Design method and construction method of compressed air energy storage underground artificial cavern sealing system

Abstract

This application discloses a design and construction method for a sealing system of an underground artificial cavern for compressed air energy storage, relating to the field of computer-aided architectural design. The technical solution includes: obtaining cavern engineering design parameters; establishing a numerical model to simulate the inflation condition and obtain the maximum tensile strain of the reinforced concrete lining; determining the selection of carbon fiber fabric based on strain compatibility conditions; calculating the load sharing of each structure and the circumferential stress of the carbon fiber composite layer based on the theory of multi-layer thick-walled cylinders; calculating the conditions under different combinations of surrounding rock conditions and thicknesses to form a circumferential stress dataset, which is then analyzed and classified using a clustering algorithm; finally, determining the thickness and number of carbon fiber composite layers from the classification based on the actual surrounding rock conditions. This application achieves digitalization, precision, and intelligence in sealing layer design, ensuring optimal structural safety and economy from the source.

Description

Technical Field

[0001] This application belongs to the field of computer-aided design technology, specifically relating to a design and construction method for a compressed air energy storage underground artificial cavern sealing system. Background Technology

[0002] The sealing system of compressed air energy storage underground artificial caverns is crucial for their long-term safe and stable operation. Its design must ensure reliability and economy under high pressure, cyclic loads, and complex geological conditions. Currently, the design of sealing structures in this field mainly relies on simplified analytical calculations based on classical elasticity formulas and engineers' experience-based judgment. In practice, designers typically obtain the physical and mechanical parameters of the surrounding rock from geological survey reports and, combined with a preset safety factor, calculate the stress and deformation of the lining and sealing layer manually or using basic calculation tools to determine the material selection and approximate thickness. This method has formed a certain technical paradigm in engineering practice, and its calculation process is relatively clear, providing a foundation for preliminary design.

[0003] However, this traditional design method gradually reveals its inherent limitations when facing complex projects such as high-pressure compressed air energy storage caverns, which have extremely high requirements for sealing performance, lightweight materials, and long-term fatigue life. First, simplified analytical models struggle to accurately simulate the complex interactions, nonlinear deformation coordination, and local effects such as construction joints among the surrounding rock, lining, and carbon fiber composite layers. This leads to biases in the prediction of key state quantities such as the maximum tensile strain of the lining, resulting in a lack of precise strain coordination basis for the selection of sealing materials (such as carbon fiber cloth), potentially leading to insufficient performance or excessive conservatism. Second, the design process fails to adequately consider the spatial variability of surrounding rock parameters, various working condition combinations, and the dispersion of material properties. It fails to fully utilize numerical simulation and big data analysis for systematic calculation and optimization of multiple parameters and scenarios, resulting in the final determined sealing layer thickness and layup scheme often based on limited working conditions, lacking guarantees of robustness and optimal economy. Furthermore, existing methods fail to effectively combine mechanical calculations, material databases, and intelligent classification algorithms, making it impossible to achieve rapid and scientific layup design recommendations based on actual engineering geological conditions. This leads to low design efficiency and heavy reliance on personal experience, hindering standardization and digitization. Summary of the Invention

[0004] The purpose of this application is to provide a sealing system for underground artificial caverns for compressed air energy storage and its construction method. This application aims to solve the technical problems of existing sealing layer design methods that rely on simplified analytical models and empirical judgments, resulting in insufficient design accuracy, poor economy, and low efficiency, as well as the problems of traditional steel plate sealing schemes such as large weight, easy fatigue, and high anti-corrosion cost. This application provides a technical solution that combines precise design and efficient construction with high reliability and digitalization.

[0005] To achieve the above objectives, this application adopts the following technical solution: In a first aspect, this application provides a design method for a sealing system of an underground artificial cavern for compressed air energy storage, comprising the following steps: S11. Obtain the engineering design parameters of the gas storage cavern, including the mechanical property parameters of the surrounding rock, reinforced concrete lining and carbon fiber composite material layer, as well as the geometric dimension parameters of the cavern. S12. Based on the engineering design parameters, establish a numerical calculation model including surrounding rock, reinforced concrete lining and carbon fiber composite material layer, and obtain the maximum tensile strain data of reinforced concrete lining under pressurized state by simulating the inflation condition. S13. Based on the strain compatibility condition, determine the selection criteria for carbon fiber cloth. The strain compatibility condition is that the ultimate breaking strain data of the selected carbon fiber cloth is greater than the maximum tensile strain data of the reinforced concrete lining. S14. Based on the theory of multi-layer thick-walled cylinder, a mechanical analytical model including surrounding rock, reinforced concrete lining and carbon fiber composite material layer is constructed. The load data of each layer structure and the circumferential stress data of carbon fiber composite material layer are calculated under the design gas storage pressure. S15. Based on the combination of different surrounding rock elastic modulus and preset carbon fiber composite layer thickness, calculate the corresponding circumferential stress data of the carbon fiber composite layer to form a multi-parameter dataset; use a clustering algorithm to analyze the dataset, with the goal of minimizing the sum of squared distances from each data point to the center of its cluster, and divide the design space into multiple engineering categories characterized by surrounding rock elastic modulus and carbon fiber composite layer thickness. S16. Based on the actual elastic modulus data of the surrounding rock at the target project site, match and determine the required carbon fiber composite layer thickness from the classified project categories, and then calculate and determine the number of carbon fiber cloth layers by combining the thickness of a single layer of carbon fiber cloth.

[0006] As a further improvement to this application, in S12, the numerical calculation model includes: The sealed structure, from the outside in, includes surrounding rock, reinforced concrete lining, and carbon fiber composite material layer; among which, the surrounding rock and reinforced concrete lining adopt C3D8 unit.

[0007] The carbon fiber composite layer was simulated using shell elements. The upper surface of the model was a free boundary, the lower surface was subject to fixed constraints, X-direction displacement constraints were applied to both sides of the model, and Y-direction displacement constraints were applied to the front and back of the model. The simulation was divided into four stages: 1) During the stress equilibrium stage, tectonic stress is applied through a predefined field, and the displacement is reset to zero; 2) During the excavation stage of the tunnel, the full-section excavation method is adopted, and reinforced concrete lining is constructed immediately after excavation; 3) During the pressurization stage, a pressure load is applied inside the carbon fiber composite layer.

[0008] As a further improvement to this application, S14 specifically includes: S141. Define the inner and outer radii of the carbon fiber composite layer, reinforced concrete lining, and surrounding rock layer as follows: r 0, r 1) ( r 1, r 2), ( r 2, r 3), of which r 0 represents the radius of the gas storage tunnel interior. r 1 represents the outer radius of the carbon fiber composite layer. r 2 represents the outer radius of influence of the reinforced concrete lining. r 3 represents the radius of the surrounding rock, indicating a sufficiently far distance unaffected by the gas storage facility, i.e., the radius of influence of gas pressure; the elastic modulus and Poisson's ratio of each layer of material are defined. S142. Based on the plane strain assumption, calculate the equivalent elastic modulus E' and equivalent Poisson's ratio μ' for each layer used in plane strain analysis; S143. Establish the stress function φ for each layer, and derive the radial stress σ for each layer accordingly. r Circumferential stress σ θ and radial displacement u r The expression:

[0009]

[0010]

[0011] In the formula, The stress function of the carbon fiber composite layer; For the stress function of reinforced concrete lining; Let A be the stress function of the surrounding rock; the expression includes the undetermined stress function coefficients A. i C i i=1,2,3 correspond to three layers respectively; The distance from the center of the gas storage facility to any point in the surrounding rock; S144. Set the boundary conditions and interlayer continuity conditions for the mechanical model. The boundary conditions include: the radial stress on the inner surface of the carbon fiber composite layer is equal to the design gas storage pressure p0; the radial stress on the outer surface of the carbon fiber composite layer is equal to the radial stress p1 on the inner surface of the reinforced concrete lining; and the radial stress at the outer boundary of the surrounding rock layer is equal to the in-situ stress p3. The interlayer continuity conditions include: the radial stress and radial displacement of adjacent layers are equal at the interface. S145. Solve all the boundary and continuity condition equations simultaneously to obtain the undetermined coefficients A for each layer. i C i ; S146. Substitute the coefficients of the undetermined stress function obtained from the solution into the stress expression to calculate the radial stress p0 on the inner surface of the carbon fiber composite layer, the radial stress p1 on the inner surface of the reinforced concrete lining, the radial stress p2 on the outer surface of the reinforced concrete lining, and the radial stress p3 on the outer surface of the surrounding rock layer, respectively. The load shared by each layer is the difference between the radial stresses on its inner and outer surfaces. The circumferential stress of the carbon fiber composite layer is obtained by calculating the stress expression.

[0012] As a further improvement to this application, in S16, the number of laying layers satisfies the following formula:

[0013] In the formula, n The number of layers to be laid, This represents the total thickness of the carbon fiber composite layer. The number of layers is calculated based on the thickness of a single layer of carbon fiber cloth. n It should be rounded up.

[0014] Secondly, this application provides a method for constructing a sealing system for an underground artificial cavern for compressed air energy storage, comprising the following steps: S101. Excavate within the selected rock mass to form a gas storage chamber; S102. Pour reinforced concrete lining on the inner surface of the surrounding rock; S103. Grind the inner surface of the reinforced concrete lining to make it rough and clean and dry. S104. Apply epoxy resin impregnation adhesive evenly to the inner surface of the reinforced concrete lining, lay the first layer of carbon fiber cloth and roll it tightly, and apply epoxy resin impregnation adhesive after the adhesive has stabilized. S105. Using a layer-by-layer staggered overlapping process, epoxy resin impregnation adhesive is repeatedly applied and carbon fiber cloth is laid. Based on the design method of the compressed air energy storage underground artificial cavern sealing system, the number of carbon fiber cloth layers is determined to form a carbon fiber composite material layer. Finally, epoxy resin surface adhesive is applied to the outermost layer. S106. After the colloid has completely cured, cover the surface of the carbon fiber composite material layer with a protective layer.

[0015] As a further improvement to this application, in S101, the gas storage cavern has a circular cross-section with a diameter of 8~20m, and the surrounding rock can withstand a high-pressure cyclic load of 5~20MPa. In S102, the thickness of the reinforced concrete lining is 500~800mm; the reinforced concrete lining includes circumferential reinforcement and longitudinal reinforcement, and is poured with concrete of not less than C40, and carbon fiber cloth is added at construction joints and expansion joints for local thickening.

[0016] As a further improvement to this application, in S104 and S105, the epoxy resin impregnating adhesive and the epoxy resin surface adhesive are two-component room temperature curing epoxy resin systems, which include component A and component B; component A contains hydrogenated bisphenol F type epoxy resin, and component B is a matching curing agent.

[0017] The mass ratio of component A to component B in the epoxy resin impregnating adhesive and epoxy resin topcoat is 10:(2~6), and the thickness of a single layer coating is 0.5mm~1mm.

[0018] As a further improvement to this application, in S104 and S105, the carbon fiber cloth is a biaxial carbon fiber cloth, comprising a first carbon fiber bundle and a second carbon fiber bundle. The first carbon fiber bundle is laid along the long axis of the cavern, and the second carbon fiber bundle is laid along the circumferential direction of the cavern; the carbon fiber bundle specification of the carbon fiber cloth is 3K~12K; Alternatively, the carbon fiber cloth may be a multiaxial carbon fiber cloth, wherein the carbon fiber bundle direction includes 0° / 45° / 90° or 0° / 30° / 60° / 90°.

[0019] As a further improvement of this application, in S105, the number of carbon fiber cloth layers is 5 to 10, the total thickness of the carbon fiber composite material layer is 5 mm to 20 mm, and it is locally thickened at the variable cross-section of the cavity; The overlap width between adjacent carbon fiber cloths shall not be less than 500mm, the seams of each layer shall be staggered by not less than 200mm, and additional carbon fiber strips shall be covered in all seam areas for sealing and reinforcement.

[0020] Thirdly, this application provides a compressed air energy storage underground artificial cavern sealing system, constructed using the aforementioned compressed air energy storage underground artificial cavern sealing system construction method, including: Reinforced concrete lining is poured on the inner surface of the gas storage cavern formed by excavation of the surrounding rock. A carbon fiber composite layer is bonded to the inner surface of the reinforced concrete lining with epoxy resin adhesive; The carbon fiber composite material layer is composed of multiple layers of carbon fiber cloth impregnated with epoxy resin and sealed with epoxy resin surface adhesive, and the carbon fiber cloth of adjacent layers is staggered and overlapped.

[0021] Compared with existing technologies, this application provides a design method for a sealing system of an underground artificial cavern for compressed air energy storage. By establishing a numerical model to simulate real working conditions and obtain key strain data, it guides the selection of carbon fiber materials based on strict strain compatibility conditions, avoiding potential performance deficiencies or waste associated with traditional experience-based selection. Utilizing the theory of multi-layer thick-walled cylinders for refined mechanical decomposition, the load-sharing ratio of each structural layer (carbon fiber composite layer, reinforced concrete lining, and surrounding rock) is clarified, providing a quantitative basis for optimized design. The multi-parameter dataset (surrounding rock modulus, composite material thickness, and circumferential stress) generated from mechanical calculations is intelligently analyzed and classified using clustering algorithms (such as K-means), simplifying the complex continuous parameter space into a finite number of typical design categories with clear engineering significance. This enables designers to quickly and scientifically match the optimal or near-optimal carbon fiber composite layer thickness and layup scheme from the established categories based on the specific site's surrounding rock conditions, greatly reducing trial-and-error costs and reliance on subjective experience. This design method ensures that the carbon fiber composite layer 3 meets both strength and deformation coordination requirements. Through systematic multi-condition calculations and cluster optimization, the number of layers is precisely controlled within the necessary minimum range, avoiding over-design and achieving an optimal balance between material cost and structural performance. This provides a basis for subsequent construction methods.

[0022] Compared with existing technologies, the method for constructing a sealing system for an underground artificial cavern for compressed air energy storage provided in this application utilizes a carbon fiber composite layer with extremely high specific strength. Under the same internal pressure, its required thickness is only in the millimeter range, significantly reducing material usage and structural weight, thus saving material, transportation, and structural support costs. The carbon fiber composite layer combines high strength with good flexibility, allowing it to deform in tandem with the reinforced concrete lining. Its strong elastic recovery effectively inhibits crack initiation and propagation, completely avoiding the risks of plastic deformation and low-cycle fatigue failure that easily occur in steel plates, significantly improving the long-term reliability of the sealing system under cyclic loading. Through epoxy resin impregnation and a continuous laying process with multiple staggered overlaps, an integral sealing layer without any welded joints is formed, fundamentally eliminating the weakest link—the traditional steel plate weld—ensuring excellent airtightness and effectively preventing high-pressure gas leakage. Carbon fiber composite layers possess excellent chemical corrosion resistance and aging resistance, eliminating the need for additional anti-corrosion coatings like steel plates. This not only saves on anti-corrosion investment during construction but also completely avoids maintenance and replacement issues caused by rust during operation, significantly reducing life-cycle costs. The soft and easily cut carbon fiber fabric allows for flexible laying processes, making it particularly suitable for complex cavity shapes such as circular and variable cross-sections. Construction eliminates the need for large-scale hoisting and welding within the cavity, greatly improving construction efficiency, shortening the construction period, and reducing the safety risks associated with high-altitude and hot work operations. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 A flowchart illustrating the design method for a sealing system of an underground artificial cavern for compressed air energy storage provided in this application; Figure 2 A schematic diagram of the modeling and calculation of the gas storage cavity provided in this application; Figure 3 This is a schematic diagram of the sealing structure of the gas storage cavity provided in this application; Figure 4 This is a schematic diagram of the carbon fiber composite material layer composition provided in this application; Figure 5 This is a schematic diagram of the carbon fiber composite layer overlap provided in this application; Wherein: 1. Surrounding rock; 2. Reinforced concrete lining; 3. Carbon fiber composite layer; 21. Circumferential reinforcement; 22. Longitudinal reinforcement; 23. Concrete; 31. Epoxy resin impregnating adhesive; 32. Carbon fiber cloth; 33. Epoxy resin surface adhesive; 321. First carbon fiber bundle; 322. Second carbon fiber bundle. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0026] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0027] In the description of the embodiments of this application, it should be noted that if terms such as "upper", "lower", "circumferential", "longitudinal", "inner", "outer", "end" appear to indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of the invention is usually placed during use, they are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0028] In the description of the embodiments of this application, it should also be noted that, unless otherwise explicitly specified and limited, the terms "dense", "pressed", "smooth", and "rolled" should be interpreted broadly. For example, they can be detected by hand or by instrument. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0029] like Figure 1 As shown, the first objective of this application is to provide a design method for a sealing system of an underground artificial cavern for compressed air energy storage, comprising the following steps: S11. Obtain the engineering design parameters of the gas storage cavern, including the mechanical properties of the surrounding rock 1, reinforced concrete lining 2 and carbon fiber composite layer 3, as well as the geometric dimensions of the cavern. S12. Based on engineering design parameters, establish a numerical calculation model including surrounding rock 1, reinforced concrete lining 2 and carbon fiber composite material layer 3, and simulate the inflation condition to obtain the maximum tensile strain generated by reinforced concrete lining 2 under pressurization. S13. Based on the strain compatibility condition, determine the selection criteria for carbon fiber cloth 32. The strain compatibility condition is: the ultimate breaking strain of the selected carbon fiber cloth 32 must be greater than the maximum tensile strain of the reinforced concrete lining 2. S14. Based on the theory of multi-layer thick-walled cylinder, a mechanical model including surrounding rock 1, reinforced concrete lining 2 and carbon fiber composite material layer 3 is constructed. The loads shared by each layer structure and the circumferential stress of carbon fiber composite material layer 3 under the design gas storage pressure are calculated. S15. Based on the combination of different elastic modulus of surrounding rock 1 and the preset thickness of carbon fiber composite layer 3, calculate the corresponding circumferential stress dataset of carbon fiber composite layer 3, and use a clustering algorithm to analyze the circumferential stress dataset of carbon fiber composite layer 3. The objective function of the clustering algorithm is to minimize the sum of squares of the distances from each point to the center of its cluster, and obtain multiple classifications characterized by the elastic modulus of surrounding rock 1 and the thickness of carbon fiber composite layer 3. S16. Based on the actual elastic modulus of the surrounding rock 1 at the target engineering site, determine the required thickness of the carbon fiber composite layer 3 from the classification, and calculate the number of carbon fiber cloth 32 layers to be laid in combination with the thickness of the single-layer carbon fiber cloth 32.

[0030] This method involves obtaining the design parameters of the cavern engineering; establishing a numerical model to simulate the air-filling condition and obtaining the maximum tensile strain of the reinforced concrete lining 2; determining the selection of carbon fiber cloth 32 based on strain compatibility conditions; calculating the load sharing of each structure and the circumferential stress of the carbon fiber composite layer 3 using the multi-layer thick-walled cylinder theory; calculating the working conditions of different combinations of surrounding rock conditions and thicknesses to form a circumferential stress dataset, which is then analyzed and classified using a clustering algorithm; finally, determining the thickness and number of carbon fiber composite layer 3 from the classification based on the actual surrounding rock conditions. This application realizes the digitalization, precision, and intelligence of sealing layer design, ensuring optimal structural safety and economy from the source.

[0031] Example 1 like Figure 1-5 As shown, to address the technical deficiencies mentioned in the background section, this embodiment provides a design method for a sealed underground gas storage facility using a carbon fiber composite material layer 3. The following is a further detailed description of this application with reference to the accompanying drawings: The first aspect, taking a circular cross-section inner lining as an example, provides a three-layer ply design method for carbon fiber composite materials, including the following steps: The sealing structure, from the outside in, includes surrounding rock 1, reinforced concrete lining 2, and carbon fiber composite material layer 3.

[0032] S101. Select a stable underground rock mass with good integrity and high strength as the gas storage cavern. Excavate the required gas storage volume within the rock mass and obtain the engineering design data for the gas storage cavern.

[0033] Specifically: Obtain engineering design data for the gas storage cavern, including the density of the surrounding rock 1 in the strata where the underground gas storage is located. p Cohesion c internal friction angle u Elastic modulus E Poisson's ratio v， Inner radius of the tunnel excavation r 1; also includes the density of the reinforced concrete lining 2. p Cohesion c internal friction angle u Elastic modulus E Poisson's ratio v、 thickness t 2, and the outer radius of the reinforced concrete lining 2 r 2.

[0034] Examples of engineering design parameters are shown in Table 1: Table 1 Examples of Engineering Design Parameters

[0035] S102: Conduct numerical simulation of the inflation status of the underground compressed air energy storage facility to obtain key parameters of the surrounding rock 1 and reinforced concrete lining 2 of the cavern.

[0036] Specifically, the maximum deformation of surrounding rock 1 Maximum tensile strain max1 and surrounding rock stress The maximum deformation of reinforced concrete lining 2 Maximum tensile strain max2 Circumferential tensile stress of reinforced concrete lining 2 .

[0037] in, , All values ​​are the maximum stresses of the corresponding structural layers extracted from simulation calculations, in MPa. max1 , max2 This represents the maximum tensile strain of the corresponding structural layer extracted from the simulation calculation; it is dimensionless.

[0038] S103: The numerical calculation model consists of three components, see Figure 2 and Figure 4 The structure is a sealed structure, consisting of surrounding rock 1, reinforced concrete lining 2, and carbon fiber composite layer 3 from the outside in. Surrounding rock 1 and reinforced concrete lining 2 are simulated using C3D8 elements. C3D8 elements are 8-node linear hexahedral fully integrated solid elements in finite element software, one of the most basic and commonly used element types in 3D solid analysis. Carbon fiber composite layer 3 is simulated using S4 shell elements. S4 shell elements are 4-node quadrilateral linear fully integrated shell elements in finite element software, a basic type in the general shell element library, suitable for simulating structures with a certain thickness but much smaller than the other two dimensions. The upper surface of the simulated shell element is a free boundary, the lower surface is subject to XYZ fixed constraints, X-direction displacement constraints are applied to both sides, and Y-direction displacement constraints are applied to the front and rear. The simulation is divided into three stages: 1) Stress equilibrium stage, where tectonic stress is applied through a predefined field and displacement is reset to zero; 2) Excavation stage, assuming a full-section excavation method, with reinforced concrete lining 2 constructed immediately after excavation; 3) Pressurization stage, where pressure loads are applied inside carbon fiber composite layer 3.

[0039] S104: Data collected and calculated; the effectiveness of the sealing structure depends on the deformation coordination between layers. To ensure that the interface between the carbon fiber composite layer 3 and the reinforced concrete lining 2 does not debond, the ultimate fracture strain of the carbon fiber cloth 32 is measured. max3 It must be greater than the maximum tensile strain generated by the reinforced concrete lining 2 under pressurized conditions. max2 It should meet the following requirements: max3 > max2 ≥ max1 Among them, the ultimate fracture strain of carbon fiber cloth 32 max3 It can be publicly searched based on information provided by the manufacturer; no unit is specified.

[0040] This strain condition is the basic basis for selecting carbon fiber cloth type 32.

[0041] S105: Calculate the load borne by different structures in the gas storage cavern using the multi-layer thick-walled cylindrical theory.

[0042] Specifically: Let r 0、 r 1. r 2. r 3 represents the inner and outer radii of each structure, where r 0 represents the radius of the gas storage tunnel interior. r 1 represents the outer radius of the carbon fiber composite layer 3. r 2 represents the outer radius of the reinforced concrete lining. r 3 represents the radius of the surrounding rock 1, indicating a sufficiently far distance unaffected by the gas storage facility, which is the radius of influence of gas pressure. p 0, p 1, p 2, p 3 represents the radial stress of each structure, where p 0 indicates the maximum designed gas storage pressure of the gas storage facility. p 1 represents the pressure of the carbon fiber composite layer 3. p 2 represents the pressure on the reinforced concrete lining 2. p 3 represents in-situ stress. Among them, the radius of influence... r 3. The radial stress of the surrounding rock of a gas storage facility under several typical operating conditions can be determined by calculating the variation of radial stress with radial distance. When the variation of radial stress with radial radius is negligible, this location can be determined as the boundary affecting the radius. p 3. Obtained through in-situ testing.

[0043]

[0044] In the formula, p 0 indicates the maximum design gas storage pressure of the gas storage facility, in MPa; r 3 indicates a sufficiently far distance unaffected by the gas storage facility, which is the radius of influence of gas pressure, in meters; The distance from the center of the gas storage cell to any point in the surrounding rock 1 is the radial radius, expressed in meters. The radial stress of the surrounding rock at the radial radius position is given in MPa. (1) The stress functions of carbon fiber composite layer 3, reinforced concrete lining 2 and surrounding rock 1 are obtained by the single-layer thick-walled cylinder theory. :

[0045]

[0046]

[0047] In the formula, Let be the stress function of carbon fiber composite layer 3; Let be the stress function of the reinforced concrete lining 2; Let be the stress function of surrounding rock 1; the expression includes undetermined stress function coefficients Ai and Ci, i=1,2,3 corresponding to the three layers respectively; The distance from the center of the gas storage cell to any point in the surrounding rock 1 is the radial radius, expressed in meters (m).

[0048] (2) Calculate the elastic modulus and Poisson's ratio of the carbon fiber composite layer 3, the reinforced concrete lining 2, and the surrounding rock 1 required for plane strain analysis:

[0049]

[0050]

[0051]

[0052]

[0053]

[0054] In the formula, These are the elastic moduli of the carbon fiber composite layer 3, the reinforced concrete lining 2, and the surrounding rock 1, respectively, in GPa. , , These are the equivalent elastic moduli of plane strain for carbon fiber composite layer 3, reinforced concrete lining 2, and surrounding rock 1, respectively, in GPa. Poisson's ratios for carbon fiber composite layer 3, reinforced concrete lining 2, and surrounding rock 1, respectively. , The equivalent Poisson's ratios for the plane strain problems of carbon fiber composite layer 3, reinforced concrete lining 2, and surrounding rock 1 are respectively. (3) Calculate the stress and displacement of the carbon fiber composite layer 3, the reinforced concrete lining 2, and the surrounding rock 1:

[0055]

[0056]

[0057]

[0058]

[0059]

[0060]

[0061]

[0062]

[0063] In the formula, These are the stress function coefficients; Corresponding to carbon fiber composite layer 3, reinforced concrete lining 2, and surrounding rock 1 respectively in radius r The displacement at a point, in meters; The radial stress is that of carbon fiber composite layer 3. The radial stress of reinforced concrete lining 2; The radial stress of surrounding rock 1 is expressed in MPa. Corresponding to carbon fiber composite layer 3, reinforced concrete lining 2, and surrounding rock 1 respectively in radius r The circumferential stress at the point is expressed in MPa.

[0064] (4) Gas storage r 0、 r 1.r 2. r 3 represents the inner and outer radii of each structure, and their relationship is as follows:

[0065]

[0066] In the formula, The thickness of the carbon fiber composite layer 3 is in meters (m). The thickness of the reinforced concrete lining is 2 meters.

[0067] (5) Boundary conditions inside and outside the gas storage facility, and boundary conditions at the junction of carbon fiber composite layer 3-reinforced concrete lining 2 and reinforced concrete lining 2-surrounding rock 1:

[0068]

[0069]

[0070]

[0071]

[0072]

[0073] (6) Substitute the formulas from steps (1) to (2) into the formula from step (3) to obtain the equation coefficients. A 1. A 2. A 3. C 1. C 2. C 3. Then, substitute the values ​​into step (5) to calculate the radial stress of each internal and external section of the cavern structure, and then calculate the load borne by each structure of the gas storage cavern:

[0074]

[0075]

[0076] In the formula, , , The difference between the radial stress at the inner interface and the radial stress at the outer interface of the carbon fiber composite layer 3, the reinforced concrete lining 2, and the surrounding rock 1 represents the load borne by each structure. Examples of the loads borne by different structures in the gas storage cavern are shown in Table 2, and the maximum circumferential stress of the carbon fiber composite layer 3 in the gas storage cavern is shown in Table 3.

[0077] Table 2 Examples of loads borne by each floor of the gas storage cavern structure ( =0.02m)

[0078] Table 3. Examples of maximum circumferential stress in carbon fiber composite layer 3 of the gas storage cavity.

[0079] S106: Based on different air pressures, the circumferential stress of layer 3 of the carbon fiber composite material is obtained. Total thickness Elastic modulus of surrounding rock E The relationship. This embodiment iteratively calculates the air pressure at 20 MPa. m, E 150 sets of circumferential stresses at 12.8, 20, and 27 GPa The data, and using K The MESSENGER clustering algorithm groups the results. The number of clusters can be adaptively selected based on the actual surrounding rock type and characteristic differences, preferably 3 to 4 clusters. This embodiment selects... k The value is 3, resulting in three thickness categories of carbon fiber composite layers with similar degradation behaviors: cluster 1, cluster 2, and cluster 3. The objective function of the MESSN clustering algorithm is to minimize the sum of squared errors within each cluster, which is the sum of squared distances from each point to the center of its cluster, i.e., the sum of squared Euclidean distances, as shown in the following formula:

[0080] In the formula, To minimize the sum of squared errors within the cluster, k It is the number of clusters. It is the first i The point set of a cluster, It belongs to Data points, It is the first i The centroid of a cluster. || represents a data point With cluster center The square of the Euclidean distance between them.

[0081] The cluster centers are shown in Table 4: Table 4 Cluster Centroids

[0082] S107: Ultimately, based on the different elastic moduli of the surrounding rock 1 E Determine the number of carbon fiber layup layers.

[0083] Specifically, the number of carbon fiber layup layers required to meet stress safety requirements is determined by calculating the following formula, taking into account the thickness of a single carbon fiber layer.

[0084]

[0085] In the formula, The total thickness of carbon fiber composite layer 3 is calculated from S106. The thickness of the selected single-layer hand lay-up plain weave carbon fiber cloth 32 is within the range of 1mm to 2mm. However, the hand lay-up process introduces errors in thickness measurement. The number of layers is calculated based on empirical thickness. n It should be rounded up.

[0086] For different air pressures and elastic moduli of surrounding rock 1, the appropriate number of layup layers is selected by calculating the strain of surrounding rock 1, the circumferential stress of carbon fiber composite layer 3, and its thickness. n Fracture strain of carbon fiber composite layer 3 max3 For example, under an air pressure of 20 MPa, the number of carbon fiber composite layer 3 layers can be controlled within a reasonable engineering range of 5 to 12 layers, depending on the elastic modulus of the surrounding rock 1. This design reduces the risk of cracking in the reinforced concrete lining 2 by sharing some of the stress, and also meets the requirements of construction economy due to the controllable number of layers.

[0087] As a further improvement of this application, when steel liner + carbon fiber composite layer 3 is used, the number of carbon fiber composite layer 3 layers can be reduced by 50%.

[0088] The principle of this design method is as follows: First, the tensile strain of key parts of the reinforced concrete lining 2 is accurately obtained through numerical simulation of the cavern pressurization process. Based on this, the material selection follows the coordination criterion that "the strain capacity of carbon fiber must be greater than the strain of reinforced concrete lining 2". Then, the load transfer and distribution between the surrounding rock 1, reinforced concrete lining 2, and carbon fiber composite layer 3 are analyzed using the multi-layer thick-walled cylinder theory, quantifying the stress borne by each layer. On this basis, the mechanical response under different combinations of surrounding rock 1 conditions and carbon fiber thickness is calculated to form a dataset. Clustering algorithms (such as K-means) are then used to intelligently classify and reduce the dimensionality of the dataset, simplifying the continuous design space into several typical and robust engineering recommended schemes. Finally, the optimal category is matched according to the surrounding rock 1 parameters of the specific site to determine the economically reasonable thickness and number of carbon fiber composite layer 3, achieving the optimal balance between safety and cost.

[0089] This application provides a method for constructing a sealing system for an underground artificial cavern for compressed air energy storage, including the following steps: S101. Excavate within the selected rock mass to form a gas storage chamber; S102. Pour reinforced concrete lining 2 on the inner surface of the surrounding rock 1; S103. Grind the inner surface of the reinforced concrete lining 2 to make it rough and clean and dry. S104. Apply epoxy resin impregnating adhesive 31 evenly to the inner surface of the reinforced concrete lining 2, lay the first layer of carbon fiber cloth 32 and roll it tightly, and apply epoxy resin impregnating adhesive 31 after the adhesive has stabilized. S105. Using a layer-by-layer staggered overlapping process, epoxy resin impregnating adhesive 31 is repeatedly coated and carbon fiber cloth 32 is laid to form a multi-layer carbon fiber composite material layer 3. Finally, epoxy resin surface adhesive 33 is coated on the outermost layer. S106. After the colloid has completely cured, cover the surface of the carbon fiber composite layer 3 with a protective layer.

[0090] In the above scheme, stable underground rock with good integrity and high strength is selected for excavation to form a cavern structure that meets the volume requirements; reinforced concrete lining 2 is poured on the inner surface of the surrounding rock 1, and after curing, the inner wall of the reinforced concrete lining 2 is ground to make its inner surface rough; epoxy resin impregnating adhesive 31 is evenly coated on the inner surface of the reinforced concrete lining 2, and carbon fiber cloth 32 is laid in a segmented progressive process and fully rolled and pressed. After the adhesive has initially set, a layer of epoxy resin topcoat 33 is applied; through a layer-by-layer staggered overlapping laying process, a carbon fiber composite material layer 3 is finally formed; after the adhesive has completely cured, a plastic film is covered on the surface of the sealing layer. The sealing structure constructed in this application has the characteristics of being lightweight and high-strength, having good fatigue resistance, and excellent air tightness, and completely eliminating the industry problems of weak welding links, electrochemical corrosion, and fatigue cracking of reinforced concrete lining 2 in traditional steel lining structures, realizing the integrated integration of corrosion prevention and sealing of the cavern inner wall. This method is simple and efficient, and compared with the traditional steel plate sealing solution, it can shorten the construction period and reduce the project cost, demonstrating significant technological advancement and economic rationality in the field of new compressed air energy storage.

[0091] The working principle of this method is as follows: First, the reinforced concrete lining 2 provides structural support and diffuses pressure to the surrounding rock 1. Then, on the treated reinforced concrete lining 2 base surface, multiple layers of carbon fiber cloth 32 are firmly bonded and composited into a whole using epoxy resin adhesive, forming the main pressure-bearing and sealing layer. The high tensile strength of the carbon fiber cloth 32 directly bears the circumferential tensile stress generated by the air pressure in the tunnel, and its multi-layered staggered laying method ensures continuous force transmission and no weak joints. The outermost adhesive and plastic film provide surface sealing and protection during construction. This method constructs a lightweight, seamless composite sealing layer, replacing the traditional heavy steel plate, fundamentally eliminating the risks of weld fatigue and electrochemical corrosion, and achieving high strength, high fatigue resistance, and superior airtightness of the sealing structure.

[0092] In the description of the embodiments of this application, it should also be noted that the carbon fiber cloth 32 can be composed of multiple carbon fiber bundles in different directions. The embodiment provides a carbon fiber cloth 32 composed of bidirectional carbon fiber bundles at 0° / 90°. Considering the stress characteristics of the actual gas storage cavern, carbon fiber bundles in other directions can be added, such as 0° / 45° / 90°, 0° / 30° / 60° / 90°, etc. For those skilled in the art, different layers and different directions of carbon fiber cloth 32 can be selected for laying according to the specific situation, but all of this falls within the scope of protection of this application.

[0093] Example 2 like Figure 3-4 As shown, to address the technical deficiencies mentioned in the background section, this embodiment provides a method for constructing a compressed air energy storage underground artificial cavern sealing system, based on Embodiment 1. The following is a further detailed description of this application in conjunction with the accompanying drawings: This application provides a method for constructing a sealing system for an underground artificial cavern with compressed air energy storage, using a circular lining as an example for illustration. Figure 3 As shown, it includes: The sealing structure, from the outside in, includes surrounding rock 1, reinforced concrete lining 2, and carbon fiber composite material layer 3.

[0094] S101. Select a stable underground rock mass with good integrity and high strength as the gas storage cavern. Excavate the required gas storage volume within the rock mass.

[0095] Specifically, to ensure structural safety, the cross-sectional dimensions should not be too large. The diameter of most underground artificial caverns for compressed air energy storage is 8 to 20 meters. In this embodiment, a cylinder with a cross-sectional dimension of 16 meters and a length of 300 meters is selected, and it is ensured that there are no active faults within a range of 3 to 5 times the diameter of the cavern.

[0096] S102. On the inner surface of the excavated surrounding rock 1, the reinforced concrete lining 2 is poured onto the inner surface of the surrounding rock 1 through a formwork. The outer surface of the reinforced concrete lining 2 must be in close contact with the inner surface of the surrounding rock 1 to ensure that the reinforced concrete lining 2 transmits pressure evenly to the surrounding rock 1.

[0097] Specifically, the reinforced concrete lining 2 uses 600mm thick C45 concrete, the specific thickness of which is determined according to the geological conditions. The reinforcement should primarily aim to limit the crack width of the reinforced concrete lining 2.

[0098] Preferably, to improve construction efficiency, an integrated steel reinforcement binding and concrete pouring method using a needle beam trolley can be adopted.

[0099] S103. Grind the inner surface of the reinforced concrete lining 2 to remove obvious protrusions, honeycombs, pitting, loose particles, and existing old coatings (such as paint, putty, etc.). The treated inner surface of the reinforced concrete lining 2 should be rough and have no smooth feel when touched. Then remove the dust from the inner surface of the reinforced concrete lining 2 and keep the surface dry.

[0100] Specifically, a dust collector can be used to thoroughly remove surface dust and ensure that the surface is dry, providing an ideal bonding substrate for the subsequent carbon fiber composite layer 3, and avoiding problems such as punctures, poor adhesion, or stress concentration during installation due to uneven substrate, dust, or moisture.

[0101] S104. Apply epoxy resin impregnating adhesive 31 evenly to the inner surface of the reinforced concrete lining 2, then lay and roll the carbon fiber cloth 32 in sections to make the carbon fiber cloth 32 adhere tightly to the inner surface of the reinforced concrete lining 2. After the epoxy resin impregnating adhesive 31 on the inner surface of the reinforced concrete lining 2 no longer drips, apply another layer of epoxy resin surface adhesive 33.

[0102] Specifically, epoxy resin impregnating adhesive 31 and the topcoat are two-component (including component A and component B) room-temperature curing epoxy resin systems. Component A mainly consists of low-viscosity, high-penetration liquid epoxy resin, and an appropriate amount of reactive diluent can be added to further adjust the viscosity and wettability. Component B (curing agent) is a compatible modified amine or other type of curing agent to ensure that the colloid can be fully cured at room temperature, and a toughening agent is added to ensure that it meets the required high-temperature resistance and toughness requirements.

[0103] Preferably, component A can be hydrogenated bisphenol F type epoxy resin, such as the YX-8000 series from Mitsubishi Chemicals of Japan, or Nan Ya Epoxy Resin 170, or bisphenol A type epoxy resin, such as room temperature curing hand lay-up epoxy resin LT-5089, or Weiligute E51 type. To ensure the extensibility of epoxy resin impregnation 31, modifiers such as Kanekazuki epoxy resin toughening agent MX-154 from Japan can be added to it. The amount of toughening agent added is 10% to 20% of the epoxy resin. Component B can be Huntsman D230 epoxy curing agent, or Ancamide 350A curing agent from Germany. The mass ratio of component A to component B is 10:(2~6).

[0104] Epoxy resin itself does not cure, but due to the presence of active epoxy and hydroxyl groups in its molecular structure, it can undergo cross-linking reactions under the action of various curing agents to generate a three-dimensional cured product. Hydrogenated bisphenol F epoxy resin combines low viscosity with excellent weather resistance; bisphenol F epoxy resin has extremely low viscosity, providing superior wettability and penetration depth for reinforcing materials such as carbon fiber cloth 32; while bisphenol A epoxy resin offers good overall performance and cost-effectiveness, suitable for large-area general structural reinforcement applications. Epoxy resin formulations are flexible, allowing for the selection of different types of epoxy resins to adjust the final properties of the impregnating adhesive based on the environment of the underground artificial cavern.

[0105] Component B curing agents can be selected based on the construction environment and performance requirements: Jeffamine D-230 modified amine curing agents have low viscosity and light color, forming a low-viscosity system with epoxy resin to ensure full wetting of carbon fiber cloth 32, and the cured product has good toughness and a long pot life; while Ancamide 350A polyamide curing agents provide extremely high fracture toughness and impact resistance, and their good adaptability to damp substrates makes them particularly suitable for potentially damp environments such as underground caverns. The toughening agent consists of core-shell structured polymer particles, focusing more on significantly improving fracture toughness and impact resistance.

[0106] Preferably, the carbon fiber cloth 32 is a high-strength Class I biaxial carbon fiber cloth 32, comprising a first carbon fiber bundle 321 and a second carbon fiber bundle 322; the carbon fiber bundles are laid along the circumferential direction of the cavern (i.e., the direction of the principal stress bearing the internal pressure of the gas storage). Figure 4 The second carbon fiber bundle 322 primarily serves a sealing function. To optimize construction efficiency and ensure bonding quality, the carbon fiber cloth 32 should be pre-cut to appropriate dimensions at the factory. A single piece of carbon fiber cloth 32 is preferably rectangular, 2-4m wide and 5-10m long. This specification effectively reduces the number of longitudinal and circumferential joints within the cavity, maximizing construction efficiency and the integrity of the sealing layer while ensuring operability.

[0107] Specifically, the first carbon fiber bundle 321 and the second carbon fiber bundle 322 are selected from the specification SYT45-3K.

[0108] S105. Lay the next layer of carbon fiber cloth 32 onto the epoxy resin impregnation adhesive 31 in a staggered manner. Each layer can be rolled tightly using rollers or other tools. During the rolling process, roll from the non-bonded area in the middle of the carbon fiber cloth 32 to both ends, and roll in the same direction multiple times. Finally, apply a layer of epoxy resin surface adhesive 33 to the carbon fiber cloth 32 to form the carbon fiber composite material layer 3.

[0109] Specifically, the carbon fiber cloth 32 has 5 to 10 layers. For each layer of carbon fiber cloth 32, a 0.5mm to 1mm layer of epoxy resin impregnation adhesive 31 is applied. The laying method is 0° / 90° bidirectional. An additional layer of carbon fiber cloth 32 can be applied at the cross-section of the cavity to achieve local thickening and ensure that there is no air leakage at the joint.

[0110] Preferably, considering the stress characteristics of the actual gas storage cavity, other multi-directional carbon fiber bundles can be added, and the laying method can also be 0° / 45° / 90° or 0° / 30° / 60° / 90°, etc.

[0111] Preferably, sufficient overlap width should be ensured between adjacent carbon fiber cloths 32. The overlap width of circumferential and longitudinal seams should not be less than 500 mm, and each layer of carbon fiber composite material 3 should be staggered with a distance of not less than 200 mm. An additional 200 mm wide strip of carbon fiber cloth 32 should be added to all seam areas, pressed tightly using the S105 roller pressing method, and ensure that the impregnating adhesive is fully applied to avoid continuous weak areas, so as to ensure the continuity of force transmission and airtightness at the seams.

[0112] S106. After the colloid hardens, ensure the surface of the carbon fiber composite layer 3 is smooth and flat to guarantee simple and clear force transmission. Once the surface of the carbon fiber composite layer 3 is no longer sticky and fully cured, apply a layer of plastic film to prevent dust and other impurities from entering. The final carbon fiber composite layer 3 has an effective permeability exceeding 1×10⁻⁶. - ¹ 7 m 2 The thickness is between 2 and 10 mm, which meets the overall anti-permeability reliability under long-term pressure cycling.

[0113] Specifically, the plastic film can be made of polyethylene film with a thickness of 0.5mm to 1mm, which can be manually removed after the gas storage facility is constructed.

[0114] Example 3 like Figure 5As shown, epoxy resin impregnating adhesive 31 and epoxy resin topcoat 33 can be replaced with polyurethane resin. Polyurethane resin is a polymer formed by the reaction of polyol and isocyanate, and its molecular network endows it with excellent mechanical and chemical properties. Depending on the formulation and raw material ratio, it can be manifested as a rigid material, a soft elastomer, or a foam. It is outstanding due to its flexibility and durability, the coating is not easy to crack, and it can withstand mechanical impact and harsh environments. The polyurethane resin can be a two-component polyurethane, where component A is isocyanate and component B is a polyether polyol mixture. Component A can be Suprasec 9258 produced by Huntsman Polyurethanes or polyether-type MDI prepolymer produced by Wanhua Chemical. The ratio of component A to component B is controlled between 1:1 and 1.2:1, and the specific ratio needs to be adjusted according to the hardness and actual environment. It is recommended to use an amine curing agent. The specific ratio of resin to curing agent can be determined by test hole or small-scale indoor test to improve reaction efficiency and shorten demolding time. The construction method of carbon fiber composite layer 3 can remain unchanged, referring to Example 1.

[0115] Example 4 like Figure 5 As shown, epoxy resin impregnating adhesive 31 and epoxy resin topcoat 33 can be replaced with vinyl resin, which has high strength, chemical corrosion resistance and good processability, but its bonding strength with concrete is slightly lower than that of epoxy resin. Vinyl resin can be 430 LV type vinyl resin, and curing agent can be Butanox M50. The specific ratio of resin to curing agent can be determined according to the test hole or small-scale indoor test. The construction method of carbon fiber composite layer 3 can remain unchanged, referring to Example 1.

[0116] In the three embodiments described above, the impregnating adhesive and topcoat illustrated only indicate that the present application can use the above-mentioned resins, but are not limited to the above-mentioned types. In practical applications, the resin, curing agent, and other additives need to comprehensively consider multiple factors such as bond strength, shear strength, peel strength, initial tack, water resistance, corrosion resistance, aging resistance, curing shrinkage, insulation performance, and environmental performance.

[0117] Example 5 like Figure 3 and Figure 4 As shown in Example 1, this example provides a method for constructing a sealing system for an underground artificial cavern for compressed air energy storage. The following is a further detailed description of this application with reference to the accompanying drawings: The sealing structure, from the outside in, includes surrounding rock 1, reinforced concrete lining 2, and carbon fiber composite material layer 3.

[0118] S101. Select underground rock masses with good integrity and high strength as gas storage caverns, excavate the required gas storage volume in the rock mass, and ensure that there are no active faults within 3 to 5 times the diameter of the cavern. Furthermore, in S101, to ensure structural safety, the cross-sectional dimensions of the gas storage cavern should not be too large, with a recommended diameter of 8~20m. The surrounding rock 1 of the gas storage cavern should be able to withstand a high-pressure cyclic load of 5~20MPa.

[0119] S102. The reinforced concrete lining 2 is poured into the inner surface of the surrounding rock 1 through the formwork. The outer surface of the reinforced concrete lining 2 must be in close contact with the inner surface of the surrounding rock 1 to ensure that the reinforced concrete lining 2 transmits the gas storage pressure evenly to the surrounding rock 1. Furthermore, in S102, the reinforced concrete lining 2 mainly includes circumferential reinforcement 21, longitudinal reinforcement 22 and concrete 23. The grade of concrete 23 is not lower than C40. A layer of carbon fiber cloth 32 is added to the construction joints and expansion joints of the reinforced concrete lining 2 to achieve local thickening.

[0120] Specifically, a thickness range of 500-800 mm ensures sufficient rigidity and strength of the reinforced concrete lining 2 under high pressure. The concrete grade is no lower than C40 (e.g., C45, C50), i.e., high-strength concrete 23 is used, which has high compressive strength, good compactness, and effectively reduces permeability. The reinforcing mesh within the reinforced concrete lining 2 consists of circumferential main bars and longitudinal distribution bars, with the primary goal of controlling crack width. Construction joints, which are unavoidable during construction, and expansion joints designed to cope with temperature stress, are potential weak points. Therefore, after completing the S103 base treatment, one to two layers of carbon fiber cloth 32 are additionally laid in these joint areas, typically extending a certain range (e.g., 300-500 mm) on both sides of the joint to achieve localized reinforcement. This reinforced concrete lining 2, as the base layer of the carbon fiber composite layer 3, provides a smooth and robust surface for the sealing layer due to its high strength and integrity. Localized thickening compensates for strength loss at the joints. This step provides a robust and complete reinforced concrete lining 2 base layer, ensuring the reliability of the pressure transmission path, and significantly improving the crack resistance and impermeability of the weak areas of the reinforced concrete lining 2 through local reinforcement, laying the foundation for the long-term stable operation of the upper sealing layer.

[0121] S103. Grind the inner surface of the reinforced concrete lining 2 to remove obvious protrusions, honeycombing, pitting, loose particles, and existing old coatings (such as paint, putty, etc.). The treated inner surface of the reinforced concrete lining 2 should have a rough "rough" finish and should not feel smooth to the touch. Then remove dust from the inner surface of the reinforced concrete lining 2 and keep the surface dry. Since the inner surface of the reinforced concrete lining 2 is already smooth, dust-free, and dry, punctures and stress concentrations will be avoided when laying the carbon fiber composite layer 3 subsequently. S104. Apply epoxy resin impregnating adhesive 31 evenly to the inner surface of the reinforced concrete lining 2. Then, lay the prefabricated carbon fiber cloth 32 in sections and roll it to make the carbon fiber cloth 32 adhere tightly to the inner surface of the reinforced concrete lining 2. After the inner surface of the reinforced concrete lining 2 is evenly coated with epoxy resin impregnating adhesive 31 and there is no dripping, apply another layer of epoxy resin impregnating adhesive 31 to fully impregnate and seal the first layer of carbon fiber cloth 32. The epoxy resin system serves as the bonding matrix, bonding the carbon fiber cloth 32 into a single unit and firmly anchoring it to the reinforced concrete lining 2. It is the core material for forming the composite sealing layer. This step provides a high-performance bonding material, ensuring high adhesion and integrity within the carbon fiber composite layer 3 and between it and the base surface of the reinforced concrete lining 2. This is crucial for the sealing layer to perform its pressure-bearing and sealing functions.

[0122] Furthermore, in S104, the carbon fiber cloth 32 can be a 0° / 90° biaxial carbon fiber cloth 32 or a 0° / 45° / 90° multiaxial carbon fiber cloth 32. The number of layers, biaxial or uniaxial orientation, and different directions need to be determined according to the stress and damage of the reinforced concrete lining 2 under internal pressure, and it can be locally thickened.

[0123] Furthermore, 0° and 90° refer to the directions of the first carbon fiber bundle 321 and the second carbon fiber bundle 322, with 0° being... Figure 4 The first carbon fiber bundle 321 is shown in the direction (along the long axis of the cavern), and 90° is shown in the direction of the second carbon fiber bundle 322 (along the circumferential direction of the cavern).

[0124] Furthermore, in S104, when the number of carbon fiber cloth layers (32) is relatively large, it can be arranged according to... Figure 4 For the installation method, the carbon fiber cloth 32 can overlap with the cloth by a certain width to ensure that there is no air leakage at the joint.

[0125] Furthermore, in S104, epoxy resin impregnating adhesive 31 and epoxy resin surface adhesive 33 are prepared in a certain proportion as required and pre-stirred evenly to ensure that there are no sediments.

[0126] In S104, both epoxy resin impregnating adhesive 31 and epoxy resin topcoat 33 are two-component (components A and B) room-temperature curing epoxy resin systems. Component A contains low-viscosity, high-penetration liquid epoxy resin and reactive diluents for adjusting viscosity and wetting properties. Component A is mainly hydrogenated bisphenol F type epoxy resin. Component B is a curing agent that is compatible with component A and contains modifiers for improving the final properties of the colloid. Huntsman D230 epoxy curing agent can be used for component B to ensure that the system can be fully cured at room temperature and that the cured adhesive layer has the required high-temperature resistance and toughness.

[0127] To control the performance of the adhesive layer and ensure construction quality, specific specifications need to be given to the mixing ratio and coating thickness of the epoxy resin adhesive. The mass ratio of component A to component B in epoxy resin impregnating adhesive 31 and epoxy resin topcoat 33 is 10:(2~6), and the single-layer coating thickness is 0.5mm~1mm. Specifically, a mass ratio of 10:2 to 10:6 (i.e., 5:1 to 1.67:1) is a preferred range verified through testing, ensuring that the mixed adhesive has a suitable working time, sufficient leveling and penetration, and good final cured mechanical properties. For example, a 10:3 ratio may offer both a longer working time and good final toughness. The single-layer coating thickness of 0.5mm~1mm is based on engineering practice; too thin a layer may lead to insufficient wetting or inadequate adhesion, while too thick a layer can easily cause sagging, high curing shrinkage stress, or air bubbles. During construction, a toothed scraper can be used to control the coating thickness.

[0128] Precise proportioning and thickness control ensure the reliability and consistency of the adhesive layer performance, allowing each layer of carbon fiber cloth 32 to be fully impregnated and form a uniform adhesive layer. By quantifying key process parameters, the performance of the bonding material is optimized and stabilized, avoiding problems such as bonding failure and stress concentration caused by improper proportioning or uneven thickness, thus improving the reliability of the sealing layer quality.

[0129] Furthermore, in S104, the carbon fiber cloth 32 is a high-strength Class I bidirectional carbon fiber cloth 32, and its second carbon fiber bundle 322 is laid along the circumferential direction of the cavern (i.e., the direction of the main stress that bears the internal pressure of the gas storage).

[0130] Specifically, "High Strength Grade I" refers to meeting the highest strength grade requirements for carbon fiber cloth 32 used for structural reinforcement in relevant national standards (such as GB 50728), with a tensile strength standard value of not less than 3400 MPa. Bidirectional carbon fiber cloth 32 refers to cloth in which carbon fiber bundles are woven along two perpendicular directions (usually 0° and 90°). During installation, the direction of the strongest filament bundle in the carbon fiber cloth 32 (usually one of the warp or weft directions) is aligned with the circumferential direction of the cavity, as this direction is the primary direction for bearing the circumferential tensile stress generated by gas pressure. In this way, the high strength characteristics of carbon fiber are utilized most effectively. This installation method allows the strength advantage of the carbon fiber material to be directly targeted at the most important load direction, efficiently bearing the circumferential tensile force generated by internal pressure. This method achieves optimal matching between material strength and structural stress, obtaining maximum load-bearing efficiency with minimal material usage, and ensuring the structural safety of the sealing layer under high pressure.

[0131] Furthermore, in S104, the carbon fiber bundles are 3K to 12K in size. The size of the carbon fiber bundles is selected according to the gas storage pressure. The tensile strength of 3K carbon fiber is as high as 4000MPa.

[0132] Furthermore, in S104, carbon fiber cloth 32, including but not limited to 0° / 90° bidirectional carbon fiber bundles, also includes 0° / 45° / 90° and 0° / 30° / 60° / 90°, etc., to analyze and study the stress characteristics of actual gas storage caverns, and carbon fiber bundles in other directions can be added. To cope with the complex stress states that may exist in the cavern structure, such as shear stress or oblique stress, it is necessary to expand the multi-directional reinforcement capability of carbon fiber cloth 32. Carbon fiber cloth 32 is a multi-axial carbon fiber cloth 32, and its fiber bundle direction includes combinations of 0° / 45° / 90° or 0° / 30° / 60° / 90°. Specifically, multi-axial carbon fiber cloth 32 is made by directly overlapping and fixing fiber bundles in different directions (e.g., 0°, 45°, 90°) with a small number of stitches during weaving, rather than traditional bidirectional woven cloth. 0° / 45° / 90° layup can effectively resist circumferential tensile stress (0° or 90° direction, depending on the alignment), longitudinal tensile stress, and shear stress simultaneously. 0° / 30° / 60° / 90° layups provide more uniform multi-directional reinforcement. In practical engineering, the most suitable multi-axial fabric can be selected based on the stress distribution characteristics of the cavity obtained from finite element analysis, or multi-axial fabric can be used locally for reinforcement in critical areas. Multi-axial layup gives the carbon fiber composite layer 3 near-isotropic mechanical properties, enabling it to more comprehensively resist complex stresses from all directions, enhancing the sealing layer's adaptability to complex stress states, and improving load-bearing redundancy. Especially in stress concentration areas such as openings, branch pipes, and variable cross-sections, it can more effectively suppress crack formation and improve overall safety.

[0133] Furthermore, in S104, the carbon fiber cloth 32 mainly serves a sealing function. The number of layers of carbon fiber cloth 32 is 5 to 10, and the thickness is 0.5 mm to 2 mm. It can be selected according to the gas storage pressure and the surrounding rock conditions. An additional layer of carbon fiber cloth 32 can be added at the variable cross-section of the cavern to achieve local thickening. The direction of its carbon fiber bundle should be consistent with the main stress conditions at the variable cross-section of the cavern.

[0134] Specifically, the number of layers, from 5 to 10, is a range derived from calculations and engineering experience regarding the required load-bearing capacity under different design pressures ranging from 5 MPa to 20 MPa. Each layer of carbon fiber cloth 32 is approximately 0.2 mm to 0.5 mm thick. Including the adhesive layer, the total thickness of the final carbon fiber composite layer 3 is between 5 mm and 20 mm. For example, for an internal pressure of 10 MPa, 7 layers may be required. At locations with changes in tunnel diameter or bends, where stress concentration occurs, 1 to 2 additional layers of carbon fiber cloth 32 are needed for localized thickening. The thickened area should extend smoothly to both sides of the section change for a sufficient length. By adjusting the number of layers, the overall thickness is controlled to meet the load-bearing capacity requirements, and localized thickening strengthens stress concentration areas. While ensuring overall pressure resistance, targeted reinforcement of weak points ensures the uniformity and reliability of the entire tunnel sealing system.

[0135] S105. Lay the next layer of carbon fiber cloth 32 onto the epoxy resin impregnation adhesive 31 in a staggered manner. Each layer can be rolled tightly using rollers or other tools. During the rolling process, roll from the non-bonded area in the middle of the carbon fiber cloth 32 to both ends, and roll in the same direction multiple times. The number of carbon fiber cloth 32 layers is 5 to 10. After each layer of carbon fiber cloth 32 is laid, apply a layer of epoxy resin impregnation adhesive 31 with a thickness of 0.5 mm to 1 mm. Finally, apply a layer of epoxy resin topcoat 33 to the last layer of carbon fiber cloth 32 to form the carbon fiber composite material layer 3.

[0136] Furthermore, in S105, air bubbles and excess colloids in the carbon fiber cloth 32 are expelled to ensure a smooth sealing layer interface and a simple, clear, and uniform force transmission path.

[0137] Furthermore, in S105, all carbon fiber fabric 32 seams must meet the minimum overlap width requirement, and the seams of each layer should be staggered. All seam areas must be fully covered and sealed with additional carbon fiber strips for reinforcement.

[0138] Specifically, the overlap width between adjacent carbon fiber cloth 32 layers should be no less than 500mm, and the seams of each layer should be staggered by no less than 200mm. Additional carbon fiber strips should be used to seal and reinforce all seam areas. For carbon fiber cloth 32 rolls with a width of 2-4m, when laid circumferentially or longitudinally, there should be at least a 500mm overlap between adjacent fabric sheets. The seams of adjacent upper and lower layers should be staggered by at least 200mm to avoid forming continuous seams. On the surface of all overlapping seam areas (i.e., the overlap area), another carbon fiber cloth 32 strip with a width of no less than 200mm should be pasted to completely cover the seam below and rolled compacted. This is equivalent to "covering" the seams for reinforcement. The wide overlap and staggered arrangement ensure effective load transfer through the seam area, avoiding stress concentration. The additional strips provide secondary sealing and reinforcement to the overlap area, completely sealing off any possible leakage paths. Through strict overlapping and joint treatment processes, the carbon fiber composite layer 3 is ensured to be a truly continuous and uniform whole, completely eliminating weak interfaces between layers and sheets, and achieving excellent overall air tightness and structural integrity.

[0139] S106. After the colloid has hardened, inspect and ensure that the surface of the carbon fiber composite layer 3 is smooth and flat to ensure simple and clear force transmission. Once the surface of the carbon fiber composite layer 3 is no longer sticky and has fully cured, apply a layer of plastic film to prevent dust and other impurities from contaminating or damaging the surface of the carbon fiber composite layer 3 during construction and commissioning.

[0140] Compared to traditional steel plate lining solutions, it has the following advantages: 1. This method fully utilizes the high performance of carbon fiber composite layer 3, including tensile strength, puncture resistance, aging resistance, lightweight, and high temperature resistance. Its specific strength is 20 times that of steel, while its density is only 1 / 4 that of steel. When subjected to the same or even higher internal pressure, its thickness is only on the millimeter scale, making it extremely lightweight and significantly reducing the structural self-weight, thus saving material and transportation costs.

[0141] 2. The carbon fiber composite material layer 3 used in this method has a tensile strength exceeding 3000MPa and a tensile fracture rate exceeding 1.5% due to toughening modification treatment. It also has high strength and flexibility, and can deform in tandem with the reinforced concrete lining 2. It has extremely strong elastic recovery ability, which can effectively inhibit crack initiation and propagation, resist stress concentration and accidental impact, and completely avoid the risk of plastic deformation and fatigue cracking.

[0142] 3. This method employs a continuous construction process of resin impregnation and multi-layered staggered bonding, forming a seamless, integral, and heat-resistant sealing system with no weak points at the joints, fundamentally solving the problem of steel plate weld failure under high temperature and high pressure.

[0143] 4. The carbon fiber composite material layer 3 used in this method has excellent chemical corrosion resistance and anti-aging properties, and there is no rust problem. Its designed service life is far longer than that of the steel plate sealing layer. Based on its excellent anti-corrosion performance, no additional anti-corrosion measures are required for the inner wall of the cave, which can significantly save on construction investment and operation and maintenance costs.

[0144] 5. The carbon fiber cloth 32 used in this method is soft and easy to cut. With the help of specially designed tooling equipment in a circular cross-section space, it can realize fully automatic integrated operation of gluing, laying and rolling. There are no special requirements for the size of the opening, which greatly improves the construction efficiency. Compared with the complicated welding and high-precision hoisting in the opening of the steel plate scheme, this method greatly saves the construction period and effectively avoids the risks of high-altitude and hot work operations.

[0145] Example 6 This embodiment provides a compressed air energy storage underground artificial cavern sealing system, obtained by the above-described construction method, including: Reinforced concrete lining 2 is poured on the inner surface of the gas storage cavern formed by excavation of surrounding rock 1; The carbon fiber composite layer 3 is bonded to the inner surface of the reinforced concrete lining 2 by epoxy resin adhesive 33. Among them, the carbon fiber composite material layer 3 is composed of multiple layers of carbon fiber cloth 32, which are compounded by epoxy resin impregnation adhesive 31 and sealed by epoxy resin surface adhesive 33, and the carbon fiber cloth 32 of adjacent layers are staggered and overlapped.

[0146] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0147] Obviously, the described embodiments are only some, not all, of the embodiments in this application. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort should fall within the scope of protection of this application.

[0148] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application and not to limit them. Although this application has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation methods of this application. Any modifications or equivalent substitutions that do not depart from the spirit and scope of this application should be covered within the protection scope of this application.

Claims

1. A design method for a sealing system of an underground artificial cavern for compressed air energy storage, characterized in that, Includes the following steps: S11. Obtain the engineering design parameters of the gas storage cavern, including the mechanical property parameters of the surrounding rock, reinforced concrete lining and carbon fiber composite material layer, as well as the geometric dimension parameters of the cavern. S12. Based on the engineering design parameters, establish a numerical calculation model including surrounding rock, reinforced concrete lining and carbon fiber composite material layer, and obtain the maximum tensile strain data of reinforced concrete lining under pressurized state by simulating the inflation condition. S13. Based on the strain compatibility condition, determine the selection criteria for carbon fiber cloth. The strain compatibility condition is that the ultimate breaking strain data of the selected carbon fiber cloth is greater than the maximum tensile strain data of the reinforced concrete lining. S14. Based on the theory of multi-layer thick-walled cylinder, a mechanical analytical model including surrounding rock, reinforced concrete lining and carbon fiber composite material layer is constructed. The load data of each layer structure and the circumferential stress data of carbon fiber composite material layer are calculated under the design gas storage pressure. S15. Based on the combination of different surrounding rock elastic modulus and preset carbon fiber composite layer thickness, calculate the corresponding circumferential stress data of the carbon fiber composite layer to form a multi-parameter dataset. Clustering algorithms were used to analyze the dataset, with the goal of minimizing the sum of squared Euclidean distances from each data point to the center of its cluster. The design space was divided into multiple engineering categories characterized by the elastic modulus of the surrounding rock and the thickness of the carbon fiber composite layer. S16. Based on the actual elastic modulus data of the surrounding rock at the target project site, match and determine the required carbon fiber composite layer thickness from the classified project categories, and then calculate and determine the number of carbon fiber cloth layers by combining the thickness of a single layer of carbon fiber cloth.

2. The design method for a sealing system of an underground artificial cavern for compressed air energy storage according to claim 1, characterized in that, In S12, the numerical calculation model includes: The sealed structure, from the outside in, includes surrounding rock, reinforced concrete lining, and carbon fiber composite material layer; among them, the surrounding rock and reinforced concrete lining are simulated using solid elements; The carbon fiber composite layer was simulated using shell elements. The upper surface of the shell element was a free boundary, the lower surface was subject to fixed constraints, X-direction displacement constraints were applied to both sides, and Y-direction displacement constraints were applied to the front and rear. The simulation consisted of: During the stress equilibrium stage, tectonic stress is applied through a predefined field, and the displacement is reset to zero. During the excavation stage of the tunnel, the full-section excavation method is adopted, and reinforced concrete lining is constructed immediately after excavation. During the pressurization phase, a pressure load is applied inside the carbon fiber composite layer.

3. The design method for a sealing system of an underground artificial cavern for compressed air energy storage according to claim 1, characterized in that, S14 specifically includes: S141. Define the inner and outer radii of the carbon fiber composite layer, reinforced concrete lining, and surrounding rock layer as follows: r 0, r 1) ( r 1, r 2), ( r 2, r 3), of which r 0 represents the radius of the gas storage tunnel interior. r 1 represents the outer radius of the carbon fiber composite layer. r 2 represents the outer radius of influence of the reinforced concrete lining. r 3 represents the radius of influence of the surrounding rock, indicating a sufficiently far distance beyond which the gas storage facility is unaffected, i.e., the radius of influence of gas pressure; the elastic modulus and Poisson's ratio of each layer material are defined. S142. Based on the plane strain assumption, calculate the equivalent elastic modulus E' and equivalent Poisson's ratio μ' for each layer used in plane strain analysis; S143. Establish the stress function φ for each layer, and derive the radial stress σ for each layer accordingly. r Circumferential stress σ θ and radial displacement u r The expression: In the formula, The stress function of the carbon fiber composite layer; For the stress function of reinforced concrete lining; Let A be the stress function of the surrounding rock; the expression includes the undetermined stress function coefficients A. i C i i=1,2,3 correspond to three layers respectively; The distance from the center of the gas storage facility to any point in the surrounding rock; S144. Set the boundary conditions and interlayer continuity conditions for the mechanical model. The boundary conditions include: the radial stress on the inner surface of the carbon fiber composite layer is equal to the design gas storage pressure p0; the radial stress on the outer surface of the carbon fiber composite layer is equal to the radial stress p1 on the inner surface of the reinforced concrete lining; and the radial stress at the outer boundary of the surrounding rock layer is equal to the in-situ stress p3. The interlayer continuity conditions include: the radial stress and radial displacement of adjacent layers are equal at the interface. S145. Solve all the boundary and continuity condition equations simultaneously to obtain the undetermined stress function coefficients A for each layer. i C i ; S146. Substitute the coefficients of the undetermined stress function obtained from the solution into the stress expression to calculate the radial stress p0 on the inner surface of the carbon fiber composite layer, the radial stress p1 on the inner surface of the reinforced concrete lining, the radial stress p2 on the outer surface of the reinforced concrete lining, and the radial stress p3 on the outer surface of the surrounding rock layer, respectively. The load shared by each layer is the difference between the radial stresses on its inner and outer surfaces. The circumferential stress of the carbon fiber composite layer is obtained by calculating the stress expression.

4. The design method for a sealing system of an underground artificial cavern for compressed air energy storage according to claim 1, characterized in that, In S16, the number of paving layers satisfies the following formula: In the formula, n The number of layers to be laid, This represents the total thickness of the carbon fiber composite layer. This refers to the thickness of a single layer of carbon fiber cloth.

5. A method for constructing a sealing system for an underground artificial cavern for compressed air energy storage, characterized in that, Includes the following steps: S101. Excavate within the selected rock mass to form a gas storage chamber; S102. Pour reinforced concrete lining on the inner surface of the surrounding rock; S103. Grind the inner surface of the reinforced concrete lining to make it rough and clean and dry. S104. Apply epoxy resin impregnation adhesive evenly to the inner surface of the reinforced concrete lining, lay the first layer of carbon fiber cloth and roll it tightly, and apply epoxy resin impregnation adhesive after the adhesive has stabilized. S105. Using a layer-by-layer staggered overlapping process, epoxy resin impregnation adhesive is repeatedly applied and carbon fiber cloth is laid; based on the design method of the compressed air energy storage underground artificial cavern sealing system according to any one of claims 1 to 4, the number of carbon fiber cloth laying layers is determined to form a carbon fiber composite material layer, and finally epoxy resin surface adhesive is applied to the outermost layer. S106. After the colloid has completely cured, cover the surface of the carbon fiber composite material layer with a protective layer.

6. The method for constructing a sealed underground artificial cavern for compressed air energy storage according to claim 5, characterized in that, In S101, the gas storage chamber has a circular cross-section with a diameter of 8~20m, and the surrounding rock can withstand a high-pressure cyclic load of 5~20MPa. In S102, the thickness of the reinforced concrete lining is 500~800mm; the reinforced concrete lining includes circumferential reinforcement and longitudinal reinforcement, and is poured with concrete of not less than C40, and carbon fiber cloth is added at construction joints and expansion joints for local thickening.

7. The method for constructing a sealed underground artificial cavern for compressed air energy storage according to claim 5, characterized in that, In S104 and S105, the epoxy resin impregnating adhesive and epoxy resin surface adhesive are two-component room temperature curing epoxy resin systems. The two-component room temperature curing epoxy resin system includes component A and component B; component A contains hydrogenated bisphenol F type epoxy resin, and component B is a matching curing agent. The mass ratio of component A to component B in the epoxy resin impregnating adhesive and epoxy resin topcoat is 10:(2~6), and the thickness of a single layer coating is 0.5mm~1mm.

8. The method for constructing a sealed underground artificial cavern for compressed air energy storage according to claim 5, characterized in that, In S104 and S105, the carbon fiber cloth is a biaxial carbon fiber cloth, including a first carbon fiber bundle and a second carbon fiber bundle. The first carbon fiber bundle is laid along the long axis of the cavern, and the second carbon fiber bundle is laid along the circumferential direction of the cavern. The carbon fiber bundle specification of the carbon fiber cloth is 3K~12K. Alternatively, the carbon fiber cloth may be a multiaxial carbon fiber cloth.

9. The method for constructing a sealed underground artificial cavern for compressed air energy storage according to claim 5, characterized in that, In S105, the number of carbon fiber cloth layers is 5 to 10, the total thickness of the carbon fiber composite material layer is 5 mm to 20 mm, and it is locally thickened at the variable cross-section of the cavity; The overlap width between adjacent carbon fiber cloths shall not be less than 500mm, the seams of each layer shall be staggered by not less than 200mm, and additional carbon fiber strips shall be covered in all seam areas for sealing and reinforcement.

10. A compressed air energy storage underground artificial cavern sealing system, constructed using the compressed air energy storage underground artificial cavern sealing system construction method according to any one of claims 5 to 9, characterized in that, include: Reinforced concrete lining is poured on the inner surface of the gas storage cavern formed by excavation of the surrounding rock. A carbon fiber composite layer is bonded to the inner surface of the reinforced concrete lining with epoxy resin adhesive; The carbon fiber composite material layer is composed of multiple layers of carbon fiber cloth impregnated with epoxy resin and sealed with epoxy resin surface adhesive, and the carbon fiber cloth of adjacent layers is staggered and overlapped.

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