Compressed air energy storage underground cavern supporting structure and design method thereof

Abstract

The invention relates to the field of underground engineering, in particular to a compressed air energy storage underground cavern supporting structure and a design method thereof. The invention provides a compressed air energy storage underground cavern supporting structure and a design method thereof, the compressed air energy storage underground cavern supporting structure is suitable for compressed air energy storage underground gas storage cavern structure design, the supporting structure enables deformation of all layers to be coordinated through structure simplification, decomposition of functions of all the layers, targeted selection of materials and design of structures of all the layers, the bearing capacity of surrounding rock can be fully utilized, and the supporting structure can be used for supporting the underground cavern. And meanwhile, the sealing performance of the cavern is ensured. Compared with an existing structure, the structure is not provided with a secondary lining and a thick steel lining, and economical efficiency is greatly improved.

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 because of their advantages such as large storage scale, flexible site selection and little impact on the surrounding environment.

[0003] Underground chambers in the transportation and water conservancy industries often use concrete as the lining structure to give full play to the role of the surrounding rock to bear external loads. For compressed gas energy storage chambers, not only do they need to withstand the external surrounding rock pressure and water pressure during the construction and operation periods, but they also need to consider the high-pressure gas load on the lining caused by cyclic filling and discharge during the operation phase. Therefore, the force mechanism is different from that of conventional underground artificial lined chambers.

[0004] The underground gas storage chamber can adopt the structure of sealed steel lining-concrete lining. In order to meet the requirements of economy, the ideal bearing and sealing system is: the steel lining plays a sealing role, and its thickness meets the structural requirements; the concrete lining is responsible for bearing the loads during the construction and maintenance periods of the chamber, and at the same time transferring the internal pressure load during the operation period; the internal pressure load during the operation period is mainly borne by the surrounding rock. In fact, the internal pressure generated by compressed air during the operation period is often high, generally greater than 10MPa or even up to 20MPa, and the concrete lining will inevitably suffer tensile failure, resulting in a weakening or even failure of the ability to transfer loads and bear loads. The existing data do not consider the deformation coordination of the surrounding rock, structure, and sealing layer, resulting in stress concentration and damage caused by the uncoordinated deformation of the multi-layer structure under high pressure. Therefore, when designing the support structure of the compressed gas energy storage underground cavern under high internal pressure, it is necessary to consider the stress and damage characteristics of the underground cavern at different stages, select materials and design the structures of each layer in a targeted manner, so that the deformation of each layer is coordinated to ensure that the cavern structure meets the safety requirements of each stage. At present, there is no unified standard and method for the design of underground cavern structures for compressed gas energy storage, which 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 purpose of the present invention is to provide a compressed gas energy storage underground cavern support structure and its design method, which is suitable for the compressed gas energy storage underground gas storage chamber structure design. The support structure simplifies the structure, decomposes the functions of each layer, selects materials and designs the structure of each layer in a targeted manner, so that the deformation of each layer is coordinated, the bearing capacity of the surrounding rock can be fully utilized, and the sealing of the cavern can be ensured at the same time. Compared with the existing structure, the structure does not have a secondary lining and a thicker steel lining, and the economic efficiency is greatly improved.

[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 shotcrete layer and a sealed steel lining, and a high-temperature resistant and high-elastic modulus filling layer is filled between the shotcrete layer and the sealed 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 surrounding rock bearing arch adopts a hollow grouting anchor, and the hollow grouting anchor 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 , Safety factor control value K during maintenance period 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 mechanism 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 value ε0 of the sealing steel lining under loading and unloading:

[0016] 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 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 steel for sealing steel lining;

[0019] S5. Calculate the safety factor K of the support structure during the maintenance period according to 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. According to 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).

[0030] Furthermore, in the design method of a compressed air energy storage underground cavern support structure, the ultimate elongation L of the annular expansion joint in S4 should satisfy:

[0031] L>πR(ε0-ε y1 ) (2)

[0032] Where R is the inner diameter of the underground cavern, ε y1 The strain of the steel plates on both sides of the joint to achieve deformation matching the deformation of the surrounding rock.

[0033] 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.

[0034] Further, 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 strength safety factor K p2 Small value in: e=min{K p1 ,K p2};

[0035] Among them, K p1 The calculation method is as follows:

[0036] S5.1. Calculate the maximum deadweight load Q of the surrounding rock damage area that the support structure needs to bear under maintenance conditions:

[0037] Q=γH (3)

[0038] Among them, γ is the bulk density of surrounding rock;

[0039] S5.2. Determine the reduction factor k1 according to 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;

[0040] S5.3. According to the reduced support parameters and material parameters in S5.2, 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 after the reduction is calculated respectively. 12 and the safety factor K of the shotcrete layer 22 ;

[0041] S5.4. Calculation of K p1 :

[0042] K p1 =K 12 +K 22 (4)

[0043] Among them, K p2 The calculation method is as follows:

[0044] S5.5. Establish a local surrounding rock stability calculation model between the anchor rods of the support structure, and calculate K through the local surrounding rock stability calculation model p2 .

[0045] Further, in the design method of a compressed air energy storage underground cavern support structure, S5.5 includes:

[0046] S5.5.1. Model establishment: Select the local area with large stress on the support structure, simplify it into a reinforced steel fiber concrete longitudinal annular continuous plate, and establish a continuous plate unit model;

[0047] S5.5.2, Boundary constraints: The plate element is constrained by supports all around to simulate the effect of anchors. The spacing between supports is determined based on the spacing between longitudinal annular anchors.

[0048] 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 anchors spreading toward the surrounding rock at an angle of 45°;

[0049] S5.5.4. Calculate the internal force of the spray layer according to the multi-point supported two-way plate, and calculate K according to the damage stage method. p2 .

[0050] Further, in the design method of a compressed air energy storage underground cavern support structure, S6 includes:

[0051] S6.1. Determine the basic ground motion parameters and seismic importance coefficients for earthquake calculation conditions;

[0052] S6.2. Based on the basic earthquake motion parameters and seismic importance coefficients determined in S6.1, a load structure model is established, and the earthquake action is equivalent to the relative displacement of the strata, the structural inertia force and the shear force of the surrounding strata, and the axial force and bending moment data of the support structure are calculated;

[0053] S6.3. Based on the axial force and bending moment data of the support structure obtained in S6.2, calculate K e .

[0054] The beneficial effects of the present invention are:

[0055] 1. The underground cavern structure of the present invention is suitable for compressed gas energy storage underground caverns. The structure simplifies the structure, decomposes the functions of each layer, selects materials and designs the structure of each layer in a targeted manner, so that the deformation of each layer is coordinated, the bearing capacity of the surrounding rock can be fully utilized, and the sealing of the cavern can be ensured. Compared with the existing structure, the structure does not have a secondary lining and a thicker steel lining, and the economic efficiency is greatly improved.

[0056] 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.

[0057] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 It is a structural schematic diagram of the underground cavern structure of the present invention;

[0059] Figure 2 A flow chart of the design method of the cavern structure according to the present invention;

[0060] Figure 3 It is a schematic diagram of calculating the stability of local surrounding rock in a maintenance working condition described in one embodiment of the present invention;

[0061] Figure 4 A cloud diagram of axial force calculation for a structure under earthquake conditions described in one embodiment of the present invention;

[0062] Figure 5 The bending moment cloud diagram of the structure calculated for the earthquake condition described in one embodiment of the present invention.

[0063] Wherein, the reference numerals represent:

[0064] Anchor rod 1; shotcrete layer 2; sealing steel lining 3; high temperature resistant and high elastic modulus filling layer 4. DETAILED DESCRIPTION

[0065] The present invention is further described in detail below in conjunction with embodiments so that those skilled in the art can implement the invention with reference to the description.

[0066] 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 "lateral", "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 on the present invention.

[0067] 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 shotcrete layer and a sealed steel liner, and a high-temperature resistant and high-elastic modulus filling layer is filled between the shotcrete layer and the sealed steel liner.

[0068] In this embodiment, the shotcrete layer uses steel fiber shotcrete, which is configured with a single-layer steel mesh connected to the anchor of the anchor surrounding rock bearing arch; the shotcrete needs to use spray surface flatness and circular section control technology to ensure the construction quality; after hardening, three-dimensional laser scanning and laser point cloud technology are used to measure the flatness and clearance size of the shotcrete base surface with high precision, and epoxy mortar is used to correct the inner contour according to the measurement results to ensure that the error between the inner contour and the design size meets the requirements. The sealing steel lining can be made of low-alloy high-strength structural steel, and the thickness of the steel lining must meet the strength and durability requirements.

[0069] Preferably, as another embodiment of the present invention, the high temperature resistant high elastic modulus filling layer is filled with asphalt.

[0070] In this embodiment, a high temperature resistant and high elastic modulus filling layer is formed by filling hot melt asphalt between the shotcrete 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 shotcrete and the sealing steel lining.

[0071] Preferably, as another embodiment of the present invention, the anchor surrounding rock bearing arch adopts a hollow grouting anchor, and the hollow grouting anchor is filled with a non-shrinkage epoxy mortar filler.

[0072] 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.

[0073] The present invention also provides a design method for the above-mentioned compressed air energy storage underground cavern support structure, comprising the following steps:

[0074] S1. Obtain the design parameters of the support structure, including the construction scale, capacity, working internal pressure, strength parameters and engineering characteristics of the surrounding rock 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 , Safety factor control value K during maintenance period pd , Earthquake safety factor control value K ed ; K cd Generally not less than 1.8~2.1.

[0075] S2. Formulate the support parameters and material parameters of the support structure, including: the support parameters of the anchor rod include the length of the anchor rod and the longitudinal spacing of the ring; the strength grade and thickness of the shotcrete;

[0076] S3. Calculate the safety factor K of the support mechanism during the construction period based on the support parameters and material parameters proposed in S2. C :

[0077] K C The calculation method includes the following steps:

[0078] S3.1. According to 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 ;

[0079] S3.2. Calculation of K C :

[0080] K C =K 11 +K 21 (1).

[0082] If K C ≤K cd , return to S2, and re-draft the support parameters of the support structure;

[0083] If K C >K cd ; Enter S4;

[0084] S4. Calculate the maximum deformation of the support structure during operation and the maximum tensile strain value ε0 of the sealing steel lining under loading and unloading:

[0085] The maximum deformation of the support structure during the operation period calculated in S4 at least includes: 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.

[0086] 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:

[0087] L>πR(ε0-ε y1 ) (2)

[0088] Where R is the inner diameter of the underground cavern, ε y1 The strain of the steel plates on both sides of the joint to achieve deformation matching the deformation of the surrounding rock.

[0089] If ε0<ε y ; Enter S4;

[0090] Among them, ε y The ultimate strain of steel for sealing steel lining;

[0091] S5. Calculate the safety factor K of the support structure during the maintenance period according to the maximum deformation of the support structure during the operation period calculated in S4. p : S5 K p is the total safety factor K during the maintenance period of the support mechanism p1 and the local spraying strength safety factor K p2 Small value in: e=min{K p1 ,K p2};

[0092] Among them, K p1 The calculation method is as follows:

[0093] S5.1. Calculate the maximum deadweight load Q of the surrounding rock damage area that the support structure needs to bear under maintenance conditions:

[0094] Q=γH (3)

[0095] Among them, γ is the bulk density of surrounding rock;

[0096] S5.2. Determine the reduction coefficient k1 according to the area of ​​the lining damaged 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 maintenance conditions. The reduction coefficient k1 can be determined according to the distribution of the damaged zone of the surrounding rock and the area of ​​the damaged zone of the lining.

[0097] S5.3. Based on the reduced support parameters and material parameters in S5.2, the total safety factor method is used to establish the load structure models of the anchor surrounding rock bearing arch and the shotcrete layer, and the safety factor K of the anchor surrounding rock bearing arch after reduction is calculated. 12 and the safety factor K of the shotcrete layer 22 ;

[0098] S5.4. Calculation of K p1 :

[0099] K p1 =K 12 +K 22 (4)

[0100] Among them, K p2 The calculation method is as follows:

[0101] S5.5. Establish a local surrounding rock stability calculation model between the anchor rods of the support structure, and calculate K through the local surrounding rock stability calculation model p2 .

[0102] Further, in the design method of a compressed air energy storage underground cavern support structure, S5.5 includes:

[0103] S5.5.1. Model establishment: Select the local area with large stress on the support structure, simplify it into a reinforced steel fiber concrete longitudinal annular continuous plate, and establish a continuous plate unit model;

[0104] S5.5.2, Boundary constraints: The plate element is constrained by supports all around to simulate the effect of anchors. The spacing between supports is determined based on the spacing between longitudinal annular anchors.

[0105] 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 anchors spreading toward the surrounding rock at an angle of 45°;

[0106] S5.5.4. Calculate the internal force of the spray layer according to the multi-point supported two-way plate, and calculate K according to the damage stage method. p2 .

[0107] If K p ≤K pd , return to S2, and re-draft the support parameters of the support structure;

[0108] If K p >K pd ; Enter S4;

[0109] S6. Calculate the safety factor K of the support structure under earthquake action e :

[0110] S6.1. Determine the basic ground motion parameters and seismic importance coefficients for earthquake calculation conditions;

[0111] S6.2. Based on the basic earthquake 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 earthquake action is equivalent to the relative displacement of the stratum, the structural inertia force and the shear force of the surrounding strata, 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 factor k2 can be determined according to the distribution of damaged areas in the surrounding rock and the area of ​​damaged areas in the lining.

[0112] S6.3. Based on the axial force and bending moment data of the support structure obtained in S6.2, calculate K e .

[0113] If K e ≤K ed , return to S2;

[0114] 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.

[0115] In addition, the present invention also provides a specific embodiment of the above-mentioned design method, such as Figure 2 As shown, the following steps are included:

[0116] S1: According to 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, 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 "Railway Tunnel Design Code" (TB10003--2016). The working internal pressure is 8~18MPa.

[0117] S2: The proposed structural support parameters and material parameters are as follows: Anchor spraying support: The anchor rod adopts φ25 hollow grouting anchor rod, with a spacing (longitudinal × ring) of 1.2m×1.2m and a length of 6m. The sprayed concrete adopts C30 steel fiber concrete with a thickness of 15cm, equipped with φ10 steel mesh, and a spacing of 15cm×15cm.

[0118] S3: The total safety factor method is used to calculate the safety factor of the support structure during the construction period as follows: The 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.

[0119] S4: Calculate the safety of the support structure under loading and unloading during operation. S4 is specifically:

[0120] S41: According to the characteristics of this project, a numerical calculation model of the structure under loading and unloading during the operation period is established. The maximum height H of the surrounding rock damage zone under the maximum working internal pressure and the minimum working internal pressure of the structure in the operation stage is calculated to be 15m, and the maximum tensile strain ε0 of the sealing steel lining is 2.5‰.

[0121] S42: The 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 annular expansion joints. 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.

[0122] 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:

[0123] 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 24.5 kN / m 3 , H is the height of the surrounding rock damage zone calculated in step S4, 15m.

[0124] S5.2: Determine the mechanical parameters of the surrounding rock and lining under maintenance conditions. Since both the surrounding rock and lining were cracked during the operation stage, the mechanical parameters of the surrounding rock and lining in step S2 can be reduced to obtain the mechanical parameters under maintenance conditions. For the surrounding rock around the cavern, damage has occurred, so its cohesion is reduced to 0. According to experience, the friction angle can generally be reduced by 0.1 to 0.7. The reduction coefficient for this calculation is 0.7. The reduction of lining strength parameters can be determined according to the range of the lining damage area. This project determines the reduction coefficient to be 0.3 based on the ratio of the damaged area to the undamaged area.

[0125] S5.3: Based on the supporting structure parameters determined in S5.2, the load structure model of the anchor rock bearing arch and the shotcrete layer under the multi-layer structure in the total safety factor method is used to calculate the safety factor K 12 , K 22 They are 1.17 and 0.55 respectively.

[0126] S5.4: Overall safety factor K p1 is 1.72, K pd Set to 1.53, Kp1 Greater than 1.53, meeting the requirements.

[0127] 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 large local stress is simplified into a reinforced steel fiber concrete longitudinal annular continuous plate. The anchor rods are used as supports around the plate. The spacing between the supports is determined according to the longitudinal annular spacing of the anchor rods, which is 1.2m×1.2m in this case. The load is the self-weight of the surrounding rock in the triangular area below the intersection after the inner ends of the two adjacent anchor rods (i.e. the pads of the sprayed concrete wall) diffuse to the surrounding rock at an angle of 45°, which is 1.5m in this case.

[0128] S5.6: Calculate the internal forces of the sprayed layer according to the multi-point supported two-way plate, and calculate the local sprayed layer strength safety factor K 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.

[0129] S6: According to steps S4-S5, calculate the safety factor of the support structure under earthquake action. The details are as follows:

[0130] 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.

[0131] S6.2: The load structure model is established by reaction displacement method for earthquake resistance calculation. The lining structure is simulated by beam unit. The interaction between lining and surrounding rock is simulated by compression spring and shear spring. The mechanical parameters and spring stiffness of lining need to be reduced on the basis of 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 in Figure 2), the safety factor K of the lining structure under earthquake action is obtained. e is 1.65.

[0132] S6.3: K ed Set to 1.53, the safety factor K under earthquake conditions e Greater than the control value K of the safety factor of earthquake conditions 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.

[0133] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation modes. 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 the embodiments shown and described herein.

Claims

1. A compressed air energy storage underground cavern support structure, comprising an anchor surrounding rock bearing arch, a shotcrete layer and a sealed steel lining, characterized in that: A high temperature resistant and high elastic modulus filling layer is filled between the sprayed concrete layer and the sealing steel liner.

2. A compressed air energy storage underground cavern support structure as claimed in claim 1, characterized in that: The high temperature resistant high elastic modulus filling layer is filled with asphalt.

3. A compressed air energy storage underground cavern support structure as claimed in 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.

4. A design method for a compressed air energy storage underground cavern support structure according to any one of claims 1 to 3, characterized in that: The following steps are involved: S1. Obtain the design parameters of the support structure and determine the safety factor control value K during the tunnel construction period cd , Safety factor control value K during maintenance period pd , Earthquake safety factor control value K ed ; S2. Formulate support parameters and material parameters of the support structure; S3. Calculate the safety factor K of the support mechanism during the construction period based on the support parameters and material parameters proposed in S2. C : If K C ≤K cd , return to S2, and re-draft the support parameters of the support structure; If K C >K cd ; Enter S4; S4. Calculate the maximum deformation of the support structure during operation and the maximum tensile strain value ε0 of the sealing steel lining under loading and unloading: 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 can meet the maximum deformation of the support structure during the operation period; If ε0<ε y ; Enter S4; Among them, ε y The ultimate strain of steel for sealing steel lining; S5. Calculate the safety factor K of the support mechanism during the maintenance period according to the maximum deformation of the support structure during the operation period calculated in S4. p : If K p ≤K pd , return to S2, and re-draft the support parameters of the support structure; If K p >K pd ; Enter S4; S6. Calculate the safety factor K of the support structure under earthquake action e : If K e ≤K ed , return to S2; 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.

5. The design method of a compressed air energy storage underground cavern support structure according to claim 4 is characterized in that: S3 K C The calculation method includes the following steps: S3.

1. According to 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 of K C : K C =K 11 +K 21 (1)。 6. The design method of a compressed air energy storage underground cavern support structure according to claim 4, characterized in that: The ultimate elongation L of the annular expansion joint in S4 should meet the following requirements: L>πR(ε0-ε y ) (2) Where R is the inner diameter of the underground cavern.

7. The design method of a compressed air energy storage underground cavern support structure according to claim 4, characterized in that: The maximum deformation of the support structure during the operation period calculated in S4 at least includes: 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.

8. The design method of a compressed air energy storage underground cavern support structure according to claim 7, characterized in that: S5 K p is the total safety factor K during the maintenance period of the support mechanism p1 and the local spraying strength safety factor K p2 Small value in: e=min{K p1 ,K p2 }; Among them, K p1 The calculation method is as follows: S5.

1. Calculate the maximum deadweight load Q of the surrounding rock damage area that the support structure needs to bear under maintenance conditions: Q=γH (3) Among them, γ is the bulk density of surrounding rock; S5.

2. Determine the reduction factor k1 according to 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; S5.

3. According to the reduced support parameters and material parameters in S5.2, 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 after the reduction is calculated respectively. 12 and the safety factor K of the shotcrete layer 22 ; S5.

4. Calculation of K p1 : K p1 =K 12 +K 22 (4) Among them, K p2 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 K through the local surrounding rock stability calculation model p2 .

9. The design method of a compressed air energy storage underground cavern support structure according to claim 8, characterized in that: S5.5 includes: S5.5.

1. Model establishment: Select the local area with large stress on the support structure, simplify it into a reinforced steel fiber concrete longitudinal annular continuous plate, and establish a continuous plate unit model; S5.5.2, Boundary constraints: The plate element is constrained by supports all around to simulate the effect of anchors. The spacing between supports is determined based on the spacing between 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 anchors spreading toward the surrounding rock at an angle of 45°; S5.5.

4. Calculate the internal force of the spray layer according to the multi-point support bidirectional plate, and calculate K according to the damage stage method. p2 .

10. The design method of a compressed air energy storage underground cavern support structure according to claim 4, characterized in that S6 include: S6.

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

2. Based on the basic earthquake motion parameters and seismic importance coefficients determined in S6.1, a load structure model is established, and the earthquake action is equivalent to the relative displacement of the strata, the structural inertia force and the shear force of the surrounding strata, and the axial force and bending moment data of the support structure are calculated; S6.

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

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