Large-diameter shield tunnel assembled track understructure and construction method thereof

Abstract

The application provides a large-diameter shield tunnel assembled track-underrun structure and a construction method thereof. The track-underrun structure comprises a middle prefabricated box culvert, a side culvert prefabricated cover plate, a side culvert arc-shaped side plate and a tunnel bottom backfill layer. The middle prefabricated box culvert is connected with the side culvert arc-shaped side plate through a pre-embedded steel bar adapter. The side culvert prefabricated cover plate is connected with the middle prefabricated box culvert and the side culvert arc-shaped side plate through bolts and limiting pins. The track-underrun structure is longitudinally connected as a whole through a middle prefabricated box longitudinal connection bolt and a cast-in-place side culvert arc-shaped side plate. The gap between the lower surface of the tunnel bottom backfill prefabricated block and the inner arc surface of the segment is filled with grouting material. The track-underrun structure adopts an assembled high-efficiency construction technology, can realize synchronous construction with shield tunneling and segment assembly, ensures the overall longitudinal stiffness and stability of the track-underrun structure, has the advantages of high mechanization degree and construction efficiency, controllable construction quality, improved tunnel construction operation environment, reduced construction safety risk and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of shield tunnel track under structure construction, and particularly relates to a large-diameter shield tunnel assembled track under structure and a construction method thereof. BACKGROUND

[0002] With the development of traffic construction and overall urban planning, influenced by factors such as environmental conditions along the line and ground traffic, the railway and the like gradually become a trend to adopt a tunnel construction method when entering the city or crossing a large river. Shield tunnel construction technology has the advantages of small influence on the surrounding environment, high degree of mechanization, controllable construction period, and is widely used in urban area and underwater tunnel engineering construction.

[0003] The internal track under structure of large-diameter shield tunnels of railways and the like at home and abroad mainly adopts the following three structure schemes according to the construction method: the first is a whole cast-in-place structure; the second is a prefabricated middle box culvert + two sides cast-in-place slab structure; and the third is a whole prefabricated structure. The first structure is gradually eliminated by the market due to low degree of mechanization, difficult construction organization and quality control; the second structure locally adopts prefabricated assembly technology, which improves the construction technical level and efficiency to a certain extent, and is the most commonly used structure form at present; the third structure has problems such as high requirement for tooling equipment and poor longitudinal integrity of the track under structure, and is generally suitable for tunnels with relatively small cross section and good geological conditions.

[0004] In recent years, there are more and more long and large railway tunnel projects crossing rivers and seas, and the track under structure construction has a great influence on the construction period of the project, and the railway tunnel has high requirements for the longitudinal stability of the track under structure. Therefore, it is an urgent problem for those skilled in the art to provide a large-diameter shield tunnel track under structure with high degree of mechanization, fast construction and no influence on the overall stability and a construction method thereof. SUMMARY

[0005] Therefore, the present application aims to provide a large-diameter shield tunnel assembled track under structure with high degree of mechanization, fast construction and good overall structure integrity and a construction method thereof.

[0006] To solve the above technical problems, the technical scheme adopted by the present application is:

[0007] The utility model provides a large diameter shield tunnel assembly type track under structure, including intermediate prefabricated box culvert, side culvert prefabricated cover plate, side culvert arc side plate and tunnel bottom backfill layer, and the bracket is equipped with on the both sides wall top end outside of intermediate prefabricated box culvert, the box culvert bottom arc plate of intermediate prefabricated box culvert is circular arc, and the inside surface of shield segment is concentric circle and reserves 50mm thick gap, hollow backfill hole is seted up on the box culvert bottom arc plate, the side culvert arc side plate is cast in situ and is constructed respectively on the both sides of intermediate prefabricated box culvert, the side culvert prefabricated cover plate is overlapped and installed on intermediate prefabricated box culvert and side culvert arc side plate, the tunnel bottom backfill layer is arranged in the hollow backfill hole of intermediate prefabricated box culvert, and fills the reserved gap between box culvert bottom arc plate and the inside surface of shield segment.

[0008] Further, the intermediate prefabricated box culvert is multiple and is arranged side by side, and four groups of inclined straight bolts are used to connect between two adjacent intermediate prefabricated box culverts.

[0009] Further, the circular arc plate connecting part of the box culvert bottom arc plate and the side culvert arc side plate of the intermediate prefabricated box culvert is connected through a pre-embedded steel bar adapter and connecting steel bars, and the pre-embedded steel bar adapter is arranged in the box culvert bottom arc plate.

[0010] Further, the intermediate prefabricated box culvert is factory prefabricated and assembled in the tunnel, and adopts a mouth-shaped structure.

[0011] Further, the four corners of the lower surface of the box culvert bottom arc plate are provided with arc-shaped supports, and the thickness of the gap reserved between the box culvert bottom arc plate and the inside surface of the shield segment and the height of the arc-shaped supports are the same.

[0012] Further, the side culvert arc side plate comprises a circular arc plate concentric with the inside surface of the shield segment and a side culvert prefabricated cover plate support bracket arranged at the top end of the circular arc plate.

[0013] Further, the side culvert prefabricated cover plate is as same as the shield segment, which is produced by factory prefabrication and assembled in the tunnel. Two bolt holes are reserved on the side culvert prefabricated cover plate lapped on one side of the middle prefabricated box culvert, two round limiting pin holes are reserved on the side culvert prefabricated cover plate lapped on one side of the side culvert arc side plate, a vertical bolt sleeve is arranged on the corbel of the middle prefabricated box culvert opposite to the bolt hole, and a limiting groove is arranged on the side culvert prefabricated cover plate support corbel of the side culvert arc side plate opposite to the limiting pin hole. After the side culvert prefabricated cover plate is installed on site, the side culvert prefabricated cover plate is fixed with the middle prefabricated box culvert and the side culvert arc side plate through the cooperation of the vertical straight bolt with the bolt hole and the vertical bolt sleeve, and the cooperation of the limiting pin with the limiting pin hole and the limiting groove.

[0014] Further, the limiting pin hole and the limiting groove are filled with micro-expansion grouting material.

[0015] Further, the size of the middle prefabricated box culvert and the side culvert prefabricated cover plate is matched with the shield segment ring. Considering the prefabricated structure assembly error, curve fitting and other factors, the length of the middle prefabricated box culvert and the side culvert prefabricated cover plate in the line direction is 20mm smaller than the width of the segment ring, and no wedge amount is arranged, and the linear fitting is realized by adjusting the gap at the assembly joint.

[0016] A large-diameter shield tunnel assembled track structure construction method, comprising the following steps:

[0017] S1: prefabricate and produce the middle prefabricated box culvert and the side culvert prefabricated cover plate in the factory by using high-precision molds. The longitudinal length of the middle prefabricated box culvert and the side culvert prefabricated cover plate is consistent with or smaller than the width of the shield segment ring. The middle prefabricated box culvert top plate and corbel and the side culvert prefabricated cover plate top surface are provided with rough surfaces with a concave-convex depth of not less than 4mm.

[0018] S2: prefabricate and process the side culvert arc side plate cage type steel reinforcement cage in the factory. The steel reinforcement cage is matched with the cast-in-place concrete form along the longitudinal length of 4-5 segment ring widths.

[0019] S3: during the shield tunneling process, the middle prefabricated box culvert is assembled synchronously after the shield segment. The middle prefabricated box culvert is installed in matching with the segment ring width. The ring-wise assembly joint of the middle prefabricated box culvert is arranged in alignment with the shield segment ring joint. The ring-wise assembly joint is connected by inclined bolts.

[0020] S4: according to the shield machine equipment configuration and the tunnel on-site construction conditions, after the middle prefabricated box culvert is assembled forwardly to a distance not less than the length of the prefabricated steel reinforcement cage of the side culvert arc side plate, the side culvert arc side plate steel reinforcement cage is installed, the connecting steel bars at the connecting part between the middle prefabricated box culvert and the side culvert arc side plate are made, and the side culvert arc side plate concrete is poured.

[0021] S5: After the side culvert arc-shaped side plate concrete reaches the strength, the side culvert prefabricated cover plate is installed on the middle prefabricated box culvert, the side culvert arc-shaped side plate support bracket by lap joint method using grouting method, and is connected with the middle prefabricated box culvert and the side culvert arc-shaped side plate through connecting bolts and limiting pins.

[0022] S6: The gap between the middle prefabricated box culvert bottom arc plate and the shield segment contact surface is filled with filling material by using the hollow part in the center of the middle prefabricated box culvert bottom arc plate, a tunnel bottom backfill layer is formed, and a steel mesh is placed in the tunnel bottom backfill layer.

[0023] S7: The above steps S3-S6 are repeated to complete the installation of the tunnel assembly type track structure, and the leveling layer is cast in place. The top surface of the track structure is cleaned before the leveling layer concrete is poured, and a steel mesh is arranged in the leveling layer to improve the integrity of the track structure.

[0024] The advantages and positive effects of the present application are: compared with the prior art, the large-diameter shield tunnel assembly type track structure and the construction method thereof disclosed by the present application comprehensively use factory prefabrication processing, assembly construction technology and concrete convenient pouring process, realize synchronous construction of the track structure and shield tunneling, effectively improve the site construction efficiency of the track structure, ensure the integrity and longitudinal stiffness of the assembly type track structure, improve the construction quality of the track structure, improve the tunnel construction operation environment, and reduce the construction safety risk. BRIEF DESCRIPTION OF DRAWINGS

[0025] The drawings that form a part of the present application serve to provide a further understanding of the present application, and the schematic embodiments of the present application and the description thereof serve to explain the present application, and do not constitute an improper limitation on the present application. In the drawings:

[0026] Figure 1 is a perspective view of the large-diameter shield tunnel assembly type track structure of the present application;

[0027] Figure 2 is a perspective view of the middle prefabricated box culvert of the large-diameter shield tunnel assembly type track structure of the present application;

[0028] Figure 3 is a perspective view of the side culvert prefabricated cover plate in the large-diameter shield tunnel assembly type track structure of the present application;

[0029] Figure 4 is a connection structure diagram of the side culvert prefabricated cover plate in the large-diameter shield tunnel assembly type track structure of the present application;

[0030] Figure 5 is a perspective view of the side culvert arc-shaped side plate in the large-diameter shield tunnel assembly type track structure of the present application;

[0031] Figure 6It is the prefabricated reinforcement cage elevation view of the side culvert arc side plate in the large-diameter shield tunnel assembled track under structure of the application;

[0032] Figure 7 It is the installation plan of the large-diameter shield tunnel assembled track under structure of the application;

[0033] Figure 8 It is the connection structure diagram of the side culvert arc side plate and the middle prefabricated box culvert in the large-diameter shield tunnel assembled track under structure of the application;

[0034] Figure 9 It is the schematic diagram of the assembled track under structure formed together with the backfill leveling layer of the application.

[0035] Explanation of reference signs:

[0036] 1: shield segment 2: middle prefabricated box culvert

[0037] 3: side culvert prefabricated cover plate 4: side culvert arc side plate

[0038] 4-1: circular arc plate 4-2: side culvert prefabricated cover plate support bracket

[0039] 5: inclined straight bolt 6: vertical straight bolt

[0040] 7: limiting pin 8: connecting steel bar

[0041] 9: steel bar adapter 10: bracket

[0042] 11: box culvert bottom arc plate 12: arc-shaped support

[0043] 13: bolt hole 14: limiting pin hole

[0044] 15: limiting groove 16: vertical bolt sleeve

[0045] 17: micro-expansion grouting material 18: steel reinforcement cage

[0046] 19: hollow backfill hole 20: tunnel bottom backfill layer

[0047] 21: leveling layer DETAILED DESCRIPTION

[0048] It should be noted that the embodiments in the application and the features in the embodiments can be combined with each other without conflict.

[0049] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0050] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0051] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0052] like Figure 1 As shown, a prefabricated track substructure for a large-diameter shield tunnel includes a prefabricated intermediate box culvert 2 and a prefabricated side culvert cover plate 3 prefabricated in a high-precision steel mold, a cast-in-place curved side culvert plate 4, and a tunnel bottom backfill layer 20.

[0053] like Figures 1-2 As shown, the intermediate precast box culvert 2, like the shield tunnel segment 1, is prefabricated in a factory and assembled in the tunnel. It adopts a U-shaped structure. The outer side of the top of the side wall of the intermediate precast box culvert 2 is provided with corbels 10. The bottom arc plate 11 of the intermediate precast box culvert 2 is arc-shaped, concentric with the inner surface of the shield tunnel segment 1, and a 50mm thick gap is reserved. Four arc-shaped supports 12 are provided at the corner of the lower surface of the bottom arc plate 11, with dimensions of 500mm (length) × 300mm (width) × 50mm (height).

[0054] like Figures 5-6As shown, the culvert arc-shaped side plate 4 includes an arc-shaped plate 4-1 concentric with the inner surface of the shield tunnel segment and a precast culvert cover plate support bracket 4-2 set at the top of the arc-shaped plate 4-1. The culvert arc-shaped side plate 4 is constructed using the formwork method, and the internal steel reinforcement skeleton 18 adopts a precast cage structure in the factory, avoiding on-site steel reinforcement binding operations and improving construction efficiency.

[0055] like Figures 3-4 As shown, the precast culvert cover plate 3, like the shield tunnel segment 1, is prefabricated in a factory and assembled inside the tunnel, overlapping and installed on the intermediate precast box culvert 2 and the arc-shaped side plate 4 of the culvert. Two bolt holes 13 are reserved on one side of the culvert cover plate 3 overlapping the intermediate precast box culvert 2, and two circular limiting pin holes 14 are reserved on one side of the culvert arc-shaped side plate 4. Vertical bolt sleeves 16 are provided on the corbel 10 of the intermediate precast box culvert 2 opposite to the bolt holes 13. Limiting grooves 15 are provided on the supporting corbel 4-2 of the culvert cover plate of the arc-shaped side plate 4 opposite to the limiting pin holes 14. The size and position of the limiting grooves 15 match those of the precast culvert cover plate 3. Considering factors such as cast-in-place construction and assembly errors, the limiting grooves 15 are designed with a longitudinal cross-section consisting of two semicircles and a rectangle. After the precast culvert cover plate 3 is installed on site, it is fixed to the intermediate precast box culvert 2 and the culvert arc-shaped side plate 4 by engaging vertical bolts 6 with bolt holes 13 and vertical bolt sleeves 16, and by engaging limiting pins 7 with limiting pin holes 14 and limiting grooves 15. Micro-expansion grout 17 is used to fill the limiting pin holes 14 and limiting grooves 15 densely. The limiting pins of the precast culvert cover plate are φ32 threaded steel bars, and micro-expansion concrete is poured into the limiting pin holes to wrap and fix the threaded steel bar limiting pins.

[0056] like Figures 7-8 As shown, there are multiple intermediate precast box culverts 2 arranged side by side. Adjacent intermediate precast box culverts 2 are connected longitudinally by four sets of diagonal straight bolts 5. Bolt handholes and embedded bolt sleeves are pre-reserved at both ends of the top plate of the intermediate precast box culverts. The dimensions of the precast cover plates of the intermediate box culverts and side culverts match the shield tunnel segment rings. Considering factors such as precast structure assembly errors and curve fitting, the length of the precast cover plates of the intermediate box culverts and side culverts along the line direction is 20mm smaller than the width of the segment rings. No wedge is provided; the alignment is achieved by adjusting the gap at the assembly joints.

[0057] The intermediate precast box culvert 2 and the arc-shaped side plate 4 of the side culvert are connected at their bottom ends by pre-embedded steel bar connectors 9 and connecting steel bars 8. The pre-embedded steel bar connectors 9 are located inside the bottom arc plate 11 of the box culvert. After the installation is completed, the tunnel bottom backfill layer 20 is poured to fill the reserved gaps. The tunnel bottom backfill layer 20 is a cement mortar filling material filled with the hollow opening in the middle of the bottom arc plate. An appropriate amount of micro-expansion agent is added to the filling material to ensure that the intermediate precast box culvert and the inner surface of the shield tunnel segment can be tightly bonded. The limiting structure formed by the hollow backfill hole 19 of the intermediate precast box culvert 2 along the longitudinal direction of the tunnel bottom backfill layer 20, the cast-in-place arc-shaped side plate 4 of the side culvert, and the backfill leveling layer 21 on top of the rail substructure together constitute the longitudinal connection system of the prefabricated rail substructure, improving the overall longitudinal stability of the rail substructure.

[0058] A construction method for prefabricated track substructure in a large-diameter shield tunnel includes the following steps:

[0059] S1: High-precision molds are used in the factory to prefabricate the intermediate precast box culverts and side culverts. The longitudinal length of the intermediate precast box culverts and side culverts is the same as or smaller than the ring width of the shield tunnel segments. The top plate of the intermediate precast box culverts and the corbels, and the top surface of the side culverts are provided with a rough surface with a concave-convex depth of not less than 4mm.

[0060] S2: Prefabricate the cage-type steel reinforcement frame of the arc-shaped side plate of the culvert in the factory. The steel reinforcement cage is 4-5 rings wide of the shield tunnel segment along the longitudinal length and matches the existing concrete formwork.

[0061] S3: During the tunnel boring machine (TBM) excavation, the intermediate precast box culvert is assembled synchronously with the TBM segments. The intermediate precast box culvert is installed with the circumference width matched with the TBM segments. The circumferential assembly joint of the intermediate precast box culvert is aligned with the circumferential joint of the TBM segments and is connected by diagonal bolts.

[0062] S4: Based on the configuration of the tunnel boring machine and the on-site construction conditions inside the tunnel, after the intermediate precast box culvert is assembled ahead of schedule at a distance not less than the length of the precast steel reinforcement cage of the side culvert's curved side plate, install the steel reinforcement skeleton of the side culvert's curved side plate, construct the connecting steel reinforcement at the connection between the intermediate precast box culvert and the side culvert's curved side plate, and pour the concrete for the side culvert's curved side plate.

[0063] S5: After the concrete of the curved side plate of the culvert reaches the required strength, the precast cover plate of the culvert is installed on the supporting bracket of the curved side plate of the intermediate precast box culvert and the curved side plate of the culvert using the grouting method. It is connected to the intermediate precast box culvert and the curved side plate of the culvert by connecting bolts and limit pins.

[0064] S6: Fill the gap between the bottom arc plate of the intermediate precast box culvert and the shield tunnel segment by injecting filling material into the hollow part of the bottom arc plate of the intermediate precast box culvert to form the tunnel bottom backfill layer. Steel mesh is placed in the tunnel bottom backfill layer to connect the intermediate precast box culvert into a whole along the longitudinal direction.

[0065] S7: Repeat steps S3-S6 above to complete the installation of the prefabricated rail substructure in the tunnel, and pour the leveling layer in place. Before pouring the leveling layer concrete, clean the rough surface of the rail substructure to remove debris. Lay steel mesh in the leveling layer to improve the integrity of the rail substructure.

[0066] The novel track-under structure and construction method employed in this invention effectively improve the overall integrity and longitudinal stiffness of the shield tunnel track-under structure, ensuring the stability of the tunnel structure and the smoothness of the track structure. It is convenient to install, highly mechanized, and improves the construction efficiency and quality of the track-under structure. Utilizing prefabricated, high-efficiency construction technology, all processes for the track-under structure can be carried out simultaneously with shield tunneling and segment assembly, while ensuring the overall longitudinal stiffness and stability of the track-under structure. It offers advantages such as high mechanization and construction efficiency, controllable construction quality, improved working environment within the tunnel, and reduced construction safety risks.

[0067] The above description is only 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 should be included within the protection scope of the present invention.

Claims

1. A prefabricated track-mounted structure for large-diameter shield tunnels, characterized in that: The system includes a precast intermediate box culvert, precast side culvert cover plates, curved side culvert side plates, and a tunnel bottom backfill layer. Corbels are provided on the outer sides of the top of both side walls of the intermediate precast box culvert. The bottom arc plate of the intermediate precast box culvert is arc-shaped and concentric with the inner surface of the shield tunnel segment. A gap is reserved between the bottom arc plate of the box culvert and the inner surface of the shield tunnel segment. Hollow backfill holes are opened on the bottom arc plate of the box culvert. The curved side culvert side plates are cast in place on both sides of the intermediate precast box culvert. The precast side culvert cover plates are overlapped and installed on the intermediate precast box culvert and the curved side culvert side plates. The tunnel bottom backfill layer is placed in the hollow backfill holes of the intermediate precast box culvert to fill the reserved gaps. The culvert arc-shaped side plate includes an arc-shaped plate concentric with the inner surface of the shield tunnel segment and a precast culvert cover plate support bracket set at the top of the arc-shaped plate. The culvert arc-shaped side plate has a built-in steel reinforcement skeleton. The connection between the bottom arc plate of the intermediate precast box culvert and the arc-shaped plate of the side culvert is made by a pre-embedded steel bar connector and a connecting steel bar. The pre-embedded steel bar connector is set inside the bottom arc plate of the box culvert. Bolt holes are pre-drilled on the precast cover plate of the side culvert that overlaps one side of the intermediate precast box culvert, and circular limiting pin holes are pre-drilled on the precast cover plate of the side culvert that overlaps one side of the arc-shaped side plate of the side culvert. Vertical bolt sleeves are provided on the brackets of the intermediate precast box culvert opposite to the bolt holes, and limiting grooves are provided on the supporting brackets of the precast cover plate of the side culvert arc-shaped side plate opposite to the limiting pin holes. After the precast cover plate of the side culvert is installed on site, the precast cover plate of the side culvert is fixed to the intermediate precast box culvert and the arc-shaped side plate of the side culvert by the cooperation of vertical bolts with bolt holes and vertical bolt sleeves, and by the cooperation of limiting pins with limiting pin holes and limiting grooves.

2. The prefabricated track-under structure for a large-diameter shield tunnel according to claim 1, characterized in that: The intermediate precast box culverts are multiple and arranged side by side, with adjacent intermediate precast box culverts connected by diagonal straight bolts.

3. The prefabricated track-under structure for a large-diameter shield tunnel according to claim 1, characterized in that: The intermediate precast box culvert adopts a U-shaped structure.

4. The prefabricated track-under structure for a large-diameter shield tunnel according to claim 1, characterized in that: Arc-shaped supports are provided at the four corners of the lower surface of the box culvert bottom arc plate. The thickness of the gap reserved between the box culvert bottom arc plate and the inner surface of the shield tunnel segment is the same as the height of the arc-shaped supports.

5. The prefabricated track-under structure for a large-diameter shield tunnel according to claim 1, characterized in that: The intermediate precast box culvert and the side culvert precast cover plates are all factory prefabricated products, assembled and constructed inside the tunnel. The dimensions of the intermediate precast box culvert and the side culvert precast cover plates are matched with the shield tunnel segments.

6. The prefabricated track-under structure for a large-diameter shield tunnel according to claim 1, characterized in that: The limiting pin hole and the limiting groove are filled with micro-expansion grout.

7. A construction method for a prefabricated track substructure in a large-diameter shield tunnel, characterized in that, Includes the following steps: S1: Prefabricate intermediate precast box culverts and side culvert precast cover plates in the factory. The longitudinal length of the intermediate precast box culverts and side culvert precast cover plates is the same as or smaller than the ring width of the shield tunnel segments. The top plate and corbel of the intermediate precast box culverts and the top surface of the side culvert precast cover plates are roughened. S2: Prefabricate the cage-type steel reinforcement frame of the arc-shaped side plate of the culvert in the factory. The steel reinforcement cage is 4-5 rings wide of the shield tunnel segment along the longitudinal length and matches the existing concrete formwork. S3: During the tunnel boring process, the intermediate precast box culvert is assembled synchronously after the shield segments. The intermediate precast box culvert is installed with the circumference matching the shield segments. The circumferential assembly joint of the intermediate precast box culvert is aligned with the circumferential joint of the shield segments and is connected by oblique bolts. S4: Based on the configuration of the tunnel boring machine and the on-site construction conditions inside the tunnel, after the intermediate precast box culvert is assembled ahead of schedule at a distance not less than the length of the precast steel cage of the side culvert's arc-shaped side plate, install the steel cage of the side culvert's arc-shaped side plate, construct the connecting steel bars at the connection between the intermediate precast box culvert and the side culvert's arc-shaped side plate, and pour the concrete for the side culvert's arc-shaped side plate. S5: After the concrete of the curved side plate of the culvert reaches the strength, the precast cover plate of the culvert is installed on the support bracket of the intermediate precast box culvert and the curved side plate of the culvert using the grouting method, and is connected to the intermediate precast box culvert and the curved side plate of the culvert by connecting bolts and limit pins. S6: Fill the gap between the bottom arc plate of the intermediate precast box culvert and the shield segment by injecting filling material into the hollow part of the bottom arc plate of the intermediate precast box culvert to form a tunnel bottom backfill layer. Steel mesh is placed in the tunnel bottom backfill layer to connect the intermediate precast box culverts into a whole along the longitudinal direction. S7: Repeat steps S3-S6 above to complete the installation of the prefabricated rail substructure in the tunnel, and pour the leveling layer in place. Before pouring the leveling layer concrete, clean the rough surface of the rail substructure to remove debris. Lay steel mesh in the leveling layer to improve the integrity of the rail substructure.

Images