Prefabricated assembly type arch-shaped open cut tunnel overlapping joint structure and construction method thereof

Abstract

The application relates to the field of tunnel construction, in particular to a prefabricated assembly type arched open-cut tunnel overlapping joint structure and a construction method thereof. The prefabricated assembly type arched open-cut tunnel overlapping joint structure comprises a tunnel segment, the tunnel segment comprises a prefabricated structure part and a plurality of U-shaped stress steel bars, the prefabricated structure part is square, the free ends of the U-shaped stress steel bars are fixedly cast in the prefabricated structure part, and the bent ends of the U-shaped stress steel bars extend out of one side of the prefabricated structure part; the application further relates to a method which comprises the following steps: S1, manufacturing the tunnel segment in a prefabricated factory building, prefabricating the end of the tunnel segment into an inverted T-shaped section, and embedding the U-shaped steel bars into the tunnel segment as stress steel bars; S2, transporting the tunnel segment to a site, assembling the tunnel segment by using a crane, cross arranging the U-shaped steel bars of the prefabricated part, and inserting inclined bolts into the embedded sleeves after completing the overlapping of the inverted T-shaped webs; and the method can improve the waterproof performance of the joint of the tunnel segment.

Description

Technical Field

[0001] This invention relates to the field of tunnel construction, and in particular to a prefabricated assembled arch-shaped open-cut tunnel composite joint structure and its construction method. Background Technology

[0002] Currently, tunnel construction mainly uses the open-cut and cast-in-place method for the main structure construction. This method is complex, has a long construction period, low cost-effectiveness, and is difficult to control in terms of construction quality. The future development of the construction industry will increasingly lean towards green and industrialized construction technologies, with this development primarily reflected in the research and application of prefabricated construction technology.

[0003] Compared to traditional open-cut construction, prefabricated open-cut tunnels offer faster construction speeds. This is because prefabricated open-cut tunnels utilize modern machinery and advanced construction technologies, allowing for simultaneous multi-tasking operations such as excavation, support, and assembly, significantly shortening the construction cycle. The construction requires less manpower and materials compared to traditional open-cut tunnels. Since the tunnel segments are prefabricated in a factory, on-site processing and fabrication are reduced, thus saving substantial material and labor costs and greatly minimizing the risk of errors and poor quality during on-site construction.

[0004] Patent application number 201710373967.8 discloses an assembly quick connector for precast concrete tunnel segments and its application method. This assembly quick connector involves inter-ring assembly quick connectors and inter-block assembly quick connectors. The inter-ring assembly quick connector includes an inter-ring male connector and an inter-ring female connector. One end of the inter-ring male connector is a male connector fitting, and the other end is a variable cross-section plug. One end of the inter-ring female connector has a connecting groove adapted to the variable cross-section plug, and the other end is provided with a female connector fitting. The inner wall of the connecting groove is provided with several wedge-shaped sliders. The bottom of the connecting groove is provided with a wedge-shaped slider pushing mechanism. The advantages of this invention are that precast concrete tunnel segments can be quickly assembled into a tunnel using inter-block assembly quick connectors and inter-ring assembly quick connectors; the plug-in connection structure has good bending moment bearing capacity.

[0005] While the aforementioned technologies can quickly assemble precast concrete segments into tunnels, improving work efficiency, the joints connecting adjacent segments are weak points in prefabricated construction, directly affecting the structure's stress performance and load-bearing capacity. Currently used joints weaken the joint's rigidity and load-bearing capacity to some extent, and also suffer from poor waterproofing and high assembly precision, causing significant problems for on-site assembly operations, severely impacting assembly speed, resulting in substantial costs, and reducing the structure's load-bearing capacity, thus hindering the promotion and application of prefabricated tunnels. Existing prefabricated tunnels employ various joint types, including mortise and tenon joints, Z-shaped lap joints, and pin joints. Mortise and tenon joints significantly reduce the integrity of precast segment connections, decrease joint stiffness, and lower the structure's load-bearing and seismic performance. Furthermore, mortise and tenon joints are more difficult to assemble, increasing on-site labor. While Z-shaped lap joints reduce assembly precision and difficulty, they weaken the joint's load-bearing capacity, making it more susceptible to damage. The overlapping of the joints also significantly weakens the overall structural integrity during assembly, increasing safety risks and requiring additional auxiliary support structures. Pin joints offer substantial improvements in overall structural performance, using high-strength materials to increase durability and load-bearing capacity. However, they are highly dependent on formwork precision and assembly accuracy, increasing construction complexity and cost, slowing tunnel construction. Significant dimensional deviations can lead to loose connections, structural instability, and compromised waterproofing. Therefore, a technology is needed to improve the structure's waterproofing performance. Summary of the Invention

[0006] This invention provides a prefabricated arched open-cut tunnel composite joint structure and its construction method, which can improve the waterproof performance of the tunnel segment joint.

[0007] To solve the above-mentioned technical problems, this application provides the following technical solution: a prefabricated assembled arched open-cut tunnel composite joint structure, comprising tunnel segments, wherein each tunnel segment includes: a prefabricated structural part and a plurality of U-shaped reinforcing bars, the prefabricated structural part being square, the free ends of the U-shaped reinforcing bars being cast and fixed within the prefabricated structural part, the bent ends of the U-shaped reinforcing bars extending out to one side of the prefabricated structural part, and the bent ends of the U-shaped reinforcing bars being evenly distributed; further comprising an inverted T-shaped cross-section, the inverted T-shaped cross-section being fixedly connected to the prefabricated structural part, the web of the inverted T-shaped cross-section being disposed at the bottom of the U-shaped reinforcing bars, and an L-shaped cross-section being fixedly fixed to the web of the inverted T-shaped cross-section, the L-shaped cross-section being used for the entry of two adjacent tunnel segments. The two prefabricated structural components are joined by an L-shaped cross-section positioned between two U-shaped reinforcing bars in the middle. The L-shaped cross-section has bolt holes for fixing the components together. The U-shaped reinforcing bars are perpendicular to the web of the inverted T-shaped cross-section and extend beyond it. When the two prefabricated structural components are joined, the U-shaped reinforcing bars overlap. The system also includes several longitudinal short bars, which are fixedly connected to the U-shaped reinforcing bars on each of the two prefabricated structural components. The space above the inverted T-shaped cross-section is a cast-in-place area. After the two prefabricated structural components are fixed, concrete is poured in place.

[0008] The basic principle and beneficial effects of this scheme are as follows: rapid installation is achieved by assembling prefabricated tunnel segments. The prefabricated tunnel segments are composed of prefabricated structural parts and several U-shaped reinforcing bars. During use, two tunnel segments are assembled, and the L-shaped sections of adjacent tunnel segments are overlapped. Then, they are fixed using bolt handholes. Finally, in the cast-in-place area, that is, the space above the web of the inverted trapezoidal section, the U-shaped reinforcing bars are buried by cast-in-place concrete.

[0009] In this design, U-shaped reinforcing bars are used. The left and right reinforcing bars are arranged in a crisscross pattern to strengthen the connection between adjacent segments. An inverted T-shaped cross-section serves as the bottom formwork and provides support between adjacent segments. The upper end of the web forms an inverted L-shape, overlapping with adjacent segments to bear the shear force generated during construction and improve structural stability. Bolt manholes are pre-embedded in sleeves in adjacent segments, which will be tightened after the overlap is completed. This improves the shear resistance of the structure during assembly and enhances the connection performance of the circumferential segments. The L-shaped cross-section, due to the upper layer of cast-in-place concrete, improves the waterproof performance of the circumferential and longitudinal connections and strengthens the overall integrity of the structure, achieving an effect equivalent to cast-in-place construction. The cast-in-place area strengthens the connection of longitudinal and circumferential segments, improves integrity and waterproof performance, achieving an effect equivalent to cast-in-place construction.

[0010] This solution improves the connectivity between segments, ensures the integrity of the structure, and thus enhances the stiffness and mechanical properties of the joints.

[0011] The combination of precast and cast-in-place concrete takes into account both the quality of the tunnel segments and the ease of construction, greatly saves on formwork, is environmentally friendly, reduces construction difficulty, increases construction speed, and improves the load-bearing capacity of the structure.

[0012] Because the top of the joint is made of cast-in-place concrete and is cast in one piece, the waterproof performance of the joint is greatly improved, increasing the durability, integrity and safety of the structure.

[0013] Furthermore, the bolt hand hole is set at an angle.

[0014] Furthermore, in the precast structural section, longitudinal shear keys are fixed on the side adjacent to the surface where the U-shaped reinforcing bars are located.

[0015] Beneficial effects: Improves the shear strength of longitudinal tunnel segments, ensures the connection performance of longitudinal tunnel segments, and enhances overall integrity. Furthermore, it also includes new and old concrete shear keys, which are fixed to the side of the U-shaped reinforcing steel bars in the precast structure.

[0016] Beneficial effects: It increases the contact area between new and old concrete, forming shear keys after the concrete is poured in place, thus improving the mechanical properties of the structure. The introduction and application of shear keys between new and old concrete can increase the contact area, forming a tongue-and-groove joint between the two concrete layers, thereby increasing shear resistance.

[0017] Furthermore, the new and old concrete shear keys include 2-4, which are evenly distributed on the side where the U-shaped reinforcing bars are located in the precast structure.

[0018] Furthermore, the inverted T-shaped cross-section and the prefabricated structural part are integrally formed.

[0019] A construction method for prefabricated assembled arched open-cut tunnel composite joints includes the following steps: S1: The tunnel segments are manufactured in the prefabrication plant. The ends of the tunnel segments are prefabricated into inverted T-shaped sections, and U-shaped steel bars are embedded in the tunnel segments as reinforcing bars. S2: Transport the tunnel segments to the site and assemble them using a crane. The U-shaped steel bars of the prefabricated part are arranged in a cross pattern. After the inverted T-shaped web is lapped, the locking bolts are inserted into the pre-embedded sleeves. S3: Tie longitudinal short bars on the intersecting U-shaped steel bars; S4: Concrete is poured in the cast-in-place area on the assembled inverted T-shaped web; S5: After the concrete reaches the required strength, waterproof membrane is applied to the joint; S6: Backfill the tunnel segments with soil and compact it layer by layer. Attached Figure Description

[0020] Figure 1 A three-dimensional rendering of a prefabricated, assembled arched open-cut tunnel composite joint structure. Figure 2 A front view of a prefabricated, assembled arched open-cut tunnel composite joint structure; Figure 3 A top view of a prefabricated, assembled arched open-cut tunnel composite joint structure; Figure 4 This is a schematic diagram of the precast tunnel segments on the left. Figure 5 This is a schematic diagram of the precast tunnel segments on the right. Figure 6 A schematic diagram of the casting process for the cast-in-place area; Figure 7 A step-by-step diagram of a construction method for a prefabricated, assembled arched open-cut tunnel composite joint structure. Figure 8 This is a cross-sectional schematic diagram of a second embodiment of a prefabricated arched open-cut tunnel composite joint structure; Figure 9 yes Figure 8 Enlarged diagram of point A in the middle. Detailed Implementation

[0021] The following detailed description illustrates the specific implementation method: The markings in the accompanying drawings include: longitudinal shear key 1, U-shaped reinforcing bar 2, inverted T-shaped section 3, bolt handhole 4, L-shaped section 5, precast structural part 6, shear key between new and old concrete 7, longitudinal short bar 8, cast-in-place area 9, first channel 10, second channel 11, filter screen 111, detection ball 12, locking bolt 13, contact platform 131, and puncture needle 132.

[0022] Example 1 is attached. Figure 1-3 As shown, a prefabricated arched open-cut tunnel composite joint structure includes tunnel segments (hereinafter referred to as prefabricated segments), and the joint structure allows two tunnel segments to be assembled and spliced ​​together. (See attached diagram) Figure 4-5 As shown, schematic diagrams of the left and right precast tunnel segments are displayed respectively. The tunnel segment includes: a precast structural part 6 and eight U-shaped reinforcing bars 2. The precast structural part 6 is square. The free ends of the U-shaped reinforcing bars 2 are cast and embedded in the precast structural part 6. The bent ends of the U-shaped reinforcing bars 2 extend out to one side of the precast structural part 6. That is, the U-shaped reinforcing bars 2 of the left precast tunnel segment extend from the right side, and the U-shaped reinforcing bars 2 of the right precast tunnel segment extend from the left side. During assembly, the U-shaped reinforcing bars 2 of the left and right precast tunnel segments correspond one-to-one and overlap each other.

[0023] The bent end of the U-shaped reinforcing bar 2 is shown in the attached figure. Figure 4-5The tunnel segments are evenly spaced as shown. The system also includes an inverted T-shaped section 3, which is fixedly connected to the precast structural section 6. The web of the inverted T-shaped section 3 is located at the bottom of the U-shaped reinforcing bars 2. An L-shaped section is also fixed to the web of the inverted T-shaped section 3. The L-shaped section is used for overlapping adjacent tunnel segments. The L-shaped section is positioned between two U-shaped reinforcing bars 2 located in the middle. In use, the L-shaped sections of the left and right precast segments overlap. Bolt holes 4 are provided on the L-shaped section, and these holes are angled. They are used for fixing the two precast structural sections 6 together with bolts. A diagram showing the completed fixing is attached. Figure 3 As shown. The U-shaped reinforcing bar 2 is perpendicular to the web surface of the inverted T-section 3 and extends beyond the web of the inverted T-section 3. In this design, the extension is 1 / 3 of the web width. When the two precast structural parts 6 are assembled, the U-shaped reinforcing bars 2 on the two precast structural parts 6 overlap. It also includes several longitudinal short bars 8. When the two precast structural parts 6 are assembled, the longitudinal short bars are fixedly connected to the U-shaped reinforcing bars 2 on the two precast structural parts 6 respectively. In this design, the longitudinal short bars 8 are tied to the U-shaped reinforcing bars 2 with wire, so that the U-shaped reinforcing bars 2 of the left and right precast segments are fixed. When the two precast structural parts 6 are assembled, the space above the inverted T-section 3 is the cast-in-place area 9. After the two precast structural parts 6 are fixed, concrete is cast in place. The effect diagram after cast-in-place is shown in the figure. Figure 6 As shown.

[0024] As attached Figure 4 As shown, in the precast structural section 6, a longitudinal shear key 1 is fixed to the side adjacent to the face where the U-shaped reinforcing bar 2 is located. It also includes new and old concrete shear keys 7, of which three are evenly distributed on the side of the precast structural section 6 where the U-shaped reinforcing bar 2 is located. The inverted T-shaped section 3 and the precast structural section 6 are integrally formed.

[0025] The specific implementation method of this scheme is as follows: The construction of the composite joint is divided into two stages. In the first stage, the tunnel segments are prefabricated into inverted T-shaped sections 3 at the ends in the prefabrication plant, and the reinforcing bars 2 use U-shaped bars. These are transported to the site and assembled using a crane. The U-shaped bars of the prefabricated parts are arranged in a crisscross pattern. After the inverted T-shaped web is lapped, locking bolts are inserted into the pre-embedded sleeves, and then reinforced with short and long bars. After the bars are tied, the left and right segments are poured. After the concrete strength reaches the required level, waterproof membrane is placed at the joint to improve the waterproof performance between the segments. Then, backfilling is carried out and compacted layer by layer. This also relates to a construction method for a prefabricated assembled arched open-cut tunnel composite joint applicable to the above-mentioned joint, including the following steps: S1: The tunnel segments are manufactured in the prefabrication plant. The ends of the tunnel segments are prefabricated into inverted T-shaped sections, and U-shaped steel bars are embedded in the tunnel segments as reinforcing bars. S2: Transport the tunnel segments to the site and assemble them using a crane. The U-shaped steel bars of the prefabricated part are arranged in a cross pattern. After the inverted T-shaped web is lapped, the locking bolts are inserted into the pre-embedded sleeves. S3: Tie longitudinal short bars on the intersecting U-shaped steel bars; S4: Concrete is poured in the cast-in-place area on the assembled inverted T-shaped web; S5: After the concrete reaches the required strength, waterproof membrane is applied to the joint; S6: Backfill the tunnel segments with soil and compact it layer by layer.

[0026] Example 2 The difference between Example 2 and Example 1 is as follows: Figure 8-9 As shown, an inclined first channel 10 is provided on the precast segment on the right. The bottom of the first channel 10 is connected to the bolt hand hole 4. The first channel 10 is constricted. A second channel 11 is also provided, which is inclined. The upper end of the second channel 11 is connected to the bottom end of the first channel 10, and the other end is located at the bottom of the precast segment on the left. The two parts of the second channel 11 on the left and right precast segments cooperate and are connected. The contact point between the end of the first channel 10 and the upper end of the second channel 11 is the minimum diameter of the first channel 10 and the second channel 11. After installation, a detection ball 12 is inserted through the opening at the upper end of the first channel 10. The detection ball 12 is made of rubber. The material of the detection ball 12 can be selected by those skilled in the art according to actual operation, ensuring that the detection ball can be pierced by the locking bolt 13. The detection ball 12 is filled with liquid pigment. The diameter of the detection ball 12 is larger than the minimum diameter of the first channel 10 but smaller than the maximum diameter of the first channel 10, so that it fits precisely at the connection point between the first channel 10 and the bolt hand hole 4. After aligning the left and right precast segments, the locking bolts 13 are screwed into the bolt holes 4 on the left precast segment and into the bolt holes 4 on the right precast segment, thus locking the two precast segments. The locking bolts 13 are as shown in the attached figure. Figure 9 As shown, a contact platform 131 is provided at the tail end. The projection of the contact platform 131 is an inverted trapezoid. The lower bottom surface of the contact platform 131 is fixed to the tail end of the locking bolt 13. A puncture needle 132 is fixed around the side of the contact platform 131. The length of the puncture needle does not exceed the upper bottom surface of the contact platform 131. A filter screen 111 is fixed at the bottom of the second channel 11. The filter holes of the filter screen 111 are smaller than 1 / 3 and larger than 1 / 4 of the bottom diameter of the second channel. This is used to prevent the broken detection ball 12 from falling out of the second channel. At the same time, the broken detection ball 12 can be pulled out from the filter holes. That is, the punctured detection ball 12 is deformed by pulling and then pulled out from the filter holes.

[0027] In actual installation, the left precast segment is first fixed, then the right precast segment is moved closer to it and the two segments are joined together. Air is blown into the first channel 10, and the gas exits from the outlet of the second pipe 11, blowing out impurities from both channels. A detection ball 12 is then placed in the first channel 10 and slides along the first channel 10 to the bottom of the bolt hand hole 4. The locking bolt 13 is then screwed in. The installer can determine whether the locking bolt 13 is properly tightened by the tactile change when it contacts the detection ball 12. Alternatively, a person skilled in the art can install a corresponding sensor on the contact platform 131 to detect whether the bolt is tightened to the contact position by the pressure change on the contact platform 131. After tightening to the contact position, tighten the locking bolt 13 to the final position, with a tightening angle of 360°-720°, i.e., one to two turns. As the locking bolt 13 is pushed forward, the contact platform 131 compresses and deforms the detection ball 12. Then, the puncture needle 132 contacts the detection ball 12. As the locking bolt 13 rotates, the detection ball 12 will be punctured at multiple points. The puncture needle 132 has four needles to ensure that the internal pigment can flow out. When tightening the locking bolt 13 to the final position, start counting down. If liquid flows out within 10 seconds, the two prefabricated blocks on the left and right are aligned. This is because, usually, the two prefabricated blocks are not aligned because the right side is lower than the left side (the left side is fixed first, and then the right side is movable during installation). If they are not aligned, the pigment will be blocked at the contact position of the first and second channels. At this time, it can be disassembled and adjusted, and then air can be blown into the channel again to blow away the impurities. The detection ball 12 can be reinserted and the above operation repeated until the requirements are met.

[0028] When the locking bolt 13 is continuously rotated while in contact with the detection ball 12, it will puncture the ball, and the pigment inside will flow out along the second channel 11. Construction workers can determine whether the two precast segments are aligned by observing whether pigment flows out of the second channel 11. Simultaneously, the detection ball 12 also serves as a guide, restricting the screwing state of the locking bolt 13. During pouring, concrete is poured layer by layer from bottom to top. When pouring above the opening of the first channel 10, concrete enters from the opening of the first channel 10, flows through the first channel 10, and flows out from the second channel 11. Workers can determine whether the two precast segments have shifted before pouring during assembly by observing whether concrete flows out of the second channel 11. In other words, the installation status of the two precast segments is checked through both the detection ball 12 and the concrete flow, preventing displacement and potential safety hazards. The concrete in the two channels can be used to re-pour the two channels, avoiding voids that could affect the stability of the structure. Meanwhile, since the bottom of the bolt handhole 4 is connected to the first channel 10, when concrete flows downward into the first channel 10, it can also enter the bolt handhole 4 from the bottom, filling the gap between the bolt handhole 4 and the locking bolt 13, further reducing the possibility of the two precast segments loosening during later use due to the gap. Furthermore, when the concrete flows into the second channel 11, part of the concrete can be blocked by the punctured detection ball 12, preventing concrete from flowing directly out of the second channel and causing waste.

[0029] The above are merely embodiments of the present invention. The invention is not limited to the fields covered by these embodiments. Commonly known structures and characteristics in the solutions are not described in detail here. Those skilled in the art are aware of all common technical knowledge in the field prior to the application date or priority date, are able to access all existing technologies in that field, and have the ability to apply conventional experimental methods prior to that date. Those skilled in the art can, under the guidance of this application, improve and implement this solution in combination with their own capabilities. Some typical known structures or methods should not be obstacles for those skilled in the art to implement this application. It should be noted that those skilled in the art can make several modifications and improvements without departing from the structure of the present invention. These should also be considered within the scope of protection of the present invention, and will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A prefabricated, assembled arched open-cut tunnel composite joint structure, comprising tunnel segments, characterized in that: An inclined first channel and a second channel are provided on the tunnel segment. The first channel is narrowed. The upper end of the second channel is connected to the bottom end of the first channel. A detection ball filled with liquid pigment is placed in the first channel. A locking bolt with a puncture needle is used to puncture the detection ball while locking the tunnel segment, so that the pigment flows out to indicate the alignment status. The tunnel segment includes a filter screen at the bottom of the second channel to prevent the punctured detection ball from falling out. The tunnel segment comprises: a prefabricated structural section and several U-shaped reinforcing bars. The prefabricated structural section is square, with the free ends of the U-shaped reinforcing bars cast and fixed within the prefabricated structural section. The bent ends of the U-shaped reinforcing bars extend out to one side of the prefabricated structural section, and the bent ends of the U-shaped reinforcing bars are evenly distributed. It also includes an inverted T-shaped section, which is fixedly connected to the prefabricated structural section. The web of the inverted T-shaped section is located at the bottom of the U-shaped reinforcing bars. An L-shaped section is also fixed to the web of the inverted T-shaped section. The L-shaped section is used for overlapping between adjacent tunnel segments. The L-shaped section is located between two U-shaped reinforcing bars in the middle position. The structure includes bolt holes for fixing two precast structural sections together with bolts. These bolt holes are embedded in sleeves between adjacent segments. The U-shaped reinforcing bars are perpendicular to the web of the inverted T-shaped section and extend beyond it. When the two precast structural sections are joined, the U-shaped reinforcing bars overlap. The structure also includes several longitudinal short bars, which are fixedly connected to the U-shaped reinforcing bars on each of the two precast structural sections. The space above the inverted T-shaped section is a cast-in-place area when the two precast structural sections are joined. After the two precast structural sections are fixed, concrete is poured in place. The structure also includes shear keys between new and old concrete sections, which are fixed to the side of the U-shaped reinforcing bars within the precast structural section.

2. The prefabricated assembled arched open-cut tunnel composite joint structure according to claim 1, characterized in that: The bolt handhole is set at an angle.

3. The prefabricated assembled arched open-cut tunnel composite joint structure according to claim 1, characterized in that: In the precast structure section, longitudinal shear keys are also fixed on the side adjacent to the surface where the U-shaped reinforcing steel bars are located.

4. The prefabricated assembled arched open-cut tunnel composite joint structure according to claim 1, characterized in that: The shear keys between the old and new concrete include 2-4, which are evenly distributed on the side where the U-shaped reinforcing bars are located in the precast structure.

5. The prefabricated assembled arched open-cut tunnel composite joint structure according to claim 1, characterized in that: The inverted T-shaped cross section and the prefabricated structure are integrally formed.

6. A construction method for a prefabricated assembled arched open-cut tunnel composite joint as described in any one of claims 1-5, characterized in that: Includes the following steps: S1: The tunnel segments are fabricated in the prefabrication plant, with the ends of the tunnel segments prefabricated into inverted T-shaped sections, and U-shaped reinforcing bars are embedded in the tunnel segments as load-bearing reinforcements; S2: The tunnel segments are transported to the site and assembled using a crane. The U-shaped reinforcing bars of the prefabricated parts are arranged in a crisscross pattern. After the inverted T-shaped web is lapped, the locking bolts are inserted into the embedded sleeves; S3: Longitudinal short bars are tied to the crisscrossing U-shaped reinforcing bars; S4: Concrete is poured in the cast-in-place area on the assembled inverted T-shaped web; S5: After the concrete reaches the required strength, waterproof membrane is applied to the joint; S6: Backfill the tunnel segments with soil and compact it layer by layer.

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