Shield tunnel prefabricated track substructure and construction method thereof

Abstract

This invention provides a precast track substructure for a shield tunnel and its construction method. The precast track substructure is composed of multiple precast structures assembled together. Each precast structure includes a precast central box culvert and precast side box culverts symmetrically arranged on both sides of the central box culvert. Matching C-type and T-type connectors are pre-embedded on the front and rear splicing surfaces of each precast central box culvert. Multiple anchors with threaded snap-fit ​​joints are pre-embedded on the top surfaces of the central and side box culverts. After installing anchoring steel bars on the top surfaces of the central and side box culverts, concrete is poured to form the track bed. This invention uses socket-type connectors in the precast central box culvert, effectively solving problems such as low assembly quality and complex assembly procedures. The pre-embedded anchors avoid the need for on-site rebar installation and casting of the top slab after the track substructure construction is completed, significantly improving the construction efficiency of the precast track substructure and achieving precise and rapid construction.

Description

Technical Field

[0001] This application relates to the field of construction technology for rail substructures in shield tunnels, and in particular to construction methods for prefabricated rail substructures in shield tunnels. Background Technology

[0002] With urban planning and the development and utilization of underground space, intercity railways and high-speed railways are increasingly adopting underground lines to connect to urban hub passenger stations. The shield tunneling method, due to its advantages such as good safety, fast tunneling speed, and minimal impact on the surrounding environment, is being used more and more widely and is gradually becoming the main construction method for urban underground tunnels. Among these, the track substructure is an indispensable internal component in large-diameter shield tunnels, serving as the load-bearing structure for vehicles, trains, and maintenance personnel to move within the tunnel. Its construction precision, quality, and efficiency determine the construction quality and speed of the remaining internal structures.

[0003] In large-diameter shield railway tunnels, the track substructure is often constructed using cast-in-place methods after tunnel completion. This method results in a long construction period, significant challenges in labor organization, and generally lower construction quality. Therefore, the rapid development of prefabricated construction technology has provided the technical conditions for rapid track substructure construction. It is necessary to study the construction technology and space utilization of the track substructure in shield tunnels, taking into account tunnel construction processes and structural forms. Adopting rapid prefabrication and assembly of track substructures can improve construction efficiency, shorten the project cycle, optimize the internal space of the shield, and reduce project costs. Currently, prefabricated track substructures mainly include two types: integral prefabricated track substructures and prefabricated track substructures. The former requires advanced lifting and assembly equipment and is more expensive; the latter has complex connection methods, cumbersome assembly procedures, and poorer construction quality. Furthermore, after the completion of the prefabricated track substructure, a train track pad layer needs to be installed, requiring drilling holes in the top slab of the prefabricated track substructure for rebar installation, which affects construction efficiency. How to obtain a more economical, simpler, and more efficient prefabricated track substructure is a major challenge in current prefabricated track substructure construction. Summary of the Invention

[0004] To address the shortcomings of existing prefabricated rail substructure forms and construction methods, the purpose of this invention is to provide a prefabricated rail substructure for shield tunnels and its rapid construction method, which can effectively achieve rapid construction of the prefabricated rail substructure and improve the construction quality and efficiency of the prefabricated rail substructure.

[0005] To achieve the above technical objectives, this invention provides a precast track substructure for a shield tunnel, including a track substructure box body structure and a track bed. The track substructure box body structure is assembled from multiple precast structures. Each precast structure includes a precast central box culvert and precast side box culverts symmetrically arranged on both sides of the precast central box culvert. Matching C-type and T-type connectors are pre-embedded on the front and rear splicing surfaces of each precast central box culvert, with corresponding pre-embedded positions. Grooves for splicing and installation are provided at the pre-embedded locations of the C-type and T-type connectors. Adjacent sets of precast central box culverts are spliced ​​together using C-type and T-type connectors. Multiple anchors with threaded snap-fits are pre-embedded on the top surfaces of the precast central box culverts and precast side box culverts. The track bed is formed by installing anchoring steel bars on the top surfaces of the precast central box culverts and precast side box culverts, followed by pouring concrete to form a reinforced concrete slab. The ends of the anchoring steel bars are connected to the threaded snap-fits of the anchors.

[0006] The preferred technical solution of the present invention is as follows: a filling layer is filled between the bottom of the precast central box culvert near both ends and the inner wall of the tunnel segment, and self-compacting concrete is filled between the bottom surface of the central box culvert and the inner wall of the tunnel segment on both sides.

[0007] The preferred technical solution of the present invention is that the channel is arranged in the installation direction of the C-type connector and the T-type connector, and the channel is parallel to the installation direction of the prefabricated middle box culvert.

[0008] The preferred technical solution of the present invention is as follows: the anchor includes a bottom anchor plate and an upper toothed pre-embedded sleeve, which are integrally formed. The pre-embedded sleeve is provided with an inverted umbrella-shaped clamp or an inverted conical internal thread clamp that is larger at the top and smaller at the bottom. The end of the anchoring steel bar is provided with a threaded connection part that matches the threaded clamp of the anchor. Each anchoring steel bar is an inverted concave shape, and its two ends are respectively threadedly engaged with two adjacent anchors. The two adjacent anchoring steel bars are connected as one unit by tie steel bars.

[0009] A preferred technical solution of the present invention is as follows: multiple sets of C-shaped connectors are provided on one side of the precast central box culvert, and the C-shaped connectors are distributed on the top plate and side plates of the precast central box culvert. Multiple sets of T-shaped connectors are provided on the other side of the precast central box culvert. The C-shaped connector includes an anchoring component and a C-shaped bayonet, and the T-shaped connector includes an anchoring component and a T-shaped head. The T-shaped head of the T-shaped connector extends out of the splicing surface of the precast central box culvert.

[0010] This invention also provides a construction method for a precast rail substructure in a shield tunnel, specifically including the following steps:

[0011] S1. During the fabrication of the precast central box culvert, matching C-type connectors and T-type connectors are pre-embedded on the front and rear splicing surfaces of the precast central box culvert, and the pre-embedded positions of the C-type connectors and T-type connectors correspond to each other. A groove is reserved in the installation direction of each C-type connector and T-type connector, and the groove is parallel to the installation direction of the precast central box culvert. Multiple anchors with threaded snaps are pre-embedded in the top plate of the precast central box culvert.

[0012] During the preparation of the precast side box culvert, multiple anchors with threaded slots are also pre-embedded in its top slab; the anchor positions are arranged according to the spacing of the anchoring steel bars, and each anchor has a threaded slot that matches the anchoring steel bar.

[0013] S2. Transport the prepared precast box culvert to the installation location, initially align the T-shaped connector of the precast box culvert to be assembled with the C-shaped connector of the assembled precast box culvert, and vertically lower the precast box culvert to be assembled along the reserved channel until the C-shaped connector and T-shaped connector complete self-locking.

[0014] S3. After the T-type connector and C-type connector have completed self-locking, check the gap between the lower part of the precast box culvert and the shield tunnel segment. The gap between the lower part of the box culvert and the shield tunnel segment needs to be filled with steel plates or other filling materials to ensure that the precast box culvert will not move vertically before the precast box culvert can be released.

[0015] S4. Construct the precast side box culverts on both sides separately. The precast side box culverts and the precast middle box culverts on both sides are equipped with matching splicing interfaces. The two precast side box culverts are directly spliced ​​on both sides of the installed precast middle box culvert.

[0016] S5. After repeating S2 to S4 for a certain distance, use self-compacting concrete to backfill the gaps between the spliced ​​precast side box culverts and the precast middle box culverts and shield segments.

[0017] S6. Repeat S2 to S5 until all precast box culverts are spliced. Use the pre-reserved anchors on the top plate of the box culvert to insert the track bed anchoring steel bars and carry out the tie steel bar construction. Finally, pour the track bed to complete the construction of the track substructure.

[0018] The preferred technical solution of this invention is as follows: In step S1, a single row of T-shaped connectors is pre-embedded on the rear splicing surface of the precast central box culvert, and a single row of C-shaped connectors is pre-embedded on the front splicing surface. Multiple T-shaped and C-shaped connectors are provided, respectively located on the top and side slabs of the precast central box culvert. The C-shaped connector includes a C-shaped notch and two pre-embedded anchor bars welded to the closed surface of the C-shaped notch. The two pre-embedded anchor bars are pre-embedded within the slab of the precast central box culvert, and the C-shaped notch is located within the corresponding reserved channel. The T-shaped connector includes a T-shaped head and two anchor bars. The two anchor bars are pre-embedded within the slab of the central box culvert, and the T-shaped head extends out of the splicing surface of the precast central box culvert.

[0019] During the pouring of the top slab concrete for the precast central box culvert and the precast side box culvert in step S1, the threaded slots of the anchors are filled to prevent concrete from entering the slots.

[0020] The preferred technical solution of the present invention is as follows: During the assembly process in step S2, the C-type connector of the pre-assembled box culvert is basically aligned with the axis of the T-type connector of the box culvert to be assembled using a visual operation device. Then, the assembly route is guided by a preset channel, and the box culvert to be assembled is slowly lowered along the channel.

[0021] The preferred technical solution of the present invention is as follows: In step S5, the backfilled self-compacting concrete is vibrated with a vibrator. A custom vibrator with a diameter of 6cm and a length of 2.5m is required to vibrate the concrete to ensure that the concrete filling is dense.

[0022] The preferred technical solution of the present invention is as follows: Before the track bed is poured in step S6, the gaps between the precast box culverts and the precast side box culverts in the same ring, as well as the gaps between adjacent precast structures, need to be sealed to avoid grout leakage during the pouring process; the anchoring steel bars are provided with connecting ends that match the threaded snaps of the anchoring components at both ends, and the extension length of the anchoring steel bars meets the anchoring length requirements of the track slab.

[0023] The beneficial effects of this invention are:

[0024] (1) The present invention simplifies the construction process by using C-type connectors and cone-shaped T-type connectors in the prefabricated box culverts, and completes the assembly of the prefabricated rail structure by using pre-embedded C-type connectors, T-type connectors and channels. The present invention effectively solves the problems of low assembly quality and complex assembly process of prefabricated box culverts by setting socket-type connectors in the prefabricated box culverts.

[0025] (2) This invention enables rapid construction of the track bed by pre-embedding anchors with threaded snaps in the top plate of the precast track under structure and using anchoring steel bars with threaded ends. This eliminates the need for drilling and rebar installation, improves construction efficiency and accuracy, avoids the process of rebar installation and casting on the top plate after the track under structure is completed, significantly improves the construction efficiency of the precast track under structure, and realizes precise and rapid construction of the precast track under structure.

[0026] The prefabricated rail substructure in this invention enables rapid assembly of the rail substructure, effectively improving construction efficiency and meeting construction quality requirements, fully leveraging the advantages of prefabricated rail substructures, and is of great significance to the construction of prefabricated rail substructures. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the tunnel cross-section in an embodiment of the present invention;

[0028] Figure 2 This is a detailed cross-sectional view of the prefabricated box culvert in an embodiment of the present invention;

[0029] Figure 3 This is a top view of the prefabricated box culvert in an embodiment of the present invention;

[0030] Figure 4 This is a side view of the prefabricated box culvert in an embodiment of the present invention;

[0031] Figure 5 These are detailed drawings of the C-type and T-type connectors in the embodiments of the present invention;

[0032] Figure 6 This is a top view of the C-type connection and T-type connector spliced ​​together in an embodiment of the present invention;

[0033] Figure 7 This is a detailed drawing of the anchor and anchoring reinforcement in an embodiment of the present invention.

[0034] Explanation of reference numerals in the attached drawings: 1—track bed, 2—precast central box culvert, 3—precast side box culvert, 4—flared-mouth guide elastic self-locking C-shaped component, 5—conical T-shaped component, 6—channel, 7—umbrella-shaped anchor, 8—anchoring steel bar, 9—shield tunnel segment, 10—filling material, 11—backfill self-compacting concrete, 12—tie steel bar. Detailed Implementation

[0035] The present invention will be further described below with reference to the accompanying drawings and embodiments. Figures 1 to 6 All accompanying drawings are simplified versions of embodiments and are intended only to clearly and concisely illustrate the embodiments of the present invention. The technical solutions shown in the drawings below are specific solutions of embodiments of the present invention and are not intended to limit the scope of the claimed invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0036] Example 1 provides a prefabricated rail substructure for a shield tunnel, such as Figures 1 to 7As shown, the structure includes a box culvert under the track and a track bed 1. The box culvert under the track is assembled from multiple prefabricated structures. Each prefabricated structure includes a prefabricated central box culvert 2 and prefabricated side box culverts 3 symmetrically arranged on both sides of the prefabricated central box culvert 2. The bottom of the prefabricated central box culvert 2 near both ends is filled with a filling layer 10 between itself and the inner wall of the tunnel segment 9. The filling material generally includes steel plates or similar steel plates. Self-compacting concrete 11 is filled between the bottom surface of the central box culvert 2 and the inner walls of the two side box culverts 3 and the tunnel segment 9. Each set of precast central box culverts 2 has pre-embedded C-type connectors 4 and T-type connectors 5 on its front and rear splicing surfaces, and the pre-embedded positions of the C-type connectors 4 and T-type connectors 5 are corresponding. Specifically, four sets of C-type connectors 4 are provided on one side of the precast central box culvert 2, two sets of C-type connectors 4 are symmetrically arranged on the top plate of the precast central box culvert 2, and the other two sets are symmetrically arranged on the side plates of the precast central box culvert 2. Four sets of T-type connectors 5 are correspondingly provided on the other side of the precast central box culvert 2. The C-type connector 4 includes an anchoring component and a C-type bayonet, and the T-type connector 5 includes an anchoring component and a T-shaped head. The T-shaped head of the T-type connector 5 extends out of the splicing surface of the precast central box culvert 2. A channel 6 for splicing installation is provided at the pre-embedded locations of the C-type connector 4 and the T-type connector 5. The channel 6 is set in the installation direction of the C-type connector 4 and the T-type connector 5, and the channel 6 is parallel to the installation direction of the precast central box culvert 2. Two adjacent sets of precast central box culverts 2 are spliced ​​into one unit by the C-type connector 4 and the T-type connector 5. Multiple anchors 7 with threaded snaps are pre-embedded on the top surface of the precast central box culvert 2 and the precast side box culvert 3. The track bed 1 is formed by installing anchor steel bars 8 on the top surface of the precast central box culvert 2 and the precast side box culvert 3 and then pouring concrete to form a concrete steel plate. The ends of the anchor steel bars 8 are connected to the threaded snaps of the anchors 7. The anchor 7 includes a bottom anchor plate and an upper toothed pre-embedded sleeve, which are integrally formed. The pre-embedded sleeve is provided with an inverted umbrella-shaped clamp or an inverted conical internal thread clamp, which is larger at the top and smaller at the bottom. The end of the anchoring steel bar 8 is provided with a threaded connection part that matches the threaded clamp of the anchor 7. Each anchoring steel bar 8 is an inverted concave shape, and its two ends are respectively threadedly engaged with two adjacent anchor 7. The two adjacent anchoring steel bars 8 are connected as one unit by tie steel bars 12.

[0037] Example 2 provides a construction method for the precast rail substructure of the shield tunnel as described in Example 1, which specifically includes the following steps:

[0038] S1. During the preparation of the precast central box culvert 2, C-type connectors 4 and T-type connectors 5 that match each other are pre-embedded on the front and rear splicing surfaces of the precast central box culvert 2, and the pre-embedded positions of the C-type connectors 2 and T-type connectors 5 correspond to each other. A groove 6 is reserved in the installation direction of each C-type connector 2 and T-type connector 5, and the groove 6 is parallel to the installation direction of the precast central box culvert 2. Multiple anchors 7 with threaded slots are pre-embedded in the top plate of the precast central box culvert 2. During the preparation of the precast side box culvert 1, multiple anchors 7 with threaded slots are also pre-embedded in the top plate of the precast side box culvert 1. The anchors 7 are arranged according to the spacing of the anchoring steel bars 8, and each anchor 7 has a threaded slot that matches the anchoring steel bars 8. When the top plate concrete of the precast central box culvert 2 and the precast side box culvert 3 is poured, the threaded slots of the anchors 7 are filled to prevent concrete from entering the slots.

[0039] Specifically, in this embodiment, a single row of T-shaped connectors 5 are pre-embedded on the rear splicing surface of the precast central box culvert 2, and a single row of C-shaped connectors 4 are pre-embedded on the front splicing surface. Four T-shaped connectors 5 and four C-shaped connectors 4 are provided, located on the top and side slabs of the precast central box culvert 2, respectively. Figure 3 and Figure 4 As shown, the C-type connector 3 includes a C-type bayonet and two pre-embedded anchor bars welded to the closed surface of the C-type bayonet. The two pre-embedded anchor bars are pre-embedded in the slab of the precast middle box culvert, and the C-type bayonet is located in the corresponding reserved channel 6. The T-type connector 5 includes a T-shaped head and two anchor bars. The two anchor bars are pre-embedded in the slab of the middle box culvert, and the T-shaped head extends out of the splicing surface of the precast middle box culvert.

[0040] S2. Transport the prepared precast box culvert 2 to the installation location. Align the T-shaped connector 5 of the precast box culvert to be assembled with the C-shaped connector 4 of the precast box culvert that has been assembled. Lower the precast box culvert to be assembled vertically along the reserved channel until the C-shaped connector 4 and the T-shaped connector 5 are self-locking. During the assembly process, use visual operation equipment to basically align the axis of the C-shaped connector 4 of the precast box culvert and the T-shaped connector 5 of the precast box culvert to be assembled. Then, use the preset channel to guide the assembly route and slowly lower the box culvert to be assembled along the channel.

[0041] S3. After the T-type connector 5 and C-type connector 4 have completed self-locking, check the gap between the lower part of the precast box culvert and the shield tunnel segment. Steel plates or other filling materials are needed to fill the gap between the lower part of the box culvert and the shield tunnel segment. After ensuring that the precast box culvert will not move vertically, the precast box culvert can be released.

[0042] S4. Construct the precast side box culverts 3 on both sides respectively. The precast side box culverts 3 on both sides and the precast middle box culvert 2 are equipped with matching splicing interfaces. The two precast side box culverts 3 are directly spliced ​​on both sides of the installed precast middle box culvert 2.

[0043] S5. After repeating S2 to S4 for a certain distance, use 10g of self-compacting concrete to backfill the gap between the spliced ​​precast side box culverts and the precast middle box culverts and the shield tunnel segments. After backfilling, use a vibrator to vibrate the backfilled self-compacting concrete. It is required to use a custom vibrator with a diameter of 6cm and a length of 2.5m to vibrate it to ensure that the concrete filling is dense.

[0044] S6. Repeat S2 to S5 until all precast box culverts are assembled. Use the pre-reserved anchors on the top slab of the box culvert to insert the track bed anchoring steel bars, and then construct the tie steel bars. Finally, pour the track bed to complete the construction of the sub-track structure. Before pouring the track bed, the gaps between the precast middle box culverts and the precast side box culverts within the same ring, as well as the gaps between adjacent precast structures, must be sealed to prevent grout leakage during pouring. The anchoring steel bars have connecting ends at both ends that match the threaded snap-fit ​​of the anchoring fasteners, and the extension length of the anchoring steel bars meets the track slab anchoring length requirements.

[0045] Those skilled in the art will readily make various modifications to this embodiment and apply the general principles described herein to other embodiments without inventive effort. Therefore, this application is not limited to the above-described embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of this application without departing from its scope should be within the protection scope of this application.

Claims

1. A precast track under-slab structure for a shield tunnel, comprising a track under-slab box structure and a track bed (1), wherein the track under-slab box structure is assembled from multiple precast structures, each precast structure comprising a precast central box culvert (2) and precast side box culverts (3) symmetrically arranged on both sides of the precast central box culvert (2), characterized in that: Each set of prefabricated central box culverts (2) has pre-embedded C-type connectors (4) and T-type connectors (5) on the front and rear splicing surfaces respectively, and the pre-embedded positions of C-type connectors (4) and T-type connectors (5) are corresponding. A groove (6) for splicing installation is opened at the pre-embedded position of C-type connectors (4) and T-type connectors (5). Two adjacent sets of prefabricated central box culverts (2) are spliced ​​together as one unit by C-type connectors (4) and T-type connectors (5). Multiple anchors (7) with threaded slots are pre-embedded on the top surface of the prefabricated central box culverts (2) and prefabricated side box culverts (3). The track bed (1) is formed by installing anchor steel bars (8) on the top surface of the prefabricated central box culverts (2) and prefabricated side box culverts (3) and then pouring concrete to form a concrete steel plate. The end of the anchor steel bar (8) is connected to the threaded slot of the anchor (7).

2. The prefabricated rail substructure for a shield tunnel according to claim 1, characterized in that: The precast central box culvert (2) is filled with a filling layer (10) between the bottom of the central box culvert (2) and the inner wall of the tunnel segment (9), and self-compacting concrete (11) is filled between the bottom surface of the central box culvert (2) and the inner wall of the side box culverts (3) and the tunnel segment (9).

3. A prefabricated rail substructure for a shield tunnel according to claim 1 or 2, characterized in that: The channel (6) is set in the installation direction of the C-type connector (4) and the T-type connector (5), and the channel (6) is parallel to the installation direction of the prefabricated middle box culvert (2).

4. A prefabricated track support structure for a shield tunnel according to claim 1 or 2, characterized in that: The anchor (7) includes a bottom anchor plate and an upper toothed pre-embedded sleeve, which are integrally formed. The pre-embedded sleeve is provided with an inverted umbrella-shaped clasp or an inverted conical internal thread clasp, which is larger at the top and smaller at the bottom. The end of the anchoring steel bar (8) is provided with a threaded connection part that matches the threaded clasp of the anchor (7). Each anchoring steel bar (8) is an inverted concave shape, and its two ends are threadedly engaged with two adjacent anchoring steel bars (7). The two adjacent anchoring steel bars (8) are connected as one unit by tie steel bars (12).

5. A prefabricated track support structure for a shield tunnel according to claim 1 or 2, characterized in that: Multiple sets of C-type connectors (4) are provided on one side of the precast central box culvert (2). The C-type connectors (4) are distributed on the top plate and side plates of the precast central box culvert (2). Multiple sets of T-type connectors (5) are provided on the other side of the precast central box culvert (2). The C-type connector (4) includes an anchoring component and a C-type bayonet. The T-type connector (5) includes an anchoring component and a T-type head. The T-type head of the T-type connector (5) extends out of the splicing surface of the precast central box culvert (2).

6. A construction method for the precast rail substructure of a shield tunnel as described in claim 2, characterized in that, Specifically, the following steps are included: S1. During the fabrication of the precast central box culvert, matching C-type connectors and T-type connectors are pre-embedded on the front and rear splicing surfaces of the precast central box culvert, and the pre-embedded positions of the C-type connectors and T-type connectors correspond to each other. A groove is reserved in the installation direction of each C-type connector and T-type connector, and the groove is parallel to the installation direction of the precast central box culvert. Multiple anchors with threaded snaps are pre-embedded in the top plate of the precast central box culvert. During the preparation of the precast side box culvert, multiple anchors with threaded slots are also pre-embedded in its top slab; the anchor positions are arranged according to the spacing of the anchoring steel bars, and each anchor has a threaded slot that matches the anchoring steel bar. S2. Transport the prepared precast box culvert to the installation location, initially align the T-shaped connector of the precast box culvert to be assembled with the C-shaped connector of the assembled precast box culvert, and vertically lower the precast box culvert to be assembled along the reserved channel until the C-shaped connector and T-shaped connector complete self-locking. S3. After the T-type connector and C-type connector have completed self-locking, check the gap between the lower part of the precast box culvert and the shield tunnel segment. The gap between the lower part of the box culvert and the shield tunnel segment needs to be filled with steel plates or other filling materials to ensure that the precast box culvert will not move vertically before the precast box culvert can be released. S4. Construct the precast side box culverts on both sides separately. The precast side box culverts and the precast middle box culverts on both sides are equipped with matching splicing interfaces. The two precast side box culverts are directly spliced ​​on both sides of the installed precast middle box culvert. S5. Repeat S2 to S4 for 50~100m, and backfill the gap between the spliced ​​precast side box culverts and the precast middle box culverts and shield segments with self-compacting concrete. S6. Repeat S2 to S5 until all precast box culverts are spliced. Use the pre-reserved anchors on the top plate of the box culvert to insert the track bed anchoring steel bars and carry out the tie steel bar construction. Finally, pour the track bed to complete the construction of the track substructure.

7. A construction method for a precast rail substructure for a shield tunnel according to claim 6, characterized in that: In step S1, a single row of T-shaped connectors is pre-embedded on the rear splicing surface of the precast central box culvert, and a single row of C-shaped connectors is pre-embedded on the front splicing surface. Multiple T-shaped and C-shaped connectors are provided, located on the top and side slabs of the precast central box culvert. Each C-shaped connector includes a C-shaped notch and two pre-embedded anchor bars welded to the closed surface of the C-shaped notch. The two anchor bars are pre-embedded within the slab of the precast central box culvert, and the C-shaped notch is located within the corresponding reserved channel. Each T-shaped connector includes a T-shaped head and two anchor bars. The two anchor bars are pre-embedded within the slab of the central box culvert, and the T-shaped head extends beyond the splicing surface of the precast central box culvert. During the pouring of the top slab concrete for the precast central box culvert and the precast side box culvert in step S1, the threaded slots of the anchors are filled to prevent concrete from entering the slots.

8. A construction method for a precast rail substructure for a shield tunnel according to claim 6, characterized in that: During the assembly process in step S2, the C-type connectors of the pre-assembled box culverts are basically aligned with the T-type connectors of the box culverts to be assembled using visual operation equipment. Then, the assembly route is guided by a preset channel, and the box culverts to be assembled are slowly lowered along the channel.

9. A construction method for a precast rail substructure for a shield tunnel according to claim 6, characterized in that: In step S5, the backfilled self-compacting concrete is vibrated with a vibrator. A custom-made vibrator with a diameter of 6cm and a length of 2.5m is required to ensure that the concrete is compacted.

10. A construction method for a precast rail substructure for a shield tunnel according to claim 6, characterized in that: Before pouring the track bed in step S6, the gaps between the precast box culverts and the precast side box culverts in the same ring, as well as the gaps between adjacent precast structures, need to be sealed to prevent grout leakage during the pouring process. The anchoring steel bars are provided with connecting ends that match the threaded snaps of the anchoring components at both ends, and the extension length of the anchoring steel bars meets the anchoring length requirements of the track slab.

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