A compressed gas energy storage underground cavern support structure and design method thereof

Abstract

The present invention relates to the field of underground engineering, and more specifically, to a compressed gas energy storage underground cavern support structure and its design method. The present invention provides a compressed gas energy storage underground cavern support structure and its design method, which are suitable for the design of compressed gas energy storage underground gas storage chamber structures. By simplifying the structure, decomposing the functions of each layer, and specifically selecting materials and designing the structures of each layer, the support structure coordinates the deformation of each layer, fully utilizing the bearing capacity of the surrounding rock, and ensuring the sealing of the cavern. Compared with existing structures, this structure does not have a secondary lining or a thicker steel lining, which greatly improves the economic efficiency.

Description

Technical Field

[0001] The present invention relates to the field of underground engineering, and more specifically to a compressed air energy storage underground cavern support structure and a design method thereof. Background Art

[0002] With the continuous maturity of compressed air energy storage technology, the design of gas storage has become the key to the construction of compressed air energy storage power stations. Among them, underground artificial caverns have attracted more and more attention from researchers and designers due to their advantages such as large storage capacity, flexible site selection and small impact on the surrounding environment.

[0003] Underground chambers in the transportation and water conservancy industries often use concrete as their lining structure, leveraging the surrounding rock to bear external loads. However, compressed gas energy storage chambers must withstand not only external surrounding rock and water pressure during construction and operation, but also the high-pressure gas loads acting on the lining during operation due to cyclical inflation and deflation. Therefore, the stress-bearing mechanism differs from that of conventional underground artificially lined chambers.

[0004] Underground gas storage chambers can utilize a sealed steel-concrete lining structure. To meet economical requirements, the ideal load-bearing and sealing system is as follows: the steel lining provides sealing, and its thickness only needs to meet structural requirements; the concrete lining bears the loads during construction and maintenance, while also transferring the internal pressure loads during operation; the internal pressure loads during operation are primarily borne by the surrounding rock. In reality, the internal pressure generated by compressed air during operation is often high, typically exceeding 10 MPa or even reaching 20 MPa. This inevitably leads to tensile failure of the concrete lining, resulting in a weakening of its load-transferring and bearing capacity, or even failure. Existing data fail to consider the coordinated deformation of the surrounding rock, structure, and sealing layer. This leads to stress concentration and failure of the multi-layer structure under high pressure due to uncoordinated deformation. Therefore, when designing support structures for compressed gas energy storage underground caverns under high internal pressure, it is crucial to consider the stress and damage characteristics of the underground cavern at different stages. Targeted material selection and layer design ensure coordinated deformation among each layer, ensuring that the cavern structure meets safety requirements at each stage. At present, there is no unified standard and method for the design of underground cavern structures for compressed gas energy storage. This has become one of the biggest bottlenecks hindering the development of the compressed gas energy storage industry. It is urgent to find a solution to break through this limitation. Summary of the Invention

[0005] The present invention aims to provide a compressed gas energy storage underground cavern support structure and design method, suitable for the design of compressed gas energy storage underground gas storage chambers. By simplifying the structure, decomposing the functions of each layer, and selectively selecting materials and designing the structure of each layer, this support structure coordinates the deformation of each layer, fully utilizing the bearing capacity of the surrounding rock while ensuring the airtightness of the cavern. Compared with existing structures, this structure does not require secondary lining or thick steel lining, significantly improving its economic efficiency.

[0006] In order to achieve these purposes and other advantages according to the present invention, a compressed air energy storage underground cavern support structure is provided, including an anchor surrounding rock bearing arch, a sprayed concrete layer and a sealed steel lining, and a high-temperature resistant and high-elastic modulus filling layer is filled between the sprayed concrete layer and the sealing steel lining.

[0007] Furthermore, in the compressed air energy storage underground cavern support structure, the high-temperature resistant and high-elastic modulus filling layer is filled with asphalt.

[0008] Furthermore, in the compressed air energy storage underground cavern support structure, the anchor rod surrounding rock bearing arch adopts a hollow grouting anchor rod, and the hollow grouting anchor rod is filled with non-shrinkage epoxy mortar filler.

[0009] The present invention also provides a design method for the above-mentioned compressed air energy storage underground cavern support structure, comprising the following steps:

[0010] S1. Obtain the design parameters of the support structure and determine the safety factor control value K during the tunnel construction period. cd , Maintenance period safety factor control value K pd , earthquake safety factor control value K ed ;

[0011] S2. Formulate support parameters and material parameters of the support structure;

[0012] S3. Calculate the safety factor K of the support structure during the construction period based on the support parameters and material parameters proposed in S2. C :

[0013] If K C ≤K cd , return to S2, and re-draft the support parameters of the support structure;

[0014] If K C >K cd ; Enter S4;

[0015] S4. Calculate the maximum deformation of the support structure during operation, and the maximum tensile strain ε0 of the sealing steel lining under loading and unloading:

[0016] If ε0≥ε y , it is necessary to set annular expansion joints between the steel plates on the sealing steel lining so that the position change between the steel plates of the sealing steel lining can meet the maximum deformation of the support structure during the operation period;

[0017] If ε0<ε y ; Enter S4;

[0018] Among them, ε y The ultimate strain of the steel material of the sealing steel lining;

[0019] S5. Calculate the safety factor K of the support structure during the maintenance period based on the maximum deformation of the support structure during the operation period calculated in S4. p :

[0020] If K p ≤K pd , return to S2, and re-draft the support parameters of the support structure;

[0021] If K p >K pd ; Enter S4;

[0022] S6. Calculate the safety factor K of the support structure under earthquake action e :

[0023] If K e ≤K ed , return to S2;

[0024] If K e >K ed , the design is completed, and the current support parameters and material parameters are used as the support parameters and material parameters of the support structure.

[0025] Furthermore, in the design method of a compressed gas energy storage underground cavern support structure, K in S3 C The calculation method includes the following steps:

[0026] S3.1. Based on the support parameters and material parameters of the support structure proposed in S2, the load structure models of the anchor surrounding rock bearing arch and the shotcrete layer are established respectively, and the safety factor K of the anchor surrounding rock bearing arch is calculated respectively. 11 and the safety factor K of the shotcrete layer 21 ;

[0027] S3.2. Calculation of K C :

[0028] K C =K 11 +K 21 (1)

[0029] Furthermore, in the design method of a compressed gas energy storage underground cavern support structure, the ultimate elongation L of the annular expansion joint in S4 should satisfy:

[0030] L>πR(ε0-ε y1 ) (2)

[0031] Where R is the inner diameter of the underground cavern, ε y1 The strain of the steel plates on both sides of the joint when the deformation matches the deformation of the surrounding rock.

[0032] Furthermore, in the design method of a compressed air energy storage underground cavern support structure, the maximum deformation of the support structure during the operation period calculated in S4 includes at least: the height H of the maximum surrounding rock damage zone and the range of the lining damage zone within the working internal pressure range of the support structure during the operation period.

[0033] Furthermore, in the design method of a compressed gas energy storage underground cavern support structure, K in S5 p is the total safety factor K during the maintenance period of the support mechanism p1 and the local spraying layer strength safety factor K p2 Small value in: e=min{K p1 ,K p2};

[0034] Among them, K p1 The calculation method is as follows:

[0035] S5.1. Calculate the maximum deadweight load Q of the surrounding rock damage zone that the support structure needs to bear under maintenance conditions:

[0036] Q=γH (3)

[0037] Wherein, γ is the bulk density of surrounding rock;

[0038] S5.2. Determine the reduction factor k1 based on the area of ​​the lining damage zone of the support structure within the operating internal pressure range during the operation period, and reduce the support parameters and material parameters of the support structure proposed in S2;

[0039] S5.3. Based on the reduced support parameters and material parameters in S5.2, establish the load structure models of the anchor surrounding rock bearing arch and the shotcrete layer, and calculate the safety factor K of the anchor surrounding rock bearing arch after the reduction. 12 and the safety factor K of the shotcrete layer 22 ;

[0040] S5.4. Calculation of K p1 :

[0041] K p1 =K 12 +K 22 (4)

[0042] Among them, K p2 The calculation method is as follows:

[0043] S5.5. Establish a local surrounding rock stability calculation model between the anchor rods of the support structure, and calculate K using the local surrounding rock stability calculation model. p2 .

[0044] Furthermore, in the design method of a compressed air energy storage underground cavern support structure, S5.5 includes:

[0045] S5.5.1. Model establishment: Select a local area of ​​the support structure with relatively large stress, simplify it into a reinforced steel fiber reinforced concrete longitudinal circumferential continuous slab, and establish a continuous slab unit model;

[0046] S5.5.2 Boundary Constraints: Supports are used around the plate element to simulate the effect of anchors. The support spacing is determined based on the spacing of the longitudinal annular anchors.

[0047] S5.5.3 Load equivalence: The load is the weight of the surrounding rock in the triangular area below the intersection of the inner ends of two adjacent anchor bolts spreading out at a 45° angle to the surrounding rock.

[0048] S5.5.4. Calculate the internal forces of the sprayed layer according to the multi-point supported two-way plate and calculate K according to the damage stage method. p2 .

[0049] Furthermore, in the design method of a compressed air energy storage underground cavern support structure, S6 includes:

[0050] S6.1. Determine the basic ground motion parameters and seismic importance factors for earthquake calculation conditions;

[0051] S6.2. Establish a load-structure model based on the basic earthquake motion parameters and seismic importance factors determined in S6.1, equating the earthquake action to relative ground displacement, structural inertia force, and surrounding ground shear force, and calculate the axial force and bending moment data of the support structure;

[0052] S6.3. Based on the axial force and bending moment data of the support structure obtained in S6.2, calculate K e .

[0053] The beneficial effects of the present invention are:

[0054] 1. The underground cavern structure of the present invention is suitable for compressed gas energy storage underground caverns. By simplifying the structure, decomposing the functions of each layer, and selectively selecting materials and designing the structures of each layer, this structure coordinates the deformation of each layer, fully utilizing the bearing capacity of the surrounding rock while ensuring the airtightness of the cavern. Compared with existing structures, this structure does not require secondary lining or thick steel lining, significantly improving its economic efficiency.

[0055] 2. The present invention also provides a design method for the above-mentioned compressed air energy storage underground cavern structure. This method fully considers the stress characteristics of the compressed air energy storage underground cavern throughout its life cycle, and divides the structural bearing calculation into four parts: calculation of the safety factor of the support structure during construction, calculation of the structural safety under loading and unloading during operation, calculation of the safety factor of the structure under the self-weight load of the surrounding rock damage zone under maintenance conditions, and calculation of the safety of the structure under earthquake action. It can analyze the structural safety more comprehensively and provide a reasonable and feasible quantitative design method for the design of the compressed air energy storage underground cavern structure.

[0056] Other advantages, objectives and features of the present invention will be reflected in part from the following description and will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 Schematic diagram of the structure of the underground cavern structure of the present invention;

[0058] Figure 2 A flow chart of the design method of the cavern structure according to the present invention;

[0059] Figure 3 Schematic diagram of calculation of local surrounding rock stability under maintenance working conditions according to one embodiment of the present invention;

[0060] Figure 4 A cloud diagram of calculated axial forces for a structure under earthquake conditions as described in one embodiment of the present invention;

[0061] Figure 5 This is a calculated bending moment cloud diagram for a structure under earthquake conditions as described in one embodiment of the present invention.

[0062] Wherein, the reference numerals represent:

[0063] Anchor rod 1; shotcrete layer 2; sealing steel lining 3; high temperature resistant and high elastic modulus filling layer 4. DETAILED DESCRIPTION

[0064] The present invention is further described in detail below with reference to the embodiments so that those skilled in the art can implement the invention with reference to the description.

[0065] It should be noted that the experimental methods described in the following embodiments are conventional methods unless otherwise specified, and the reagents and materials are commercially available unless otherwise specified; in the description of the present invention, the terms "horizontal", "longitudinal", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present invention.

[0066] like Figure 1 As shown, an embodiment of the present invention provides a compressed air energy storage underground cavern support structure, including an anchor surrounding rock bearing arch, a sprayed concrete layer and a sealed steel lining, and a high-temperature resistant and high-elastic modulus filling layer is filled between the sprayed concrete layer and the sealed steel lining.

[0067] In this embodiment, the shotcrete layer utilizes steel fiber shotcrete, with a single layer of steel mesh connected to the anchor bolts of the surrounding rock bearing arch. Shotcrete requires surface smoothing and circular cross-section control to ensure construction quality. After hardening, 3D laser scanning and laser point cloud technology are used to perform high-precision measurements of the shotcrete base surface's flatness and clearance dimensions. Based on the measurement results, epoxy mortar is used to correct the internal contour to ensure that the error between the internal contour and the design dimensions meets the required tolerance. The sealing steel lining can be made of low-alloy, high-strength structural steel, and the thickness of the steel lining must meet strength and durability requirements.

[0068] Preferably, as another embodiment of the present invention, the high temperature resistant high elastic modulus filling layer is filled with asphalt.

[0069] In this embodiment, a high-temperature resistant and high-elastic modulus filling layer is formed by filling hot-melt asphalt between the sprayed concrete layer and the sealing steel lining. The high-temperature resistant and high-elastic modulus filling layer can also serve as a sliding layer between the sprayed concrete and the sealing steel lining.

[0070] Preferably, as another embodiment of the present invention, the anchor rod surrounding rock bearing arch adopts a hollow grouting anchor rod, and the hollow grouting anchor rod is filled with a non-shrinkage epoxy mortar filler.

[0071] In this embodiment, the anchor rod adopts a hollow grouting anchor rod and is equipped with a grouting plug with an exhaust and pressure stabilization function. The anchor rod hole grouting adopts a non-shrinkage epoxy mortar filler to ensure the dense grouting of the anchor rod hole and the bonding strength with the surrounding rock under repeated inflation and deflation conditions; the anchor rod end pad adopts an arc-shaped steel lining, and the excess rod body needs to be cut off after the anchor rod is installed.

[0072] The present invention also provides a design method for the above-mentioned compressed air energy storage underground cavern support structure, comprising the following steps:

[0073] S1. Obtain the design parameters of the support structure, specifically including the construction scale, capacity, working internal pressure, strength parameters of the surrounding rock, and engineering characteristics of the gas storage project, determine the cross-sectional dimensions, burial depth, and layout of the cavern, and determine the safety factor control value K during the tunnel construction period. cd , Maintenance period safety factor control value K pd , earthquake safety factor control value K ed ;K cd Generally not less than 1.8~2.1.

[0074] S2. Drafting support parameters and material parameters of the support structure, including: anchor support parameters including anchor length and ring longitudinal spacing; strength grade and thickness of shotcrete;

[0075] S3. Calculate the safety factor K of the support structure during the construction period based on the support parameters and material parameters proposed in S2. C :

[0076] K C The calculation method includes the following steps:

[0077] S3.1. Based on the support parameters and material parameters of the support structure proposed in S2, the load structure models of the anchor surrounding rock bearing arch and the shotcrete layer are established respectively, and the safety factor K of the anchor surrounding rock bearing arch is calculated respectively. 11 and the safety factor K of the shotcrete layer 21 ;

[0078] S3.2. Calculation of K C :

[0079] K C =K 11 +K 21 (1)

[0080] If K C ≤K cd , return to S2, and re-draft the support parameters of the support structure;

[0081] If K C >K cd ; Enter S4;

[0082] S4. Calculate the maximum deformation of the support structure during operation, and the maximum tensile strain ε0 of the sealing steel lining under loading and unloading:

[0083] The maximum deformation of the support structure during the operation period calculated in S4 includes at least: the height H of the maximum surrounding rock damage zone and the range of the lining damage zone within the working internal pressure range of the support structure during the operation period.

[0084] If ε0≥ε y , it is necessary to set an annular expansion joint between the steel plates on the sealing steel lining so that the position change between the steel plates of the sealing steel lining meets the maximum deformation of the support structure during the operation period; specifically, the ultimate elongation L of the annular expansion joint should meet the following requirements:

[0085] L>πR(ε0-ε y1 ) (2)

[0086] Where R is the inner diameter of the underground cavern, ε y1 The strain of the steel plates on both sides of the joint when the deformation matches the deformation of the surrounding rock.

[0087] If ε0<ε y ; Enter S4;

[0088] Among them, ε y The ultimate strain of the steel material of the sealing steel lining;

[0089] S5. Calculate the safety factor K of the support structure during the maintenance period based on the maximum deformation of the support structure during the operation period calculated in S4. p :K in S5 p is the total safety factor K during the maintenance period of the support mechanism p1 and the local spraying layer strength safety factor K p2 Small value in: e=min{K p1 ,K p2};

[0090] Among them, K p1 The calculation method is as follows:

[0091] S5.1. Calculate the maximum deadweight load Q of the surrounding rock damage zone that the support structure needs to bear under maintenance conditions:

[0092] Q=γH (3)

[0093] Wherein, γ is the bulk density of surrounding rock;

[0094] S5.2. Determine the reduction coefficient k1 based on the area of ​​the lining damage zone of the support structure within the working internal pressure range during the operation period, and reduce the support parameters and material parameters of the support structure proposed in S2. Since both the surrounding rock and the lining are cracked during the operation stage, the mechanical parameters of the surrounding rock and the lining in step S2 can be reduced to obtain the mechanical parameters under the maintenance condition. The reduction coefficient k1 can be determined based on the distribution of the damage zone in the surrounding rock and the area of ​​the damage zone in the lining.

[0095] S5.3. Based on the reduced support parameters and material parameters in S5.2, use the total safety factor method to establish the load structure model of the anchor surrounding rock bearing arch and the shotcrete layer, and calculate the reduced safety factor K of the anchor surrounding rock bearing arch. 12 and the safety factor K of the shotcrete layer 22 ;

[0096] S5.4. Calculation of K p1 :

[0097] K p1 =K 12 +K 22 (4)

[0098] Among them, K p2 The calculation method is as follows:

[0099] S5.5. Establish a local surrounding rock stability calculation model between the anchor rods of the support structure, and calculate K using the local surrounding rock stability calculation model. p2 .

[0100] Furthermore, in the design method of a compressed air energy storage underground cavern support structure, S5.5 includes:

[0101] S5.5.1. Model establishment: Select a local area of ​​the support structure with relatively large stress, simplify it into a reinforced steel fiber reinforced concrete longitudinal circumferential continuous slab, and establish a continuous slab unit model;

[0102] S5.5.2 Boundary Constraints: Supports are used around the plate element to simulate the effect of anchors. The support spacing is determined based on the spacing of the longitudinal annular anchors.

[0103] S5.5.3 Load equivalence: The load is the weight of the surrounding rock in the triangular area below the intersection of the inner ends of two adjacent anchor bolts spreading out at a 45° angle to the surrounding rock.

[0104] S5.5.4. Calculate the internal forces of the sprayed layer according to the multi-point supported two-way plate and calculate K according to the damage stage method. p2 .

[0105] If K p ≤K pd , return to S2, and re-draft the support parameters of the support structure;

[0106] If K p >K pd ; Enter S4;

[0107] S6. Calculate the safety factor K of the support structure under earthquake action e :

[0108] S6.1. Determine the basic ground motion parameters and seismic importance factors for earthquake calculation conditions;

[0109] S6.2. Based on the basic seismic motion parameters and seismic importance coefficients determined in S6.1, the reaction-displacement method is used to establish a load-structure model for seismic calculations. The seismic action is equivalent to the relative displacement of the stratum, the structural inertia force and the shear force of the surrounding stratum, and the axial force and bending moment data of the support structure are calculated; the reaction-displacement method is used to establish a load-structure model for seismic calculations. The lining structure is simulated by beam units, and the interaction between the lining and the surrounding rock is simulated by compression springs and shear springs. The mechanical parameters and spring stiffness of the lining need to be reduced on the basis of S2. The reduction coefficient k2 can be determined according to the distribution of the damaged area of ​​the surrounding rock and the area of ​​the damaged area of ​​the lining.

[0110] S6.3. Based on the axial force and bending moment data of the support structure obtained in S6.2, calculate K e .

[0111] If K e ≤K ed , return to S2;

[0112] If K e >K ed , the design is completed, and the current support parameters and material parameters are used as the support parameters and material parameters of the support structure.

[0113] In addition, the present invention also provides specific embodiments of the above-mentioned design method, such as Figure 2 As shown, the following steps are included:

[0114] S1: Based on the construction scale, capacity, working internal pressure and other engineering characteristics of the gas storage project, the cross-sectional dimensions of the cavern are determined to be a circular cavern with an inner diameter of 20m and a burial depth of 250m. The layout is a flat tunnel type, the surrounding rock grade is Grade III, and the calculated values ​​of the surrounding rock physical and mechanical parameters are the upper 1 / 3 quantile of the recommended range values ​​in the "Code for Design of Railway Tunnels" (TB10003--2016). The working internal pressure is 8-18MPa.

[0115] S2: The proposed structural support parameters and material parameters are as follows: Anchor and shotcrete support: The anchor rods are φ25 hollow grouting anchor rods, with a spacing (longitudinal × circular) of 1.2m × 1.2m and a length of 6m. The shotcrete is C30 steel fiber concrete, 15cm thick, with φ10 steel mesh and a spacing of 15cm × 15cm.

[0116] S3: The safety factor of the support structure during construction is calculated using the total safety factor method as follows: Safety factor of the anchor rock bearing arch K 11 The safety factor K of the spray layer is 9.6. 21 is 2.68, then the total safety factor K during the construction period is C=12.28, K cd Set to 1.8, then K cd Greater than 1.8, meeting the requirements.

[0117] S4: Calculate the safety of the support structure under loading and unloading during operation. S4 is specifically:

[0118] S41: Based on the characteristics of this project, a numerical calculation model of the structure under loading and unloading during the operation period was established. The maximum surrounding rock damage zone height H of the structure under the maximum working internal pressure and the minimum working internal pressure during the operation stage was calculated to be 15m, and the maximum tensile strain ε0 of the sealing steel lining was 2.5‰.

[0119] S42: Ultimate strain ε of the steel lining selected for this project y It is 2‰, which is less than the calculated maximum strain value ε0, so it is necessary to set up a circumferential expansion joint. A total of 4 joints are set up in this project. The maximum elongation of each joint is 40mm, and it has self-recovery ability. At this time, the deformation of the steel lining meets the requirements.

[0120] S5: Based on the calculation results of S4, calculate the safety factor of the support structure under the deadweight load of the surrounding rock failure zone under maintenance conditions. S5 is specifically:

[0121] S5.1: Determine that the deadweight load Q of the surrounding rock failure zone that the support structure needs to bear under maintenance conditions is 367kN / m 2 , Q = γH, where γ is the bulk density of the surrounding rock 24.5kN / m 3 , H is the height of the surrounding rock damage zone calculated in step S4, which is 15m.

[0122] S5.2: Determine the mechanical parameters of the surrounding rock and lining under maintenance conditions. Since both the surrounding rock and lining experienced cracking during the operational phase, the mechanical parameters of the surrounding rock and lining obtained in step S2 can be reduced to obtain the mechanical parameters under maintenance conditions. The surrounding rock surrounding the cavern has already been damaged, so its cohesion is reduced to zero. Based on experience, the friction angle is generally reduced by a factor of 0.1 to 0.7. This calculation uses a reduction factor of 0.7. The reduction of lining strength parameters can be determined based on the extent of the damaged area. For this project, a reduction factor of 0.3 was determined based on the ratio of the damaged area to the undamaged area.

[0123] S5.3: Based on the support structure parameters determined in S5.2, the safety factor K is calculated using the load structure model of the anchor rock bearing arch and the sprayed layer under the multi-layer structure in the total safety factor method. 12 , K 22 They are 1.17 and 0.55 respectively.

[0124] S5.4: Overall safety factor K p1 is 1.72, K pd Set to 1.53, Kp1 Greater than 1.53, meeting the requirements.

[0125] S5.5: Select the arch top position with large local stress and establish the local surrounding rock stability calculation model between the anchors, such as Figure 3 As shown in the figure, the vault part with relatively large local stress is simplified into a longitudinal circumferential continuous plate of reinforced steel fiber concrete. Anchor rods serve as supports around the plate. The spacing between the supports is determined according to the longitudinal circumferential spacing of the anchor rods, which is 1.2m×1.2m in this example. The load is the self-weight of the surrounding rock in the triangular area below the intersection after the inner ends of two adjacent anchor rods (i.e., the pads of the sprayed concrete wall) spread to the surrounding rock at a 45° angle, which is 1.5m in this example.

[0126] S5.6: Calculate the internal forces of the shotcrete layer according to the multi-point supported two-way slab and calculate the safety factor K of the local shotcrete layer strength according to the damage stage method. p2 is 1.7, K p2 Greater than K pd , you can proceed to the next step of calculation.

[0127] S6: According to steps S4-S5, calculate the safety factor of the support structure under earthquake action. The details are as follows:

[0128] S6.1: The basic seismic motion parameters and seismic importance coefficients for earthquake calculation conditions are determined as follows: The characteristic period of the basic seismic acceleration response spectrum of Class II sites within the site area of ​​this project is 0.40s, the basic seismic peak acceleration of the site is 0.15g, and the seismic importance coefficient is 1.0.

[0129] S6.2: Use the reaction displacement method to establish a load structure model for seismic calculation. The lining structure is simulated by beam elements. The interaction between the lining and the surrounding rock is simulated by compression springs and shear springs. The mechanical parameters and spring stiffness of the lining need to be reduced based on S2. The earthquake action is equivalent to the relative displacement of the stratum, the structural inertia force and the shear force of the surrounding stratum. The axial force and bending moment of the lining structure (such as Figure 4-Figure 5 As shown), the safety factor K of the lining structure under earthquake action is obtained e is 1.65.

[0130] S6.3:K ed Set to 1.53, the safety factor K under earthquake conditions e Greater than the earthquake safety factor control value K ed , then the requirements are met and the current support parameters and material parameters are used as the support parameters and material parameters of the support structure.

[0131] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the description and implementation methods. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and embodiments shown and described herein.

Claims

1. A design method for a compressed air energy storage underground cavern support structure, wherein the compressed air energy storage underground cavern support structure comprises an anchor surrounding rock bearing arch, a sprayed concrete layer, and a sealed steel liner, wherein a high-temperature resistant high elastic modulus filling layer is filled between the sprayed concrete layer and the sealed steel liner, characterized in that: The following steps are involved: S1. Obtain the design parameters of the support structure and determine the safety factor control value during the tunnel construction period , Safety factor control value during maintenance period , Safety factor control value for earthquake conditions ; S2. Formulate support parameters and material parameters of the support structure; S3. Calculate the safety factor of the support structure during the construction period based on the support parameters and material parameters proposed in S2 : like , return to S2, and re-draft the support parameters of the support structure; like ; Enter S4; S4. Calculate the maximum deformation of the support structure during operation and the maximum tensile strain of the sealing steel lining under loading and unloading. : like , it is necessary to set annular expansion joints between the steel plates on the sealing steel lining so that the position change between the steel plates of the sealing steel lining can meet the maximum deformation of the support structure during the operation period; like ; Enter S5; in, The ultimate strain of the steel material of the sealing steel lining; S5. Calculate the safety factor of the support structure during the maintenance period based on the maximum deformation of the support structure during the operation period calculated in S4. : like , return to S2, and re-draft the support parameters of the support structure; like ; Enter S6; S6. Calculate the safety factor of the support structure under earthquake action : like , return to S2; like , the design is completed, and the current support parameters and material parameters are used as the support parameters and material parameters of the support structure.

2. The design method of a compressed air energy storage underground cavern support structure according to claim 1, characterized in that: S3 The calculation method includes the following steps: S3.

1. Based on the support parameters and material parameters of the support structure proposed in S2, the load structure models of the anchor surrounding rock bearing arch and the shotcrete layer are established respectively, and the safety factor K of the anchor surrounding rock bearing arch is calculated respectively. 11 and the safety factor K of the shotcrete layer 21 ; S3.2 Calculation : （1）。 3. The design method of a compressed air energy storage underground cavern support structure according to claim 1, characterized in that: The ultimate elongation L of the circumferential expansion joint in S4 should meet the following requirements: （2） Where R is the inner diameter of the underground cavern.

4. The design method of a compressed air energy storage underground cavern support structure according to claim 1, characterized in that: The maximum deformation of the support structure during the operation period calculated in S4 includes at least: the height of the maximum surrounding rock damage zone of the support structure within the working internal pressure range during the operation period. and the extent of the lining damage area.

5. The design method of a compressed air energy storage underground cavern support structure according to claim 4, characterized in that: S5 is the total safety factor during the maintenance period of the support mechanism and local spraying strength safety factor Small value in: ; in, The calculation method is as follows: S5.

1. Calculate the maximum deadweight load of the surrounding rock damage zone that the support structure needs to bear under maintenance conditions. : （3） in, is the bulk density of surrounding rock; S5.

2. Determine the reduction factor based on the area of ​​the lining damage zone within the operating internal pressure range of the support structure during operation.

1. Reduce the support parameters and material parameters of the support structure proposed in S2; S5.

3. Based on the reduced support parameters and material parameters in S5.2, establish the load structure model of the anchor surrounding rock bearing arch and the shotcrete layer respectively, and calculate the safety factor of the anchor surrounding rock bearing arch after the reduction. and the safety factor of the shotcrete layer ; S5.

4. Calculation : （4） in, The calculation method is as follows: S5.

5. Establish a local surrounding rock stability calculation model between the anchor rods of the support structure, and calculate the local surrounding rock stability calculation model .

6. The design method of a compressed air energy storage underground cavern support structure according to claim 5, characterized in that: S5.5 includes: S5.5.

1. Model establishment: Select a local area of ​​the support structure with relatively large stress, simplify it into a reinforced steel fiber reinforced concrete longitudinal circumferential continuous slab, and establish a continuous slab unit model; S5.5.2 Boundary Constraints: Supports are used around the plate element to simulate the effect of anchors. The support spacing is determined based on the spacing of the longitudinal annular anchors. S5.5.3 Load equivalence: The load is the weight of the surrounding rock in the triangular area below the intersection of the inner ends of two adjacent anchor bolts spreading out at a 45° angle to the surrounding rock. S5.5.

4. Calculate the internal forces of the sprayed layer according to the multi-point support two-way plate and calculate them according to the damage stage method. .

7. The design method of a compressed air energy storage underground cavern support structure according to claim 1, characterized in that S6 include: S6.

1. Determine the basic ground motion parameters and seismic importance factors for earthquake calculation conditions; S6.

2. Establish a load-structure model based on the basic earthquake motion parameters and seismic importance factors determined in S6.1, equating the earthquake action to relative ground displacement, structural inertia force, and surrounding ground shear force, and calculate the axial force and bending moment data of the support structure; S6.

3. Based on the axial force and bending moment data of the support structure obtained in S6.2, calculate .

8. The design method of a compressed air energy storage underground cavern support structure according to claim 1, characterized in that: The high-temperature-resistant and high-elastic modulus filling layer is filled with asphalt.

9. The design method of a compressed air energy storage underground cavern support structure according to claim 1, characterized in that: The anchor rod surrounding rock bearing arch adopts a hollow grouting anchor rod, and the hollow grouting anchor rod is filled with non-shrinkage epoxy mortar filling material.

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