Compressed air energy storage flexible sealing stiff concrete lining structure of coal mine tunnel and construction method of compressed air energy storage flexible sealing stiff concrete lining structure

Abstract

The invention discloses a coal mine tunnel compressed air energy storage flexible sealing stiff concrete lining structure and a construction method thereof, and relates to the technical field of waste coal mine underground space utilization and compressed air energy storage, the coal mine tunnel compressed air energy storage flexible sealing stiff concrete lining structure comprises a combined steel plate layer, a spraying layer, geotechnical cloth and a plurality of flexible sealing air bags connected in series, the invention provides an efficient and safe novel structural system and a construction method for implementing large-scale compressed air energy storage by using the abandoned coal mine tunnel.

Description

Technical Field

[0001] The present invention relates to the technical field of the utilization of underground space in abandoned coal mines and compressed air energy storage technology, and particularly to a flexible sealed rigid concrete lining structure for compressed air energy storage in coal mine roadways and its construction method. Background Art

[0002] To meet the needs of large-scale application of renewable energy and the green transformation of the energy structure, compressed air energy storage (CAES) technology has become an important energy storage method for solving the problems of intermittent renewable energy fluctuations such as wind energy and solar energy due to its high efficiency, safety, and environmental protection characteristics. The construction cost of traditional artificial gas storage caverns is high and the construction is complex. Therefore, using abandoned coal mine rock roadways and chambers for compressed air energy storage can give full play to the advantages of the underground space resources in abandoned coal mines and achieve low-cost and high-efficiency energy storage, with broad application prospects. However, compared with hard rock chambers excavated manually, the surrounding rock of coal mine roadways is generally softer and the in-situ stress is lower, which are unfavorable conditions for compressed air energy storage, making the popularization and application of the existing steel plate (sealing layer)-concrete lining structure in compressed air energy storage in underground coal mine spaces face challenges. There is an urgent need for a new type of sealed load-bearing structure form that can adapt to the conditions of underground coal mine spaces and can appropriately share the load of the surrounding rock to improve the overall stability and load-bearing capacity of the gas storage cavern.

[0003] Sealing performance is the core requirement of high-pressure gas storage caverns. Traditional sealing methods mainly include steel plate sealing layers and polymer sealing layers, but both have obvious limitations. Although the steel plate sealing layer has good airtightness, the welding construction is complex, the cost is high, and the yield deformation ability is low. It is difficult to adapt to the deformation of the surrounding rock and is prone to fatigue failure under the action of cyclic charging and discharging loads. The on-site welding of polymer sealing layers (such as rubber) is difficult, and they are prone to aging, peeling, or increased permeability under the action of long-term high pressure and underground environment, resulting in a decline in the sealing effect. In addition, there are still technical problems in the reasonable selection of slip layer materials at present, making the long-term reliability of the sealing system insufficient. At the same time, there are great difficulties in air leakage monitoring and maintenance of traditional gas storage caverns. It is difficult to quickly locate the leakage point, and the maintenance process is complex, affecting the long-term operation stability of the system. In addition, the environment of coal mine roadways is limited by the narrow space and complex layout. The construction of traditional steel plate sealing structures is restricted, and there are great difficulties in construction links such as material transportation and welding, affecting the construction quality and efficiency. The amount of steel plate welding work is large, and the construction quality control requirements are high, increasing the difficulty and cost of project implementation. At the same time, the replacement and maintenance of the sealing layer are complex, resulting in higher long-term operation costs.

[0004] In summary, the traditional methods have the following defects: 1. The sealing performance of existing compressed air energy storage chambers mainly depends on the steel plates set on the innermost layer of the chambers. However, although steel has good sealing performance, there are many problems and disadvantages in its actual application. First of all, the cost of steel plates is relatively high, increasing the engineering cost. Secondly, the yield deformation ability of steel plates is relatively low (only about 0.2%), making it difficult to adapt to the deformation of surrounding rocks, especially under the energy storage conditions in the underground space of abandoned coal mines where the surrounding rocks are soft and have large deformations. In the case of cracks in the concrete lining, the steel plates may be embedded in the cracks, affecting the sealing effect. In addition, during the air release process, the steel plates may undergo yield failure, and under the cyclic load of repeated charging and discharging, fatigue damage may also occur. Especially in special scenarios such as abandoned coal mine roadways with complex spatial layouts and limited cross-sectional dimensions, it is difficult to transport steel plate materials, and on-site welding and installation are restricted, with a large amount of construction work and high quality control requirements, thus increasing the difficulty and risk of project implementation.

[0005] 2. In the traditional gas storage structure, the surrounding rock is the main or even the only carrier to bear the high internal gas pressure, while the role of ordinary concrete lining is mainly to transfer the load to the surrounding rock and make the stress and deformation uniform, and it may share a very small part of the load of the gas storage. However, the tensile strength of ordinary reinforced concrete is relatively low, and under the action of high internal pressure, there is a great risk of cracking in the lining concrete, which may affect the long-term stability and sealing performance of the gas storage.

[0006] 3. The composite structure of traditional gas storage usually consists of surrounding rock, concrete lining and steel plate sealing layer. However, there are huge challenges in constructing this three-layer closely-fitted composite structure. The conventional construction process includes first welding the steel plate sealing layer, then formwork support, and finally pouring the concrete lining layer between the surrounding rock and the steel plate. However, in narrow coal mine roadways, this construction process will become extremely difficult, affecting the feasibility and efficiency of project implementation. In addition, in order to ensure the normal operation of the steel plate sealing layer, it is necessary to reduce the friction between the concrete lining and the steel plate, and usually a slip layer is applied between the two. However, there are still difficulties in the reasonable selection of slip layer materials (usually asphalt materials), and in the above construction process, how to ensure the integrity of the slip layer and prevent it from being damaged is a major technical problem. These problems increase the complexity of construction and the difficulty of quality control.

[0007] 4. There are great difficulties in locating and repairing air leakage in traditional gas storage, which are mainly reflected in the difficult accurate identification of leakage points, limited detection means and complex maintenance process, affecting the operation efficiency and safety of the gas storage. Summary of the Invention

[0008] To solve the problems existing in the prior art, the object of the present invention is to provide a flexible sealed rigid concrete lining structure for compressed air energy storage in coal mine roadways and its construction method, and the present invention provides an efficient and safe new structural system and construction method for implementing large-scale compressed air energy storage using abandoned coal mine roadways.

[0009] To achieve the above object, the technical solution adopted by the present invention is: a flexible sealed rigid concrete lining structure for compressed air energy storage in coal mine roadways, including a combined steel plate layer, a sprayed coating and a geotextile cloth sequentially arranged in the surrounding rock layer of the mining roadway, and a plurality of flexible sealed air bags arranged in series.

[0010] As a further improvement of the present invention, outer layer reinforcement bars are arranged on the outer side of the combined steel plate layer, inner layer reinforcement bars are arranged on the inner side of the combined steel plate layer, and the outer layer reinforcement bars and the inner layer reinforcement bars are fixed by stirrups.

[0011] As a further improvement of the present invention, the combined steel plate layer includes multiple steel plates, and adjacent steel plates are fixedly connected by splicing steel plates through bolts.

[0012] As a further improvement of the present invention, a first layer of shotcrete is provided between the surrounding rock layer and the outer layer reinforcement bars, a second layer of lining concrete is provided between the outer layer reinforcement bars and the combined steel plate layer, a third layer of lining concrete is provided between the combined steel plate layer and the inner layer reinforcement bars, and airtight concrete is poured near the steel plate splicing joints to improve the sealing performance of the structure.

[0013] As a further improvement of the present invention, the thickness of the first layer of shotcrete is 50mm - 150mm.

[0014] As a further improvement of the present invention, a drain pipe is provided in the first layer of shotcrete.

[0015] As a further improvement of the present invention, the sprayed coating and the geotextile cloth are made of EVA material and have a thickness of 3mm - 6mm.

[0016] As a further improvement of the present invention, anchor nails are buried around the mining roadway.

[0017] As a further improvement of the present invention, a plurality of the flexible sealed air bags are connected by pressure pipelines.

[0018] The present invention also discloses a construction method of the flexible sealed rigid concrete lining structure for compressed air energy storage in coal mine roadways as described above, including: Step 1: Select a coal mine rock roadway for constructing a gas storage reservoir, and bury anchor nails around the mining roadway; Step 2: Spray a first layer of shotcrete on the surface of the surrounding rock layer of the mining roadway, and then support the outer layer reinforcement bars on the surface of the first layer of shotcrete; Step 3: Start connecting the composite steel plate layer at a preset distance from the outer layer of reinforcement. Then, reinforce the inner layer of reinforcement at equal distances. Pour the second layer of lining concrete between the outer layer of reinforcement and the composite steel plate layer, and pour the third layer of lining concrete between the composite steel plate layer and the inner layer of reinforcement. Pour airtight concrete near the steel plate splicing joints. Step 4: Spray a sprayed coating and geotextile on the surface of the inner layer of reinforcement, and serially set flexible sealing airbags in the innermost layer.

[0019] The present invention adopts three high-pressure air sealing barriers, including an integral rubber airbag (flexible sealing layer) in the innermost layer, EVA material sprayed on the surface of the reinforced concrete lining, and steel plates integrally cast in the concrete. Compared with the traditional single-layer steel plate seal, the three-layer seal structure of the present invention significantly improves the sealing reliability of the gas storage reservoir, reduces the risk of air leakage caused by material aging or construction defects, and greatly improves the sealing performance of the gas storage reservoir. In addition, the flexible airbag and EVA material are low-cost and convenient for construction, which can reduce the construction cost and construction difficulty at the same time.

[0020] By placing the steel plates in ordinary reinforced concrete and integrally casting to form a reinforced concrete lining, the present invention effectively improves the mechanical properties of the lining structure. The tensile strength and stiffness of the reinforced concrete are greatly improved compared with ordinary reinforced concrete, which can significantly reduce the cracking risk of the concrete. It can not only effectively transfer high internal pressure, but also share more loads, improve the long-term stability and safety of the structure, and ensure the long-term and efficient operation of the gas storage reservoir.

[0021] When constructing a gas storage reservoir in an abandoned coal mine roadway, according to the traditional gas storage reservoir design concept, steel plate welding and material transportation are restricted by space, with high construction difficulty and complex processes. The present invention reduces welding operations, lowers construction difficulty, shortens the construction period and cost by mechanically connecting steel plates in the concrete lining and combining with cast-in-place concrete to form an integral reinforced concrete lining. At the same time, a coiled geotextile is laid on the inner surface of the reinforced concrete as a protective layer for the sealing layer, improving the durability and reliability of the sealing system and further optimizing the construction process.

[0022] Adopting a modular sealing structure design, by connecting multiple independent airbags with pressure pipelines to make them independent sealing units, it can achieve zoned sealing and precise leakage detection. This design can shorten the leakage detection time and greatly improve the maintenance efficiency. In addition, since a single airbag can be independently replaced, it avoids the situation of large-scale repair required for the traditional gas storage reservoir system due to seal failure, reduces the maintenance cost, and greatly improves the maintainability and long-term operation stability of the system.

[0023] Traditional hard rock gas storage caverns rely on surrounding rocks to bear high internal pressure, while the present invention optimizes the load-bearing mode of the gas storage cavern by using steel fiber reinforced concrete lining to share part of the gas storage load. The high strength and low deformation characteristics of steel fiber reinforced concrete enable the thickness of the lining layer to be reduced under the same gas storage pressure, thereby increasing the gas storage space; under the same lining thickness, the maximum gas storage pressure can be increased, effectively improving the energy storage efficiency. It can increase the energy storage capacity of the gas storage cavern, providing a more efficient and safe optimized technical solution for the construction and utilization of a large-scale compressed air energy storage system using abandoned coal mine roadways.

[0024] The beneficial effects of the present invention are as follows: The present invention follows the basic design concept of "flexible sealing" for the lining chamber of compressed air energy storage, changes the traditional structure form of steel plate sealing layer - ordinary concrete lining, and proposes a new type of "compressed air energy storage chamber structure with flexible sealing layer - steel fiber reinforced concrete lining". This structure uses an integral flexible sealing layer (airbag) as the main sealing structure for high-pressure air, and at the same time moves the steel plate inward and places it in the concrete lining to form a steel fiber reinforced concrete lining. Utilizing the characteristics of high strength, large stiffness, and excellent crack resistance of steel fiber reinforced concrete, it reduces the risk of concrete cracking and the problem of crack propagation, and improves the load-bearing capacity of the lining structure. In addition, the steel plate integrally cast in the concrete (connected by mechanical means) can not only avoid the problems of large construction workload, difficult construction, and high cost of traditional welded steel plates, but also serve as the third sealing barrier for high-pressure air (the second sealing barrier is a polymer material sprayed on the inner wall of the concrete), further enhancing the sealing performance and structural stability of the gas storage cavern.

[0025] Through the above innovation of the sealing structure, the present invention can effectively overcome the challenges such as soft surrounding rocks (low elastic modulus) and low strength faced in the construction of high-pressure gas storage caverns in abandoned coal mine underground spaces (roadways), realize the design of a gas storage cavern system with reliable sealing, optimized load-bearing, convenient construction, and efficient maintenance, and provide an efficient and safe new structural system and construction method for implementing large-scale compressed air energy storage using abandoned coal mine roadways. Description of the Drawings

[0026] Figure 1 It is a schematic diagram of the reinforcement of the wall of an abandoned coal mine roadway in an embodiment of the present invention; Figure 2 It is a schematic diagram of propping up the outer layer of steel reinforcement and assembling the steel plates in an embodiment of the present invention; Figure 3 It is a schematic diagram of the compressed air energy storage flexible sealing steel fiber reinforced concrete lining structure of an abandoned coal mine roadway in an embodiment of the present invention; Figure 4 It is a schematic diagram of the assembled steel plate layer in an embodiment of the present invention; Figure 5 It is a schematic diagram of the flexible sealing airbag (in series) in an embodiment of the present invention; Figure 6This is a schematic cross-sectional view of the flexible seal rigid concrete lining structure for compressed air energy storage in abandoned coal mine roadways in the embodiments of the present invention.

[0027] Reference numerals: 1, surrounding rock stratum; 2, anchor bolts; 3, first layer of shotcrete; 4, drain pipe; 5, outer layer of reinforcement; 6, second layer of lining concrete; 7, composite steel plate layer; 8, third layer of lining concrete; 9, inner layer of reinforcement; 10, EVA material spray coating and geotextile; 11, flexible seal airbag; 12, stirrups; 701, bolts; 702, splicing steel plates. Specific embodiments

[0028] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0029] Embodiment As Figures 1-6 shown, a flexible seal rigid concrete lining structure for compressed air energy storage in coal mine roadways. In view of the defects of the existing gas storage structure in terms of sealing performance, construction difficulty and structural adaptability, this embodiment proposes a design including three high-pressure air seal barriers, including the integral flexible seal airbag 11 (flexible seal layer) at the innermost layer, the EVA material spray coating and geotextile 10 sprayed on the surface of the rigid concrete lining, and the composite steel plate layer 7 integrally cast in the concrete. These three seal barriers can not only effectively improve the sealing performance of the gas storage, but also overcome the problems of complex construction and high cost of the traditional steel plate seal layer. Among them, the flexible seal airbag 11 and EVA material are low-cost and convenient for construction, which can reduce the project cost and construction difficulty; the composite steel plate layer 7, as the third seal layer, not only enhances the sealing effect of the structure, but also can share the high internal pressure and restrain the deformation of the concrete, thereby improving the mechanical properties of the concrete, reducing its cracking risk, and enhancing the long-term stability and safety of the system.

[0030] An outer layer of reinforcement 5 is arranged on the outside of the composite steel plate layer 7, and an inner layer of reinforcement 9 is arranged on the inside of the composite steel plate layer 7. The outer layer of reinforcement 5 and the inner layer of reinforcement 9 are fixed by stirrups 12; specifically, the composite steel plate layer 7 includes multiple steel plates, and adjacent steel plates are fixedly connected by splicing steel plates 702 through bolts 701; a first layer of shotcrete 3 is provided between the surrounding rock stratum 1 and the outer layer of reinforcement 5, a second layer of lining concrete 6 is provided between the outer layer of reinforcement 5 and the composite steel plate layer 7, a third layer of lining concrete 8 is provided between the composite steel plate layer 7 and the inner layer of reinforcement 9, the thickness of the first layer of shotcrete 3 is 100 mm, and a drain pipe 4 is provided in the first layer of shotcrete 3.

[0031] The thickness of the EVA material spray coating and geotextile 10 is 5 mm, anchor bolts 2 are buried around the mining roadway, and multiple flexible seal airbags 11 are connected by pressure pipelines.

[0032] This embodiment also provides a construction method for the flexible-sealed rigid concrete lining structure of a coal mine roadway for compressed air energy storage as described above, including: First, select a suitable coal mine roadway for constructing a gas storage cavern. Bury anchor bolts 2 around the excavation roadway, then spray the first layer of shotcrete 3 on the surface of the surrounding rock layer of the excavation roadway. Next, set up the outer layer of reinforcement bars 5 on the surface of the first layer of shotcrete 3. After that, start connecting the composite steel plate layer 7 at a preset distance from the outer layer of reinforcement bars 5. Then, support the inner layer of reinforcement bars 9 at equal distances, and pour the second layer of lining concrete 6 and the third layer of lining concrete 8 between the outer layer of reinforcement bars 5 and the composite steel plate layer 7, and between the composite steel plate layer 7 and the inner layer of reinforcement bars 9 respectively. Finally, spray an EVA material spray coating and geotextile 10 on the surface of the inner layer of reinforcement bars 9, and serially set up flexible sealing airbags 11 in the innermost layer.

[0033] This embodiment aims at the defects of the steel plate sealing layer and ordinary reinforced concrete lining in the traditional gas storage cavern structure in terms of mechanical properties, sealing effect and construction complexity, and proposes an innovative structural design. By placing steel plates inside ordinary reinforced concrete and integrally casting to form rigid concrete lining, this structure makes full use of the superior properties of rigid concrete, such as high strength, large stiffness, restricting the deformation of concrete and limiting its cracking. While maintaining similar material conditions to the traditional steel plate sealing layer - ordinary reinforced concrete lining, the present invention significantly improves the mechanical properties of the lining structure, enabling it not only to efficiently transfer high internal pressure, but also to bear more loads, and at the same time effectively inhibiting the cracking of concrete. This innovative structural design concept breaks through the traditional sealing and load-bearing modes of gas storage caverns, forming a new gas storage cavern structure design method combining flexible sealing and combined load-bearing, providing a new solution for the safety, stability and construction convenience of gas storage caverns.

[0034] This embodiment aims at the defects of the existing technology in terms of construction complexity, difficulty in steel plate installation and protection of the sealing layer, and proposes an optimized gas storage cavern structure design. Aiming at the difficulties in the coal mine roadway space limitation, complex construction, and material transportation, steel plate welding, maintenance and replacement in the design of traditional hard rock gas storage caverns, an optimized construction and maintenance plan is proposed. By mechanically connecting steel plates in the concrete lining and combining with cast-in-place concrete to form a rigid concrete lining with excellent overall performance, the construction difficulty is effectively reduced, the welding operation is reduced, and the feasibility of project implementation is improved. In addition, a coiled geotextile is laid on the inner surface of the rigid concrete as a protective layer for the sealing layer, further enhancing the durability and reliability of the sealing system. This design scheme significantly optimizes the construction process, improves the convenience and efficiency of project implementation, reduces the construction difficulty, and provides a more feasible technical solution for the construction of gas storage cavern structures.

[0035] In view of the deficiencies of the prior art in terms of sealing reliability, leak detection, and maintenance difficulty, this embodiment proposes a modular sealing structure design. By connecting several integral airbags with appropriate capacities through pressure pipelines, each airbag becomes an independent gas sealing unit, achieving zonal sealing. This design can not only improve the sealing reliability of the system but also accurately locate the leak position by real-time monitoring of the pressure changes at the air inlet and outlet of each airbag, thus greatly enhancing the efficiency of fault detection. In addition, the modular design makes it more convenient to replace a single airbag without the need for large-scale disassembly and repair of the entire system, thereby reducing the maintenance cost and improving the maintainability and operational stability of the gas storage system.

[0036] In view of the challenges brought about by the relatively low strength and small stiffness of the surrounding rock when implementing compressed air energy storage in abandoned coal mine roadways, this embodiment proposes an optimized structural design, breaking through the load-bearing mode of traditional hard rock gas storage caverns that mainly rely on hard rock to withstand high internal gas pressure, and creatively putting forward the "combined load-bearing" design concept, that is, the designed steel fiber reinforced concrete lining shares part of the load caused by high gas pressure. Due to the high strength, large stiffness, and low deformation characteristics of steel fiber reinforced concrete, compared with traditional concrete linings, its cracking risk is lower and crack development is more restricted, which helps to improve the protection effect on the sealing layer. In addition, the steel fiber reinforced concrete lining has high strength and large stiffness. Under the same gas storage pressure, the thickness of the lining layer can be reduced, thereby increasing the gas storage space; while under the same lining thickness, the maximum gas storage pressure can be increased, thus enhancing the efficiency and energy storage capacity of the compressed air energy storage system.

[0037] Currently, there are mainly two traditional practices. One is steel plate sealing layer - concrete lining - surrounding rock, and the other is polymer sealing layer - concrete lining - surrounding rock. In both cases, the lining is ordinary concrete, and its main function is to transfer high internal gas pressure to the surrounding rock and achieve uniform deformation and stress. Therefore, in the previous design concepts, the surrounding rock is the main load-bearing component, while the design concept of this embodiment is that the steel fiber reinforced concrete and the surrounding rock jointly bear the load, which is a new "combined load-bearing" design concept.

[0038] The above-described embodiments only represent the specific implementation manners of the present invention, and their descriptions are relatively specific and detailed, but should not be construed as limiting the scope of the patent of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention.

Claims

1. A flexible sealed rigid concrete lining structure for compressed air energy storage in coal mine roadways, characterized in that, It includes a combined steel plate layer, a sprayed coating layer, a geotextile, and multiple serially arranged flexible sealing airbags that are successively arranged in the surrounding rock layer of the mining roadway.

2. The flexible sealed rigid concrete lining structure for compressed air energy storage in coal mine roadways according to claim 1, characterized in that An outer layer of steel reinforcement is arranged on the outer side of the combined steel plate layer, and an inner layer of steel reinforcement is arranged on the inner side of the combined steel plate layer. The outer layer of steel reinforcement and the inner layer of steel reinforcement are fixed by stirrups.

3. The flexible sealed rigid concrete lining structure for compressed air energy storage in coal mine roadways according to claim 2, wherein The combined steel plate layer includes multiple steel plates, and adjacent steel plates are fixedly connected by splicing steel plates through bolts.

4. The flexible sealed rigid concrete lining structure for compressed air energy storage in coal mine roadways according to claim 2, characterized in that A first layer of shotcrete is provided between the surrounding rock layer and the outer layer of steel reinforcement, a second layer of lining concrete is provided between the outer layer of steel reinforcement and the combined steel plate layer, a third layer of lining concrete is provided between the combined steel plate layer and the inner layer of steel reinforcement, and airtight concrete is poured near the steel plate splicing joints to improve the tightness of the structure.

5. The flexible sealed rigid concrete lining structure for compressed air energy storage in coal mine roadways according to claim 4, characterized in that, The thickness of the first layer of shotcrete is 50 mm - 150 mm.

6. The flexible sealed rigid concrete lining structure for compressed air energy storage in coal mine roadways according to claim 4, characterized in that, A drain pipe is provided in the first layer of shotcrete.

7. The flexible sealed rigid concrete lining structure for compressed air energy storage in coal mine roadways according to claim 1, wherein The sprayed coating layer and the geotextile are made of EVA material and have a thickness of 3 mm - 6 mm.

8. The flexible sealed rigid concrete lining structure for compressed air energy storage in coal mine roadways according to claim 1, characterized in that, Anchoring nails are buried around the mining roadway.

9. The flexible sealed rigid concrete lining structure for compressed air energy storage in coal mine roadways according to claim 1, wherein Multiple flexible sealing airbags are connected by pressure pipelines.

10. A construction method for a flexible sealed rigid concrete lining structure for compressed air energy storage in coal mine roadways as described in any one of claims 2-9, characterized in that, It includes: Step 1: Select a coal mine rock roadway for building a gas storage reservoir, and bury anchoring nails around the mining roadway; Step 2: Spray the first layer of shotcrete on the surface of the surrounding rock layer of the mining roadway, and then support the outer layer of steel reinforcement on the surface of the first layer of shotcrete; Step 3: Start connecting the combined steel plate layer at a preset distance from the outer layer of steel reinforcement, then support the inner layer of steel reinforcement at an equal distance, and pour the second layer of lining concrete and the third layer of lining concrete between the outer layer of steel reinforcement and the combined steel plate layer, and between the combined steel plate layer and the inner layer of steel reinforcement respectively, and pour airtight concrete near the steel plate splicing joints; Step 4: Spray the sprayed coating layer and the geotextile on the surface of the inner layer of steel reinforcement, and serially arrange flexible sealing airbags in the innermost layer.

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