetrically on both sides, with a height difference of no more than 50cm. After pouring, the culvert is covered with plastic sheeting and watered for curing; during the precast concrete pouring process, the wall formwork is reinforced with tie rods and double Φ48 steel pipe clamps. Before the formwork is installed, the formwork installation line must be determined to ensure the correct position of each structural part; when precasting the box body concrete, the soil above the box bottom is pressed into the box bottom at the front end to enhance its bearing capacity and prevent the bow slope from collapsing. The slope and length are determined according to the specific implementation and site conditions, for example, the slope is about 1% and the length is within 1m.

[0024] (5) Jacking construction: The tunnel frame is jacked in one go using the jacking method. The jacks continuously jack the culvert body into place in one go. Hydraulic jacks are arranged at equal intervals, and multiple jacks are configured for backup. Various specifications of jacking irons and jacking columns are set up. The jacking irons and jacking columns of force transmission equipment are set up with jacking irons (columns) with jacking strokes of 10cm, 20cm, 30cm, 60cm, 1m, 2m and 4m. When placing them, the axis of the jacking irons and jacking columns should be consistent with the jacking force axis, and the supporting surface should be in close contact. If deformation (such as arching, bending, etc.) is found during jacking, jacking should be stopped immediately and adjustments should be made. It should be flat, smooth and straight, and perpendicular to the horizontal irons or beams. Then, the equipment is debugged and graded test jacking is carried out to check whether the jacking equipment is normal, whether the jacking force is uniform, and whether there are any abnormalities in the back wall, sliding plate and box body. The box body and sliding plate should be separated. During the test jacking, the oil pump should be pressurized gradually. After each pressurization, it should be stabilized for 10 minutes. The cracks in the equipment, sliding plate, back wall and other parts should be checked. The oil pump pressure boosting magnitude and interval are shown below: a. Each relevant location and observation point should have designated personnel responsible for monitoring changes at all times; B. After starting the pump, 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 promptly. C. When the jack piston begins to extend and the jacking rod (jacking iron) is pressed down, the jacking should be stopped immediately. After checking the condition of each part, if there are no abnormalities, the pump can be restarted until the tank body starts.

[0025] d. After the trial jacking is completed, a comprehensive inspection should be carried out. If all parts are in good condition, the formal jacking operation can be carried out.

[0026] Once normal operation is achieved, formal jacking operations commence. After each jacking stroke, the jacks are returned to their original positions, matching jacking blocks are replaced, and crossbeams are installed. Simultaneously, the box girder's axis and elevation are monitored. If deviations occur, corrections are made by adjusting the jacking force on one side, activating the oil pumps in sections, wedging the jacking blocks on one side, and adding lateral supports to the front of the box girder. During the jacking process, the elevation of the tunnel floor markers is monitored daily. After each jacking stroke, the box girder's axis and elevation monitoring data are fully recorded. Specifically, during the jacking construction period, a slow-moving plan is implemented on the existing railway's seven tracks, with a speed limit of 45 km / h. Throughout the construction process, track deformation and settlement are monitored. If deformation and settlement exceed the limits, jacking operations must be immediately stopped, the track repaired, and traffic safety ensured.

[0027] a. Check the hydraulic system, jacking installation, and backing changes during each jacking operation.

[0028] b. After each stroke of the jack, the oil circuit should be switched and the piston of the jacking jack should be returned to its original position; the anti-jacking iron should be added according to the jacking length, the long jacking iron should be replaced, and the crossbeam should be installed.

[0029] c. The axis and elevation should be observed after each advance of the box culvert, and any deviations should be corrected in a timely manner.

[0030] d. Before jacking, adjust the axis and elevation in a timely manner, and do not make major adjustments to the box culvert on the roadbed.

[0031] e. Before the box culvert is jacked up, the original data of the mileage, axis and elevation of the original position of the box culvert are determined and recorded.

[0032] f. During the jacking process of the box culvert, the elevation of the observation markers set on the bottom plate of the box culvert is observed regularly every day.

[0033] g. During the jacking process, the axis and elevation of the jacking body should be observed and recorded in detail every time the jacking body advances a certain distance. If any deviation is found, the jacking commander should be notified in a timely manner to take measures to correct the deviation.

[0034] Specifically, to adjust the left or right deviation, increase or decrease the jacking force on one side: that is, open or close the valve on one side of the jack to increase or decrease the jacking force. If it deviates to the left, close and reduce the jacking force on the right side; if it deviates to the right, do the opposite.

[0035] 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.

[0036] Adjust using the backrest, top iron, and top post: When adding or replacing the top iron, depending on the size of the deviation, tighten one side of the top iron and loosen the other side or leave a gap of 1-3cm.

[0037] 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 of the box body, and the other end is supported on the excavation surface, which forces it to adjust to the side being pushed when it is pushed.

[0038] At the junction of the old and new tunnels, an Ω-shaped detachable waterstop is installed using the existing reserved waterstop groove and pre-embedded bolts, and the construction joint is filled with sealant to achieve first-level waterproofing. (6) Backfilling construction: After the jacking is completed, the back, guide pier, roadbed retaining wall and retaining pile cap beam should be removed, and then the gap between the jacking section and the existing railway roadbed should be backfilled with foamed lightweight soil.

[0039] Those skilled in the art should understand that the embodiments of the present invention described above and shown in the accompanying drawings are merely examples and do not limit the present invention. The objectives of the present invention have been fully and effectively achieved. The functions and structural principles of the present invention have been shown and explained in the embodiments, and any modifications or variations of the embodiments of the present invention may be made without departing from the stated principles.

Claims

1. A method for jacking construction of shallow-buried passenger tunnels near existing railway lines, characterized in that, The construction steps include the following: (1) Reinforcement of the operating line: bored piles are constructed on both sides of the tunnel. After the bored piles reach the design strength, the existing slope protection shoulder is removed and the cap beam and cross bracing are constructed in sequence. The retaining wall is constructed by excavating trenches in sections. The length of each section of the retaining wall is about 4m. The longitudinal steel bars are connected by welding. The lap length of the steel bars is reserved and the lap position is staggered. The line is restored after the retaining wall is completed. (2) Remove existing frame slope protection and shoulder: After the reinforcement of the operating line is completed, use a small breaker to remove the frame beam and shoulder within the jacking range, and excavate the soil inside the protective pile to the end of the existing passenger tunnel; throughout the construction process, arrange professional line workers to observe, inspect and record the status of the railway line in real time, and deal with line safety hazards in a timely manner. (3) Construction of sliding plate and guide pier: First, a 20cm thick layer of crushed stone is compacted in the foundation, and then a 20cm thick C25 reinforced concrete sliding plate is poured; a 30cm×45cm ground anchor beam with the same length as the tunnel floor is set every 3m under the sliding plate, and the ground anchor beam is poured integrally with the sliding plate; the sliding plate uses a 2m×2m grid to embed Φ16 steel bar heads, and the leveling is done at points during concrete pouring to control the elevation of the sliding plate surface. After the concrete has initially set, a ≤2cm thick M10 cement mortar is applied to the surface, and a 1:3 machine oil talcum powder lubricating layer is applied to the top surface. A plastic sheet isolation layer is laid in front of the precast tunnel; the elevation deviation of the top surface of the sliding plate is controlled to be +20~-30mm, the unevenness within a 2m length does not exceed 3mm, and the overall flatness is ≤5mm; concrete guide piers are poured on both sides of the sliding plate, and a 10cm gap is reserved between the guide piers and the edge of the tunnel frame. (4) Prefabricated passenger tunnel frame: The center line of the tunnel frame, the center line of the bottom plate, and the center line of the jacking bridge are aligned using a total station for positioning; steel formwork is used in combination with wooden formwork, and Φ16 tie rods are used in combination with back ribs for reinforcement. The top plate is made of 1.5cm high-strength bamboo plywood. The longitudinal 10×10cm square timber distribution beams are spaced at 20cm, and the transverse 10×10cm square timber distribution beams are spaced at 90cm; the support is made of Φ60 reinforced disc-type steel pipe support. Adjusting screws are set at the top of the steel pipes to adjust the height. The support can only be removed after the top plate concrete reaches 100% of the design strength. The frame culvert is poured in two stages: the first stage is the bottom slab and ribs, and the second stage is the side walls and top slab. The concrete is poured in layers and symmetrically on both sides, with a height difference of no more than 50cm. After pouring, the culvert is covered with plastic sheeting and watered for curing. When precasting the box body concrete, the front end of the box bottom has a bow slope to press the soil that is higher than the box bottom into the box bottom, which enhances its bearing capacity and prevents the head from collapsing. (5) Jacking construction: The tunnel frame is jacked up in one step using the jacking method; hydraulic jacks are arranged at equal intervals, and various specifications of jacking irons and jacking columns are set up. The axis of the jacking irons and jacking columns is consistent with the jacking force axis, and the support surface is in close contact; then the equipment is debugged and graded test jacking is carried out. After normal operation, the formal jacking operation is carried out. After each jacking stroke is completed, the jacks are returned to their original positions, the matching jacking irons are replaced and crossbeams are set up. The axis and elevation of the box body are observed simultaneously. If the box body deviates, the jacking force is increased or decreased on one side, the oil pump is turned on in sections, the jacking irons on one side are wedged, and the horizontal support is added to the front end of the box body for correction; at the junction of the new and old tunnels, the existing reserved waterstop grooves and pre-embedded bolts are used to install Ω-shaped detachable waterstops. The construction joints are filled with sealant to achieve first-level waterproofing. (6) Backfilling construction: After the jacking is completed, the back, guide pier, roadbed retaining wall and retaining pile cap beam should be removed, and then the gap between the jacking section and the existing railway roadbed should be backfilled with foamed lightweight soil.

2. The method for jacking construction of a shallow-buried passenger tunnel near an existing railway line according to claim 1, characterized in that: During the trial jacking operation, the jack piston begins to extend. After the jacking column (jacking iron) is pressed tight, the jacking should be stopped immediately. After checking the condition of each part, if there are no abnormalities, the pump can be restarted until the tank body starts.

3. The method for jacking construction of a shallow-buried passenger tunnel near an existing railway line according to claim 2, characterized in that: During the construction of the sliding plate, the ground anchor beam adopts a direct trenching and pouring process, which does not require additional support formwork.

4. The method for jacking construction of a shallow-buried passenger tunnel near an existing railway line according to claim 3, characterized in that: During the precast casting process of the tunnel, the wall formwork is reinforced with tie rods and double Φ48 steel pipe clamps.

5. The method for jacking construction of a shallow-buried passenger tunnel near an existing railway line according to claim 4, characterized in that: During the jacking process, the elevation of the tunnel floor observation markers is monitored daily, and the axis and elevation monitoring data of the box girder are fully recorded after each jacking section is completed.

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