A preset deformed underground artificial chamber structure system and construction method

Abstract

The application discloses a preset deformation underground artificial cavern structure system and a construction method, and belongs to the technical field of underground energy storage structure. In view of the problems of uncontrollable crack of the secondary lining structure of the compressed air energy storage underground cavern under the action of high internal pressure, poor effect of surrounding rock reinforcement and long construction period, a preset deformation concept is provided. The structure system comprises a surrounding rock reinforcement system, a preset deformation assembly type secondary lining structure and an inner lining sealing structure. The surrounding rock reinforcement system is provided with prestressed anchor cables aiming at the plastic zone in the operation period; the assembly type secondary lining structure is assembled by prefabricated segments, the segments are connected by elbow bolts and rear sealing steel plates of high ductility material, and a preset weak link is formed to guide and control crack development; and the inner lining sealing structure is filled with an asphalt layer between the secondary lining to eliminate the influence of uneven segments. The application realizes active control of crack position, has strong reinforcement pertinence, is high in construction efficiency, and is suitable for large compressed air energy storage, hydrogen storage and other high-pressure underground cavern projects.

Description

Technical Field

[0001] This invention belongs to the field of large-scale compressed air energy storage and integrated energy utilization technology, specifically relating to a pre-deformed underground artificial chamber structure system and construction method. Background Technology

[0002] Compressed air energy storage (CAES) technology is one of the key technologies for achieving large-scale, long-term energy storage. Among these technologies, the underground artificial chamber, as the gas storage container, is crucial for both structural safety and economic efficiency. Currently, the design internal pressure of large-scale CAES underground chambers typically reaches 18-20 MPa, placing extremely high demands on the structure's load-bearing capacity and sealing performance.

[0003] In existing technologies, underground artificial chambers typically employ a structural form of "initial support + cast-in-place reinforced concrete secondary lining + steel inner lining sealing". However, under immense and cyclical internal pressure, this structural system suffers from the following insurmountable drawbacks: 1. Difficulty in crack control: Under high pressure, the cast-in-place reinforced concrete secondary lining will crack comprehensively, and the location and width of the cracks are random and uncontrollable. When local cracks develop too large, the inner steel lining sealing layer will undergo plastic deformation or even tear due to stress concentration, leading to high-pressure gas leakage. This is the core problem currently restricting the development of high-pressure gas storage chambers.

[0004] 2. Poor structural tightness: Current processes often use a steel lining as a formwork for pouring secondary lining concrete. Due to the limited underground space, concrete vibration is difficult, and the collapse and shrinkage of the arch concrete make it difficult to form a tight contact between the secondary lining concrete and the steel lining, and between the secondary lining and the surrounding rock. Subsequent grouting also cannot completely fill the voids, resulting in an unclear force transmission path and a complex stress state.

[0005] 3. Inadequate surrounding rock reinforcement: Current initial support mainly relies on system anchors and shotcrete, lacking targeted reinforcement of the plastic zone of the surrounding rock during operation. In addition, consolidation grouting is usually carried out without secondary lining, and the grout is prone to flow away from the free face under high pressure, greatly reducing the reinforcement effect and failing to effectively mobilize the self-supporting capacity of the surrounding rock.

[0006] 4. Long construction period: Cast-in-place reinforced concrete secondary lining requires a long curing time to reach the design strength, and the overlapping of various construction processes is restricted, resulting in a long overall construction period and poor economic efficiency.

[0007] To address the aforementioned issues, existing patents have proposed prefabricated lining structures, such as improving structural performance by applying circumferential prestress or setting up polymer sealing layers. However, these solutions either have complex structures and are difficult to construct, or fail to fundamentally solve the coupling problem between uncontrollable cracking and non-closed structural fit. Therefore, there is an urgent need for a new underground chamber structural system that has a clear structure, is feasible to construct, and can effectively control cracking while ensuring airtightness. Summary of the Invention

[0008] The purpose of this invention is to overcome the above-mentioned defects in the prior art and provide a pre-deformed underground artificial chamber structure system and construction method to solve the problem of difficulty in crack control during the construction of underground artificial chambers in the prior art.

[0009] This invention provides a pre-deformed underground artificial cavern structure system, including... The surrounding rock reinforcement system is installed within the surrounding rock of the chamber.

[0010] A pre-deformable prefabricated secondary lining structure is installed inside the surrounding rock reinforcement system. It comprises multiple precast reinforced concrete segments, which are assembled circumferentially and axially along the chamber to form the secondary lining structure. Adjacent precast reinforced concrete segments are connected by connecting components whose stiffness is less than that of the segments, thus creating pre-designed weak points. By artificially reducing the stiffness of the connecting nodes, they act as "fuse" within the entire secondary lining structure. Under immense internal pressure, structural deformation and cracking will preferentially occur and develop at these pre-designed weak points, thereby preventing uncontrollable wide cracks from forming in the main body of the segments or at unexpected locations. This achieves proactive planning and control of structural damage patterns, fundamentally solving the problem of random and uncontrollable cracking in cast-in-place secondary linings, ensuring that the location and width of cracks are within the design limits, and protecting the integrity of the inner sealing structure.

[0011] The inner sealing structure is located on the inner side of the pre-deformable prefabricated secondary lining structure, and is used to withstand the internal air pressure and transmit the pressure to the pre-deformable prefabricated secondary lining structure and the surrounding rock reinforcement system.

[0012] Furthermore, the surrounding rock reinforcement system includes: Prestressed anchor cables are arranged according to the boundary of the plastic zone of the surrounding rock during the operation period as determined by numerical simulation, and are used to reinforce the rock mass in the plastic zone.

[0013] Consolidation grouting steel pipes are inserted into the loosened zone of the surrounding rock around the chamber through grouting holes pre-drilled in the precast reinforced concrete segments for consolidation grouting. A reinforced mesh shotcrete leveling layer is placed between the chamber excavation surface and the pre-deformed prefabricated secondary lining structure.

[0014] Numerical simulations were used to pre-identify potential failure zones (plastic zones) in the surrounding rock during the operational phase, and high-prestressed anchor cables were employed for active reinforcement, directly strengthening the areas most in need of reinforcement. Simultaneously, the completed secondary lining structure was used as a "template" and "reaction wall," and grouting of the loosened rock zone was performed via pre-embedded steel pipes, ensuring sufficient grout pressure and preventing grout loss. The surrounding rock reinforcement was targeted and highly efficient, effectively mobilizing the self-supporting capacity of the surrounding rock and reducing the load acting on the secondary lining; the quality of consolidation grouting was fundamentally guaranteed, and the integrity and stiffness of the surrounding rock were significantly improved.

[0015] Furthermore, the connection component includes: Elbow bolts, inserted into the bolt holes of adjacent precast reinforced concrete segments, are used to provide circumferential connection force.

[0016] The post-sealing steel plate is welded to the embedded steel plate of the adjacent precast reinforced concrete segments and covers the gaps between the segments. Both the elbow bolts and the post-sealing steel plate are made of high-ductility materials, and their mechanical properties are designed to preferentially deform under structural stress. The high-ductility elbow bolts and post-sealing steel plate have a deformation capacity far exceeding that of ordinary reinforcing bars. When the structure is subjected to internal pressure, they will be the first to enter the elastic deformation stage, adapting to the relative displacement and rotation between the segments through stretching and bending, thereby precisely achieving the "pre-set deformation." Simultaneously, the welded and sealed post-sealing steel plate not only constitutes a connection node but also acts as a "backing plate" for the inner lining sealing structure, providing continuous and smooth support and preventing the inner lining from sinking into the segment gaps and causing "crack failure," thus achieving precise guidance and control of cracks. The ingenious structure of the post-sealing steel plate combines the triple functions of connection, force transmission, and support for the sealing layer, simplifying the construction and improving reliability.

[0017] Furthermore, the inner liner sealing structure includes: An asphalt layer is filled between the pre-deformed prefabricated secondary lining structure and the sealing material layer to adapt to local unevenness on the secondary lining surface and transmit uniform pressure.

[0018] A sealing material layer, disposed inside the asphalt layer, is made of high-ductility steel plate or a flexible sealing material with fatigue resistance, durability, and airtightness. Asphalt, as a viscoelastic material, has fluidity under high temperature or pressure, and can fully fill any tiny steps and gaps that may exist after the secondary lining structure is assembled, forming a perfect contact interface. When internal pressure is applied, the asphalt layer can evenly transfer the pressure to the secondary lining, avoiding local stress concentration caused by point or line contact. This effectively overcomes the inherent disadvantage that the surface flatness of prefabricated structures cannot match that of cast-in-place structures, ensuring the uniformity of stress on the inner lining sealing layer, reducing the thickness requirements and cost of the sealing material, and improving the fatigue durability of the overall sealing system.

[0019] Furthermore, the precast reinforced concrete segments are assembled along the axial direction of the chamber using a continuous-joint assembly method. In areas with high circumferential tensile stress in the secondary lining, as determined by numerical simulation, the arc length of the precast segments is reduced, and the number of weak connection nodes between segments is increased. This continuous-joint assembly provides greater freedom for circumferential deformation, facilitating the smooth implementation of pre-set deformation. In high-stress areas, the density of weak nodes is equivalent to setting more "deformation joints" and "energy release points" in these areas, allowing for more precise release of enormous circumferential tensile stress, avoiding stress concentration, and resulting in a more refined and intelligent structural design. This allows for the non-uniform distribution of weak points according to stress requirements, optimizing the overall structural performance and material utilization rate.

[0020] This invention also provides a construction method for a pre-deformed underground artificial chamber structure system, comprising the following steps: Step 1: Grouting and preliminary support: Remove loose rock blocks, construct prestressed anchor cables, hang steel mesh and spray concrete to form the initial support leveling layer, and leave installation gaps.

[0021] Step 2: Secondary Lining Structure Installation: Assemble precast reinforced concrete segments to form the secondary lining structure. Grout the gap between the segments and the initial support leveling layer through the grouting holes of the segments. After the grouting strength reaches the standard, weld the back sealing steel plate between adjacent segments.

[0022] Step 3: Construction of asphalt layer and sealing layer: Install the sealing material layer on the inside of the secondary lining structure, and pour asphalt concrete into the gap between the sealing material layer and the secondary lining structure to form the asphalt layer.

[0023] Furthermore, in step 2, the precast reinforced concrete segments are circumferentially connected by elbow bolts, and a special trolley arm is used for the installation of the segments; after the grouting reaches 50% of the design strength, the trolley arm disengages and moves to the position of the next ring segment; after the grouting reaches 70% of the design strength, the welding of the post-sealing steel plate is carried out.

[0024] Furthermore, in step 3, a specially designed trolley arm is used to weld and install the sealing material layer in a complete ring; after the sealing material layer is precisely positioned, asphalt concrete is poured into the gap between the sealing material layer and the secondary lining structure; after the asphalt concrete reaches 50% of its design strength, the trolley arm detaches and moves forward to the next ring position.

[0025] Furthermore, in step 1, a 2-5cm gap is reserved in the initial shotcrete leveling layer to facilitate the installation of the secondary lining structure; and a drainage structure and monitoring elements are pre-installed inside the initial support structure.

[0026] Furthermore, in step 2, after welding is completed, the installation hand holes of the elbow bolts are backfilled with micro-expansion concrete.

[0027] The aforementioned construction method transforms the critical secondary lining structure from "cast-in-place underground" to "prefabricated on the ground and assembled underground," and utilizes a specially designed trolley arm for rapid and precise positioning and installation, achieving "dry construction." Phased strength control (50%, 70%) and the cyclical operation of the trolley arm enable streamlined operations for prefabricated secondary lining construction and subsequent processes (such as welding and asphalt grouting), significantly shortening underground work time, eliminating the concrete curing waiting period, and substantially reducing the construction cycle. The quality of ground prefabrication is controllable, avoiding common quality defects in underground concrete construction. The process is tightly integrated, resulting in high construction efficiency and low overall cost.

[0028] Compared with the prior art, the present invention has the following beneficial effects: 1. Active and controllable cracks: By pre-setting weak links at high-ductility connection nodes, the secondary lining structure is made to generate controllable deformation and cracks prior to these points under high pressure, avoiding the random and uncontrollable defects of cracks in cast-in-place structures and effectively protecting the integrity of the inner sealing layer.

[0029] 2. Precise and efficient surrounding rock reinforcement: Based on numerical simulation, the plastic zone during the operation period is determined, and prestressed anchor cables are used for targeted active reinforcement; after the secondary lining is completed, consolidation grouting is carried out, with sufficient grouting pressure and no loss, significantly improving the reinforcement quality.

[0030] 3. Uniform and reliable stress distribution of the sealing layer: The rear sealing steel plate serves as a backing plate for the steel lining, preventing it from sinking into the gaps between the segments and causing damage; the asphalt layer fills the uneven areas of the segments, ensuring uniform internal pressure transmission, avoiding stress concentration, reducing the thickness of the steel lining, and lowering costs.

[0031] 4. Short construction cycle and high quality: The secondary lining adopts ground prefabrication and underground assembly, eliminating the need for underground curing time and realizing assembly line operation; it avoids problems such as difficulty in vibration, curing, and quality defect detection of cast-in-place concrete, and has a high degree of standardization and good forming quality. Attached Figure Description

[0032] Figure 1 This is a cross-sectional schematic diagram of a pre-deformed underground artificial cavern structure system provided in an embodiment of the present invention.

[0033] Figure 2 This is a schematic diagram of the assembled secondary lining segments provided in an embodiment of the present invention.

[0034] Figure 3 This is a schematic diagram of the connection node of the prefabricated secondary lining structure provided in an embodiment of the present invention.

[0035] Figure 4 This is a schematic diagram of the end node of the prefabricated double-lining structure provided in an embodiment of the present invention.

[0036] The components include: 1. Bedrock outside the tunnel; 2. Initial support leveling layer; 3. Prefabricated secondary lining segment; 4. Asphalt layer; 5. Sealing structure layer; 6. Consolidation grouting steel pipe; 7. Prestressed anchor cable; 8. Boundary of plastic zone of surrounding rock during operation period (numerical simulation); 9. Prefabricated segment one; 10. Prefabricated segment two; 11. Bolt hole for connecting elbow between segments; 12. Hand hole for installing nut on connecting elbow between segments; 13. Embedded steel plate for prefabricated secondary lining segment; 14. Embedded anchor bar for prefabricated secondary lining segment; 15. Post-sealing steel plate; 16. V-groove connection weld. Detailed Implementation

[0037] The specific embodiments of the present invention are described below to enable those skilled in the art to understand the present invention. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes are obvious as long as they are within the spirit and scope of the present invention as defined and determined by the appended claims. All inventions utilizing the concept of the present invention are protected.

[0038] like Figure 1 As shown, this embodiment provides a pre-deformed underground artificial chamber structure system. The chamber is excavated in the bedrock 1 outside the chamber, with a designed diameter of approximately 15 meters, and is used for a large compressed air energy storage power station.

[0039] The structural system mainly consists of three parts: the surrounding rock reinforcement system, the pre-deformable prefabricated secondary lining structure, and the inner lining sealing structure.

[0040] The surrounding rock reinforcement system includes prestressed anchor cables 7, consolidated grouting steel pipes 6, and an initial support leveling layer 2. First, the mechanical response of the surrounding rock during the tunnel's operation period is analyzed using finite element numerical simulation software to accurately determine the boundary 8 of the plastic zone of the surrounding rock during operation. The prestressed anchor cables 7 are precisely positioned and constructed according to this boundary 8, penetrating deep into the plastic zone rock mass and providing active restraint force. The initial support leveling layer 2 is a layer of sprayed concrete, approximately 15-20 cm thick, after the steel mesh is installed. Its surface is smoothed to provide a basically flat base for subsequent structures and is tightly connected to the ends of the prestressed anchor cables 7, forming an integrated load-bearing system.

[0041] The prefabricated modular secondary lining structure is assembled from multiple factory-prefabricated reinforced concrete segments. For example... Figure 2 , Figure 3 and Figure 4 As shown, the tunnel segments are divided into precast segment 1 (9) and precast segment 2 (10), which are assembled along the axial direction of the tunnel using a continuous joint. Each segment has a precast steel plate 13 embedded in its edge, and is firmly anchored to the main body of the segment by precast anchor bars 14.

[0042] The connection between adjacent segments is the key to this invention. The specific connection structure is as follows: First, elbow bolts made of high-ductility materials (such as Q345D grade steel) are inserted into the elbow bolt holes 11 between the segments, and the nuts are tightened in the elbow nut mounting holes 12 between the segments to provide initial circumferential preload. Then, on the outside of the segment joint, a rear sealing steel plate 15 (also made of high-ductility material) is aligned with the embedded steel plates 13 on the two adjacent segments, and fully welded using a V-groove weld 16. The cross-sectional dimensions of the elbow bolts and the rear sealing steel plate 15 are precisely calculated to ensure that their overall stiffness is less than that of the segment body, thus becoming a pre-designated weak point that preferentially deforms and cracks under structural stress. In areas with high predicted circumferential tensile forces (such as the waist of the chamber), the arc length of the segments can be reduced accordingly, and such connection nodes can be added.

[0043] The inner lining sealing structure comprises an asphalt layer 4 and a sealing structure layer 5. The sealing structure layer 5 is constructed from 8mm thick high-ductility steel plates, assembled and welded in sections using a specially designed trolley arm to form a complete airtight barrier. A gap of approximately 5-8cm exists between the sealing structure layer 5 and the inner prefabricated secondary lining segment 3. This gap is filled with hot asphalt to form a dense asphalt layer 4. After cooling and hardening, the asphalt layer 4 can withstand pressure and, through its plastic flow, perfectly conforms to the secondary lining surface, compensating for any unevenness.

[0044] The construction method of the structural system described in this embodiment is described in detail below.

[0045] Step 1: Trimming and initial support of the burr.

[0046] After the chamber was excavated, loose rock blocks on the tunnel walls were first manually removed. Then, based on the plastic zone boundary 8 determined by numerical simulation, anchor cable holes were drilled, and prestressed anchor cables 7 were installed and tensioned. After tensioning, steel mesh was hung and connected to the ends of the anchor cables 7. Subsequently, C25 concrete was sprayed in layers to form the initial support leveling layer 2. During spraying, the surface flatness was strictly controlled, and a gap of about 3cm was reserved for the subsequent installation of the secondary lining segments 3. Drainage pipes and stress and displacement monitoring elements were pre-embedded during the construction of the initial support leveling layer 2.

[0047] Step 2: Installation of the secondary lining structure.

[0048] The precast reinforced concrete tunnel segments 3 are transported to the tunnel chamber. For example... Figure 2As shown, a specially designed hydraulic lifting and gripping trolley arm is used to position the tunnel segments sequentially. First, the bottom segment is installed, followed by the side and top segments, forming a closed ring. Elbow bolts are inserted and initially tightened after every two adjacent segments are installed. After the entire ring is assembled, all bolts are finally tightened. Then, through the pre-drilled grouting holes on the segments, consolidation grouting steel pipes 6 are inserted to pressure grout the gap between the segments and the initial support leveling layer 2, while simultaneously consolidation grouting is performed on the loose ring around the chamber. When the grout strength reaches 50% of the design strength, the trolley arm can detach from the currently stabilized segment ring and move to the next ring position to begin assembly. Once the grout strength of the current ring reaches 70% of the design strength, as... Figure 3 As shown, the post-sealing steel plate 15 is welded to permanently seal the gaps between the segments. After welding, micro-expansion concrete is used to backfill and compact the manholes 12 for installing the elbow nuts between the segments, and then smooth the surface.

[0049] Step 3: Construction of asphalt layer and sealing layer.

[0050] After the secondary lining structure installation and post-treatment are completed, the inner lining sealing structure will be constructed. For example... Figure 1 As shown, using another specially designed trolley arm, the prefabricated arc-shaped sealing structure layer 5 (high-ductility steel plate) is hoisted, positioned, and spliced ​​piece by piece to finally form a complete ring of sealed steel lining. All circumferential and longitudinal welds are welded and inspected as required. During the installation of the steel lining, precise positioning brackets ensure that the designed gap between it and the secondary lining segment 3 is uniform. After a section of steel lining (e.g., 3-4 rings) is installed and inspected, temporary injection holes are opened at the bottom of the steel lining, and hot-mix asphalt concrete with a temperature controlled at 180-220℃ is injected into the gap between the steel lining and the secondary lining. The injection is carried out slowly from one end to the other to ensure that air is expelled. After the asphalt concrete cools and reaches 50% of its design strength, the trolley arm can detach from that section of steel lining and move to the next section for cyclical operation. In this way, a continuous, dense asphalt layer 4 with a preset deformation capacity is formed.

[0051] Through the aforementioned structure and construction method, the underground chamber constructed in this embodiment, when subjected to cyclic internal pressure up to 20 MPa, exhibits controllable micro-deformation and cracking at the pre-designed weak connection nodes, effectively releasing circumferential tensile stress, while the main body of the tunnel segments and the sealing structure layer 5 remain intact. The asphalt layer 4 ensures uniform pressure transmission, and the post-sealing steel plate 15 provides a solid backing for the steel lining, jointly guaranteeing the long-term safety and airtightness of the structure.

Claims

1. A pre-deformable underground artificial chamber structure system, characterized in that, include: The surrounding rock reinforcement system is installed within the surrounding rock of the chamber; A pre-deformable prefabricated secondary lining structure is set inside the surrounding rock reinforcement system, including multiple precast reinforced concrete pipe segments (3). The multiple precast reinforced concrete pipe segments (3) are assembled along the circumferential and axial directions of the chamber to form a secondary lining structure. Adjacent precast reinforced concrete pipe segments (3) are connected by connecting components, and the stiffness of the connecting components is less than the stiffness of the precast reinforced concrete pipe segments (3). The inner sealing structure is located on the inner side of the pre-deformable prefabricated secondary lining structure, and is used to withstand the internal air pressure and transmit the pressure to the pre-deformable prefabricated secondary lining structure and the surrounding rock reinforcement system.

2. The pre-deformed underground artificial chamber structure system according to claim 1, characterized in that, The surrounding rock reinforcement system includes: Prestressed anchor cables (7) are arranged according to the boundary (8) of the plastic zone of the surrounding rock during the operation period determined by numerical simulation; The consolidation grouting steel pipe (6) is inserted into the loosened ring of the surrounding rock around the chamber through the grouting hole reserved on the precast reinforced concrete pipe segment (3); A reinforced concrete sprayed layer (2) is set between the excavation surface of the chamber and the pre-deformed prefabricated secondary lining structure.

3. The pre-deformed underground artificial chamber structure system according to claim 1, characterized in that, The connection component includes: Elbow bolts are inserted into the connecting elbow bolt holes (11) of adjacent precast reinforced concrete pipe segments (3); The back sealing steel plate (15) is welded to the prefabricated secondary lining structure embedded steel plate (13) of the adjacent precast reinforced concrete pipe segment (3) and covers the gap between the pipe segments.

4. The pre-deformed underground artificial chamber structure system according to claim 1, characterized in that, The inner lining sealing structure includes: The asphalt layer (4) is filled between the pre-deformed prefabricated secondary lining structure and the sealing structure layer (5) to adapt to local unevenness on the secondary lining surface and transmit uniform pressure. A sealing structure layer (5) is disposed inside the asphalt layer (4).

5. The pre-deformed underground artificial chamber structure system according to claim 1, characterized in that, The precast reinforced concrete pipe segments (3) are assembled along the axial direction of the chamber using a through-joint method. In areas where the circumferential tension of the secondary lining is large, as determined by numerical simulation, the arc length of the precast pipe segments is reduced and the number of weak connection nodes between the pipe segments is increased.

6. A construction method for an underground artificial chamber structure system with pre-deformation as described in any one of claims 1 to 5, characterized in that, Includes the following steps: Step 1: Grouting and preliminary support: Remove loose rock blocks, construct prestressed anchor cables (7), hang steel mesh and spray concrete to form the initial support leveling layer (2), and reserve installation gaps; Step 2: Installation of secondary lining structure: Assemble precast reinforced concrete pipe segments (3) to form secondary lining structure. Grout the gap between the pipe segments and the initial support leveling layer (2) through the grouting holes of the pipe segments. After the grouting strength reaches the standard, weld the back sealing steel plate (15) between adjacent pipe segments. Step 3: Construction of asphalt layer and sealing layer: Install sealing structure layer (5) on the inside of the secondary lining structure, and pour asphalt concrete into the gap between sealing structure layer (5) and secondary lining structure to form asphalt layer (4).

7. The construction method according to claim 6, characterized in that, In step 2, the precast reinforced concrete segments (3) are connected circumferentially by elbow bolts. A special trolley arm is used to operate when installing the segments. After the grouting reaches 50% of the design strength, the trolley arm disengages and moves to the next segment position. After the grouting reaches 70% of the design strength, the welding of the back sealing steel plate (15) is carried out.

8. The construction method according to claim 6, characterized in that, In step 3, a special trolley arm is used to weld and install the sealing structure layer (5) in a complete ring; after the sealing structure layer (5) is precisely positioned, asphalt concrete is poured into the gap between the sealing structure layer (5) and the secondary lining structure. Once the asphalt concrete reaches 50% of its design strength, the trolley arm disengages and moves forward to the next ring position.

9. The construction method according to claim 6, characterized in that, In step 1, a gap of 2-5cm is reserved in the initial shotcrete leveling layer (2) to facilitate the installation of the secondary lining structure; and a drainage structure and monitoring elements are pre-installed inside the initial support structure.

10. The construction method according to claim 6, characterized in that, In step 2, after welding is completed, the inter-segment connection elbow nut installation hand hole (12) of the elbow bolt is backfilled with micro-expansion concrete.

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