A municipal under-railway pipe-roof construction method

Abstract

The present application relates to the technical field of municipal underground passage construction, and particularly relates to a municipal underground passage construction method for passing under a railway, steps S1, measuring and lofting are performed on both sides of the railway to determine the position of the foundation pit, step S2, a support column is constructed on the retaining pile on the side of the foundation pit close to the railway foundation, a support beam is arranged below the railway, step S3, grooving is simultaneously performed on the side of the foundation pit close to the railway on both sides, after the grooving, the positioning beam and the guide beam are poured and positioned by taking the inner wall of the soil groove as a formwork, step S4, after the excavation reaches the corresponding pipe cover elevation above the to-be-excavated underground passage, a jacking device is installed, and the pipe cover is jacked after a insertion hole is drilled on the retaining pile; step S5, the two sides of the steel sheet pile are synchronously excavated by the excavation equipment, and the pipe cover on both sides and below the to-be-excavated underground passage is jacked according to the excavation progress; the support column and the support beam are arranged on both sides of the railway, forming an active support system for the railway foundation, and effectively controlling the settlement and deformation of the railway foundation.

Description

Technical Field

[0001] This invention belongs to the technical field of municipal underground passage construction, specifically relating to a method for constructing a municipal railway underpass pipe jacking. Background Technology

[0002] With the rapid construction of urban municipal infrastructure, a large number of municipal underground passages, integrated utility tunnels, and other projects need to pass under existing operating railway lines. Railway operations have extremely high standards for controlling roadbed settlement, track deformation, and soil disturbance, and conventional open-cut and tunnel boring machine construction techniques have significant limitations in scenarios involving railway underpasses.

[0003] Pipe jacking, a trenchless or shallow-buried tunneling construction technique, forms a pipe jacking structure by inserting steel pipes around the area to be excavated. This effectively controls ground deformation and ensures the stability of the railway line above. However, existing pipe jacking construction techniques struggle to guarantee the stability of the railway subgrade and rails during foundation pit excavation, leading to issues such as subgrade settlement and lateral displacement. Furthermore, the coordinated construction process of sheet pile support and pipe jacking is imperfect, resulting in poor synchronization of soil excavation on both sides and the generation of uneven earth pressure. This can cause minor settlement or displacement of the railway subgrade, affecting railway operational safety.

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

[0005] The purpose of this invention is to overcome the shortcomings of the prior art. This invention provides a method for constructing a municipal underpass railway pipe curtain.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A method for constructing a municipal railway underpass pipe jacking system includes the following steps: Step S1: Determine the location of the foundation pit by surveying and setting out on both sides of the railway, and then simultaneously construct the retaining piles around the foundation pit on both sides of the railway. Step S2: Construct support columns on the retaining piles on the side of the foundation pit closest to the railway foundation, install support beams under the rails, and fix the two ends of the support beams to the support columns on both sides of the foundation pit. Step S3: Simultaneously excavate trenches on the side of the foundation pits closest to the railway on both sides. After excavation, use the inner wall of the trench as a template to cast positioning beams. The two ends of the positioning beams are fixed together with the retaining piles on both sides of the foundation pit. A trench is dug in the middle of the receiving pit and the launching pit. After the trench is dug, the inner wall of the trench is used as a template to pour the guide beam. The two ends of the guide beam are fixed to the retaining piles on both sides of the pit. Step S4: Using the guide beam as a guide, steel sheet piles are driven. After partially excavating the foundation pit between the steel sheet piles and the railway to the corresponding pipe curtain elevation above the underground passage to be excavated, the jacking device is installed. After excavating to the corresponding pipe curtain elevation above the underground passage to be excavated, the jacking device is installed, and the pipe curtain is jacked in after drilling holes in the retaining piles. Step S5: Simultaneous excavation is carried out on both sides of the steel sheet pile using excavation equipment, and the pipe curtain on both sides and below the underground passage to be excavated is jacked up according to the excavation progress. Step S6: After the pipe jacking construction is completed, pull out the sheet piles, excavate the soil on both sides of the sheet piles to the base of the foundation pit, and pour concrete to harden the bottom of the foundation pit.

[0007] Preferably, the retaining pile is a mixing pile. Before the mixing pile at the corresponding support column point is initially set, a rotary drilling machine is used to drill a hole at the upper end of the mixing pile. A steel cage is placed in the rotary drilling hole, and the lower end of the support column extends into the rotary drilling hole and is connected to the corresponding steel cage. The support column and the mixing pile are solidified into one by concrete pouring. Multiple support columns are equidistantly distributed along the side of the railway corresponding to the foundation pit.

[0008] Preferably, the bottom of the trench corresponding to the positioning beam is provided with a steel mold corresponding to the pipe curtain, and the lower surface of the steel mold is provided with multiple arc-shaped grooves that correspond to the pipe curtain above the underground passage to be excavated.

[0009] Preferably, after the soil layer is excavated to the steel formwork, a positioning ring corresponding to the pipe curtain is welded below the arc-shaped groove.

[0010] Preferably, the guide beam has a strip-shaped hole extending along its length in the middle, and the width of the strip-shaped hole is adapted to the thickness of the steel sheet pile. The bottom of the sheet pile is inserted below the elevation of the foundation pit.

[0011] Preferably, a slope protection steel plate is provided on the slope of the railway foundation, the lower edge of the slope protection steel plate is fixed to the upper edge of the retaining piles of the foundation pit, and a crossbar supported by a support column is provided in the middle and upper part of the slope protection steel plate.

[0012] Preferably, the support column is an I-beam, and diagonal bracing is provided between the upper middle part of the support column and the positioning beam.

[0013] Preferably, in step S5, the excavation height of the soil on the side of the sheet pile away from the railway is higher than that on the side of the sheet pile close to the railway, and the height difference between the two is not less than 1 meter.

[0014] Preferably, in step S3, a capping beam is provided on the foundation pit at the upper end of the retaining piles, and the supporting column, positioning beam, guide beam and capping beam are cast together as one piece.

[0015] Beneficial effects: The installation of support columns and beams on both sides of the railway forms an active support system for the railway foundation, effectively controlling the settlement and deformation of the railway subgrade; the installation of sheet piles isolates the railway foundation from the excavation area, and the construction method of simultaneous excavation on both sides is adopted. The soil on both sides of the sheet piles retains an excavation height difference of not less than 1 meter, avoiding direct disturbance to the railway subgrade caused by close-range excavation. At the same time, in conjunction with the steel plate protection of the railway foundation slope, the railway foundation structure is protected in all aspects, achieving low-disturbance construction.

[0016] The support columns and mixing piles adopt a construction process of pre-setting rotary excavation and rebar installation followed by concrete consolidation. Combined with diagonal bracing for auxiliary reinforcement, this significantly improves the load-bearing capacity and connection stability of the support structure. The support beams spanning under the railway can effectively offset vertical settlement stress, ensuring from multiple dimensions that the railway subgrade will not experience excessive deformation. Attached Figure Description

[0017] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. Wherein: Figure 1 This is a schematic diagram of the pipe jacking construction above the underground passage to be constructed in a specific embodiment of the present invention; Figure 2 This is a schematic diagram of the pipe curtain construction under the underground passage to be constructed in a specific embodiment of the present invention.

[0018] In the diagram: 1. Railway foundation; 2. Crown beam; 3. Guide beam; 4. Positioning beam; 5. Sheet pile; 6. Jacking device; 7. Pipe curtain; 8. Retaining pile; 9. Slope protection steel plate; 10. Support beam; 11. Support column. Detailed Implementation

[0019] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.

[0020] In the description of this invention, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," and "bottom," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and do not require the invention to be constructed and operated in a specific orientation; therefore, they should not be construed as limitations on the invention. The terms "connected" and "linked" used in this invention should be interpreted broadly. For example, they can refer to a fixed connection or a detachable connection; they can refer to a direct connection or an indirect connection through intermediate components. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0021] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other.

[0022] like Figure 1 and Figure 2 As shown, a method for constructing a municipal railway underpass pipe jacking system includes the following steps: Step S1: Based on the design drawings and the on-site railway line and subgrade topographic parameters, conduct precise surveying and layout on both sides of the railway. The surveying and layout should be based on the design drawings and on-site control points, using surveying equipment such as total stations and GPS to accurately determine the plane position and elevation of the foundation pit. Mark the boundaries and construction points of the starting and receiving pits, and determine the excavation range and the construction location of the retaining structure. After completing the layout and verification, simultaneously carry out the construction of retaining piles 8 on both sides of the railway. The construction progress on both sides should be consistent to ensure the balance of foundation pit construction on both sides and avoid adverse effects on the railway foundation 1 caused by unbalanced ground stress due to unilateral construction. The retaining piles 8 will construct a foundation retaining system for subsequent foundation pit excavation and support structure construction, preventing soil collapse and water seepage on the outside of the foundation pit.

[0023] In step S2, support columns 11 are constructed at fixed points on the retaining piles 8 on the side of the foundation pit closest to the railway foundation 1. Multiple support columns 11 are evenly distributed at equal intervals along the side of the foundation pit corresponding to the railway to ensure uniform support stress. At the same time, support beams 10 are installed under the railway rails, running transversely through the subgrade. The two ends of the support beams 10 are fixed to the tops of the support columns 11 on both sides of the railway foundation pit. The support columns 11 and the support beams 10 form a rigid support frame spanning under the railway. The support beams 10 span under the railway rails, connecting the support columns 11 on both sides into an integrated force-bearing system, forming active support for the railway foundation 1, effectively transferring and dispersing the railway load, and suppressing the settlement and lateral deformation of the railway subgrade.

[0024] In step S3, trenching is carried out simultaneously on the side of the foundation pit closest to the railway on both sides. After trenching, the flat inner wall of the trench is used as a formwork for casting, and positioning beams 4 are cast on site. The two ends of positioning beams 4 are rigidly fixed to the retaining piles 8 on both sides of the foundation pit to form an inner limiting support structure for the foundation pit. At the same time, trenching is carried out simultaneously in the middle of the receiving pit and the launching pit of the foundation pit. Similarly, the inner wall of the trench is used as a formwork for casting guide beams 3. The two ends of guide beams 3 are fixed to the retaining piles 8 on both sides of the foundation pit. Guide beams 3 serve as the guiding reference structure for the subsequent driving of sheet piles 5 and the jacking of pipe curtain 7.

[0025] Positioning beam 4 is installed along the side of the foundation pit closest to the railway, providing a benchmark for the elevation and horizontal position of the pipe jacking 7; guide beam 3 is installed in the middle of the receiving pit and the launching pit, providing guidance for the driving of the sheet piles 5. The inner wall of the earthen trench is used as a formwork for pouring, eliminating the traditional formwork erection process and reducing construction costs. At the same time, positioning beam 4 and guide beam 3 are in close contact with the surrounding soil, enhancing the integrity and stability of the structure.

[0026] In step S4, using the formed guide beam 3 as a precise guiding benchmark, the sheet piles 5 are continuously driven along the guide beam 3. The driving of the sheet piles 5 is guided by the guide beam 3, ensuring the construction accuracy of the sheet piles 5. The bottom of the sheet piles 5 extends below the foundation pit elevation, improving the overall support stability of the sheet piles 5. After the sheet pile support system is formed, excavation equipment is used to excavate the foundation pit soil between the sheet piles 5 and the railway in layers and sections, strictly controlling the excavation rate and excavation thickness to avoid over-excavation and disturbance to the railway subgrade.

[0027] Once the excavation of the foundation pit reaches the design elevation of the pipe curtain 7 above the underground passage to be excavated, the excavation is stopped and the working surface is leveled. The jacking device 6 is then installed. The jacking device 6 can be a hydraulic pipe jacking machine, jacks, or other equipment.

[0028] Holes are drilled in the protective wall formed by the retaining piles 8 on the side corresponding to the railway. The holes are adapted to the outer diameter of the pipe curtain 7 and the points involved. The initial jacking construction of the pipe curtain 7 above the underground passage is completed by the jacking device 6. The holes play an initial guiding role for the pipe curtain 7.

[0029] In step S5, after the sheet piles 5 are formed, symmetrical and synchronous excavation is carried out on both sides of the sheet piles 5. Synchronous excavation maintains a relative balance of earth pressure on both sides of the sheet piles 5, preventing tilting or deformation due to excessive earth pressure difference on one side. This ensures the balance of earth pressure on both sides and guarantees the support effect of the sheet piles 5 on the railway foundation 1. The excavation height of the soil on the side of the sheet piles 5 away from the railway is higher than that on the side closer to the railway, with a height difference of no less than 1 meter. The excavation height difference is strictly controlled during construction. This stepped excavation method forms an unloading platform on the side of the sheet piles 5 away from the railway, reducing the active earth pressure acting on the sheet piles 5 while increasing the passive earth pressure on the side closer to the railway. This helps maintain the stability of the sheet piles 5 and further ensures the safety of the railway foundation 1.

[0030] According to the progress of the layered excavation of the soil, the jacking operation rhythm is dynamically matched, and the jacking construction of the pipe curtain 7 on both sides and below the underground passage to be excavated is completed in the order of "first the two sides, then the bottom", so that the multiple sections of pipe curtain 7 are spliced ​​together to form a complete closed pipe curtain 7 support system.

[0031] Step S6: After the entire pipe jacking structure 7 is completed and the support system is stable, the sheet piles 5 are removed symmetrically to avoid sudden changes in soil stress caused by one-time removal. After the sheet piles 5 are removed, the remaining soil on both sides of the sheet piles 5 is excavated and leveled to the designed foundation elevation of the pit. Finally, concrete is poured on the bottom of the pit to complete the foundation hardening treatment, forming a flat and stable foundation for the underground passage construction, creating conditions for the subsequent construction of the main structure of the underground passage.

[0032] In an optional embodiment, the retaining piles 8 are mixed-mixing piles, with multiple mixed-mixing piles arranged linearly along the edge of the foundation pit, and adjacent mixed-mixing piles interlocking to form a retaining wall. The support columns 11 are made of I-beams. Before the mixed-mixing piles at the corresponding support column 11 points initially set, a rotary drilling machine is used to precisely drill holes at the upper end of the mixed-mixing piles. A precast steel cage is then tied and placed inside the rotary drilling hole. Subsequently, the lower end of the I-beam support column 11 is inserted into the rotary drilling hole and precisely connected and fixed with the steel cage. Finally, concrete is poured on-site to completely solidify the support column 11 and the mixed-mixing piles into one unit. The rotary drilling creates an embedded section in the mixed-mixing piles, making the support column 11 and the retaining piles 8 form an integral load-bearing structure. This significantly improves the connection stiffness and overall bearing capacity of the support column 11 and the retaining piles 8, enhances the stiffness and stability of the support system, and simplifies the construction process and reduces construction steps.

[0033] Multiple support columns 11 are provided, and the multiple support columns 11 are distributed at equal intervals along the side of the railway corresponding to the foundation pit. The support columns 11 on both sides of the railway correspond one to one, so as to support the support beam 10.

[0034] In an optional embodiment, a steel mold matching the shape of the pipe curtain 7 is pre-embedded at the bottom of the trench corresponding to the positioning beam 4. The lower surface of the steel mold is provided with an arc-shaped groove corresponding to the pipe curtain 7 above the underground passage to be excavated. Multiple arc-shaped grooves are respectively matched with each section of the pipe curtain 7 above the underground passage to be excavated. The shape of the arc-shaped groove matches the outer contour of the pipe curtain 7, providing precise spatial guidance for the jacking of the pipe curtain 7, effectively controlling the horizontal and vertical deviations of the jacking of the pipe curtain 7, and improving the regularity of the pipe curtain 7 formation.

[0035] After the soil layer is excavated to the bottom elevation of the steel formwork, a positioning ring is welded to the bottom of the arc-shaped groove of the steel formwork. The inner diameter of the positioning ring is matched with the outer diameter of the pipe curtain 7. The positioning ring makes the pipe curtain 7 circumferentially constrained during the jacking process, further preventing the pipe curtain 7 from deviating or tilting during the jacking process, and ensuring that the jacking direction of the pipe curtain 7 is consistent with the design axis.

[0036] Furthermore, a through-hole is formed along the length of the guide beam 3. The width of the through-hole is adapted to the thickness of the sheet pile 5. The sheet pile 5 is driven into the soil from top to bottom through the through-hole. The through-hole provides a precise guiding channel for the driving of the sheet pile 5. The top of the sheet pile 5 is fixed and limited through the through-hole, which effectively improves the verticality and overall stability of the sheet pile 5 and prevents it from deforming or tilting under stress. At the same time, the bottom of the sheet pile 5 is inserted into the undisturbed soil layer below the foundation pit elevation, using the constraint force of the deep soil to enhance the support effect.

[0037] In step S3, a capping beam 2 is installed on the foundation pit at the top of the retaining piles 8. The capping beam 2 is cast uniformly, and the supporting column 11, positioning beam 4, and guide beam 3 are cast together with the capping beam 2. The setting of the capping beam 2 connects the top of the retaining piles 8 into a whole, which improves the overall rigidity of the retaining structure. The supporting column 11, positioning beam 4, guide beam 3 and capping beam 2 form a complete load-bearing frame system. The components work together to jointly bear and transfer the load, improve the overall rigidity of the entire foundation pit support and pipe curtain 7 construction system, effectively resist the lateral pressure of the soil, and improve the overall stability of the foundation pit retaining structure.

[0038] In another alternative embodiment, protective steel plates are installed on the slope of the railway foundation 1, and multiple protective steel plates are distributed in parallel along the railway direction, thereby forming a closed slope protection structure on the outer wall of the railway foundation 1.

[0039] The lower edge of the slope protection steel plate 9 is fixedly overlapped with the upper edge of the foundation pit retaining pile 8 to achieve bottom fixation. The middle and upper part of the slope protection steel plate 9 is equipped with crossbars, and the two ends of the crossbars are supported and fixed on the two side support columns 11. Through the combination structure of the slope protection steel plate 9 and the crossbars, the slope protection steel plate 9 becomes a component of the support system, thereby protecting the slope soil of the railway foundation 1, preventing the slope soil from collapsing and water and soil erosion, and avoiding the potential hazards of hollowing and settlement of the railway foundation 1.

[0040] Preferably, the support column 11 is an I-beam, and an inclined bracing structure is installed at the upper part of the support column 11 between it and the positioning beam 4. The two ends of the inclined bracing are rigidly connected to the support column 11 and the positioning beam 4 respectively. The inclined bracing forms a triangular stable force-bearing structure, which shares the vertical load and horizontal lateral pressure of the support column 11, thereby improving the overturning resistance and deformation resistance of the overall support system.

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

Claims

1. A method for constructing a municipal railway underpass pipe jacking system, characterized in that, Includes the following steps: Step S1: Determine the location of the foundation pit by surveying and setting out on both sides of the railway, and then simultaneously construct the retaining piles around the foundation pit on both sides of the railway. Step S2: Construct support columns on the retaining piles on the side of the foundation pit closest to the railway foundation, install support beams under the rails, and fix the two ends of the support beams to the support columns on both sides of the foundation pit. Step S3: Simultaneously excavate trenches on the side of the foundation pits closest to the railway on both sides. After excavation, use the inner wall of the trench as a template to cast positioning beams. The two ends of the positioning beams are fixed together with the retaining piles on both sides of the foundation pit. A trench is dug in the middle of the receiving pit and the launching pit. After the trench is dug, the inner wall of the trench is used as a template to pour the guide beam. The two ends of the guide beam are fixed to the retaining piles on both sides of the pit. Step S4: Using the guide beam as a guide, steel sheet piles are driven. After partially excavating the foundation pit between the steel sheet piles and the railway to the corresponding pipe curtain elevation above the underground passage to be excavated, the jacking device is installed. After excavating to the corresponding pipe curtain elevation above the underground passage to be excavated, the jacking device is installed, and the pipe curtain is jacked in after drilling holes in the retaining piles. Step S5: Simultaneous excavation is carried out on both sides of the steel sheet pile using excavation equipment, and the pipe curtain on both sides and below the underground passage to be excavated is jacked up according to the excavation progress. Step S6: After the pipe jacking construction is completed, pull out the sheet piles, excavate the soil on both sides of the sheet piles to the base of the foundation pit, and pour concrete to harden the bottom of the foundation pit.

2. The method for constructing a municipal railway underpass pipe jacking according to claim 1, characterized in that, The retaining piles are mixing piles. Before the mixing piles at the corresponding support column points are initially set, the upper end of the mixing piles is drilled into a hole using a rotary drilling machine. A steel cage is placed in the rotary drilling hole, and the lower end of the support column extends into the rotary drilling hole and is connected to the corresponding steel cage. The support column and the mixing pile are then solidified into one unit by concrete pouring. Multiple support columns are equidistantly distributed along the side of the railway corresponding to the foundation pit.

3. The method for constructing a municipal railway underpass pipe jacking according to claim 1, characterized in that, The bottom of the trench corresponding to the positioning beam is equipped with a steel mold corresponding to the pipe curtain. The lower surface of the steel mold is equipped with multiple arc-shaped grooves that correspond to the pipe curtain above the underground passage to be excavated.

4. The method for constructing a municipal railway underpass pipe jacking according to claim 3, characterized in that, After the soil layer is excavated to the steel formwork, the positioning rings corresponding to the pipe curtain are welded below the arc-shaped groove.

5. The method for constructing a municipal railway underpass pipe jacking according to claim 1, characterized in that, The guide beam has a strip-shaped hole extending along its length in the middle, and the width of the strip-shaped hole is adapted to the thickness of the steel sheet pile. The bottom of the sheet pile is inserted below the elevation of the foundation pit.

6. The method for constructing a municipal railway underpass pipe jacking according to claim 1, characterized in that, A slope protection steel plate is installed on the slope of the railway foundation. The lower edge of the slope protection steel plate is fixed to the upper edge of the retaining piles of the foundation pit. A crossbar supporting the support column is installed in the middle and upper part of the slope protection steel plate.

7. The method for constructing a municipal railway underpass pipe jacking according to claim 1, characterized in that, The support column is made of I-beams, and diagonal bracing is provided between the upper middle part of the support column and the positioning beam.

8. The method for constructing a municipal railway underpass pipe jacking according to claim 1, characterized in that, In step S5, the excavation height of the soil on the side of the sheet pile away from the railway is higher than that on the side of the sheet pile close to the railway, and the height difference between the two is not less than 1 meter.

9. The method for constructing a municipal railway underpass pipe jacking according to claim 1, characterized in that, In step S3, a capping beam is installed on the foundation pit at the top of the retaining piles, and the supporting columns, positioning beams, guide beams and capping beams are cast together as one unit.

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