Main line tunnel and jacking pipe T-joint construction method

Abstract

The invention discloses a main line tunnel and jacking pipe T-joint construction method, and belongs to the technical field of underground engineering construction. The main line tunnel and jacking pipe T-joint construction method is characterized by comprising the following steps that S1, construction preparation is conducted; s2, a sleeve is installed; s3, opening a tunnel portal; s4, a plugging sleeve is filled; s5, pipe jacking construction; s6, the sleeve is dismantled; s7, shell discarding and cutting; s8, blocking a tunnel portal; and S9, concrete ring beam construction and seam wrapping construction in the pipe jacking shell are conducted, and the effect of improving the T-joint quality of the main pipe tunnel and the engineering safety is achieved.

Description

Technical Field

[0001] The present application relates to the technical field of underground engineering construction, and in particular to a main line tunnel and pipe jacking T-connection construction method. Background Art

[0002] In urban underground pipe network projects, with the continuous development and expansion of cities, the efficient use of underground space has become particularly important to meet the increasingly complex infrastructure construction needs. The traditional pipe network connection method mainly relies on working wells on the ground, but due to the dense underground pipelines in the city and the limitations of various buildings, this traditional connection method faces many challenges, especially in the central areas of cities with heavy traffic and dense buildings. Therefore, exploring efficient underground pipe network connection methods has become a research hotspot in this field.

[0003] At present, in order to achieve effective connection of underground pipelines, two common construction methods are usually used in the industry. One is the traditional ground operation method, that is, digging a working well on the ground and connecting the pipelines through the working well. This method is suitable for areas with ample space and less traffic pressure. However, in the central area of ​​the city, the limitations of ground space make this method difficult to operate. Another commonly used method is to directly connect underground. This method mainly uses pre-designed connection ports to directly connect pipelines underground to reduce the impact on the ground environment. However, this method also faces challenges brought by complex geological conditions.

[0004] However, in the above-mentioned existing technical solutions, when the diameters of the main pipeline and the branch pipeline are similar, directly opening a connection port in the main tunnel will result in a large opening ratio, which not only destroys the geometric shape of the original main tunnel and reduces its geometric stability, but also has a serious impact on its force balance. In particular, the pipe segments near the interface will experience significant changes in mechanical properties, such as changes in internal forces such as axial force, shear force and bending moment, which will cause local deformation of the pipe segments and may even cause instability in the surrounding soil, increasing the risk of leakage and soil and sand gushing during construction. Therefore, how to achieve safe T-connection of pipelines while ensuring the force performance of the main pipeline has become a key issue that needs to be solved urgently. Summary of the invention

[0005] In order to improve the T-connection quality of the main tunnel and the engineering safety, the present invention provides a main line tunnel and jacking pipe T-connection construction method.

[0006] The present invention provides a main line tunnel and pipe jacking T-connection construction method using the following technical solutions: A main line tunnel and jacking pipe T-connection construction method, comprising the following steps: S1. Construction preparation: Reinforce the soil around the main tunnel construction site and set up support equipment at the construction site; S2. Install the sleeve: place the sleeve in the main tunnel so that the axis of the sleeve is perpendicular to the axis of the main tunnel, and then weld and fix the sleeve to the steel pipe segments around the preset tunnel portal; S3, opening the tunnel door: removing the steel pipe segments at the preset positions to open the tunnel door; S4. Fill and seal the sleeve: inject grout into the sleeve to maintain pressure, and seal the end of the sleeve away from the tunnel; S5, Pipe jacking construction: The pipe jacking machine is constructed and pushed into the sleeve. At the same time, the gap between the main tunnel and the pipe jacking shell is blocked, and the welding and blocking of the last pipe jacking section and the tail stop of the pipe jacking are completed; S6. Remove the sleeve: After the water stop meets the requirements, remove the sleeve; S7, shell cutting: dismantle and move the equipment outside the jacking shell in the main tunnel, and then cut the jacking shell; S8, tunnel door sealing: sealing the gap between the jacking pipe shell and the tunnel door; S9. Construction of concrete ring beam inside the jacking pipe shell and sealing of joints.

[0007] By adopting the above technical solution, before the pipe jacking machine enters the main tunnel, it is first necessary to carry out construction in the main tunnel, reinforce the soil around the portal to be opened, and set up supporting equipment around the portal opening position in the main tunnel to reinforce the main tunnel and reduce the possibility of deformation of the main tunnel. Secondly, install a sleeve at the portal position inside the main tunnel, open the portal, and then fill the sleeve with mortar to ensure the pressure inside the sleeve, reduce the possibility of soil loosening and then pouring into the sleeve, and thus improve the T-joint quality and engineering safety of the main tunnel.

[0008] Then the pipe jacking machine is directly put into the sleeve until it reaches the end position and then stops. Then the gap between the pipe jacking machine casing and the outside of the main tunnel is filled to achieve the effect of water stopping and reinforcement, improve the quality of the main tunnel T-joint and engineering safety. At the same time, the tail of the pipe jacking is welded to the last pipe segment of the pipe jacking.

[0009] After removing the sleeve, the pipe jacking equipment in the main tunnel also needs to be removed, leaving only the pipe jacking casing, cutting the redundant casing in the main tunnel, and filling and sealing all the gaps after removing the sleeve to further enhance the effect of water-stopping reinforcement. Finally, the ring beam construction and the mouth construction are carried out. After completion, the entire project of the main line tunnel and the pipe jacking T-connection is completed. This main line tunnel and pipe jacking T-connection construction method can effectively ensure the safety and stability of the pipe jacking construction process, improve construction efficiency, and can be constructed even in a complex environment of underground pipelines. It also ensures the construction quality through precise sealing and water-stopping measures, reducing the workload of later maintenance.

[0010] Preferably, in step S1, soil reinforcement includes freezing reinforcement of the soil around the tunnel portal, and three circles of freezing holes are arranged in the soil freezing reinforcement, two circles within the jacking pipe range and one circle outside the jacking pipe range, and freezing pipes for freezing the soil are inserted in the freezing holes.

[0011] By adopting the above technical solution, freezing reinforcement measures were implemented on the soil around the tunnel portal and freezing pipes were inserted into the freezing holes, which effectively enhanced the stability of the soil structure and ensured the safety and reliability of the subsequent construction process.

[0012] Preferably, in step S1, soil reinforcement also includes grouting reinforcement on the side of the main tunnel away from the portal, and the pipe segments at the construction site of the main tunnel are all porous grouting pipe segments.

[0013] By adopting the above technical solution, grouting reinforcement measures are added on the side of the main tunnel away from the portal, and it is ensured that the pipe segments used at the main tunnel construction site have a porous grouting function, which effectively enhances the overall structural stability of the side of the main tunnel away from the portal and improves construction safety.

[0014] Preferably, in step S2, the sleeve is hollow.

[0015] By adopting the above technical solution, the hollow sleeve is convenient for removing the portal segments, and when removing the segments, although some soil falls, the soil will be directly in the sleeve and will not affect the construction.

[0016] Preferably, in step S4, a blocking plate is used to block the end away from the tunnel entrance, and the blocking plate abuts against the inner wall of the main tunnel.

[0017] By adopting the above technical solution, the arc surface of one end of the sleeve away from the tunnel portal is arranged and abutted against the inner wall of the main tunnel, so that the sleeve can be installed in the main tunnel more stably, the reliability of the installation is improved, and the displacement or shaking caused by improper installation is reduced, thereby ensuring the stability during the subsequent construction of the jacking shell.

[0018] Preferably, in step S4, the sleeve is filled with a mixture of mortar and bentonite.

[0019] By adopting the above technical solution, the mixture of mortar and bentonite inside the sleeve is combined with the external soil of the main tunnel, and the pressure difference with the external soil will not be too large, and the jacking of the pipe jacking machine can be guaranteed, further ensuring the safety and stability during the construction process.

[0020] Preferably, in step S5, a plurality of grouting holes are circumferentially arranged in the jacking pipe shell, and grouting is performed into the gap between the jacking pipe shell and the main tunnel through the grouting holes of the jacking pipe shell, so as to achieve sealing and water stopping.

[0021] By adopting the above technical solution, the sealing and water-stopping effect of the gap between the jacking pipe shell and the main tunnel is effectively enhanced, and the construction quality is improved.

[0022] Preferably, in step S5, the last ring of the jacking pipe segment is provided with a steel pipe segment with a variable ring width, and the other jacking pipe segments are all steel concrete pipe segments with fixed lengths.

[0023] By adopting the above technical solution, after the pipe jacking machine enters the main tunnel, the distance between the tail of the jacking pipe and the jacking pipe section is uncertain. When connecting with the jacking pipe, the variable ring width steel pipe section can adapt to different size differences and improve the connection accuracy and stability; other jacking pipe sections are fixed-length steel concrete pipe sections to ensure the structural strength and sealing performance during the jacking process.

[0024] Preferably, in step S8, inside the main tunnel, arc-shaped blocking steel plates are welded to the main tunnel steel pipe segments and the jacking pipe shell to block the gap between the tunnel portal and the jacking pipe shell, and then the gap between the blocking steel plates and the soil is filled with grouting.

[0025] By adopting the above technical solution, the arc-shaped sealing steel plate can effectively improve the sealing of the gap between the tunnel portal and the jacking pipe shell; and then the gap between the sealing steel plate and the soil is filled with grouting, which further enhances the overall stability and waterproof performance of the structure.

[0026] In summary, the present invention has the following beneficial effects: Before the pipe jacking machine enters the main tunnel, it is necessary to first carry out construction in the main tunnel, reinforce the soil around the portal to be opened, and set up supporting equipment around the portal opening position in the main tunnel to reinforce the main tunnel and reduce the possibility of deformation of the main tunnel. Secondly, it is necessary to open the portal, install a sleeve in the portal, and fill the sleeve with mortar to ensure the pressure inside the sleeve, reduce the possibility of soil loosening and then pouring into the sleeve, and thus improve the T-joint quality and engineering safety of the main tunnel. After the pipe jacking machine enters the sleeve, it will stop until it reaches the end position. Then fill the gap between the pipe jacking machine casing and the outside of the main tunnel to achieve the effect of water stopping and reinforcement, and improve the T-joint quality and engineering safety of the main tunnel. At the same time, weld the tail of the pipe jacking pipe to the last section of the pipe jacking pipe. After removing the sleeve, it is also necessary to remove the pipe jacking equipment in the main tunnel, leaving only the pipe jacking machine casing, cut the excess casing in the main tunnel, and fill and seal all the gaps after the sleeve is removed to further enhance the effect of water stopping and reinforcement. Finally, the ring beam construction and the mouth construction are carried out. After completion, the entire project of the main line tunnel and the top pipe T-connection is completed. This main line tunnel and top pipe T-connection construction method can effectively ensure the safety and stability of the top pipe construction process, improve construction efficiency, and ensure the construction quality through precise sealing and water-stopping measures, reducing the workload of later maintenance. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The present invention is a flow chart of a main line tunnel and pipe jacking T-connection construction method.

[0028] Figure 2 This is a schematic diagram of the location of the freezing curtain and the main tunnel.

[0029] Figure 3 This is a schematic diagram of the position of the sleeve and the main tunnel.

[0030] Figure 4 It is a schematic diagram of the structure of the pipe jacking machine pushing into the interior of the sleeve.

[0031] Figure 5 It is a schematic diagram of the structure after the gap between the top pipe and the main tunnel is sealed.

[0032] Figure 6 It is a schematic diagram of the structure after pipe jacking cutting.

[0033] Figure 7 It is a schematic diagram of the structure after the construction of the internal ring beam of the jacking pipe.

[0034] Figure 8 yes Figure 7 Enlarged schematic diagram of part A.

[0035] Description of reference numerals: 1. Main tunnel; 11. Portal; 2. Refrigeration curtain; 3. Support equipment; 4. Sleeve; 5. Jacking pipe section; 6. Jacking pipe shell; 7. Sealing steel plate; 8. Concrete ring beam. DETAILED DESCRIPTION

[0036] The present invention is further described in detail below in conjunction with the accompanying drawings.

[0037] A main line tunnel and jacking pipe T-connection construction method, referring to Figure 1 , including the following steps: S1, construction preparation; S2, installation of sleeve 4; S3, opening of tunnel door 11; S4, filling and sealing sleeve 4; S5, jacking construction; S6, removal of sleeve 4; S7, abandoned shell cutting; S8, sealing of tunnel door 11; S9, construction of concrete ring beam 8 in jacking shell 6 and sealing of joints.

[0038] Further, see Figure 2 In step S1, construction preparation includes reinforcing the soil around the construction site of the main tunnel 1 and setting up supporting equipment 3 at the construction site.

[0039] Reference Figure 2 and Figure 3, soil reinforcement includes freezing reinforcement of the soil around the portal 11. Specifically, three circles of freezing holes are arranged for freezing reinforcement, two circles within the top pipe range and one circle outside the top pipe range. Freezing pipes are inserted into the freezing holes to complete the freezing reinforcement of the soil, and the freezing curtain 2 is fan-shaped. In addition, it also includes grouting reinforcement on the side of the main tunnel 1 away from the preset portal 11. Multi-porous grouting pipe segments are set in the front and back five rings of the main tunnel 1 construction site to facilitate grouting construction. In this way, the stability of the soil around the portal 11 can be significantly improved, and the possibility of soil collapse during construction can be reduced, thereby ensuring the safety and stability of subsequent construction.

[0040] The stability of the soil around the tunnel portal 11 during construction is ensured by freezing and grouting the soil.

[0041] Reference Figure 2 Specifically, the supporting device 3 is provided with five continuous rings of supporting reaction force systems on both sides of the preset portal 11 of the main tunnel 1.

[0042] Further, see Figure 3 In step S2, the sleeve 4 is installed by placing the sleeve 4 in the main tunnel 1, with its axis perpendicular to the axis of the main tunnel 1, and then welding one end of the sleeve 4 to the steel pipe sheet around the tunnel door 11. The sleeve 4 is hollow.

[0043] Further, see Figure 3 In step S3, opening the tunnel door 11 means removing the steel pipe segments at the preset positions to open the tunnel.

[0044] In this embodiment, the specific operation of opening the tunnel door 11 is to use special disassembly tools, such as a hand winch and a gas cutting device, to remove the steel pipe segments at predetermined positions to form the tunnel door 11.

[0045] The outer diameter of the main tunnel 1 segment is 3500mm, the inner diameter is 3000mm, and the ring width is 1200mm. The outer diameter of the top pipe is about 2400mm, and the diameter of the portal 11 is about 2700mm.

[0046] Further, see Figure 3 In step S4, filling the plugging sleeve 4 means injecting grout into the sleeve 4 to maintain pressure, and using a plugging plate to plug the end face of the sleeve 4 away from the tunnel portal 11. The plugging plate is in close contact with the inner wall of the main tunnel 1, and a support structure is provided between the center of the end face of the sleeve 4 away from the tunnel portal 11 and the main tunnel 1 to enhance the stability of the contact surface.

[0047] The sleeve 4 abuts against the inner wall of the main tunnel 1, so that the sleeve 4 can be installed in the main tunnel 1 more stably, improving the reliability of the installation, and reducing the displacement or shaking caused by improper installation, ensuring the stability of the subsequent jacking shell 6 during construction.

[0048] Reference Figure 3 The grouting and pressure maintenance of sleeve 4 is to fill the sleeve 4 with a mixture of mortar and bentonite. The mixture is in contact with the external soil of the main tunnel 1, and the mixture inside the sleeve 4 has the same pressure as the external soil, which can ensure the advancement of the pipe jacking machine and further ensure the safety and stability during the construction process.

[0049] The mixture is fluid and can fill the gaps in the soil outside the main tunnel 1, thereby achieving physical contact between the surfaces of the mixture and the soil outside the main tunnel 1. That is, friction will be generated between the surface of the mixture and the soil, and this friction can help the mixture maintain a good connection with the soil.

[0050] Further, see Figure 4 and Figure 5 In step S5, the jacking construction refers to the construction of the jacking machine and the jacking into the sleeve 4. At the same time, the gap between the main tunnel 1 and the jacking shell 6 is blocked, and the welding and blocking of the last jacking pipe section 5 and the tail stop of the jacking pipe are completed.

[0051] After the pipe jacking machine enters the sleeve 4, it stops until the pipe jacking machine reaches the end position. The position where the diameter of the sleeve 4 changes is the end position of the pipe jacking machine.

[0052] Reference Figure 5 The jacking shell 6 of the jacking machine is provided with multiple grouting holes in the circumferential direction. During the jacking process of the jacking machine, the reserved grouting holes in the jacking shell 6 are used to grout the gap between the jacking shell 6 and the main tunnel 1 to seal the water, so as to ensure that a dense contact surface is formed between the jacking shell 6 and the sleeve 4.

[0053] Reference Figure 5 The last ring of the jacking pipe shell 6 is provided with a steel pipe section with a variable ring width, and the remaining jacking pipe sections 5 are all steel concrete pipe sections with fixed lengths.

[0054] After the pipe jacking machine enters the main tunnel 1, the distance between the tail of the pipe jacking and the pipe section 5 is uncertain. When connecting with the pipe jacking, the variable-width steel pipe section can adapt to different size differences and improve the connection accuracy and stability; the other pipe jacking sections 5 are all fixed-length steel-concrete pipe sections to ensure the structural strength and sealing performance during the pipe jacking process.

[0055] Further, see Figure 6 In step S6, the sleeve 4 is removed safely after the water stop meets the requirements. During the operation, the sleeve 4 is removed using a special disassembly tool, such as a hand chain hoist or a special disassembly tool for gas cutting equipment, to avoid affecting the integrity of the main tunnel structure. In this process, it is necessary to ensure that the main tunnel will not be damaged when the sleeve 4 is removed.

[0056] Further, see Figure 6 In step S7, the shell cutting refers to dismantling and moving the equipment outside the jacking shell 6 in the main tunnel 1, and then cutting the jacking shell 6.

[0057] Further, see Figure 6 and Figure 7 In step S8 , the tunnel door 11 is sealed by sealing the gap between the jacking pipe shell 6 and the tunnel door 11 .

[0058] Reference Figure 6 and Figure 8 After the sleeve 4 is removed, a gap is left between the top pipe shell 6 and the tunnel door 11, and a sealing steel plate 7 is welded inside the main tunnel 1 to seal the gap. Specifically, arc-shaped steel plates are welded in sections along the circumference of the top pipe, so that the arc-shaped sealing steel plate 7 is fixedly connected to the steel pipe segment of the main tunnel 1 and the top pipe shell 6. The thickness of the sealing steel plate 7 is about 30 mm, and the material is corrosion-resistant stainless steel. The arc-shaped design can improve the fit with the main tunnel 1. The side of the sealing steel plate 7 away from the inside of the main tunnel 1 is filled with grout to ensure that the gap is completely closed.

[0059] The arc-shaped plugging steel plate 7 can effectively improve the sealing performance of the gap between the tunnel door 11 and the top pipe shell 6. Grouting is then performed to fill the gap between the plugging steel plate 7 and the soil, further enhancing the overall stability and waterproof performance of the structure.

[0060] Further, see Figure 7 In step S9, the concrete ring beam 8 is constructed in the jacking shell 6 and the joints are covered. The concrete ring beam 8 is constructed in the jacking shell 6, and the joints are covered to form a strong structural connection between the jacking shell 6 and the main tunnel. In this embodiment, the concrete ring beam 8 is made of C40 and P10 concrete materials. The joints are covered with corrosion-resistant rubber materials to enhance the sealing performance and ensure the stability and durability of the overall structure.

[0061] The principle of use of this application is as follows: before the pipe jacking machine enters the main tunnel 1, it is first necessary to carry out construction in the main tunnel 1, reinforce the soil around the portal 11 to be opened, and set support equipment 3 around the opening position of the portal 11 in the main tunnel 1 to reinforce the main tunnel 1 and reduce the possibility of deformation of the main tunnel 1. Secondly, it is necessary to open the portal 11, install the sleeve 4 in the portal 11, and fill the sleeve 4 with mortar to ensure the pressure in the sleeve 4, reduce the possibility of soil loosening and then pouring into the sleeve 4, and thus improve the T-joint quality of the main tunnel and the safety of the project.

[0062] After the pipe jacking machine enters the sleeve 4, it stops until it reaches the end position. Then fill the gap between the pipe jacking machine casing and the outside of the main tunnel 1 to achieve the effect of water stopping and reinforcement, improve the quality of the main tunnel T-joint and engineering safety. At the same time, weld the tail of the pipe jacking pipe to the last pipe segment of the pipe jacking pipe.

[0063] After removing the sleeve 4, the pipe jacking equipment in the main tunnel 1 also needs to be removed, leaving only the pipe jacking casing, cutting the redundant casing in the main tunnel 1, and filling and sealing all the gaps after the sleeve 4 is removed to further enhance the effect of water-stopping reinforcement. Finally, the ring beam construction and the mouth construction are carried out. Through multi-step construction measures, the effective connection between the pipe jacking and the main line tunnel is finally achieved.

[0064] The main line tunnel and jacking pipe T-connection construction method can effectively ensure the safety and stability during the jacking pipe construction process, improve construction efficiency, and ensure the construction quality through precise sealing and water-stopping measures, reducing the workload of subsequent maintenance.

[0065] The embodiments of this specific implementation method are all preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Therefore, any equivalent changes made based on the structure, shape, and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A main line tunnel and jacking pipe T-connection construction method, characterized in that: The following steps are involved: S1. Construction preparation: The soil around the construction site of the main tunnel (1) is reinforced and supporting equipment (3) is installed at the construction site, wherein the soil reinforcement includes freezing reinforcement of the soil around the tunnel portal (11); S2, installing the sleeve (4): placing the sleeve (4) in the main tunnel (1) so that the axis of the sleeve (4) is perpendicular to the axis of the main tunnel (1), and then welding the sleeve (4) to the steel pipe segments around the preset tunnel door (11); S3, opening a tunnel door (11): removing the steel pipe segments at the preset positions to open a tunnel; S4, filling and plugging the sleeve (4): injecting grout into the interior of the sleeve (4) to maintain pressure, and plugging the end face of the sleeve (4) away from the tunnel door (11); S5, jacking construction: the jacking machine is constructed and pushed into the sleeve (4), and at the same time, the gap between the main tunnel (1) and the jacking shell (6) is blocked, and the welding and blocking of the last jacking pipe section (5) and the tail stop of the jacking pipe are completed; S6, removing the sleeve (4): after the water stop meets the requirements, the sleeve (4) is removed; S7, shell cutting: dismantling and moving the equipment outside the jacking shell (6) in the main tunnel (1), and then cutting the jacking shell (6); S8, sealing the tunnel door (11): sealing the gap between the jacking pipe shell (6) and the tunnel door (11); S9, construction of the concrete ring beam (8) inside the jacking pipe shell (6) and construction of sealing the joints.

2. A main line tunnel and jacking pipe T-connection construction method according to claim 1, characterized in that: In step S1, three circles of freezing holes are arranged for soil freezing reinforcement, two circles within the jacking pipe range and one circle outside the jacking pipe range, and freezing pipes for freezing the soil are inserted into the freezing holes.

3. A main line tunnel and jacking pipe T-connection construction method according to claim 1, characterized in that: In step S1, soil reinforcement also includes grouting reinforcement on the side of the main tunnel (1) away from the preset tunnel portal (11), and the pipe segments at the construction site of the main tunnel (1) are all porous grouting pipe segments.

4. A main line tunnel and jacking pipe T-connection construction method according to claim 1, characterized in that: In step S2, the sleeve (4) is hollow.

5. A main line tunnel and jacking pipe T-connection construction method according to claim 1, characterized in that: In step S4, a blocking plate is used to block the end away from the tunnel door (11), and the blocking plate abuts against the inner wall of the main tunnel (1).

6. A main line tunnel and jacking pipe T-connection construction method according to claim 1, characterized in that: In step S4, the sleeve (4) is filled with a mixture of mortar and bentonite.

7. A main line tunnel and jacking pipe T-connection construction method according to claim 1, characterized in that: In step S5, a plurality of grouting holes are provided in the circumferential direction of the jacking pipe shell (6), and grouting is performed into the gap between the jacking pipe shell (6) and the main tunnel (1) through the grouting holes of the jacking pipe shell (6), thereby achieving sealing and water stopping.

8. A main line tunnel and jacking pipe T-connection construction method according to claim 1, characterized in that: In step S5, the last ring of the jacking pipe section (5) is provided with a steel pipe section with a variable ring width, and the other jacking pipe sections (5) are all steel concrete pipe sections with fixed length.

9. A main line tunnel and jacking pipe T-connection construction method according to claim 1, characterized in that: In step S8, arc-shaped steel plates are welded in sections along the circumference of the top pipe inside the main tunnel (1), so that the arc-shaped blocking steel plates (7) are fixedly connected to the steel pipe segments of the main tunnel (1) and the top pipe shell (6), the gap between the tunnel door (11) and the top pipe shell (6) is blocked, and then the side of the blocking steel plates (7) away from the inside of the main tunnel (1) is filled with grout.

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