Method for analyzing anti-heave stability of compressed air energy storage cavern under influence of geological fault

Abstract

This invention discloses a method for analyzing the uplift stability of compressed gas storage caverns under the influence of geological faults. It combines the upper bound theorem of limit analysis with the rigid body equilibrium method to establish uplift failure models in ideal intact rock masses and under the influence of geological faults. By calculating the first and second ultimate internal pressures and taking the smaller value as the engineering ultimate internal pressure, it can accurately reflect the weakening effect of geological faults on the uplift stability of the cavern, avoiding the overestimation of engineering safety in fault-containing strata by traditional methods. A safety factor is defined; if the safety factor does not meet the requirements, the design internal pressure or the distance from the cavern to the fault during the cavern operation phase can be adjusted. This provides an efficient and accurate quantitative analysis method for the site selection and uplift stability design of compressed gas storage caverns in areas affected by geological faults. This method can be used to evaluate the rationality of compressed gas storage cavern layout schemes in areas affected by geological faults, and has significant implications for the promotion and construction of artificial cavern compressed gas storage projects.

Description

Technical Field

[0001] This invention relates to the field of underground energy storage technology, particularly compressed air energy storage engineering. Specifically, it relates to a method for analyzing the uplift stability of compressed air energy storage caverns under the influence of geological faults, which can quickly solve the problems of site selection and uplift stability design for compressed air energy storage projects in areas affected by geological faults. Background Technology

[0002] Renewable energy sources are significantly affected by natural conditions, exhibiting marked intermittency, volatility, and randomness. Large-scale grid connection can lead to problems such as grid frequency fluctuations and voltage instability, severely restricting their safe and stable operation in the energy system. Therefore, developing efficient and reliable energy storage technologies has become a core support for addressing the intermittency and volatility of renewable energy, improving energy utilization efficiency, and ensuring grid security. The strategic importance and practical necessity of energy storage projects are becoming increasingly prominent.

[0003] Compressed air energy storage (CAES), as an important type of large-capacity, long-term energy storage technology, has advantages such as large storage capacity, long service life, and environmental friendliness, making it particularly suitable for large-scale renewable energy consumption scenarios. Among them, artificial cavern CAES projects have become one of the mainstream development directions of current CAES technology because they can make full use of underground space resources, have minimal disturbance to the surface environment, and are adaptable to various terrain conditions. Their geological applicability is significantly better than that of surface energy storage facilities and salt cavern energy storage.

[0004] However, as engineering applications expand to complex geological areas, geological conditions containing faults, joints, and other unfavorable geological interfaces are becoming increasingly common. Existing engineering stability analysis methods largely rely on the Norwegian criterion, studying the heave stability of the overlying rock mass under high internal pressure within the cavern based on principles of mechanical or energy equilibrium. Xu Yingjun et al., based on the upper bound theorem of limit analysis, assumed the rock mass obeyed the Hoek-Brown criterion and derived the heave failure function and safety factor calculation method for intact rock masses. Yi Qi, Sun Guanhua et al., assuming the rock mass obeyed the Mohr-Coulomb criterion, used the three-moment equilibrium equation to give a reference range for the design parameters of compressed gas storage caverns under Class III surrounding rock conditions. Qiu Kai et al., based on the upper bound theorem of limit analysis, studied the heave failure calculation method for underground gas storage cavern groups. These studies provide calculation methods for the stability and safe burial depth of compressed gas storage caverns constructed in intact strata, but they do not consider the influence of faults on the mechanical properties of the rock mass, stress transmission paths, and failure modes. Furthermore, if the design method for the safe burial depth is flawed, it may lead to faults penetrating the cavern axis, causing new stability problems. More importantly, if the impact of geological interface slippage is ignored and the above method is directly applied, the safety of the project will be overestimated in strata containing geological faults, resulting in insufficient calculation accuracy. This makes it difficult to meet the actual needs of engineering design and safety verification, thus becoming a key technical bottleneck restricting the promotion of CAES projects to complex geological areas.

[0005] This invention addresses the aforementioned technical problems by overcoming the limitations of traditional methods in geological adaptation. It constructs a stability calculation system for compressed air energy storage caverns that is compatible with both complete strata and geological faults. This provides a precise quantitative tool for engineering design under complex geological conditions and has significant engineering value and strategic importance for improving the safety of compressed air energy storage projects, expanding their application scenarios, and promoting the large-scale development of renewable energy. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a method for analyzing the uplift stability of compressed gas storage caverns under the influence of geological faults, which addresses the shortcomings of the existing technology and provides an efficient and accurate quantitative analysis method for the site selection and uplift stability design of compressed gas storage caverns in areas affected by geological faults.

[0007] The technical solution adopted by this invention to solve the above-mentioned technical problems is: a method for analyzing the stability of compressed gas storage caverns against uplift under the influence of geological faults, comprising the following steps: S1. Establish a heave failure model of a compressed air storage cavern in an ideal intact rock mass. Based on the rock mechanics parameters, empirical parameters of the Hoek-Brown criterion, and the burial depth and radius of the compressed air storage cavern, apply the upper limit theorem of limit analysis to calculate the volume work of the heave rock mass and the internal force work of the heave failure curve in the ideal intact rock mass, and obtain the corresponding first engineering limit internal pressure and the corresponding first heave failure curve. S2. Establish a model of uplift failure of compressed gas storage cavern under the influence of geological faults. Based on rock mechanics parameters, empirical parameters of the Hoek-Brown criterion, burial depth and radius of the compressed gas storage cavern, fault angle and distance from the cavern to the fault, use the upper limit theorem of limit analysis and rigid body equilibrium method to calculate the volume work of the uplifted rock mass and the internal force work of the uplift failure curve under the influence of geological faults, and obtain the corresponding second engineering ultimate internal pressure and the corresponding second uplift failure curve. S3. By comparing the magnitudes of the first and second engineering ultimate internal pressures, the smaller value is taken as the engineering ultimate internal pressure, and the corresponding heave failure curve is used as the cavern heave failure curve function. S4. Calculate the ratio of the ultimate internal pressure of the project to the maximum design internal pressure of the cavern during operation. This ratio is the safety factor of the project. S5. If the engineering safety factor meets the safety factor requirements, output the engineering design parameters; if the engineering safety factor does not meet the safety factor requirements, adjust the design internal pressure of the cavern during the operation phase or the distance from the cavern to the fault until the safety factor requirements are met.

[0008] The method of this invention first derives the first uplift failure curve. Considering the presence of geological faults, the uplifted rock mass is divided into the original sliding body and the rock mass affected by the geological fault, thus forming a second uplift failure curve involving rock mass uplift and fault slip. Then, the second engineering ultimate internal pressure is calculated using the rigid body equilibrium method within the combined failure surface. The calculation results show that the stability of the cavern is highly correlated with the distance from the cavern to the fault, revealing the shortcomings of existing safe burial depth calculation models and uplift stability analysis methods from a mechanistic perspective. Simultaneously, considering the cavern safety factor control factors under the influence of geological faults, namely the engineering ultimate internal pressure and... The interaction mechanism of the maximum design internal pressure during the operation phase and the methods for adjusting engineering design parameters include: if the power of the compressed gas storage cavern is already redundant, the design internal pressure of the cavern during the operation phase can be appropriately reduced to increase the safety factor; if the design internal pressure of the compressed gas storage cavern cannot be adjusted, or if other factors necessitate optimizing the site selection to meet engineering safety, since increasing the burial depth will lead to adverse situations such as the distance from the fault to the cavern being closer, the reduction in the volume work and internal force work of the surrounding area being greater, and the decrease in the economic benefits of the project, it is necessary to increase the ultimate internal pressure of the project by adjusting the distance from the cavern to the fault to increase the safety factor.

[0009] Because artificial cavern compressed gas storage (CGS) projects have good geological applicability, this invention combines the upper limit theorem of limit analysis with the rigid body equilibrium method. By studying the influence of geological faults on the volumetric work of uplifted rock masses and the internal force work of the uplift failure curve, a calculation expression for surrounding rock uplift failure is established, coupling cavern site selection, rock mass mechanical parameters, fault dip angle, and the distance from the cavern to the fault. This clarifies that the uplift failure of CGS caverns exhibits a segmented evolution pattern: in the initial stage, it develops along the first uplift failure curve in an ideal, intact rock mass; when the failure curve extends to the geological fault, it transitions to slip failure along the fault, forming a second uplift failure curve. This invention can be used to evaluate the rationality of CGS cavern layout schemes in areas affected by geological faults. It can solve problems such as overestimating project safety and unreasonable cavern planar site selection in existing stability analysis and design methods in fault-containing strata, and has significant implications for the promotion and construction of artificial cavern compressed gas storage projects.

[0010] Specifically, in step S1, the process of obtaining the corresponding first engineering ultimate internal pressure and the corresponding first bulge failure curve is as follows: Ignoring various geological structures, determine the radius of the cavern. burial depth Rock mass Uniaxial compressive strength of intact rock and empirical parameters of the Hoek-Brown criterion and Based on the Hoek-Brown criterion, the law of plastic flow, and the geometric relationships on the pre-defined cavern heave failure curve, expressions for the volumetric work of the heave rock mass and the internal force work of the heave failure curve in an ideal intact rock mass are derived, where: The expression for the volumetric work of the uplifted rock mass is: In the formula, For any allowable velocity field, The volume enclosed by the bulge-damping curve. The x-coordinate of the intersection of the uplift failure curve and the ground surface. The horizontal distance from any point on the uplift failure curve to the center of the cavern. The first uplift failure curve function; The expression for the internal force work of the uplift failure curve is: In the formula, For rock tensile stress parameters, for The first derivative; Based on the upper bound theorem of limit analysis, the expression for the ultimate internal pressure of the first engineering project is obtained: In the formula, This represents the ultimate internal pressure of the first engineering project. Then, using the first-order variational method, the functional extremum of the first engineering ultimate internal pressure is solved, and the expressions for the first engineering ultimate internal pressure and the first heave failure curve are calculated: ; In the formula, , The integral constant obtained from solving the total differential equation is specifically determined by the mechanical and geometric boundary conditions.

[0011] In the process of establishing the first engineering ultimate internal pressure and the first uplift failure curve, based on the Hoek-Brown criterion and the plastic flow law, the functional extremum of the first engineering ultimate internal pressure is solved by the first-order variational method. This allows us to skip the complex elastoplastic analysis process and directly obtain the explicit expression of the first uplift failure curve and the corresponding first ultimate internal pressure. Thus, under the condition of an ideal intact rock mass that ignores geological structures, we can accurately calculate the volume work of the uplifted rock mass and the internal force work of the uplift failure curve. This provides an accurate benchmark solution for subsequent consideration of fault influence, and the calculation process is rigorous and efficient.

[0012] Specifically, in step S2, when the cavern uplift failure curve develops to the fault, the fault is considered to be a non-cohesive, weak geological interface, and its geometric distribution (fault dip angle and geometric location) is taken into account while its internal force contribution is ignored. Based on the fault dip angle and geometric location, the corresponding second engineering ultimate internal pressure and the corresponding second uplift failure curve are obtained, as follows: Determine the following geometric coordinates: Geometric coordinates of the intersection point of the first uplift failure curve and the ground surface. Geometric coordinates of the intersection of the geological fault and the failure curve of the first uplift Geometric coordinates of the intersection of a geological fault and the Earth's surface ; The presence of geological faults leads to changes in the volume of the uplifted rock mass as follows: ; The change in the volumetric work of the uplifted rock mass is then obtained as follows: ; When uplift failure occurs, the amount of internal work that the uplifted rock mass needs to do less is: ; According to the rigid body equilibrium method, the ultimate internal pressure of the second project is calculated by combining the uplifted rock mass and the geological fault influence zone of the first uplift failure curve, and its expression is: ; In the formula, This represents the ultimate internal pressure of the second engineering project. At this point, the failure curve of the second uplift is formed by the geometric curve function that develops along the fault after the failure curve of the first uplift reaches the geological fault. The expression for the failure curve of the second uplift is: ; In the formula, The fault dip angle, This represents the distance from the fault to the cavern along the y-axis.

[0013] In the process of establishing the ultimate internal pressure and the failure curve of the second uplift in the above-mentioned second project, geometric parameters such as fault dip angle and distance from the cavern to the fault are introduced to quantitatively calculate the change in volumetric work of the uplifted rock mass caused by the geological fault and the internal force work done less by the uplifted rock mass. Based on the rigid body equilibrium method, the second ultimate internal pressure and the failure curve of the second uplift are obtained. This can accurately depict the segmented evolution mode of the uplift failure curve from the curve of the intact rock mass to the fault and then to the sliding along the fault, providing a reliable mechanical model for the stability analysis of the compressed gas storage cavern in fault-containing strata.

[0014] If the geological fault and the failure curve of the first uplift do not intersect, that is, the fault is located outside the influence range of the cavern uplift failure, then the failure curve of the first uplift is used as the function of the cavern uplift failure curve to avoid unnecessary calculations and quickly determine the ultimate internal pressure and safety factor of the project.

[0015] Specifically, in step S5, the rules for adjusting the design internal pressure of the cavern during operation or the distance between the cavern and the fault are as follows: if the compressed gas storage cavern already has redundant power, reduce the design internal pressure during operation; if the design internal pressure of the compressed gas storage cavern cannot be adjusted, increase the ultimate internal pressure by adjusting the distance between the cavern and the fault. These adjustment rules, while meeting safety factor requirements, avoid adverse consequences such as fault penetration of the cavern axis that might result from blindly increasing the burial depth, providing a clear and economical guiding path for engineering parameter optimization and site selection decisions.

[0016] Compared with existing technologies, this invention has the following advantages: The method combines the upper bound theorem of limit analysis with the rigid body equilibrium method to establish uplift failure models under the influence of ideal intact rock masses and geological faults. By calculating the first and second limit internal pressures and taking the smaller value as the engineering limit internal pressure, it can accurately reflect the weakening effect of geological faults on the uplift stability of the cavern, avoiding the overestimation of engineering safety in fault-containing strata by traditional methods. A safety factor is defined using the ratio of the engineering limit internal pressure to the maximum design internal pressure during operation. If the safety factor does not meet the requirements, the design internal pressure during the cavern operation stage or the distance from the cavern to the fault can be adjusted, thus providing an efficient and accurate quantitative analysis method for the site selection and uplift stability design of compressed gas storage caverns in areas affected by geological faults. This invention can be used to evaluate the rationality of compressed gas storage cavern layout schemes in areas affected by geological faults, solving problems such as overestimation of engineering safety and unreasonable cavern planar site selection in existing stability analysis and design methods in fault-containing strata. It has significant implications for the promotion and construction of artificial cavern compressed gas storage projects. Attached Figure Description

[0017] Figure 1 A schematic diagram of the uplift failure mode of a compressed air energy storage cavern in an ideal, intact rock mass; Figure 2 This is a schematic diagram of the uplift failure mode of a compressed gas storage cavern under the influence of a geological fault. Detailed Implementation

[0018] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0019] Example: A method for analyzing the uplift stability of compressed gas storage caverns under the influence of geological faults, including the following steps: S1. Establish a heave failure model of a compressed air energy storage cavern in an ideal intact rock mass. Based on the rock mechanics parameters, empirical parameters of the Hoek-Brown criterion, and the burial depth and radius of the compressed air energy storage cavern, apply the upper limit theorem of limit analysis to calculate the volume work of the heave rock mass and the internal force work of the heave failure curve in the ideal intact rock mass, and obtain the corresponding first engineering limit internal pressure and the corresponding first heave failure curve.

[0020] In step S1, the process of obtaining the corresponding first engineering ultimate internal pressure and the corresponding first bulge failure curve is as follows: Ignoring various geological structures, determine the radius of the cavern. burial depth Rock mass Uniaxial compressive strength of intact rock and empirical parameters of the Hoek-Brown criterion and Based on the Hoek-Brown criterion, the expressions for the volumetric work of the heaving rock mass and the internal force work of the heaving failure curve in an ideal intact rock mass are derived, based on the plastic flow law and the geometric relationship on the pre-set cavern heaving failure curve.

[0021] The Hoek-Brown criterion is a plasticity criterion that can practically reflect the nonlinear characteristics of engineering rock masses. Its expression is: ; In the formula: It is shear stress. It is normal stress. and For the empirical parameters of the Hoek-Brown criterion, The uniaxial compressive strength of intact rock. The tensile stress parameter of the rock; The expression is: ;

[0022] In the formula: The empirical parameter based on GSI in the Hoek-Brown criterion. , These are empirical parameters for rocks. These are the parameters based on GSI in the Hoek-Brown criterion. ; Its corresponding plastic potential function is: .

[0023] The upper limit theorem in limit analysis is a theorem that applies to a given allowable velocity field. In the case of calculating the upper limit value of the system's ultimate load, the method first considers, for example, Figure 1 The stratigraphic situation of the ideal intact rock mass is shown, assuming that the angle between the tangent on the failure surface and the horizontal is . The radius of the cavern is , burial depth is According to the principle of virtual work, the expression for the upper limit theorem in engineering limit analysis can be obtained as follows: ; In the formula: To disrupt the curve, To disrupt the force vector on the curve, For the velocity field vector, It is the volume enclosed by the bulge failure curve. The area is subjected to forces that cause damage. and These represent the stress and strain in the plastic zone, respectively.

[0024] For a raised rock mass within an ideal, intact rock mass, according to Figure 1 Geometric relationships in, select For a unit thickness of rock mass, the expressions for its shear strain rate and normal strain rate can be obtained as follows: ; In the formula: This is the function of the first uplift failure curve. for The first derivative, It is the horizontal distance from any point on the uplift failure curve to the center of the cavern.

[0025] Meanwhile, according to the plastic flow law, the shear strain rate and normal strain rate are: ; In the formula: It is a proportionality coefficient.

[0026] The expression for the normal stress of the rock mass on the uplifted failure surface can then be written as: ; The expression for the internal force work on the first uplift failure curve is: ; According to the upper bound theorem of limit analysis, the volume work done by body forces (i.e., the volume work done by the uplifted rock mass) can be expressed as: ; In the formula: For any allowable velocity field, The rock mass is of high density. The x-coordinate is the intersection of the uplift failure curve and the ground surface.

[0027] The first heave failure curve of the compressed gas storage cavern under the allowable speed field (e.g.) Figure 1 Medium curve OE, Figure 2 The work done by the internal forces in the rock mass along the ODE curve (i.e., the work done by the internal forces along the uplift failure curve) can be expressed as: ; The expression for the ultimate internal pressure of the first engineering project is obtained as follows: In the formula, This represents the ultimate internal pressure of the first engineering project. Then, using the first-order variational method, the functional extremum of the first engineering ultimate internal pressure is solved, and the expressions for the first engineering ultimate internal pressure and the first heave failure curve are calculated: ; In the formula, , The integral constant obtained from solving the total differential equation is specifically determined by the mechanical and geometric boundary conditions.

[0028] S2. Establish a model of uplift failure of compressed gas storage cavern under the influence of geological faults. Based on rock mechanics parameters, empirical parameters of the Hoek-Brown criterion, burial depth and radius of the compressed gas storage cavern, fault angle and distance from the cavern to the fault, use the upper limit theorem of limit analysis and rigid body equilibrium method to calculate the volume work of the uplifted rock mass and the internal force work of the uplift failure curve under the influence of geological faults, and obtain the corresponding second engineering ultimate internal pressure and the corresponding second uplift failure curve. In step S2, based on the fault dip angle and geometric distribution location, the corresponding second engineering ultimate internal pressure and the corresponding second uplift failure curve are obtained, as follows: like Figure 2 As shown, when a geological fault (i.e., straight line CD) exists, its distance from the y-axis of the cavern is... The distance from the cavern along the x-axis is The fault dip angle is .

[0029] The expression for the fault distribution function is: ;

[0030] Determine the following geometric coordinates: Point E is the intersection of the first uplift failure curve and the ground surface. The intersection of the geological fault and the failure curve of the first uplift is point D. Its geometric coordinates are... Point C is the intersection of the geological fault and the Earth's surface. Its geometric coordinates are... Considering the intersection of the fault and the failure curve of the first uplift, the influence of the geological fault existing on the side of the cavern on the cavern stability is the sum of the contribution of the volumetric work of the enclosed part and the contribution of the internal force work of the ideal failure curve of the enclosed area. The volume of the enclosed area is (i.e., the change in the volume of the uplifted rock mass caused by the presence of the geological fault): ; The volumetric work corresponding to its enclosed volume (i.e., the change in volumetric work of the uplifted rock mass) is: ; When uplift failure occurs, the reduction in internal work done by the sliding body (i.e., the reduction in internal work done by the uplifted rock mass) is: ; According to the rigid body equilibrium method, the ultimate internal pressure of the second project is calculated by combining the uplifted rock mass of the first uplift failure curve with the area affected by the geological fault. The expression for the ultimate internal pressure of the second project at this time is: ; In the formula, This represents the ultimate internal pressure of the second engineering project. At this point, the failure curve of the second uplift is formed by the geometric curve function that develops along the fault after the failure curve of the first uplift reaches the geological fault. The expression for the failure curve of the second uplift is: .

[0031] S3. By comparing the magnitudes of the ultimate internal pressure of the first project and the ultimate internal pressure of the second project, the smaller value is selected. The first ultimate internal pressure is taken as the engineering ultimate internal pressure, and the corresponding uplift failure curve is taken as the cavern uplift failure curve function. Specifically, when the first ultimate internal pressure is less than the second ultimate internal pressure, the first ultimate internal pressure is taken as the engineering ultimate internal pressure, that is, the actual ultimate internal pressure of the cavern. This indicates that the geological fault has a weak influence on the stability of the cavern. At this time, the cavern uplift failure mode is consistent with the first uplift failure curve, and the first uplift failure curve is taken as the cavern uplift failure curve function. When the first ultimate internal pressure is greater than the second ultimate internal pressure, the second ultimate internal pressure is taken as the actual ultimate internal pressure of the cavern. This indicates that the geological fault has a significant influence on the stability of the cavern. At this time, the uplift failure of the cavern under the ultimate state first follows the failure law of intact rock mass. When the failure develops to the fault position, sliding failure will occur along the fault interface. The second uplift failure curve is taken as the cavern uplift failure curve function.

[0032] S4, Calculate the ultimate internal pressure of the engineering project Maximum design internal pressure during the operation phase of the cavern ratio This ratio is the engineering safety factor.

[0033] S5. From the expression for the ultimate internal pressure of the second project, it can be seen that when constructing a compressed gas storage cavern in an area affected by a geological fault, if the initial site selection does not meet the safety factor requirements, and the power of the compressed gas storage cavern cannot be adjusted, increasing the burial depth will lead to adverse situations such as the distance from the fault to the cavern decreasing, the reduction in the volumetric work and internal force work of the surrounding area increasing, and the decrease in the economic benefits of the project. Therefore, it is necessary to adjust the horizontal distance from the cavern to the geological fault to control the stability of the project. Therefore, if the project safety factor meets the safety factor requirements, the project design parameters are output; if the project safety factor does not meet the safety factor requirements, the design internal pressure of the cavern during the operation phase or the distance from the cavern to the fault is adjusted until the safety factor requirements are met, thus achieving anti-uplift analysis and design. Among them, the rules for adjusting the design internal pressure of the cavern during the operation phase or the distance from the cavern to the fault are as follows: if the power of the compressed gas storage cavern is already redundant, the design internal pressure of the cavern during the operation phase is reduced; if the design internal pressure of the compressed gas storage cavern cannot be adjusted, the ultimate internal pressure of the project is increased by adjusting the distance from the cavern to the fault, and steps S2-S4 are repeated until the safety factor requirements are met.

[0034] Specific application case: A region plans to construct an artificial cavern for compressed air energy storage, with an overlying rock mass depth of 135m and a rock mass weight of 2400 kg / m³. 3Hoek-Brown criterion parameters = 50MPa, A = 0.75, B = 0.7, , There is a fault geological structure about 30m to the side of the cavern, with a fault dip angle of 70°. According to the current mainstream design parameters, the cavern diameter is 15m, the maximum operating pressure is 20MPa, the gas injection time is 8h, the gas release time is 4h, and the gas storage time in between is 6h.

[0035] Based on step S1, by substituting the tunnel engineering parameters, the functional expression of the first uplift failure curve is confirmed as follows: ; Solve for the ultimate internal pressure of the first engineering problem: .

[0036] At this point, the first uplift failure curve is the ideal failure curve function. Its intersection with the ground surface is about 242m away from the center of the cavern, which means that the radius of the affected area when the cavern experiences uplift failure is about 242m.

[0037] The fault distribution parameters were determined, and the coordinates of the intersection point between the fault and the failure curve of the first uplift were calculated. The intersection of the fault and the surface is The intersection of the uplift curve and the ground surface is .

[0038] The change in volumetric work caused by the presence of geological faults is as follows: ; The change in internal force work caused by sliding along a geological fault is as follows: ; Solve for the ultimate internal pressure of the second project: ; because Therefore .

[0039] Under the uplift failure mode influenced by geological faults, the functional expression of the second uplift failure curve of the compressed gas storage cavern is as follows: ; The fault curve shows that the horizontal distance between the intersection of the fault distribution side and the ground surface and the center of the cavern is approximately 79m, indicating that the affected area shrinks to 79m when the cavern undergoes uplift and failure.

[0040] If a safety control method that reduces the design internal pressure during the cavern's operational phase is adopted, then the maximum design internal pressure during the cavern's operational phase should be: .

[0041] If a safety control method is adopted that controls the distance between the cavern and the fault, then S2-S4 are repeated to obtain the safe cavern distance from the fault. .

[0042] In contrast, if the traditional design method is used, the ultimate internal pressure of the project is 61.18 MPa, and the failure function curve is as follows: ; The safety factor is 3.09, thus meeting the requirement of a safety factor greater than 2.0. However, the safety factor calculated according to the method of this invention is 1.82, and the result is that it does not meet the safety factor requirement.

[0043] If a design approach that reduces operational pressure is adopted, then the operational pressure should be reset to [presumably a different value]. .

[0044] Using the design method that controls the distance between the cavern and the fault, steps 2-4 are repeated to obtain the safe distance between the cavern and the fault. .

[0045] The comparison shows that traditional design methods may overestimate the safety of engineering projects. This invention can greatly improve the accuracy of the uplift stability analysis of compressed gas storage caverns in complex geological conditions such as fault distribution areas, and can further optimize the design of engineering projects.

Claims

1. A method for analyzing the uplift stability of compressed gas storage caverns under the influence of geological faults, characterized in that, Includes the following steps: S1. Establish a heave failure model of a compressed air storage cavern in an ideal intact rock mass. Based on the rock mechanics parameters, empirical parameters of the Hoek-Brown criterion, and the burial depth and radius of the compressed air storage cavern, apply the upper limit theorem of limit analysis to calculate the volume work of the heave rock mass and the internal force work of the heave failure curve in the ideal intact rock mass, and obtain the corresponding first engineering limit internal pressure and the corresponding first heave failure curve. S2. Establish a model of uplift failure of compressed gas storage cavern under the influence of geological faults. Based on rock mechanics parameters, empirical parameters of the Hoek-Brown criterion, burial depth and radius of the compressed gas storage cavern, fault angle and distance from the cavern to the fault, use the upper limit theorem of limit analysis and rigid body equilibrium method to calculate the volume work of the uplifted rock mass and the internal force work of the uplift failure curve under the influence of geological faults, and obtain the corresponding second engineering ultimate internal pressure and the corresponding second uplift failure curve. S3. By comparing the magnitudes of the first and second engineering ultimate internal pressures, the smaller value is taken as the engineering ultimate internal pressure, and the corresponding heave failure curve is used as the cavern heave failure curve function. S4. Calculate the ratio of the ultimate internal pressure of the project to the maximum design internal pressure of the cavern during operation. This ratio is the safety factor of the project. S5. If the engineering safety factor meets the safety factor requirements, output the engineering design parameters; if the engineering safety factor does not meet the safety factor requirements, adjust the design internal pressure of the cavern during the operation phase or the distance from the cavern to the fault until the safety factor requirements are met.

2. The method for analyzing the uplift stability of compressed gas storage caverns under the influence of geological faults according to claim 1, characterized in that, In step S1, the process of obtaining the corresponding first engineering ultimate internal pressure and the corresponding first bulge failure curve is as follows: Ignoring various geological structures, determine the radius of the cavern. burial depth Rock mass Uniaxial compressive strength of intact rock and empirical parameters of the Hoek-Brown criterion and Based on the Hoek-Brown criterion, the law of plastic flow, and the geometric relationships on the pre-defined cavern heave failure curve, expressions for the volumetric work of the heave rock mass and the internal force work of the heave failure curve in an ideal intact rock mass are derived, where: The expression for the volumetric work of the uplifted rock mass is: In the formula, For any allowable velocity field, The volume enclosed by the bulge-damping curve. The x-coordinate of the intersection of the uplift failure curve and the ground surface. The horizontal distance from any point on the uplift failure curve to the center of the cavern. The first uplift failure curve function; The expression for the internal force work of the uplift failure curve is: In the formula, For rock tensile stress parameters, for The first derivative; Based on the upper bound theorem of limit analysis, the expression for the ultimate internal pressure of the first engineering project is obtained: In the formula, This represents the ultimate internal pressure of the first engineering project. Then, using the first-order variational method, the functional extremum of the first engineering ultimate internal pressure is solved, and the expressions for the first engineering ultimate internal pressure and the first heave failure curve are calculated: ； In the formula, , The integral constant obtained from solving the total differential equation is specifically determined by the mechanical and geometric boundary conditions.

3. The method for analyzing the stability of compressed gas storage caverns under the influence of geological faults according to claim 2, characterized in that, In step S2, based on the fault dip angle and geometric distribution location, the corresponding second engineering ultimate internal pressure and the corresponding second uplift failure curve are obtained, as follows: Determine the following geometric coordinates: Geometric coordinates of the intersection point of the first uplift failure curve and the ground surface. Geometric coordinates of the intersection of the geological fault and the failure curve of the first uplift Geometric coordinates of the intersection of a geological fault and the Earth's surface ; The presence of geological faults leads to changes in the volume of the uplifted rock mass as follows: ； The change in the volumetric work of the uplifted rock mass is then obtained as follows: ; When uplift failure occurs, the amount of internal work that the uplifted rock mass needs to do less is: ； According to the rigid body equilibrium method, the ultimate internal pressure of the second project is calculated by combining the uplifted rock mass and the geological fault influence zone of the first uplift failure curve, and its expression is: ； In the formula, This represents the ultimate internal pressure of the second engineering project. At this point, the failure curve of the second uplift is composed of a geometric curve function that develops along the fault after the failure curve of the first uplift reaches the geological fault. The expression for the failure curve of the second uplift that slides along the geological fault is: ； In the formula, The fault dip angle, This represents the distance from the fault to the cavern along the y-axis.

4. The method for analyzing the stability of compressed gas storage caverns under the influence of geological faults according to claim 3, characterized in that, If the geological fault and the first uplift failure curve do not intersect, then the first uplift failure curve is used as the function of the cavern uplift failure curve.

5. The method for analyzing the uplift stability of compressed gas storage caverns under the influence of geological faults according to claim 1, characterized in that, In step S5, the rules for adjusting the design internal pressure of the cavern during the operation phase or the distance from the cavern to the fault are as follows: if the power of the compressed gas storage cavern is already redundant, reduce the design internal pressure of the cavern during the operation phase; if the design internal pressure of the compressed gas storage cavern cannot be adjusted, then increase the ultimate internal pressure of the project by adjusting the distance from the cavern to the fault.

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