A method and system for evaluating the stability of surrounding rock of a gas storage crossing a fault fracture zone

Abstract

The present application relates to the technical field of underground gas storage engineering, and particularly relates to a method and system for evaluating the stability of surrounding rock of a gas storage crossing a fault fracture zone. The method comprises obtaining fault geometric parameters, fault mechanical parameters, surrounding rock mechanical parameters, dynamic attenuation law of the fault mechanical parameters under cyclic loading, and relative position relationship between the fault and the gas storage cavern; establishing a multi-scale simulation model coupled with the fault and the gas storage cavern; determining the spatial range of the overlying rock mass and establishing a failure model; obtaining the anti-lifting safety factor of the overlying rock mass and getting the anti-lifting stability checking result; applying cyclic gas pressure loading to the multi-scale simulation model that passes the checking to simulate the gas charging and discharging process; extracting fault plane stress evolution data, displacement response data and plastic zone expansion data; and obtaining the comprehensive evaluation result of the surrounding rock stability. The present application can realize the quantitative characterization of the cumulative damage of the fault under cyclic loading, and complete the unified evaluation of the anti-lifting and sliding stability.

Description

Technical Field

[0001] This invention relates to the field of underground gas storage engineering technology, and in particular to a method and system for evaluating the stability of surrounding rock in gas storage facilities that traverse fault fracture zones. Background Technology

[0002] Compressed air energy storage (CAES) technology, as a large-scale, long-term energy storage method, has broad application prospects in renewable energy consumption and grid peak shaving. Its underground gas storage facilities typically utilize artificially excavated hard rock caverns as storage spaces. During operation, these caverns must withstand high-frequency, high-amplitude cyclic internal pressure, typically ranging from 10 MPa to 15 MPa or even higher. Due to the complexity of natural geological conditions, it is often difficult to completely avoid geological discontinuities such as fault fracture zones during site selection and construction. Crossing or being adjacent to fault fracture zones is an unavoidable practical problem in engineering. During long-term operation, the cyclic internal pressure not only exerts fatigue loading effects on the surrounding rock of the cavern but also continuously alters the stress state of the fault region, potentially inducing fault slippage, fracture propagation, or even penetration, thereby leading to gas storage sealing failure or overall structural instability. Furthermore, the burial depth design of gas storage facilities must also meet the requirements for uplift stability, meaning that the self-weight and shear strength of the overlying strata must be sufficient to resist the uplift force generated by the high-pressure internal pressure, preventing the overall uplift and failure of the gas storage facility. These two failure mechanisms—local fault sliding instability and overall uplift instability—are independent yet mutually influential, posing a dual challenge to the site selection evaluation and burial depth design of underground gas storage facilities.

[0003] Regarding the stability of the surrounding rock in underground compressed air energy storage (CAES) storage facilities, existing technologies mostly focus on the static stability analysis of the cavern under intact surrounding rock conditions, lacking a systematic evaluation method that specifically considers the geometric characteristics, mechanical parameters, and cyclic load coupling effects of fault fracture zones. Specifically, this manifests as follows: (1) Existing analysis models are difficult to accurately characterize the spatial interaction between fault zones and caverns, ignoring the influence of fault attitude, width, filling material properties, and spatial distribution on the evolution of the surrounding rock stress field; (2) Most analysis methods still use static or quasi-static loading methods, failing to truly reflect the cumulative effect of periodic pressure fluctuations on the mechanical response of faults during CAES operation, and lacking dynamic loading simulation that matches the actual gas filling and releasing cycle conditions; (3) Existing methods generally lack an independent verification link to counteract uplift stability, failing to incorporate the overall uplift risk of the overlying rock mass and the risk of local fault sliding into a unified layered progressive analysis framework; (4) Currently, there is a lack of quantitative fault sliding instability discrimination indicators and graded evaluation standards, making it difficult to provide quantitative basis for engineering site selection, burial depth optimization, and reinforcement design. The aforementioned shortcomings restrict the engineering application of CAES underground gas storage facilities under complex geological conditions, and there is an urgent need to establish a comprehensive evaluation method for the stability of surrounding rock that takes into account the effects of faults and cyclic loading. Summary of the Invention

[0004] The purpose of this invention is to provide a method and system for evaluating the stability of surrounding rock in gas storage facilities that traverse fault fracture zones, in order to solve the problem in the prior art of lacking a systematic evaluation of the stability of surrounding rock in underground compressed air energy storage facilities that traverse fault fracture zones under the action of cyclic internal pressure.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: This invention discloses a method for evaluating the stability of surrounding rock in gas storage facilities traversing fault fracture zones, comprising: Obtain the fault geometric parameters, fault mechanical parameters, surrounding rock mechanical parameters, dynamic attenuation law of the fault mechanical parameters under cyclic loading, and the relative positional relationship between the fault and the proposed gas storage cavern in the target area. Based on the fault geometric parameters, the relative positional relationship, the fault mechanical parameters, and the surrounding rock mechanical parameters, a multi-scale simulation model of the coupling effect between the fault and the gas storage cavern is established. The spatial range of the overlying rock mass above the gas storage cavern is determined based on the multi-scale simulation model, and a failure model of the overlying rock mass is established in combination with the surrounding rock mechanical parameters; The fracture surface morphology of the overlying rock mass is determined based on the failure model, and the uplift resistance safety factor of the overlying rock mass is obtained by combining the spatial range of the overlying rock mass and the surrounding rock mechanical parameters. The stability verification result of the gas storage cavern's resistance to uplift is obtained by comparing the anti-uplift safety factor with the preset safety threshold. Based on the dynamic attenuation law, the multi-scale simulation model that has passed the anti-lift stability check is subjected to cyclic gas pressure loading conditions to simulate the gas storage cavern's filling and releasing process under different operating conditions during its operation. By acquiring stress evolution data, displacement response data, and plastic zone expansion data of the fault plane during the simulated inflation and deflation process, and combining these with the stability verification results, a comprehensive stability evaluation result of the surrounding rock is obtained.

[0006] Optionally, establishing a multi-scale simulation model of the coupling effect between the fault and the gas storage cavern based on the fault geometric parameters, the relative positional relationship, the fault mechanical parameters, and the surrounding rock mechanical parameters includes: Based on the fault geometry parameters and the relative positional relationship, determine the regional scale range that includes all the faults and the surrounding rock, as well as the local scale range that includes the gas storage cavern, the surrounding rock, and the faults. Based on the determined regional scale range and local scale range, a regional scale geometric model and a local scale geometric model are constructed respectively, and the regional scale geometric model and the local scale geometric model are respectively meshed to obtain a discretized multi-scale geometric model; The shear failure behavior of the surrounding rock and the fault in the multi-scale geometric model is described by the Mohr-Coulomb constitutive model, and the mechanical parameters of the fault and the mechanical parameters of the surrounding rock are respectively assigned to the corresponding regions in the multi-scale geometric model to obtain the multi-scale simulation model.

[0007] Optionally, determining the spatial extent of the overlying rock mass above the gas storage cavern based on the multi-scale simulation model, and establishing a failure model of the overlying rock mass in conjunction with the surrounding rock mechanical parameters, includes: Based on the spatial location of the gas storage cavern in the multi-scale simulation model, combined with the fault geometric parameters and the relative positional relationship, the spatial range of the overlying rock mass above the gas storage cavern is determined; Based on the spatial location of the gas storage cavern and the surrounding rock mechanical parameters, the spatial location of the fracture surface of the overlying rock mass within the spatial range of the overlying rock mass is determined; Based on the spatial location of the fracture surface and the spatial location of the fault in the fault geometry parameters, it is determined whether the fracture surface is cut by the fault; Based on the judgment results, a cone or frustum-shaped failure model of the overlying rock mass is established, centered on the gas storage cavern and combined with the spatial location of the fracture surface.

[0008] Optionally, based on the judgment result, establishing a cone or frustum-shaped failure model of the overlying rock mass, centered on the gas storage cavern and considering the spatial location of the fracture surface, includes: When it is determined that the fault has not cut the fracture surface, the first angle between the fracture surface of the overlying rock mass and the vertical direction is determined by the limit equilibrium theory using the surrounding rock mechanical parameters. Based on the first included angle, and combined with the spatial range of the overlying rock mass and the spatial location of the fracture surface, a cone or frustum-shaped failure model of the overlying rock mass is established with the gas storage cavern as the center. When it is determined that the fault cuts the fracture surface, the overlying rock mass is divided into multiple independent blocks along the fault according to the spatial location of the fault. The spatial range of each independent block is determined, and the fracture surface of each independent block is determined by the second angle between the vertical direction and the vertical direction using the surrounding rock mechanics parameters and the limit equilibrium theory. Based on the second included angle, and combined with the spatial range of each independent block and the spatial position of the fracture surface, a cone or frustum-shaped failure model of each independent block is established with the gas storage cavern as the center.

[0009] Optionally, the step of determining the fracture surface morphology of the overlying rock mass based on the failure model, and obtaining the uplift resistance safety factor of the overlying rock mass by combining the spatial range of the overlying rock mass and the surrounding rock mechanical parameters, includes: Based on the geometric analysis of the failure model, the depth of the overlying rock mass, the thickness of each layer of the overlying rock mass along the thickness direction, and the angle between the fracture surface in the overlying rock mass and the vertical direction are determined. Based on the angle between the fracture surface and the vertical direction, the depth of the overlying rock mass, and the surrounding rock mechanical parameters such as unit weight and lateral pressure coefficient, the normal stress on the fracture surface is calculated. The functional expression for calculating the normal stress is as follows:

[0010] In the formula, This represents the normal stress on the fracture surface. Indicates the unit weight of the surrounding rock. Indicates the angle between the fracture surface and the vertical direction. Indicates the lateral pressure coefficient. Indicates the depth of the overlying rock mass; Based on the normal stress and the cohesion and average internal friction angle in the surrounding rock mechanical parameters, the shear stress on the fracture surface is calculated, and the functional expression for calculating the shear stress is:

[0011] In the formula, This represents the shear stress on the fracture surface. This represents the average internal friction angle of the overlying rock mass. Indicates the cohesion of the overlying rock mass; Based on the thickness of each layer along the thickness direction of the overlying rock mass, the angle between the fracture surface and the vertical direction in the overlying rock mass, the normal stress, and the shear stress, the normal pressure and shear force on the fracture surface are calculated respectively. The functional expressions for calculating the normal pressure and the shear force are as follows:

[0012]

[0013] In the formula, This represents the normal pressure on the fracture surface. This represents the thickness of the i-th layer of the overlying rock mass along the thickness direction. Indicates a hierarchical index. This represents the shear resistance on the fracture surface. This indicates the unit width along the axial direction of the gas storage chamber. The number of gas storage caverns is determined based on the design and operation parameters of the gas storage caverns. Combined with the positive pressure and the shear force, the uplift force and uplift force of the overlying rock mass under the corresponding number of caverns are obtained. Based on the uplift resistance and the uplift force, the uplift resistance safety factor of the overlying rock mass is calculated. The functional expression for calculating the uplift resistance safety factor is as follows:

[0014] In the formula, This indicates the safety factor against uplift of the overlying rock mass. This indicates the uplift resistance experienced by the overlying rock mass. This indicates the uplift force exerted on the overlying rock mass.

[0015] Optionally, determining the number of gas storage caverns based on the design and operating parameters of the gas storage caverns, and obtaining the uplift resistance and uplift force of the overlying rock mass under the corresponding number of caverns, in conjunction with the normal pressure and the shear force, includes: Based on the geometric analysis of the failure model, the volume of the overlying rock mass and the horizontal projected area of ​​the gas storage cavern are determined. Based on the design and operating parameters of the gas storage cavern, the maximum internal pressure of the gas storage cavern during the operation period and the cavern edge distance when there are multiple caverns are determined. When the number of caverns in the gas storage facility is determined to be a single cavern, the first self-weight of the overlying rock mass above the single cavern is calculated based on the volume of the overlying rock mass and the unit weight of the surrounding rock. The functional expression for calculating the first self-weight is as follows:

[0016] In the formula, This represents the first self-weight of the overlying rock mass in the case of a single chamber. Indicates the volume of the overlying rock mass; Based on the first self-weight, the angle between the fracture surface and the vertical direction in the overlying rock mass, the normal pressure, and the shear force, the first uplift force on the overlying rock mass above the single cavern is calculated. The functional expression for calculating the first uplift force is:

[0017] In the formula, This indicates the first uplift force acting on the overlying rock mass; Based on the maximum internal pressure and the horizontal projected area of ​​the gas storage cavern, the first uplift force on the overlying rock mass located above the single cavern is calculated. The functional expression for calculating the first uplift force is:

[0018] In the formula, This indicates the first uplift force acting on the overlying rock mass. This indicates the maximum internal pressure of the gas storage cavern during its operational period. This represents the horizontal projected area of ​​the gas storage cavern; When the number of caverns in the gas storage facility is determined to be multiple caverns, the second self-weight of the overlying rock mass above the multiple caverns is calculated based on the number of caverns, the distance between the edges of the caverns, the thickness of each layer of the overlying rock mass along the thickness direction, and the unit weight of the surrounding rock at the corresponding depth of each layer. The functional expression for calculating the second self-weight is as follows:

[0019] In the formula, This indicates the second self-weight of the overlying rock mass located above the multi-cavity structure. Indicates the number of caverns. Indicates the radius of the cavern. Indicates the distance between the edges of the cavern. Indicates the first inch of the overlying rock mass along the thickness direction. The thickness of the layers, Indicates a hierarchical index. Indicates the first inch of the overlying rock mass along the thickness direction. The unit weight of the surrounding rock at the corresponding depth of each layer. This indicates the total number of layers in the overlying rock mass along the thickness direction; The multi-scale simulation model was used to simulate the excavation of multiple tunnels. The tensile stress in the rock mass between each tunnel was extracted during the simulation. Combined with the distance between the tunnel edges, the resultant force of the tensile stress in the rock mass between each tunnel was calculated. The functional expression for the resultant force is as follows:

[0020] In the formula, This represents the resultant force of tensile stress in the rock mass between the various chambers. Indicates the first Tensile stress in the rock mass between adjacent caverns; Based on the second self-weight, the angle between the fracture surface and the vertical direction in the overlying rock mass, the resultant force, the normal pressure, and the shear force, the second uplift force on the overlying rock mass located above the multi-cavity is calculated. The functional expression for calculating the second uplift force is:

[0021] In the formula, This indicates the second uplift resistance experienced by the overlying rock mass; Based on the number of caverns, the maximum internal pressure, and the horizontal projected area of ​​the gas storage caverns, the second uplift force on the overlying rock mass located above the multiple caverns is calculated. The functional expression for calculating the second uplift force is:

[0022] In the formula, This indicates the second uplift force experienced by the overlying rock mass.

[0023] Optionally, the step of applying cyclic gas pressure loading conditions to the multi-scale simulation model that has passed the anti-lift stability check, based on the dynamic attenuation law, to simulate the gas filling and discharging process of the gas storage cavern under different operating conditions during its operation includes: The multi-scale simulation model verified by the anti-lift stability is determined as the basic model, and the measured in-situ stress at the burial depth of the gas storage cavern in the target area is obtained. An initial geostress field is applied to the foundation model based on the measured geostress, and displacement boundary conditions including bottom fixed constraints and lateral normal constraints are applied to the foundation model to obtain a first simulation model loaded with initial conditions. Based on the dynamic attenuation law, the fault mechanical parameters in the first simulation model are successively reduced and updated. At the same time, a gas pressure load with periodic changes in gas pressure between the upper and lower limits of the operating pressure is applied to the inner wall of the gas storage cavern in the first simulation model, so as to obtain a second simulation model in which the fault mechanical parameters attenuate with the cycle and are subjected to the cycle gas pressure. The second simulation model is used to simulate the mechanical response of the gas storage cavern in the filling, stabilizing and venting stages in chronological order, thus simulating the filling and venting process of the gas storage cavern under different operating conditions during its operation.

[0024] Optionally, the step of acquiring stress evolution data, displacement response data, and plastic zone expansion data of the fault plane during the simulated inflation / deflation process, and combining them with the stability verification results to analyze and obtain a comprehensive stability evaluation result of the surrounding rock, includes: From the simulation results of the inflation and deflation process of the second simulation model, the stress evolution data, displacement response data, and plastic zone expansion data of the fault are extracted respectively. Based on the stress evolution data, displacement response data, and plastic zone expansion data, a comparative analysis of fault-affected and fault-free working conditions is conducted, and the influence of the fault on the displacement field and plastic zone in the surrounding rock is obtained based on the analysis results. The stress intensity ratio of the fault is calculated based on the stress evolution data, and the sliding safety factor of the fault is determined based on the displacement response data and the plastic zone expansion data. Based on the sliding safety factor and the influence effect of the fault, and combined with the stability verification results, a quantitative evaluation of the stability of the surrounding rock is performed to obtain a comprehensive evaluation result of the stability of the surrounding rock.

[0025] This invention also discloses a stability evaluation system, employing the aforementioned method for evaluating the stability of surrounding rock in gas storage facilities. The stability evaluation system includes: The parameter acquisition module is used to acquire the fault geometric parameters, fault mechanical parameters, surrounding rock mechanical parameters, dynamic attenuation law of the fault mechanical parameters under cyclic loading, and relative positional relationship between the fault and the proposed gas storage cavern in the target area. The simulation model construction module is used to establish a multi-scale simulation model of the coupling effect between the fault and the gas storage cavern based on the fault geometric parameters, the relative positional relationship, the fault mechanical parameters and the surrounding rock mechanical parameters; The failure model construction module is used to determine the spatial range of the overlying rock mass above the gas storage cavern based on the multi-scale simulation model, and to establish a failure model of the overlying rock mass in combination with the surrounding rock mechanical parameters; The safety factor acquisition module is used to determine the fracture surface morphology of the overlying rock mass based on the failure model, and to obtain the uplift resistance safety factor of the overlying rock mass by combining the spatial range of the overlying rock mass and the surrounding rock mechanical parameters. The anti-lift stability verification module is used to obtain the stability verification result of the gas storage cavern against the lift by comparing the anti-lift safety factor with the preset safety threshold. The cyclic loading simulation module is used to apply cyclic gas pressure loading conditions to the multi-scale simulation model that has passed the anti-lift stability check, according to the dynamic attenuation law, to simulate the gas filling and releasing process of the gas storage cavern under different working conditions during its operation. The stability comprehensive evaluation module is used to acquire stress evolution data, displacement response data, and plastic zone expansion data of the fault plane during the simulated inflation and deflation process. Combined with the stability verification results, the module analyzes and obtains the comprehensive stability evaluation results of the surrounding rock.

[0026] The present invention also discloses a storage medium storing a computer program, which, when executed by a processor, implements the above-described method for evaluating the stability of the surrounding rock of a gas storage facility.

[0027] Compared with the prior art, the beneficial effects of the gas storage surrounding rock stability evaluation method and system provided by the embodiments of the present invention are as follows: By independently acquiring the dynamic attenuation law of fault mechanical parameters under cyclic loading and combining it with a multi-scale simulation model to numerically characterize the coupling effect between the fault and the gas storage cavern, the successive attenuation of fault mechanical parameters under cyclic gas pressure loading with the gas filling and releasing process can be quantitatively described. This provides a simulation basis for obtaining fault stress evolution data, displacement response data, and plastic zone expansion data, reflecting the degradation of material properties. On this basis, the uplift resistance safety factor of the overlying rock mass is obtained through a failure model and compared with a preset safety threshold, forming an independent check for the uplift resistance stability of the gas storage cavern. The overall uplift risk and the local fault slip risk under cyclic loading are incorporated into a unified analysis framework. Finally, by combining the uplift resistance stability check results with multi-source response data of the fault plane, a comprehensive quantitative evaluation of the surrounding rock stability is achieved. Attached Figure Description

[0028] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. In the accompanying drawings: Figure 1 A schematic flowchart illustrating the steps of the gas storage surrounding rock stability evaluation method provided in this embodiment of the invention; Figure 2 A graph showing the periodic change of gas pressure over time under cyclic gas pressure loading conditions provided in an embodiment of the present invention; Figure 3 Simulation diagram of a multi-scale simulation model of the coupling effect between faults and gas storage caverns provided in an embodiment of the present invention; Figure 4 This is an enlarged schematic diagram of a local scale model within a multi-scale simulation model provided in an embodiment of the present invention; Figure 5 A schematic diagram illustrating the direction of the maximum horizontal principal stress within the multi-scale simulation model provided in this embodiment of the invention; Figure 6 A schematic diagram illustrating the directions of the minimum horizontal principal stress and vertical principal stress within the multi-scale simulation model provided in this embodiment of the invention; Figure 7 A schematic diagram illustrating the calculation results of the overlying rock mass uplift resistance safety factor provided in an embodiment of the present invention; Figure 8 The mechanical analysis simulation diagram of the cone or frustum-shaped failure model of the overlying rock mass provided in the embodiment of the present invention. Detailed Implementation

[0029] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0030] This invention discloses a method for evaluating the stability of surrounding rock in gas storage facilities traversing fault fracture zones, such as... Figure 1 As shown, it includes: S1. Obtain the fault geometric parameters, fault mechanical parameters, surrounding rock mechanical parameters, dynamic attenuation law of fault mechanical parameters under cyclic loading, and relative positional relationship between the fault and the proposed gas storage cavern in the target area. S2. Based on the fault geometric parameters, relative positional relationships, fault mechanical parameters, and surrounding rock mechanical parameters, establish a multi-scale simulation model of the coupling effect between the fault and the gas storage cavern; S3. Determine the spatial range of the overlying rock mass above the gas storage cavern based on the multi-scale simulation model, and establish a failure model of the overlying rock mass in combination with the surrounding rock mechanics parameters; S4. Determine the fracture surface morphology of the overlying rock mass based on the failure model, and obtain the overlying rock mass's uplift resistance safety factor by combining the spatial range of the overlying rock mass and the surrounding rock mechanical parameters. S5. Based on the comparison between the anti-lift safety factor and the preset safety threshold, obtain the stability verification results of the gas storage cavern's anti-lift. S6. Based on the dynamic attenuation law, apply cyclic gas pressure loading conditions to the multi-scale simulation model that has passed the anti-lift stability check to simulate the gas filling and releasing process of the gas storage cavern under different working conditions during its operation. S7. Obtain stress evolution data, displacement response data, and plastic zone expansion data of the fault plane during the simulated inflation and deflation process. Combine these with the stability verification results to analyze and obtain the comprehensive stability evaluation results of the surrounding rock.

[0031] The following is a detailed analysis of the implementation of the above-mentioned method for evaluating the stability of the surrounding rock of a gas storage facility: First, the fault geometric parameters and their relative position to the proposed gas storage cavern were obtained through geological exploration. The fault geometric parameters included the fault's spatial location, attitude, width, and fracture zone extent. Fault mechanical parameters and surrounding rock mechanical parameters were obtained through laboratory or field tests. Fault mechanical parameters included cohesion and internal friction angle, while surrounding rock mechanical parameters included unit weight, cohesion, internal friction angle, and lateral pressure coefficient. The dynamic attenuation law of fault mechanical parameters under cyclic loading was obtained through cyclic loading tests, and the relationship between cohesion and internal friction angle gradually decreasing with increasing cyclic loading was characterized, thereby establishing a complete input dataset.

[0032] For example, for a certain compressed air energy storage underground project, based on the preliminary site selection and investigation, in response to the key and difficult issues in the underground engineering investigation of the project, a comprehensive investigation method, including geological mapping, geophysical exploration, engineering geological drilling, in-situ testing and laboratory testing, was adopted to reveal the characteristics of the structural planes and faults developed at the site and the rock mass conditions.

[0033] Based on the scale of each fault and its impact on the gas storage facility, the main considerations are faults 1 and 2 to the north of the storage facility, fault 4 to the south, and fault 3 through which the storage facility crosses. Fault 1 is a normal fault, with an orientation of NE28° and NW∠75°, a fault zone width of 1m~2m, and an influence zone width of 10m~20m. Fault 2 is a normal fault, with an orientation of NW77° and SW∠75°, a fault zone width of 1m~2m, and an influence zone width of 10m~15m. Fault 3 is a reverse fault, with an orientation of NE25° and SE∠75°, a fault zone width of 0.3m~1m, and an influence zone width of 10m~15m. Fault 4 is a reverse fault, with an orientation of NE17° and SE∠61°, a fault zone width of approximately 1m, and an influence zone width of 10m~25m.

[0034] Based on existing borehole in-situ test and laboratory test data, combined with similar engineering data and relevant specifications, the mechanical parameters of the structural surface are shown in Table 1, and the main characteristic parameters of the surrounding rock mass are shown in Table 2.

[0035] Table 1 Mechanical parameters of structural surfaces

[0036] Table 2 Main characteristic parameters of the surrounding rock mass

[0037] Secondly, a multi-scale simulation model of the coupling effect between faults and gas storage caverns is established. Preferably, this multi-scale simulation model can include a regional-scale model and a local-scale model: the regional-scale model covers the entire fault zone and surrounding rock, and is used to calculate the initial geostress field and boundary conditions; the local-scale model covers the gas storage cavern and its surrounding rock and fault zone, and is used for refined analysis of the coupling effect between faults and gas storage caverns. Therefore, the initial geostress field and boundary conditions of the regional-scale model can be transferred to the local-scale model, so that the local-scale model has accurate far-field stress boundaries while maintaining a refined grid, avoiding the contradiction that a single-scale model cannot simultaneously take into account the accuracy of large-scale geostress field inversion and the accuracy of local fault-cavern interaction analysis.

[0038] like Figure 3 and Figure 4 As shown. Preferably, the multi-scale simulation model is 1144m long and 794m wide, with a total of 104938 nodes and 563133 elements. The model divides the soil from the surface to the gas storage layer into two layers: strongly weathered and weakly weathered. The soil layer parameters and fault strength parameters are the same as those in Tables 1 and 2.

[0039] Furthermore, a failure model for the overlying rock mass is established, preferably a cone or frustum-shaped failure model based on limit equilibrium theory. The spatial extent of the overlying rock mass is determined by the three-dimensional geological geometric boundaries in the multi-scale simulation model, including the overlying rock mass region bounded by the surface morphology, stratigraphic interfaces, and fault interfaces. Therefore, the morphology of the fracture surface in the failure model can be determined within this spatial extent by the surrounding rock mechanical parameters through limit equilibrium theory. Simultaneously, the uplift resistance safety factor of the overlying rock mass is obtained by combining the spatial extent of the overlying rock mass and the surrounding rock mechanical parameters. The uplift resistance safety factor of the overlying rock mass can be calculated based on the normal stress and shear stress on the fracture surface and the self-weight of the overlying rock mass: the normal stress consists of the component of the rock mass's self-weight on the fracture surface and the component of the horizontal lateral geostress on the fracture surface; the shear stress consists of the normal stress multiplied by the friction coefficient plus the cohesion. The uplift resistance safety factor can be defined as the ratio of the overlying rock mass's resistance to the uplift force, where the resistance to uplift consists of the overlying rock mass's self-weight and the shear force on the fracture surface; the uplift force is generated by the internal pressure of the gas storage cavern.

[0040] Subsequently, the stability verification results of the gas storage cavern against uplift were obtained by comparing the uplift resistance safety factor with the preset safety threshold. These uplift resistance stability verification results were obtained independently before the fault mechanical parameters underwent cyclic decay, reflecting the pure uplift resistance storage capacity unaffected by cyclic load deterioration. Simultaneously, cyclic gas pressure loading conditions were applied to the multi-scale simulation model that passed the uplift resistance stability verification according to the dynamic decay law. During the application of cyclic gas pressure loading conditions, the fault mechanical parameters within the multi-scale simulation model were successively reduced and updated with each cycle according to this dynamic decay law, ensuring that the fault cohesion and internal friction angle were lower than the corresponding values ​​of the previous cycle during each cyclic loading. This allowed the dynamic evolution of fault mechanical parameters with gas filling and releasing cycles to be realized in the simulation model.

[0041] Finally, stress evolution data, displacement response data, and plastic zone expansion data of the fault plane were acquired during the simulated inflation and deflation process. The stress evolution data reflects the changes in normal and shear stresses on the fault plane with the number of cycles; the displacement response data reflects the cumulative increase in the relative slip between the two fault plates with the number of cycles; and the plastic zone expansion data reflects the spatial extent of the fault zone and its affected area as the fault strength decreases. These three types of data were combined with the independently acquired gas storage cavern uplift stability verification results, allowing the analysis conclusions of both overall uplift instability risk and local fault slip instability risk to be used simultaneously as input for the comprehensive evaluation of surrounding rock stability. This enables a comprehensive quantitative evaluation of the analysis conclusions of two different failure mechanisms within the same framework, solving the technical problem of the inability to uniformly output multi-source evaluation results, which led to a lack of comprehensive evaluation basis for engineering decisions.

[0042] Furthermore, based on fault geometric parameters, relative positional relationships, fault mechanical parameters, and surrounding rock mechanical parameters, a multi-scale simulation model of the coupling effect between the fault and the gas storage cavern is established, including: Based on the fault's geometric parameters and relative positional relationships, the regional scale range encompassing all faults and surrounding rocks, as well as the local scale range encompassing the gas storage cavern, surrounding rocks, and faults, are determined. Based on the determined regional scale range and local scale range, regional scale geometric models and local scale geometric models are constructed respectively, and the regional scale geometric models and local scale geometric models are meshed to obtain the discretized multi-scale geometric models; The Mohr-Coulomb constitutive model is used to describe the shear failure behavior of the surrounding rock and fault in the multi-scale geometric model. The fault mechanical parameters and the surrounding rock mechanical parameters are respectively assigned to the corresponding regions in the multi-scale geometric model to obtain the multi-scale simulation model.

[0043] The following is a detailed analysis of the implementation of the above-mentioned method for evaluating the stability of the surrounding rock of a gas storage facility: First, the regional scale encompasses all faults and surrounding rock, while the local scale encompasses the gas storage cavern and surrounding rock, as well as the fault itself. The regional scale is used to invert the far-field stress field. Once the regional scale is determined, the distance between the fault and the regional scale boundary is sufficiently large to ensure that the stress field at the fault is not affected by boundary effects, thus guaranteeing that the stress field inverted from the regional scale model represents the true stress environment of the fault. The local scale is used for refined analysis of the coupling effect between the fault and the gas storage cavern. Once the local scale is determined, the gas storage cavern is located at the center of the local scale model, and the fault is completely contained within the local scale, ensuring that the analysis of the coupling effect between the fault and the gas storage cavern is not affected by the local scale boundary truncation effect.

[0044] Secondly, regional-scale and local-scale geometric models were constructed separately, and discretized multi-scale geometric models were obtained through mesh generation. The regional-scale geometric model adopted a mesh size matching the accuracy of the geostress field inversion, with the mesh density gradually varying along the depth direction according to the stratigraphic properties. Appropriate mesh densification was applied within the fault depth range to ensure the continuity of stress distribution on the fault plane during geostress field inversion. The local-scale geometric model used a denser mesh in the gas storage cavern and fault regions, with the mesh size smaller than the smaller of the cavern radius and fault zone width. This allowed the mesh to capture stress concentration areas at the cavern excavation face and stress gradients within the fault zone. After discretization, the regional-scale and local-scale geometric models were interpolated at their interface using node displacement interpolation. The regional-scale mesh did not need to maintain a one-to-one node correspondence with the local-scale mesh at the interface, and the local-scale mesh did not need to extend to the regional-scale boundary, thus avoiding node mismatch problems caused by excessive differences in mesh size between the two scales.

[0045] The Mohr-Coulomb constitutive model is used to describe the shear failure behavior of the surrounding rock and fault in a multi-scale geometric model. The failure criterion of the Mohr-Coulomb constitutive model is as follows: ,in For shear stress, It is normal stress. It is the internal friction angle. The cohesion is used. Fault mechanical parameters and surrounding rock mechanical parameters are respectively assigned to corresponding regions in the multi-scale geometric model, so that the surrounding rock and fault have different cohesion and internal friction angles under the same constitutive framework. That is, the cohesion and internal friction angle in the fault region are smaller than the corresponding values ​​in the surrounding rock region, causing the fault to preferentially reach the shear failure condition under the same external load. Simultaneously, the surrounding rock and fault share nodes to transfer stress-strain. The deformation constraint of the surrounding rock on the fault is achieved through nodal displacement coordination, and the stress disturbance of the fault on the surrounding rock is also transferred through the same nodes, avoiding stress discontinuity at the fault-surrounding rock interface caused by constitutive inconsistency.

[0046] The Mohr-Coulomb constitutive model is typically an elastoplastic mechanical model describing the shear failure behavior of granular materials such as soil and rock. Preferably, the mechanical behavior of faults can be simulated using surface elements and solid elements.

[0047] Surface elements are used to simulate discontinuous surfaces and exist on the boundaries of adjacent solid elements. Their constitutive model describes the force-displacement relationship in the tangential and normal directions: the shear strength in the tangential direction is defined by cohesion, friction angle, and dilatation angle, and slip occurs after reaching its peak; the normal direction can separate or overlap, and the normal stiffness controls the closure response. A key feature is that the fault is idealized as a zero-thickness discontinuity, and the rock masses on both sides can undergo independent relative displacement. Solid elements refer to treating the fault zone as a solid element region with a certain thickness, assigning it mechanical parameters lower than those of the surrounding rock. Key features include finite thickness; adherence to the Mohr-Coulomb criterion; and continuous stress-strain transfer between the fault zone and the surrounding rock through shared nodes. For layered or densely jointed rock masses, distributed joint models and anisotropic distributed joint models can also be used, embedding weak surfaces in the dominant direction within solid elements to simulate the anisotropic strength and deformation behavior of the rock mass.

[0048] The rationality analysis based on the actual characteristics of the fault is as follows: (1) Geometric features of faults Table 3 Comparison of fault geometric features

[0049] Reasonableness assessment: Actual faults are not idealized "one-size-fits-all" surfaces, but rather complex systems with fracture zones of a certain thickness and fault gouge filling. For faults with significant thickness, the solid element method better reflects the physical reality.

[0050] (2) Fault mechanical behavior Table 4 Comparison of Fault Mechanical Behavior

[0051] Reasonableness judgment: For the activation problem of pre-existing faults under operational loads, the surface element method more realistically reflects the slip mechanism; for the gradual failure process within the fault zone (such as yielding and fragmentation of fault material), the solid element method is the only choice. (3) Fault material characteristics Actual fault zones usually contain infill materials such as fault breccia and fault gouge, and their mechanical properties are significantly different from those of the surrounding rocks on both sides: the solid element method can assign independent physical and mechanical parameters (elastic modulus) to the fault zone area. The surface element method can only define the mechanical parameters of the contact surface and cannot simulate the volume deformation and internal failure of the filling material.

[0052] In summary, the preferred scenarios for solid elements are as follows: fault zone thickness cannot be ignored (> 1 to 2 times the element size); focus on the development of the plastic zone and the progressive failure process within the fault zone; study the "overall disturbance effect" of the fault zone on the stress field and displacement field; study the spatial variability of the mechanical parameters of the fault zone; and analyze the evolution process of the fault zone as a seepage channel.

[0053] The limitations are as follows: large displacement slip may cause mesh distortion, leading to difficulty in computational convergence; it is difficult to simulate the "stick-slip" or "sudden opening" behavior of the fault plane; and extremely fine meshes are required for thin faults (such as <0.2m), resulting in high computational cost.

[0054] The preferred scenarios for surface elements are as follows: faults are thin structural surfaces (such as joints and bedding planes) with negligible thickness; the core focus is on the slip, opening, and evolution of the fault; the control effect of faults on the discontinuity of the displacement field; fault activation (opening-closing-slip) under cyclic loading during operation; and large relative displacements on both sides of the fault (such as slope sliding and fault displacement). Limitations include: inability to simulate the internal failure process of the fault zone; unclear physical meaning of parameters (normal stiffness, tangential stiffness) and their values ​​relying on experience; and inability to simulate the influence of fault zone thickness on stress diffusion.

[0055] For fault-crossing studies of gas storage facilities, the solid element (weakened) method is a more reasonable choice because it can accurately reflect the finite thickness characteristics of the fault zone and support the evolution analysis of the plastic zone. The surface element method is more suitable as a supplementary tool for refining the analysis of the slip behavior of the fault plane or for method comparison and verification.

[0056] Furthermore, the spatial extent of the overlying rock mass above the gas storage cavern is determined based on a multi-scale simulation model, and a failure model of the overlying rock mass is established in conjunction with surrounding rock mechanical parameters, including: Based on the spatial location of the gas storage cavern in the multi-scale simulation model, and combined with the fault geometric parameters and relative positional relationships, the spatial range of the overlying rock mass above the gas storage cavern is determined. Based on the spatial location of the gas storage cavern and the mechanical parameters of the surrounding rock, determine the spatial location of the fracture surface of the overlying rock mass within the spatial range of the overlying rock mass; Based on the spatial location of the rupture surface and the spatial location of the fault through the fault geometry parameters, determine whether the rupture surface has been cut by the fault. Based on the assessment results, a cone or frustum-shaped failure model of the overlying rock mass is established, centered on the gas storage cavern and taking into account the spatial location of the fracture surface.

[0057] Furthermore, based on the assessment results, and taking the gas storage cavern as the center, and considering the spatial location of the fracture surface, a cone or frustum-shaped failure model of the overlying rock mass is established, including: When it is determined that the fault has not cut the fracture surface, the first angle between the fracture surface of the overlying rock mass and the vertical direction is determined by using the surrounding rock mechanical parameters and the limit equilibrium theory. Based on the first included angle, combined with the spatial range of the overlying rock mass and the spatial location of the fracture surface, a cone or frustum-shaped failure model of the overlying rock mass is established with the gas storage cavern as the center. When determining the fracture surface of a fault, the overlying rock mass is divided into multiple independent blocks along the fault according to the spatial location of the fault. The spatial extent of each independent block was determined, and the second angle between the fracture surface of each independent block and the vertical direction was determined by using the limit equilibrium theory based on the surrounding rock mechanics parameters. Based on the second included angle, and combined with the spatial range of each independent block and the spatial location of the rupture surface, a cone or frustum-shaped failure model of each independent block is established with the gas storage cavern as the center.

[0058] The following is a detailed analysis of the implementation of the above-mentioned method for evaluating the stability of the surrounding rock of a gas storage facility: First, the spatial location of the gas storage cavern can be directly extracted from the multi-scale simulation model. The spatial extent of the overlying rock mass above the gas storage cavern is determined. This spatial extent extends upwards from the gas storage cavern to the surface, with its lateral boundary defined by the spatial location of the fault and its relative orientation to the gas storage cavern. When the fault is located on one side of the gas storage cavern, the lateral boundary of the overlying rock mass is truncated at the fault location, thus separating the overlying rock masses on both sides of the fault. When the fault is located above the gas storage cavern, the top boundary of the overlying rock mass contacts the footwall of the fault. This determined spatial extent of the overlying rock mass serves as the geometric boundary for subsequent determination of the fracture surface's spatial location and the establishment of the failure model. This spatial extent encompasses the entire area that the fault may cut, allowing the spatial intersection relationship between the fault and the fracture surface to be fully determined within this spatial extent.

[0059] The spatial location of the gas storage cavern and the surrounding rock mechanics parameters jointly determine the spatial location of the fracture surface of the overlying rock mass within the overlying rock mass. The fracture surface extends from the sidewall of the gas storage cavern along the dip direction to the surface or to the point where it is truncated by a fault. Its direction of extension is determined by the internal friction angle in the surrounding rock mechanics parameters using limit equilibrium theory. Once the spatial location of the fracture surface is determined, it divides the overlying rock mass into the main body of the overlying rock mass inside the fracture surface and the rock mass outside the fracture surface. The main body of the overlying rock mass is the object of subsequent calculations of the uplift resistance safety factor.

[0060] Secondly, the spatial location of the rupture surface and the spatial location of the fault in the fault geometry parameters are used together to determine whether the rupture surface has been cut by the fault. The spatial location of the fault in the fault geometry parameters includes the spatial extent of the fault plane and the spatial extent of the fault breccia zone. When the spatial location of the rupture surface overlaps with the spatial extent of the fault breccia zone, the rupture surface is cut by the fault; when there is no spatial overlap, the rupture surface is not cut by the fault. This determination determines whether the failure model of the overlying rock mass is established as a whole or in blocks, because after the rupture surface is cut by the fault, the fault divides the overlying rock mass into multiple independent blocks along the direction of the rupture surface, and the responses of each independent block under earthquake or internal pressure are independent of each other.

[0061] When it is determined that the fault has not cut the fracture surface, the surrounding rock mechanics parameters are used to determine the first angle between the fracture surface of the overlying rock mass and the vertical direction through the limit equilibrium theory. This first angle is determined by the internal friction angle in the surrounding rock mechanics parameters. The larger the internal friction angle, the larger the first angle, the gentler the fracture surface, the larger the volume enclosed by the fracture surface of the overlying rock mass, and the greater the uplift resistance provided by the self-weight of the overlying rock mass. Based on the first angle, combined with the spatial range of the overlying rock mass and the spatial location of the fracture surface, a cone or frustum-shaped failure model of the overlying rock mass is established with the gas storage cavern as the center. The axis of symmetry of this cone or frustum-shaped failure model passes through the central axis of the gas storage cavern. The fracture surface extends upward from the sidewall of the gas storage cavern at the first angle to the ground surface or to the calculation boundary. Within the spatial range of the overlying rock mass, the fracture surface encloses the overlying rock mass into a cone or frustum-shaped failure body centered on the gas storage cavern.

[0062] When determining the fault fracture surface, the overlying rock mass is divided into multiple independent blocks along the fault based on its spatial location. The spatial extent of each independent block is determined, and the second angle between the fracture surface and the vertical direction of each independent block is determined using the limit equilibrium theory based on the surrounding rock mechanics parameters. The spatial extent of each independent block is jointly determined by the spatial location of the fault and the spatial location of the fracture surface. The second angle between the fracture surface and the vertical direction of each independent block is determined by the surrounding rock mechanics parameters at the location of that independent block. Based on the second angle, combined with the spatial extent of each independent block and the spatial location of the fracture surface, a cone or frustum-shaped failure model is established for each independent block, centered on the gas storage cavern. Each independent block is symmetrical about the central axis of the gas storage cavern. The fracture surface extends upward from the sidewall of the gas storage cavern, along the second angle of each independent block, to the location of the fault or to the surface. The cone or frustum-shaped failure model of each independent block is truncated at the fault. The failure models of the hanging wall and footwall of the fault are independent at the fault.

[0063] As mentioned above, specifically: Internal friction angle in surrounding rock mechanics parameters Obtained through indoor or field tests. The limit equilibrium theory assumes that when the overlying rock mass undergoes shear slip along the fracture surface, the angle between the fracture surface and the direction of the maximum principal stress is... Due to the action of horizontal geostress, this angle further manifests as the angle between the rupture surface and the vertical direction. .thus, Directly derived from the internal friction angle in the surrounding rock mechanics parameters Determined through the theory of limit equilibrium.

[0064] When the fault has not cut the fracture surface, the internal friction angle in the surrounding rock mechanical parameters is used as an example. The first angle between the fracture surface of the overlying rock mass and the vertical direction was determined using the limit equilibrium theory. . Once determined, the rupture surface extends from the sidewall of the gas storage chamber. Extending the angle upwards to the surface, the spatial morphology of the fracture surface is uniquely determined. This fracture surface and the spatial extent of the overlying rock mass together define the boundary of the cone or frustum-shaped failure model, establishing a cone or frustum-shaped failure model of the overlying rock mass with the gas storage cavern as the center.

[0065] When cutting the fracture surface along a fault, the overlying rock mass is divided into multiple independent blocks according to the spatial location of the fault, and the spatial extent of each independent block is determined. The internal friction angle from the surrounding rock mechanics parameters is then used to analyze each independent block. The second angle between the fracture surface of each independent block and the vertical direction was determined using the limit equilibrium theory. , ...each independent block After the values ​​are determined, the fracture surface of each independent block is located at the position of the side wall of the gas storage cavern with its respective... Extending the angle upwards to the location of the fault, the spatial morphology of the fracture surface of each independent block is uniquely determined. Conical or frustum-shaped failure models of each independent block are established with the gas storage cavern as the center. The failure models of the hanging wall and the footwall are independent at the fault and do not connect with each other.

[0066] Furthermore, based on the failure model, the fracture surface morphology of the overlying rock mass is determined. Combined with the spatial extent of the overlying rock mass and the surrounding rock mechanical parameters, the uplift resistance safety factor of the overlying rock mass is obtained, including: Based on the geometric analysis of the failure model, the depth of the overlying rock mass, the thickness of each layer of the overlying rock mass along the thickness direction, and the angle between the fracture surface in the overlying rock mass and the vertical direction are determined. Based on the angle between the fracture surface and the vertical direction, the depth of the overlying rock mass, and the surrounding rock mechanical parameters such as unit weight and lateral pressure coefficient, the normal stress on the fracture surface is calculated. The functional expression for calculating the normal stress is as follows:

[0067] In the formula, This represents the normal stress on the fracture surface, in kPa. Indicates the unit weight of the surrounding rock. ; Indicates the angle between the fracture surface and the vertical direction; dimensionless. This represents the lateral pressure coefficient, which is dimensionless. Indicates the depth of the overlying rock mass, in units of ; Based on the normal stress and the cohesion and average internal friction angle in the surrounding rock mechanical parameters, the shear stress on the fracture surface is calculated. The functional expression for calculating the shear stress is as follows:

[0068] In the formula, This represents the shear stress on the fracture surface, in kPa. This represents the average internal friction angle of the overlying rock mass, expressed in kPa. This represents the cohesion of the overlying rock mass, expressed in kPa. Based on the thickness of each layer of the overlying rock mass along the thickness direction, the angle between the fracture surface and the vertical direction in the overlying rock mass, the normal stress, and the shear stress, the normal pressure and shear force on the fracture surface are calculated respectively. The functional expressions for calculating the normal pressure and shear force are as follows:

[0069]

[0070] In the formula, This represents the normal force on the fracture surface, expressed in kN. The thickness of the i-th layer of the overlying rock mass along the thickness direction is expressed in meters (m). Indicates a hierarchical index; This represents the shear strength on the fracture surface, expressed in kN. This indicates the unit width along the axis of the gas storage chamber, in meters (m). The number of gas storage caverns is determined based on the design and operation parameters of the gas storage caverns. Combined with the normal pressure and shear force, the uplift force and uplift force of the overlying rock mass under the corresponding number of caverns are obtained. Based on the uplift resistance and the overlying force, the uplift resistance safety factor of the overlying rock mass is calculated. The functional expression for calculating the uplift resistance safety factor is:

[0071] In the formula, This represents the safety factor against uplift of the overlying rock mass, and is dimensionless. This indicates the uplift resistance of the overlying rock mass, expressed in kN. This indicates the uplift force exerted on the overlying rock mass, expressed in kN.

[0072] The following is a detailed analysis of the implementation of the above-mentioned method for evaluating the stability of the surrounding rock of a gas storage facility: First, the depth of the overlying rock mass, the thickness of each layer along the thickness direction of the overlying rock mass, and the angle between the fracture surface and the vertical direction in the overlying rock mass are all determined from the geometric analysis of the failure model. The depth of the overlying rock mass determines the stress level at which the normal stress on the fracture surface is calculated; the greater the depth, the greater the vertical stress. The thickness of each layer along the thickness direction of the overlying rock mass determines the contribution weight of each layer to the normal pressure and shear force; the thicker the layer, the greater its contribution to the normal pressure and shear force. The angle between the fracture surface and the vertical direction in the overlying rock mass determines the distribution of the gravity components in the normal and tangential directions of the fracture surface; the larger the angle, the smaller the gravity component in the normal direction and the larger the gravity component in the tangential direction. These three parameters describe the geometric characteristics of the fracture surface from different dimensions and together form the geometric basis for the subsequent calculation of normal stress, shear stress, normal pressure, and shear force.

[0073] The normal stress on the fracture surface is determined by the angle between the fracture surface and the vertical direction, the depth of the overlying rock mass, and the unit weight and lateral pressure coefficient of the surrounding rock in the rock mechanics parameters. The unit weight of the surrounding rock is obtained through laboratory tests, and the lateral pressure coefficient is obtained through laboratory tests or field tests. The vertical stress equals the unit weight of the surrounding rock multiplied by the depth of the overlying rock mass, and the horizontal stress equals the lateral pressure coefficient multiplied by the vertical stress. The normal stress consists of the component of the vertical stress in the direction normal to the fracture surface and the component of the horizontal stress in the direction normal to the fracture surface. The component of the vertical stress in the direction normal to the fracture surface is equal to the vertical stress multiplied by the lateral pressure coefficient. The square of the horizontal stress component along the normal to the rupture surface is equal to the horizontal stress multiplied by 1 / 2. The square of the stress. When the angle between the fracture surface and the vertical direction changes, the proportions of the vertical and horizontal stress components in the normal stress also change. As the angle increases, the vertical stress component decreases while the horizontal stress component increases. The normal stress is determined by the ebb and flow of these two stress components.

[0074] The shear stress on the fracture surface is jointly determined by normal stress and the cohesion and mean internal friction angle in the surrounding rock mechanics parameters. The mean internal friction angle and cohesion are obtained through laboratory or field tests. Shear stress consists of a frictional component and a cohesive component. The frictional component equals the normal stress multiplied by the tangent of the mean internal friction angle, while the cohesive component equals the cohesion itself. The frictional component increases linearly with increasing normal stress, while the cohesive component remains unchanged. When the normal stress is large, the frictional component dominates, and the shear resistance of the fracture surface is mainly provided by friction. When the normal stress is small, the cohesive component contributes relatively significantly, and the shear resistance of the fracture surface is jointly provided by friction and cohesion.

[0075] The thickness of each layer along the thickness direction of the overlying rock mass, the angle between the fracture surface and the vertical direction in the overlying rock mass, and the normal stress and shear stress together determine the normal pressure and shear resistance on the fracture surface. The actual length of the i-th layer in the direction of the fracture surface is the thickness of that layer divided by... The normal pressure is equal to the normal stress multiplied by the actual length of the i-th layer along the fracture surface, and the shear force is equal to the shear stress multiplied by the actual length of the i-th layer along the fracture surface. The actual area of ​​the fracture surface varies continuously along the depth direction, and the normal stress and shear stress are different at different depths. The width parameter B is the unit width along the axis of the gas storage cavern, which is taken as 1m in the two-dimensional profile analysis. This unit width is used to convert the line load in the two-dimensional profile analysis into the force in the three-dimensional analysis, so that the normal pressure and shear force are changed from forces per unit width to forces over the actual width. By dividing the overlying rock mass into multiple layers along the thickness direction and calculating and summing the results for each layer, the calculation of normal pressure and shear force reflects the changes in normal stress and shear stress along the depth direction. The larger the angle between the fracture surface and the vertical direction, the longer the actual length of the fracture surface corresponding to the same layer thickness, and the greater the normal pressure and shear force.

[0076] The number of gas storage caverns is determined based on the design and operating parameters of the caverns. The uplift resistance and shear force experienced by the overlying rock mass under the corresponding number of caverns are obtained by combining the normal pressure and shear force. The uplift resistance is determined by the self-weight of the overlying rock mass, the normal pressure, and the shear force, while the uplift force is generated by the internal pressure within the caverns. The uplift resistance and uplift force together determine the safety factor against uplift of the overlying rock mass. The safety factor against uplift is equal to the uplift resistance divided by the uplift force. The safety factor against uplift reflects the overlying rock mass's reserve capacity to resist uplift under internal pressure. When the safety factor against uplift is greater than 1, the overlying rock mass has the reserve capacity to resist uplift under internal pressure. When the safety factor against uplift is equal to 1, the overlying rock mass is in a critical equilibrium state. When the safety factor against uplift is less than 1, the overlying rock mass undergoes overall uplift failure under internal pressure.

[0077] Furthermore, based on the design and operating parameters of the gas storage caverns, the number of caverns is determined. Combining the normal pressure and shear force, the uplift resistance and uplift force experienced by the overlying rock mass under the corresponding number of caverns are obtained, including: Based on the geometric analysis of the failure model, the volume of the overlying rock mass and the horizontal projected area of ​​the gas storage cavern are determined. Based on the design and operation parameters of the gas storage cavern, the maximum internal pressure of the gas storage cavern during the operation period and the distance between the cavern edges when there are multiple caverns are determined. When the number of caverns in the gas storage facility is determined to be a single cavern, the first self-weight of the overlying rock mass above the single cavern is calculated based on the volume of the overlying rock mass and the unit weight of the surrounding rock. The functional expression for calculating the first self-weight is as follows:

[0078] In the formula, This represents the first self-weight of the overlying rock mass in a single-chamber configuration, expressed in kN. The volume of the overlying rock mass is expressed in units of 1. ; Based on the first self-weight, the angle between the fracture surface and the vertical direction in the overlying rock mass, the normal pressure, and the shear force, the first uplift force on the overlying rock mass above the single cavern is calculated. The functional expression for calculating the first uplift force is:

[0079] In the formula, This represents the first uplift resistance force experienced by the overlying rock mass, expressed in units of... ; Based on the maximum internal pressure and the horizontal projected area of ​​the gas storage cavern, the first uplift force on the overlying rock mass above the single cavern is calculated. The functional expression for calculating the first uplift force is:

[0080] In the formula, This represents the first uplift force acting on the overlying rock mass, expressed in units of... ; This indicates the maximum internal pressure of the gas storage cavern during its operational period, expressed in kPa. This represents the horizontal projected area of ​​the gas storage cavern, in units of... ; When the number of caverns in the gas storage facility is determined to be multi-cavity, the second self-weight of the overlying rock mass above the multi-cavity is calculated based on the number of caverns, the distance between the cavern edges, the thickness of each layer of the overlying rock mass along the thickness direction, and the unit weight of the surrounding rock at the corresponding depth of each layer. The functional expression for calculating the second self-weight is as follows:

[0081] In the formula, This represents the second self-weight of the overlying rock mass located above the multi-cavity structure, expressed in kN. Indicates the number of chambers; dimensionless. Indicates the radius of the cavern, in units of ; Indicates the distance between the edges of the cavern, in units of ; Indicates the first inch of the overlying rock mass along the thickness direction. Layer thickness, in units of ; Indicates a hierarchical index. Indicates the first inch of the overlying rock mass along the thickness direction. The unit weight of the surrounding rock at the corresponding depth of each layer, in units of ; This represents the total number of layers of the overlying rock mass along the thickness direction; it is dimensionless. The excavation of multiple tunnels was simulated using a multi-scale simulation model. The tensile stress in the rock mass between each tunnel was extracted during the simulation. Combined with the distance to the tunnel edges, the resultant force of the tensile stress in the rock mass between each tunnel was calculated. The functional expression for the resultant force is as follows:

[0082] In the formula, This represents the resultant tensile stress in the rock mass between the various chambers, expressed in kN. Indicates the first Tensile stress in the rock mass between adjacent caverns, in kPa; Based on the second self-weight, the angle between the fracture surface and the vertical direction in the overlying rock mass, the resultant force, the normal pressure, and the shear force, the second uplift force on the overlying rock mass located above the multi-cavity is calculated. The functional expression for calculating the second uplift force is:

[0083] In the formula, This represents the second uplift resistance force on the overlying rock mass, expressed in kN. Based on the number of caverns, the maximum internal pressure, and the horizontal projected area of ​​the gas storage caverns, the second uplift force on the overlying rock mass located above the multiple caverns is calculated. The functional expression for calculating the second uplift force is:

[0084] In the formula, This represents the second uplift force on the overlying rock mass, expressed in kN.

[0085] The following is a detailed analysis of the implementation of the above-mentioned method for evaluating the stability of the surrounding rock of a gas storage facility: First, the volume of the overlying rock mass and the horizontal projected area of ​​the gas storage cavern are determined through geometric analysis of the failure model. These two parameters respectively contain core information about the source and range of the uplift force. The volume of the overlying rock mass is the volume of a cone or frustum-shaped failure body confined by the fracture surface and the spatial range of the overlying rock mass. The size of this volume directly determines the total weight of the overlying rock mass, which is one of the main sources of uplift force. The horizontal projected area of ​​the gas storage cavern is the effective area for the upward transmission of internal pressure. The size of this area directly determines the total uplift force, and the uplift force generated by the internal pressure acting on this area is a core component of the denominator in the uplift safety factor. There are fundamental differences between single-cavity and multi-cavity caverns in both weight and uplift force calculations. The volume of the overlying rock mass of a single-cavity cavern is only constrained by the geometric boundary of the single cavern, and its weight calculation is relatively independent. However, the volume of the overlying rock mass of a multi-cavity cavern is not only constrained by the cavern boundary but also affected by the stress redistribution caused by excavation and unloading between adjacent caverns.

[0086] When the number of caverns in the gas storage facility is determined to be a single cavern, the vertical components of the shear force and the normal pressure each have opposite effects on the first uplift resistance. The shear force acts tangentially to the fracture surface, and its vertical component resists uplift, thus contributing positively to the first uplift resistance. The normal pressure acts normally to the fracture surface, and its vertical component compresses the fracture surface downwards. While increasing friction, it also generates a downward component in the vertical direction, thus contributing negatively to the first uplift resistance. The first uplift resistance equals the first self-weight plus the vertical component of the shear force minus the vertical component of the normal pressure. This mechanical equilibrium reflects the stress state of the overlying rock mass in the vertical direction. The first self-weight serves as the foundation of the uplift resistance, the vertical component of the shear force acts as a reinforcing factor, and the vertical component of the normal pressure acts as a weakening factor; together, these three factors determine the total capacity of the overlying rock mass to resist uplift under internal pressure. The first upward force is equal to the maximum pressure of the gas storage cavern during its operation period multiplied by the horizontal projected area of ​​the gas storage cavern. This upward force is the resultant force of the internal pressure being transmitted upward, and its direction of action is opposite to the anti-uplift force.

[0087] When the number of caverns in a gas storage facility is determined to be multi-cavity, the calculation of the second self-weight needs to simultaneously consider the influence of the number of caverns, the cavern radius, and the distance between the cavern edges on the range of rock mass cut by the fracture surface. The rock mass between adjacent caverns experiences horizontal tensile stress due to the unloading during bidirectional excavation. This tensile stress is extracted through a multi-scale simulation model of the multi-cavity excavation. The extracted tensile stress is multiplied by the cavern edge distance and then summed to obtain the resultant force of the tensile stress in the rock mass between each cavern. This resultant force reflects the enhancing effect of the tensile stress in the rock mass between adjacent caverns on the overall uplift resistance of the overlying rock mass under multi-cavity layout conditions. Its physical meaning is the additional uplift resistance contribution of the rock mass between caverns to the overlying rock mass under horizontal tensile stress.

[0088] Subsequently, the second uplift resistance is composed of the second self-weight, the vertical component of the shear force, the vertical component of the normal pressure, and the resultant force of the tensile stress in the rock mass between the chambers. The resultant force of the tensile stress in the rock mass between the chambers is added as an additional uplift resistance term. The second uplift force equals the number of chambers multiplied by the maximum pressure of the gas storage chambers during operation multiplied by the horizontal projected area of ​​the gas storage chambers. The uplift force increases linearly with the number of chambers. In the case of multiple chambers, the uplift resistance increases due to the addition of the resultant tensile stress term, while the uplift force increases exponentially with the increase in the number of chambers. The competitive relationship between these two factors directly determines the value of the uplift resistance safety factor.

[0089] The uplift resistance safety factor is equal to the uplift resistance force divided by the uplift force. When this ratio is greater than 1, the overlying rock mass has the reserve capacity to resist uplift under internal pressure. When this ratio is equal to 1, the overlying rock mass is in a critical equilibrium state. When this ratio is less than 1, the overlying rock mass will undergo overall uplift failure under the action of internal pressure.

[0090] In summary, in this embodiment of the invention, in the case of a single cavern, the first uplift resistance and the first uplift force are calculated independently and directly compared. In the case of multiple caverns, the second uplift resistance increases due to the resultant tensile stress of the rock mass between the caverns, and the second uplift force increases exponentially with the number of caverns. The two working conditions correspond to different uplift resistance safety factors, enabling the calculation of the overlying rock mass uplift resistance safety factor to adapt to different layouts of gas storage caverns.

[0091] Preferably, the model range for verifying uplift stability can be determined based on the relative positional relationship between the gas storage facility and the fault. For example, for a certain project, an analysis model is established using faults 1 and 2 to the north of the gas storage facility, fault 4 to the south, and fault 3 through which the gas storage facility crosses, considering two working conditions: Condition 1: The northern boundary of the model is fault 1, the eastern boundary is fault 2, the southern fault is fault 4, and the western boundary is the fracture surface, which is the inclined plane extending from the left waist of the westernmost gas storage to the ground surface. The angle between the inclined plane and the vertical plane is the fracture angle of the surrounding rock in the buried section of the gas storage.

[0092] Condition 2: The northern boundary of the model is fault 1, the eastern boundary is the fracture surface, that is, the inclined plane extending from the right waist of the easternmost gas storage to the surface, the southern fault is fault 4, the western boundary is the fracture surface, that is, the inclined plane extending from the left waist of the westernmost gas storage to the surface, and the angle between the inclined plane and the vertical plane is the fracture angle of the surrounding rock in the buried section of the gas storage.

[0093] In this project, since there is a fault 3 that cuts through the gas storage facility along its vertical axis, it is necessary to consider the uplift stability of block 1 between fault 3 and fault 1, the uplift stability of block 2 between fault 3 and fault 4, and the overall uplift stability of the model.

[0094] For general gas storage projects, the boundaries perpendicular to the gas storage axis should be based on the fracture surface. The angle between the fracture surface and the vertical plane is the fracture angle of the surrounding rock at the gas storage depth. The boundaries parallel to the gas storage axis should primarily be based on the fault, and secondarily on the model boundary. Uplift stability calculations should be conducted under the most unfavorable working conditions.

[0095] The above-mentioned method for calculating the safety factor against lifting is based on the following principle: Figure 8 As shown, the self-weight of the rock mass can be obtained by multiplying the rock mass volume by its unit weight. P is the maximum pressure during the operation period, and the uplift force and resistance force are calculated using the corresponding functions. Based on this calculation method, the results for working conditions one and two are as follows: The calculation results for working condition 1 are shown in Table 5: Table 5. Calculation results of anti-lifting stability under operating condition 1

[0096] The calculation results for working condition 2 are shown in Table 6: Table 6. Calculation results of stability under secondary resistance lifting conditions.

[0097] like Figure 7 As shown in the figure, block 2 has a relatively large safety factor. Since the gas storage volume in block 2 only accounts for 13.5% of the total gas storage volume, the lifting force is small, and cohesion is not considered. internal friction angle The situation already fully meets the requirements for resistance to heave and stability. Calculations show that, without considering the three blocks... The safety factors for the anti-lift stability calculations are all greater than 2.0. The safety factors for the anti-lift stability calculation are all greater than 3.0, which meets the requirements of the specifications, further demonstrating that the burial depth of the gas storage facility meets the overall stability requirements of the gas storage facility.

[0098] Furthermore, based on the dynamic attenuation law, a cyclic gas pressure loading condition is applied to the multi-scale simulation model that has passed the anti-lift stability check to simulate the gas filling and discharging process of the gas storage cavern under different operating conditions during its operation, including: The multi-scale simulation model with anti-lift stability verification is used as the basic model, and the measured in-situ stress at the burial depth of the gas storage cavern in the target area is obtained. An initial geostress field is applied to the foundation model based on the measured geostress, and displacement boundary conditions including bottom fixed constraints and lateral normal constraints are applied to the foundation model to obtain the first simulation model with initial conditions. Based on the dynamic decay law, the fault mechanical parameters in the first simulation model are successively reduced and updated. At the same time, a gas pressure load with periodic changes in gas pressure between the upper and lower limits of the operating pressure is applied to the inner wall of the gas storage cavern in the first simulation model, so as to obtain a second simulation model in which the fault mechanical parameters decay with the cycle and are subjected to the cycle gas pressure. The second simulation model was used to simulate the mechanical response of the gas storage cavern in the filling, stabilizing and venting stages in chronological order, thus simulating the filling and venting process of the gas storage cavern under different operating conditions during its operation.

[0099] The following is a detailed analysis of the implementation of the above-mentioned method for evaluating the stability of the surrounding rock of a gas storage facility: First, the measured in-situ stress can be obtained through hydraulic fracturing stress measurement. An initial in-situ stress field is applied to the foundation model based on the measured stress, ensuring that the stress distribution within the foundation model matches the actual in-situ stress state. The initial in-situ stress field can include the maximum horizontal principal stress, the minimum horizontal principal stress, and the vertical principal stress, corresponding to the three principal stress components of the measured in-situ stress data. Displacement boundary conditions, including bottom fixed constraints and lateral normal constraints, are applied to the foundation model. The bottom fixed constraints restrict the vertical and horizontal displacements of the foundation model's bottom, while the lateral normal constraints restrict the displacement of the foundation model's lateral boundaries in the normal direction while allowing free tangential sliding. This allows the foundation model to produce a deformation response consistent with the field conditions under its own weight and tectonic stress.

[0100] Preferably, fixed constraints are applied to the bottom of the model, and normal constraints are applied in the X and Y directions. The load during the excavation stage is a gravity load, and the load during the operation stage is a combination of gravity and gas pressure loads. The gas storage axial direction is NW48.6°, and the direction of the maximum principal stress is NE61°. The layout of the gas storage and the principal stress directions are as follows: Figure 5 and Figure 6 As shown. According to the results of water pressure fracturing in-situ stress measurement, the maximum horizontal principal stress at the burial depth of the gas storage is 7.38 MPa, the minimum horizontal principal stress is 3.85 MPa, and the vertical principal stress is 3.02 MPa.

[0101] The displacement boundary conditions and the initial geostress field together constitute the mechanical boundary environment of the basic model, resulting in the first simulation model with initial conditions. The initial stress state and initial displacement state of each node within the first simulation model are determined by the initial geostress field and the displacement boundary conditions, respectively. The stress and displacement changes caused by the subsequently applied gas pressure load are all superimposed on this initial state.

[0102] Secondly, the dynamic attenuation law was obtained in advance through cyclic loading experiments, characterizing the relationship between the gradual decrease of fault mechanical parameters and the increase of the number of cyclic loading cycles. The fault mechanical parameters in the first simulation model were successively reduced and updated, with each reduction and update corresponding to a complete inflation and deflation cycle. The reduced and updated fault mechanical parameters were used to calculate the mechanical response of the next cycle.

[0103] In the first simulation model, a gas pressure load is applied to the inner wall of the gas storage cavern. The periodic changes in the gas pressure load are synchronized with the successive reduction and updating of the fault mechanical parameters. In each cycle of loading, the fault mechanical parameters are lower than the corresponding values ​​of the previous cycle. In the second simulation model, where the fault mechanical parameters decay with each cycle and are subjected to cyclic gas pressure, the strength parameters of the fault region continuously decrease with the number of cycles. The gas pressure load on the inner wall of the gas storage cavern changes periodically with time. These two changes coexist and interact in the same simulation model. The decrease in fault strength leads to a successive increase in the deformation of the fault under the same gas pressure load. The increase in deformation further promotes the deterioration of the internal structure of the fault, forming a coupled feedback between mechanical response and material deterioration.

[0104] Finally, the second simulation model was used to simulate the mechanical response of the gas storage cavern in the filling, stabilizing and venting stages in chronological order: during the filling stage, the gas pressure rises from the lower limit of the operating pressure to the upper limit of the operating pressure; during the stabilizing stage, the gas pressure remains near the upper limit of the operating pressure; and during the venting stage, the gas pressure drops from the upper limit of the operating pressure to the lower limit of the operating pressure.

[0105] During the filling stage, the gas pressure on the inner wall of the gas storage cavern gradually increases. The surrounding rock undergoes radial compression deformation as the pressure increases, leading to an increase in both normal and shear stress within the fault region. After this stage, the fault mechanical parameters are updated according to a dynamic attenuation law. During the stabilization stage, the gas pressure remains constant near the upper limit of the operating pressure. The surrounding rock undergoes creep deformation during this stage, and shear stress continues to act under constant normal stress within the fault region. After this stage, the fault mechanical parameters continue to be updated according to a dynamic attenuation law. During the venting stage, the gas pressure decreases from the upper limit to the lower limit of the operating pressure. The gas pressure on the inner wall of the gas storage cavern gradually decreases, and the surrounding rock undergoes unloading and rebound during the pressure reduction. The normal and shear stress within the fault region decrease, and after this stage, the fault mechanical parameters are updated again according to a dynamic attenuation law.

[0106] Therefore, the gas pressure change rates corresponding to the inflation stage, pressure stabilization stage and deflation stage are different. The fault mechanical response in each stage is calculated under the gas pressure change conditions of that stage. After each stage, the fault mechanical parameters are reduced and updated according to the dynamic decay law, thus completing the simulation of the inflation and deflation process of the gas storage cavern under different working conditions during its operation.

[0107] Preferably, the cyclic load is specifically as follows: Figure 2As shown. The maximum gas pressure is 15 MPa, and the minimum is 9 MPa. A complete cycle consists of "8 hours of inflation - 4 hours of stabilization - 4 hours of deflation - 8 hours of stabilization." In the first cycle, from 0 to 8 hours, the gas pressure increases from zero to 15 MPa (inflation stage); from 8 to 12 hours, the gas pressure slowly decreases from 15 MPa to 14 MPa (stabilization stage); from 12 to 16 hours, the gas pressure decreases from 14 MPa to 10 MPa (deflation stage); and from 16 to 24 hours, the gas pressure slowly decreases from 10 MPa to 9 MPa (stabilization stage). In the second cycle, from 0 to 8 hours, the gas pressure increases from 9 MPa to 15 MPa during the inflation stage; the time and gas pressure for the other three stages are the same as in the first cycle.

[0108] Furthermore, stress evolution data, displacement response data, and plastic zone expansion data of the fault plane during the simulated inflation and deflation process are obtained. Combined with the stability verification results, a comprehensive stability evaluation result of the surrounding rock is obtained, including: From the simulation results of the inflation and deflation process of the second simulation model, the stress evolution data, displacement response data, and plastic zone expansion data of the fault are extracted respectively. Based on stress evolution data, displacement response data, and plastic zone expansion data, a comparative analysis was conducted on fault-affected and non-fault-affected working conditions, and the influence of faults on the displacement field and plastic zone in the surrounding rock was obtained based on the analysis results. The stress intensity ratio of the fault is calculated based on stress evolution data, and the slip safety factor of the fault is determined based on displacement response data and plastic zone expansion data. Based on the sliding safety factor and the impact effect, and combined with the stability verification results, a quantitative evaluation of the surrounding rock stability is carried out, and a comprehensive evaluation result of the surrounding rock stability is obtained.

[0109] The following is a detailed analysis of the implementation of the above-mentioned method for evaluating the stability of the surrounding rock of a gas storage facility: First, after the second simulation model completes the inflation and deflation process, stress evolution data, displacement response data, and plastic zone expansion data of the fault are extracted from the simulation results of the second simulation model. The stress evolution data records the stress tensor components of the fault region at each simulation time step, including the continuous changes of normal stress and shear stress over time. The displacement response data records the relative displacement of the two sides of the fault at each simulation time step, including the cumulative increase of tangential slip and normal opening over time. The plastic zone expansion data records the expansion of the spatial distribution range of yield units in the fault zone and surrounding rock over simulation time. These three types of data describe the response characteristics of the fault under cyclic loading from three dimensions: stress state, deformation degree, and failure range. The stress evolution data reflects the impact of fault strength deterioration on bearing capacity; the displacement response data reflects the precursory characteristics of fault slip instability; and the plastic zone expansion data reflects the evolution trend of the fault failure range.

[0110] Secondly, a comparative analysis was conducted on fault-containing and fault-free working conditions based on three types of data to obtain the impact of faults on the displacement field and plastic zone of the surrounding rock. The fault-containing working condition refers to the condition in which the second simulation model includes a fault and the fault mechanical parameters decrease with each cycle. The fault-free working condition refers to the control condition in which the second simulation model does not contain a fault or the fault is replaced by surrounding rock material. By comparing the displacement response data of the fault-containing and fault-free working conditions, the additional displacement caused by the fault was obtained, i.e., the magnitude of the increase in the surrounding rock displacement field due to the presence of a fault. Similarly, by comparing the plastic zone expansion data of the fault-containing and fault-free working conditions, the additional range of the plastic zone caused by the fault was obtained, i.e., the extra range of the plastic zone extending along the fault zone due to the presence of a fault. The impact of faults on the surrounding rock displacement field and plastic zone quantifies the degree to which the fault weakens the stability of the surrounding rock under cyclic loading. The displacement field impact reflects the difficulty of deformation control, while the plastic zone impact reflects the difficulty of failure control.

[0111] Furthermore, the stress-intensity ratio of the fault is obtained, and the slip safety factor is determined. The stress-intensity ratio is determined by the ratio of the actual shear stress in the fault region at the current cycle number to the shear strength of the fault. The shear strength is calculated from the cohesion and internal friction angle after dynamic attenuation at the current cycle number. The actual shear stress at the current cycle number is extracted from the stress evolution data. When the stress-intensity ratio is greater than 1, the actual shear stress on the fault plane exceeds the shear strength, and the fault undergoes shear failure; when the stress-intensity ratio is less than 1, the actual shear stress on the fault plane is lower than the shear strength, and the fault is in a stable state. The slip safety factor is jointly determined by the displacement response data and the plastic zone expansion data. When the cumulative growth rate of tangential slip in the displacement response data exceeds a preset threshold, the slip safety factor decreases; when the extension length of the yield region along the fault zone in the plastic zone expansion data exceeds a preset threshold, the slip safety factor further decreases.

[0112] Subsequently, the quantitative evaluation uses the numerical value of the sliding safety factor and the spatial range of the impact effect as inputs, and the stability verification result as a prerequisite. When the stability verification result shows that the anti-uplift stability meets the requirements, the sliding safety factor is greater than the preset safety threshold and the impact effect is within the preset allowable range, then the comprehensive evaluation result of the surrounding rock stability is stable; if the sliding safety factor is less than or equal to the preset safety threshold or the impact effect exceeds the preset allowable range, then the comprehensive evaluation result of the surrounding rock stability is unstable, and the burial depth of the gas storage cavern needs to be adjusted or reinforcement measures need to be taken. The comprehensive evaluation result of the surrounding rock stability reflects the analytical conclusions of both the overall anti-uplift stability and the local fault sliding stability.

[0113] Preferably, the preset safety threshold can be determined according to the design level and engineering specifications of the gas storage cavern. Different design levels correspond to different preset safety thresholds, and the higher the design level, the larger the preset safety threshold.

[0114] The threshold for slip / plastic zone can be determined based on the allowable deformation of the surrounding rock of the gas storage cavern and the criterion for plastic zone penetration. The allowable deformation is determined based on the structural design requirements of the gas storage cavern, and the criterion for plastic zone penetration is determined based on whether the plastic zone penetrates to the surface or whether it penetrates the rock mass between adjacent caverns.

[0115] The dynamic decay law can be obtained in advance through cyclic loading experiments and fitted into a functional relationship that varies with the number of cycles. The form of this functional relationship is determined based on the fitting results of the experimental data.

[0116] The above comprehensive evaluation results reflect the analytical conclusions from both the overall uplift stability and the local fault sliding stability. The overall uplift stability is characterized by the uplift stability verification results, while the local fault sliding stability is jointly characterized by the sliding safety factor and the influence of the fault on the surrounding rock displacement field and plastic zone distribution.

[0117] Preferably, in the study of the stability of gas storage facilities crossing faults, the typical profile method and the strength reduction method each have their own characteristics, and the combination of the two can realize a complete analytical chain from "mechanistic understanding" to "quantitative evaluation".

[0118] The typical profile method can intuitively display the continuous distribution of key indicators such as displacement, plastic zone, and stress intensity ratio along the profile. Compared with the three-dimensional full model, the two-dimensional profile model has a significantly reduced number of elements, faster calculation speed, and is convenient for multi-condition comparative analysis. The profile cloud map can clearly present the spatial pattern of the "fault-cavity" interaction, making it easy to identify key information such as abrupt displacement zones and plastic zone continuity paths, which is of great value for mechanism explanation and engineering judgment. However, this method has limitations such as two-dimensional simplification distortion, sensitivity to boundary effects, and inability to assess overall stability.

[0119] The strength reduction method reduces rock mass strength parameters (cohesion c and internal friction angle) by gradually reducing them. The strength reduction method continues until the model reaches a critical failure state; the reduction factor at this point is the safety factor. The strength reduction method can output a quantified safety factor, which typical profile methods cannot directly provide. By searching for the reduction factor F, the influence of strength parameter changes on system stability can be studied, and controlling parameters can be identified. The strength reduction method can simultaneously consider shear failure and tensile failure, which often coexist in fault-affected zones. However, this method also has limitations, including the subjectivity of critical criteria, the need for caution in the parameter reduction range, and high computational cost.

[0120] The two methods complement each other in the stability analysis of gas storage facilities across faults: the typical profile method reveals the expansion path of the plastic zone of the fault, the location of displacement concentration, and the distribution law of stress intensity ratio, while the strength reduction method quantifies the overall safety margin after fault weakening, providing a basis for engineering decisions. When applying the strength reduction method, the strength difference between the fault zone and the surrounding rock needs to be considered: different reduction coefficients are used for the fault zone and the surrounding rock, but the reduction ratio relationship needs to be clearly defined.

[0121] The typical profile method serves as a fundamental analytical tool, used to: identify the extent and degree of fault influence on displacement and plastic zones; compare the effects of different fault dip angles and crossing angles; and optimize support schemes (such as the location and depth of grouting reinforcement). The strength reduction method serves as an evaluation and decision-making tool, used to: quantify the safety margin of fault-crossing schemes; determine the reasonable range of operational internal pressure; and establish a long-term stability evaluation index system. When the conclusions of the two methods contradict each other: the safety factor of the strength reduction method should be prioritized as the decision-making basis; simultaneously, the typical profile analysis should be revisited to check for any omissions of key failure modes; and three-dimensional full model verification should be considered to eliminate the bias of two-dimensional simplification.

[0122] Excavation and unloading remove the lateral constraints of the rock mass, causing the surrounding rock to rebound into the tunnel space. The deformation modulus of the fault zone's soil and rock mass is much lower than that of intact surrounding rock, resulting in greater elastic and plastic strain under the same unloading stress. The stress redistribution caused by excavation generates relative shear stress in the hanging wall and footwall of the fault. As a naturally weak surface, the fault is prone to small shear slips, which directly contribute to the total deformation. Gas injection and pressurization apply radial pressure to the tunnel wall. The high porosity and compressibility of the fault zone cause compression deformation far exceeding that of dense rock under pressure, leading to a significant increase in the radial convergence displacement of the fault surface. Simultaneously, changes in internal gas pressure adjust the normal and shear stresses of the fault plane. In some cases, gas pressure may reduce the effective normal stress of the fault plane. According to the Coulomb friction criterion, this weakens its anti-slip force, inducing small shear slips and contributing additional irreversible deformation.

[0123] Table 7 shows the maximum displacement of the surrounding rock before and after the fault, during the excavation and gas injection pressurization stages. Without considering the fault, the maximum displacement of the profile during the excavation stage is 0.311 cm to 0.440 cm, and during the gas injection pressurization stage, it is 0.820 cm to 1.201 cm. Considering the fault, the maximum displacement of the profile during the excavation stage is 0.311 cm to 0.469 cm, and during the gas injection pressurization stage, it is 0.828 cm to 1.281 cm. Due to the fault, the maximum displacement of the surrounding rock increases by 0% to 36.38% during the excavation stage and by 0.09% to 14.62% during the gas injection pressurization stage.

[0124] Table 7 Maximum displacement (cm) before and after the fault excavation and gas injection pressurization stages

[0125] Table 8 shows the volume of the plastic zone during the excavation and gas injection pressurization stages, considering the fault. Without considering the fault, the volume of the plastic zone in the excavation stage profile is 39.92. ~348.35 The volume of the plastic zone in the cross-section during the gas injection and pressurization stage is 201.26. ~1363.16 When considering faults, the volume of the plastic zone in the cross-section during the excavation stage is 39.92. ~345.45 The volume of the plastic zone in the cross-section during the gas injection and pressurization stage is 201.26. ~1356.73 Due to the influence of the fault, the volume of the plastic zone increased by 0% to 36.23% during the excavation stage and by -5.86% to 12.48% during the gas injection and pressurization stage.

[0126] Table 8. Volume of the plastic zone (m3) considering the excavation and gas injection pressurization stages before and after the fault.

[0127] Faults are the dominant factor in deformation and failure, causing a significant discontinuity in displacement distribution. The maximum displacement is concentrated in the area where the fault intersects with the cavern, but the displacement value does not exceed the design allowable threshold. The plastic zone extends locally along the fault zone, but no plastic channels connecting the surface or adjacent caverns appear. Simulation results under excavation unloading and gas injection pressurization conditions show that the presence of faults has a significant local weakening effect on the displacement field and plastic zone distribution of the gas storage surrounding rock. When considering the fault, the maximum displacement of the surrounding rock during the excavation stage is 0.469 cm, an increase of 6.74% compared to not considering the fault; the maximum displacement during the gas injection pressurization stage is 1.281 cm, an increase of 11.88% compared to not considering the fault; the maximum volume of the plastic zone during the excavation stage is 345.45. Compared to excluding faults (0.83%), the depth of the plastic zone in section 4 of gas storage cell #1 increased by 6.253%, and the depth of the plastic zone in section 2 of gas storage cell #4 increased by 4.484%; the maximum volume of the plastic zone during the gas injection and pressurization stage was 1356.73. Compared to not considering the fault increase of -0.47%, the plastic zone depth of section 2 of gas storage No. 1 increased by 22.159%, the plastic zone depth of section 3 of gas storage No. 2 increased by 45.559%, and the plastic zone depth of section 2 of gas storage No. 4 increased by 5.026%.

[0128] Comprehensive analysis shows that the fault has a relatively small impact on the overall stability of the gas storage facility. With reasonable support and surrounding rock reinforcement measures, the engineering scheme for the gas storage facility to cross the fault is feasible.

[0129] This invention also discloses a stability evaluation system, which employs the above-mentioned method for evaluating the stability of surrounding rock in gas storage facilities. The stability evaluation system includes: The parameter acquisition module is used to acquire the fault geometric parameters, fault mechanical parameters, surrounding rock mechanical parameters, dynamic attenuation law of fault mechanical parameters under cyclic loading, and relative positional relationship between the fault and the proposed gas storage cavern in the target area. The simulation model building module is used to establish a multi-scale simulation model of the coupling effect between the fault and the gas storage cavern based on the fault geometric parameters, relative positional relationship, fault mechanical parameters and surrounding rock mechanical parameters; The failure model construction module is used to determine the spatial range of the overlying rock mass above the gas storage cavern based on the multi-scale simulation model, and to establish a failure model of the overlying rock mass in combination with the surrounding rock mechanics parameters; The safety factor acquisition module is used to determine the fracture surface morphology of the overlying rock mass based on the failure model, and to obtain the overlying rock mass's uplift resistance safety factor by combining the spatial range of the overlying rock mass and the surrounding rock mechanical parameters. The anti-lift stability verification module is used to obtain the stability verification results of the gas storage cavern's resistance to uplift by comparing the anti-lift safety factor with the preset safety threshold. The cyclic loading simulation module is used to apply cyclic gas pressure loading conditions to a multi-scale simulation model that has passed the anti-lift stability check, based on the dynamic decay law, to simulate the gas filling and releasing process of the gas storage cavern under different operating conditions during its operation. The stability comprehensive evaluation module is used to acquire stress evolution data, displacement response data, and plastic zone expansion data of the fault plane during the simulated inflation and deflation process. Combined with the stability verification results, it analyzes and obtains the comprehensive stability evaluation results of the surrounding rock.

[0130] The present invention also discloses a storage medium on which a computer program is stored, which, when executed by a processor, implements the above-mentioned method for evaluating the stability of the surrounding rock of a gas storage facility.

[0131] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0132] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, as well as combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0133] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0134] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0135] It should be understood that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Those skilled in the art can modify the technical solutions described in the above embodiments, or make equivalent substitutions for some of the technical features; and all such modifications and substitutions should fall within the protection scope of the appended claims of the present invention.

Claims

1. A method for evaluating the stability of surrounding rock in a gas storage facility traversing a fault fracture zone, characterized in that, The method for evaluating the stability of the surrounding rock of the gas storage facility includes: Obtain the fault geometric parameters, fault mechanical parameters, surrounding rock mechanical parameters, dynamic attenuation law of the fault mechanical parameters under cyclic loading, and the relative positional relationship between the fault and the proposed gas storage cavern in the target area. Based on the fault geometric parameters, the relative positional relationship, the fault mechanical parameters, and the surrounding rock mechanical parameters, a multi-scale simulation model of the coupling effect between the fault and the gas storage cavern is established. The spatial range of the overlying rock mass above the gas storage cavern is determined based on the multi-scale simulation model, and a failure model of the overlying rock mass is established in combination with the surrounding rock mechanical parameters; The fracture surface morphology of the overlying rock mass is determined based on the failure model, and the uplift resistance safety factor of the overlying rock mass is obtained by combining the spatial range of the overlying rock mass and the surrounding rock mechanical parameters. The stability verification result of the gas storage cavern's resistance to uplift is obtained by comparing the anti-uplift safety factor with the preset safety threshold. Based on the dynamic attenuation law, the multi-scale simulation model that has passed the anti-lift stability check is subjected to cyclic gas pressure loading conditions to simulate the gas storage cavern's filling and releasing process under different operating conditions during its operation. By acquiring stress evolution data, displacement response data, and plastic zone expansion data of the fault plane during the simulated inflation and deflation process, and combining these with the stability verification results, a comprehensive stability evaluation result of the surrounding rock is obtained.

2. The method for evaluating the stability of surrounding rock in a gas storage facility according to claim 1, characterized in that, The establishment of a multi-scale simulation model of the coupling effect between the fault and the gas storage cavern, based on the fault geometric parameters, the relative positional relationship, the fault mechanical parameters, and the surrounding rock mechanical parameters, includes: Based on the fault geometry parameters and the relative positional relationship, determine the regional scale range that includes all the faults and the surrounding rock, as well as the local scale range that includes the gas storage cavern, the surrounding rock, and the faults. Based on the determined regional scale range and local scale range, a regional scale geometric model and a local scale geometric model are constructed respectively, and the regional scale geometric model and the local scale geometric model are respectively meshed to obtain a discretized multi-scale geometric model; The shear failure behavior of the surrounding rock and the fault in the multi-scale geometric model is described by the Mohr-Coulomb constitutive model, and the mechanical parameters of the fault and the mechanical parameters of the surrounding rock are respectively assigned to the corresponding regions in the multi-scale geometric model to obtain the multi-scale simulation model.

3. The method for evaluating the stability of surrounding rock in a gas storage facility according to claim 2, characterized in that, The process of determining the spatial extent of the overlying rock mass above the gas storage cavern based on the multi-scale simulation model, and establishing a failure model of the overlying rock mass in conjunction with the surrounding rock mechanical parameters, includes: Based on the spatial location of the gas storage cavern in the multi-scale simulation model, combined with the fault geometric parameters and the relative positional relationship, the spatial range of the overlying rock mass above the gas storage cavern is determined; Based on the spatial location of the gas storage cavern and the surrounding rock mechanical parameters, the spatial location of the fracture surface of the overlying rock mass within the spatial range of the overlying rock mass is determined; Based on the spatial location of the fracture surface and the spatial location of the fault in the fault geometry parameters, it is determined whether the fracture surface is cut by the fault; Based on the judgment results, a cone or frustum-shaped failure model of the overlying rock mass is established, centered on the gas storage cavern and combined with the spatial location of the fracture surface.

4. The method for evaluating the stability of surrounding rock in a gas storage facility according to claim 3, characterized in that, Based on the judgment result, taking the gas storage cavern as the center and combining the spatial position of the fracture surface, a cone or frustum-shaped failure model of the overlying rock mass is established, including: When it is determined that the fault has not cut the fracture surface, the first angle between the fracture surface of the overlying rock mass and the vertical direction is determined by the limit equilibrium theory using the surrounding rock mechanical parameters. Based on the first included angle, and combined with the spatial range of the overlying rock mass and the spatial location of the fracture surface, a cone or frustum-shaped failure model of the overlying rock mass is established with the gas storage cavern as the center. When it is determined that the fault cuts the fracture surface, the overlying rock mass is divided into multiple independent blocks along the fault according to the spatial location of the fault. The spatial range of each independent block is determined, and the fracture surface of each independent block is determined by the second angle between the vertical direction and the vertical direction using the surrounding rock mechanics parameters and the limit equilibrium theory. Based on the second included angle, and combined with the spatial range of each independent block and the spatial position of the fracture surface, a cone or frustum-shaped failure model of each independent block is established with the gas storage cavern as the center.

5. The method for evaluating the stability of surrounding rock of a gas storage facility according to claim 1, characterized in that, The step of determining the fracture surface morphology of the overlying rock mass based on the failure model, and obtaining the uplift resistance safety factor of the overlying rock mass by combining the spatial range of the overlying rock mass and the surrounding rock mechanical parameters, includes: Based on the geometric analysis of the failure model, the depth of the overlying rock mass, the thickness of each layer of the overlying rock mass along the thickness direction, and the angle between the fracture surface in the overlying rock mass and the vertical direction are determined. Based on the angle between the fracture surface and the vertical direction, the depth of the overlying rock mass, and the surrounding rock mechanical parameters such as unit weight and lateral pressure coefficient, the normal stress on the fracture surface is calculated. The functional expression for calculating the normal stress is as follows: In the formula, This represents the normal stress on the fracture surface. Indicates the unit weight of the surrounding rock. Indicates the angle between the fracture surface and the vertical direction. Indicates the lateral pressure coefficient. Indicates the depth of the overlying rock mass; Based on the normal stress and the cohesion and average internal friction angle in the surrounding rock mechanical parameters, the shear stress on the fracture surface is calculated, and the functional expression for calculating the shear stress is: In the formula, This represents the shear stress on the fracture surface. This represents the average internal friction angle of the overlying rock mass. Indicates the overlying rock mass Cohesion; Based on the thickness of each layer along the thickness direction of the overlying rock mass, the angle between the fracture surface and the vertical direction in the overlying rock mass, the normal stress, and the shear stress, the normal pressure and shear force on the fracture surface are calculated respectively. The functional expressions for calculating the normal pressure and the shear force are as follows: In the formula, This represents the normal pressure on the fracture surface. This represents the thickness of the i-th layer of the overlying rock mass along the thickness direction. Indicates a hierarchical index. This represents the shear resistance on the fracture surface. This indicates the unit width along the axial direction of the gas storage chamber. The number of gas storage caverns is determined based on the design and operation parameters of the gas storage caverns. Combined with the positive pressure and the shear force, the uplift force and uplift force of the overlying rock mass under the corresponding number of caverns are obtained. Based on the uplift resistance and the uplift force, the uplift resistance safety factor of the overlying rock mass is calculated. The functional expression for calculating the uplift resistance safety factor is as follows: In the formula, This indicates the safety factor against uplift of the overlying rock mass. This indicates the uplift resistance experienced by the overlying rock mass. This indicates the uplift force exerted on the overlying rock mass.

6. The method for evaluating the stability of surrounding rock of a gas storage facility according to claim 5, characterized in that, The process of determining the number of gas storage caverns based on the design and operation parameters of the gas storage caverns, and obtaining the uplift resistance and uplift force of the overlying rock mass under the corresponding number of caverns, in conjunction with the normal pressure and the shear force, includes: Based on the geometric analysis of the failure model, the volume of the overlying rock mass and the horizontal projected area of ​​the gas storage cavern are determined. Based on the design and operating parameters of the gas storage cavern, the maximum internal pressure of the gas storage cavern during the operation period and the cavern edge distance when there are multiple caverns are determined. When the number of caverns in the gas storage facility is determined to be a single cavern, the first self-weight of the overlying rock mass above the single cavern is calculated based on the volume of the overlying rock mass and the unit weight of the surrounding rock. The functional expression for calculating the first self-weight is as follows: In the formula, This represents the first self-weight of the overlying rock mass in a single-chamber configuration. Indicates the volume of the overlying rock mass; Based on the first self-weight, the angle between the fracture surface and the vertical direction in the overlying rock mass, the normal pressure, and the shear force, the first uplift force on the overlying rock mass above the single cavern is calculated. The functional expression for calculating the first uplift force is: In the formula, This indicates the first uplift force acting on the overlying rock mass; Based on the maximum internal pressure and the horizontal projected area of ​​the gas storage cavern, the first uplift force on the overlying rock mass located above the single cavern is calculated. The functional expression for calculating the first uplift force is: In the formula, This indicates the first uplift force experienced by the overlying rock mass. This indicates the maximum internal pressure of the gas storage cavern during its operational period. This represents the horizontal projected area of ​​the gas storage cavern; When the number of caverns in the gas storage facility is determined to be multiple caverns, the second self-weight of the overlying rock mass above the multiple caverns is calculated based on the number of caverns, the distance between the edges of the caverns, the thickness of each layer of the overlying rock mass along the thickness direction, and the unit weight of the surrounding rock at the corresponding depth of each layer. The functional expression for calculating the second self-weight is as follows: In the formula, This indicates the second self-weight of the overlying rock mass located above the multi-cavity structure. Indicates the number of caverns. Indicates the radius of the cavern. Indicates the distance between the edges of the cavern. Indicates the first inch of the overlying rock mass along the thickness direction. The thickness of the layers, Indicates a hierarchical index. Indicates the first inch of the overlying rock mass along the thickness direction. The unit weight of the surrounding rock at the corresponding depth of each layer. This indicates the total number of layers in the overlying rock mass along the thickness direction; The multi-scale simulation model was used to simulate the excavation of multiple tunnels. The tensile stress in the rock mass between each tunnel was extracted during the simulation. Combined with the distance between the tunnel edges, the resultant force of the tensile stress in the rock mass between each tunnel was calculated. The functional expression for the resultant force is as follows: In the formula, This represents the resultant force of tensile stress in the rock mass between the various chambers. Indicates the first Tensile stress in the rock mass between adjacent caverns; Based on the second self-weight, the angle between the fracture surface and the vertical direction in the overlying rock mass, the resultant force, the normal pressure, and the shear force, the second uplift force on the overlying rock mass located above the multi-cavity is calculated. The functional expression for calculating the second uplift force is: In the formula, This indicates the second uplift resistance experienced by the overlying rock mass; Based on the number of caverns, the maximum internal pressure, and the horizontal projected area of ​​the gas storage caverns, the second uplift force on the overlying rock mass located above the multiple caverns is calculated. The functional expression for calculating the second uplift force is: In the formula, This indicates the second uplift force experienced by the overlying rock mass.

7. The method for evaluating the stability of surrounding rock of a gas storage facility according to claim 1, characterized in that, The step of applying cyclic gas pressure loading conditions to the multi-scale simulation model, which has passed the anti-lift stability check, based on the dynamic attenuation law, to simulate the gas filling and discharging process of the gas storage cavern under different operating conditions during its operation includes: The multi-scale simulation model verified by the anti-lift stability is determined as the basic model, and the measured in-situ stress at the burial depth of the gas storage cavern in the target area is obtained. An initial geostress field is applied to the foundation model based on the measured geostress, and displacement boundary conditions including bottom fixed constraints and lateral normal constraints are applied to the foundation model to obtain a first simulation model loaded with initial conditions. Based on the dynamic attenuation law, the fault mechanical parameters in the first simulation model are successively reduced and updated. At the same time, a gas pressure load with periodic changes in gas pressure between the upper and lower limits of the operating pressure is applied to the inner wall of the gas storage cavern in the first simulation model, so as to obtain a second simulation model in which the fault mechanical parameters attenuate with the cycle and are subjected to the cycle gas pressure. The second simulation model is used to simulate the mechanical response of the gas storage cavern in the filling, stabilizing and venting stages in chronological order, thus simulating the filling and venting process of the gas storage cavern under different operating conditions during its operation.

8. The method for evaluating the stability of surrounding rock of a gas storage facility according to claim 7, characterized in that, The process of acquiring stress evolution data, displacement response data, and plastic zone expansion data of the fault plane during the simulated inflation and deflation process, combined with the stability verification results, analyzes and obtains a comprehensive stability evaluation result of the surrounding rock, including: From the simulation results of the inflation and deflation process of the second simulation model, the stress evolution data, displacement response data, and plastic zone expansion data of the fault are extracted respectively. Based on the stress evolution data, displacement response data, and plastic zone expansion data, a comparative analysis of fault-affected and fault-free working conditions is conducted, and the influence of the fault on the displacement field and plastic zone in the surrounding rock is obtained based on the analysis results. The stress intensity ratio of the fault is calculated based on the stress evolution data, and the sliding safety factor of the fault is determined based on the displacement response data and the plastic zone expansion data. Based on the sliding safety factor and the influence effect, and combined with the stability verification results, a quantitative evaluation of the surrounding rock stability is performed to obtain a comprehensive stability evaluation result of the surrounding rock.

9. A stability evaluation system, characterized in that, The stability evaluation system for gas storage surrounding rock, as described in any one of claims 1-8, comprises: The parameter acquisition module is used to acquire the fault geometric parameters, fault mechanical parameters, surrounding rock mechanical parameters, dynamic attenuation law of the fault mechanical parameters under cyclic loading, and relative positional relationship between the fault and the proposed gas storage cavern in the target area. The simulation model construction module is used to establish a multi-scale simulation model of the coupling effect between the fault and the gas storage cavern based on the fault geometric parameters, the relative positional relationship, the fault mechanical parameters and the surrounding rock mechanical parameters; The failure model construction module is used to determine the spatial range of the overlying rock mass above the gas storage cavern based on the multi-scale simulation model, and to establish a failure model of the overlying rock mass in combination with the surrounding rock mechanical parameters; The safety factor acquisition module is used to determine the fracture surface morphology of the overlying rock mass based on the failure model, and to obtain the uplift resistance safety factor of the overlying rock mass by combining the spatial range of the overlying rock mass and the surrounding rock mechanical parameters. The anti-lift stability verification module is used to obtain the stability verification result of the gas storage cavern against the lift by comparing the anti-lift safety factor with the preset safety threshold. The cyclic loading simulation module is used to apply cyclic gas pressure loading conditions to the multi-scale simulation model that has passed the anti-lift stability check, according to the dynamic attenuation law, to simulate the gas filling and releasing process of the gas storage cavern under different working conditions during its operation. The stability comprehensive evaluation module is used to acquire stress evolution data, displacement response data, and plastic zone expansion data of the fault plane during the simulated inflation and deflation process. Combined with the stability verification results, the module analyzes and obtains the comprehensive stability evaluation results of the surrounding rock.

10. A storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the gas storage surrounding rock stability evaluation method according to any one of claims 1-8.

Images