Underground reservoir coal pillar protective layer fracture water inrush large deformation prediction method and system

Abstract

The invention relates to an underground reservoir coal pillar protective layer fracture water inrush large deformation prediction method and system. The method comprises the steps that a particle model containing a coal pillar protective layer, reservoir water flow and a support boundary is generated based on preset particle precision; based on a particle model, a response process of a coal pillar protection layer under a water storage-excavation coupling working condition is simulated through a meshless particle method, and the method comprises the following steps: dynamically updating particle distribution of an excavation area by adopting a particle inactivation algorithm, and simulating a thickness change of the coal pillar protection layer; based on a fluid-structure interaction contact algorithm, calculating the interaction force between the reservoir water flow and the coal pillar protection layer; the number of damaged particles is counted in real time according to the stress state of the coal pillar protective layer particles, and the crack expansion, penetration and fracture processes are identified; and generating a critical protective layer thickness, water inrush outburst time and a fracture influence range based on the damage evolution data, and outputting visual data. Through model construction, dynamic simulation, damage identification and parameter prediction, the technical bottleneck of a traditional grid method in large deformation simulation can be broken through.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of safety engineering, in particular to a large deformation prediction method for water inrush of coal pillar protection layer of underground reservoir and a system thereof. BACKGROUND

[0002] The coal pillar protection layer is usually used to prevent water flow penetration in the abandoned coal mine underground reservoir. In the prior art, the finite element method has high accuracy in static analysis, but the calculation is distorted due to grid distortion in large deformation and fluid-structure coupling dynamic problems. Although the meshless methods such as discrete element method (DEM) and smoothed particle hydrodynamics (SPH) have certain advantages, there are still problems such as insufficient accuracy of three-dimensional modeling, incomplete boundary processing and the like. The hybrid method (such as CFD-DEM) faces the difficulties in parameter calibration and the bottleneck of calculation efficiency.

[0003] The existing researches mostly use a segmented method to independently analyze the damage of the protection layer and the water inrush process, ignoring the coupling effect of the two, and failing to consider the coupling effects of multiple factors such as reservoir impoundment and excavation disturbance. SUMMARY

[0004] The technical problem to be solved by the present disclosure is to provide a large deformation prediction method for water inrush of coal pillar protection layer of underground reservoir and a system thereof, which can break through the technical bottleneck of traditional grid method in large deformation simulation.

[0005] To achieve the above-mentioned purpose, the present disclosure provides a large deformation prediction method for water inrush of coal pillar protection layer of underground reservoir, comprising:

[0006] Generating a particle model containing the coal pillar protection layer, the reservoir water flow and the support boundary based on a preset particle accuracy;

[0007] Based on the particle model, simulating the response process of the coal pillar protection layer under the water storage-excavation coupling condition by using the meshless particle method, including: using the particle inactivation algorithm to dynamically update the particle distribution of the excavation area, simulating the thickness change of the coal pillar protection layer; calculating the interaction force between the reservoir water flow and the coal pillar protection layer based on the fluid-structure coupling contact algorithm;

[0008] According to the stress state of the coal pillar protection layer particles, the number of damaged particles is counted in real time to identify the crack propagation, penetration and rupture process;

[0009] Based on the damage evolution data, the critical protection layer thickness, water inrush time and rupture influence range are generated, and the visual data is output.

[0010] As an improvement of the above-mentioned scheme, the preset particle accuracy is millimeter level, and a plurality of comparison values of the coal pillar protection layer thickness are preset for iterative calculation.

[0011] As an improvement of the above scheme, in the fluid-structure coupling contact algorithm, the stress of the coal pillar protection layer particles is calculated by using a rate-dependent constitutive model, and the expression of the constitutive model is:

[0012]

[0013] wherein, is the total stress, p solid is the spherical stress tensor, is the shear stress tensor, τ y is the particle flow initial stress, is the shear strain rate; μ eff is the equivalent viscosity, and m and n are constitutive model parameters.

[0014] As an improvement of the above scheme, the number of damaged particles is counted in real time according to the stress state of the coal pillar protection layer particles, and specifically includes:

[0015] If the maximum tensile stress of the particle exceeds the tensile strength, the particle is marked as a tensile damaged particle;

[0016] If the particle satisfies the Drucker-Prager yield criterion, the particle is marked as a shear damaged particle;

[0017] The total number of damaged particles is counted in real time, and damage field evolution data is generated.

[0018] As an improvement of the above scheme, the critical protection layer thickness is determined by iterative simulation: the coal pillar protection layer thickness is repeatedly reduced until the crack penetrates, and the minimum thickness of the crack that does not penetrate is taken as the critical value.

[0019] As an improvement of the above scheme, the visualization data includes binary VTK format files of displacement field, stress field and damage field, which are used to display the dynamic evolution process in a visualization tool.

[0020] The underground reservoir coal pillar protection layer rupture and water inrush large deformation prediction system provided by the embodiments of the present disclosure comprises:

[0021] The modeling module is used to generate a particle model comprising a coal pillar protection layer, reservoir water flow and a support boundary based on a preset particle precision;

[0022] The coupling module is used to simulate the response process of the coal pillar protection layer under the water storage-excavation coupling condition by using a meshless particle method, including: using a particle inactivation algorithm to dynamically update the particle distribution in the excavation area, simulating the change of the coal pillar protection layer thickness; and calculating the interaction force between the water flow and the coal pillar protection layer based on a fluid-structure coupling contact algorithm;

[0023] The evolution module is used to count the number of damaged particles in real time according to the stress state of the coal pillar protection layer particles, and identify the crack propagation, penetration and rupture process;

[0024] Output module: Used to generate critical protective layer thickness, water inrush failure time and rupture impact range based on damage evolution data, and output visualized data.

[0025] This disclosure also provides a terminal device, including a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor. When the processor executes the computer program, it implements the method for predicting large deformation caused by rupture and water inrush in underground reservoir coal pillar protective layer as described above.

[0026] This disclosure also provides a computer-readable storage medium, which includes a stored computer program, wherein the computer program, when running, controls the device where the computer-readable storage medium is located to execute the method for predicting large deformation due to rupture and water inrush in underground reservoir coal pillar protective layer as described above.

[0027] This disclosure also provides a computer program product, which includes a computer program or computer instructions. When the computer program or computer instructions are executed by a processor, they implement the method for predicting large deformation caused by rupture and water inrush in underground reservoir coal pillar protective layer as described above.

[0028] Compared with the prior art, the beneficial effects of the method and system for predicting large deformation due to rupture and water inrush in underground reservoir coal pillar protective layer provided in this disclosure are as follows:

[0029] (1) Breaking through the technical bottleneck of traditional mesh methods in simulating large deformation and water inrush in coal pillar protective layers. By introducing the SPH meshless method, the problem of large deformation simulation interruption caused by mesh distortion in the finite element method (FEM) is solved. An interaction model between reservoir water and coal pillar protective layer considering the "water storage-sudden increase in water pressure" condition is established, which can accurately simulate the progressive damage, dynamic crack propagation and rupture process of coal pillar protective layer under the combined action of water storage and water inrush pressure. This solves the technical defects of traditional methods in handling fluid-structure interaction and large deformation simulation analysis, and provides a high-precision numerical analysis tool for the safety assessment of coal pillar protective layers in underground reservoirs of abandoned mines.

[0030] (2) Realize dynamic modeling and calculation of complex working conditions such as coal pillar protection layer excavation and reservoir impoundment. Develop a 3D modeling technology based on a meshless particle adaptive distribution algorithm, and obtain rock mechanics parameters through indoor tests, eliminating the need for empirical parameter calibration. Through a dynamic particle inactivation algorithm, the interaction process between underground reservoir impoundment and coal pillar protection layer excavation can be accurately characterized, realizing dynamic simulation of the entire process from initial impoundment to water inrush disaster;

[0031] (3) Construct a dynamic prediction algorithm for the entire process of crack propagation and disaster in coal pillar protective layer. A numerical simulation method for coal pillar protective layer rupture driven by water inrush pressure is proposed to overcome the simulation problem of the entire process of crack initiation, penetration, and water inrush channel formation in coal pillar protective layer under fluid-structure interaction. Through the calculation of inter-particle interaction forces without mesh, the displacement field, stress field, and damage field evolution data of coal pillar protective layer are output, and the critical protective layer thickness, water inrush failure time, and rupture impact range of critical coal pillar failure are predicted, providing key indicators for the risk quantification of underground reservoir coal pillar protective layer engineering.

[0032] (4) Supporting risk management and decision-making throughout the entire lifecycle of underground reservoirs. This method can provide core technical means for early warning of water inrush disasters in the coal pillar protective layer of abandoned mine underground reservoirs. By predicting the damage and failure process of the coal pillar protective layer under different water storage and excavation schemes, it can guide the design of the coal pillar protective layer thickness, provide decision-making basis for formulating underground reservoir water storage construction schemes and emergency plans, and reduce the safety risks in the process of utilizing water resources in abandoned mines. Attached Figure Description

[0033] Figure 1 This is a flowchart illustrating a preferred embodiment of a method for predicting large deformation due to rupture and water inrush in the protective layer of an underground reservoir coal pillar, as provided in this disclosure.

[0034] Figure 2 This is a schematic diagram of a coal pillar protective layer inrush water model under the excavation-hydraulic pressure coupling action provided in this disclosure.

[0035] Figure 3 This disclosure provides comparative results of water column collapse tests at different times.

[0036] Figure 4 Comparison of crack propagation morphology in concrete specimens under uniaxial compression provided in this disclosure;

[0037] Figure 5 This disclosure describes the crack propagation process of a coal pillar protective layer with a thickness of 4.5m when no water inrush occurs.

[0038] Figure 6 This disclosure describes the crack propagation process of a coal pillar protective layer with a protective layer thickness of 2.5m under conditions of sudden water inrush.

[0039] Figure 7 The damage evolution process of the protective layer of the coal pillar with a protective layer thickness of 2.5m is disclosed in this paper;

[0040] Figure 8 This disclosure describes the crack propagation process of a coal pillar protective layer with a thickness of 2.6m under conditions where no sudden water inrush occurs.

[0041] Figure 9This is a schematic diagram of a preferred embodiment of a system for predicting large deformation due to rupture and water inrush in underground reservoir coal pillar protective layer provided in this disclosure;

[0042] Figure 10 This is a schematic diagram of a preferred embodiment of a terminal device provided in this disclosure. Detailed Implementation

[0043] The technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments of this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0044] Please see Figures 1 to 10 , Figure 1 This is a flowchart illustrating a preferred embodiment of a method for predicting large deformation due to rupture and water inrush in the protective layer of an underground reservoir coal pillar, as provided in this disclosure. Figure 2 This is a schematic diagram of a coal pillar protective layer inrush water model under the excavation-hydraulic pressure coupling action provided in this disclosure. Figure 3 This disclosure provides comparative results of water column collapse tests at different times. Figure 4 Comparison of crack propagation morphology in concrete specimens under uniaxial compression provided in this disclosure; Figure 5 This disclosure describes the crack propagation process of a coal pillar protective layer with a thickness of 4.5m when no water inrush occurs. Figure 6 This disclosure describes the crack propagation process of a coal pillar protective layer with a protective layer thickness of 2.5m under conditions of sudden water inrush. Figure 7 The damage evolution process of the protective layer of the coal pillar with a protective layer thickness of 2.5m is disclosed in this paper; Figure 8 This disclosure describes the crack propagation process of a coal pillar protective layer with a thickness of 2.6m under conditions where no sudden water inrush occurs. Figure 9 This is a schematic diagram of a preferred embodiment of a system for predicting large deformation due to rupture and water inrush in underground reservoir coal pillar protective layer provided in this disclosure; Figure 10 This is a schematic diagram of a preferred embodiment of a terminal device provided in this disclosure.

[0045] Please see Figure 1 , Figure 1 This is a flowchart illustrating a preferred embodiment of a method for predicting large deformation due to rupture and water inrush in an underground reservoir's coal pillar protective layer, as provided in this disclosure. The method includes:

[0046] Step S1: Generate a particle model containing the coal pillar protection layer, reservoir water flow and support boundary based on the preset particle precision.

[0047] Step S2, based on the particle model, simulates the response process of the coal pillar protection layer under the coupled water storage-excavation condition using the meshless particle method, including:

[0048] Step S21: The particle distribution in the excavation area is dynamically updated using a particle inactivation algorithm to simulate the change in the thickness of the coal pillar protective layer;

[0049] Step S22: Calculate the interaction force between the reservoir water flow and the coal pillar protective layer based on the fluid-structure interaction contact algorithm;

[0050] Step S3: Based on the stress state of the coal pillar protective layer particles, the number of damaged particles is counted in real time to identify the crack propagation, penetration and rupture process.

[0051] Step S4: Based on the damage evolution data, generate the critical protective layer thickness, water inrush failure time, and rupture impact range, and output visualized data.

[0052] In step S1, a particle model including the coal pillar protection layer, reservoir water flow, and support boundaries is generated based on a preset particle precision. Specifically, this includes: ① Underground reservoir structure modeling: an initial 3D model is constructed using millimeter-level particle precision, covering the coal pillar protection layer and support boundaries, achieving high-fidelity modeling; ② Coal pillar protection layer thickness design: the thickness of the coal pillar protection layer can be determined according to the actual design scheme, serving as a key water-blocking structure for the underground reservoir; ③ Reservoir model: an underground reservoir and initial water flow model are established. The reservoir water level can be determined according to the actual reservoir operation scheme, simulating the impact process of the underground reservoir water flow after the failure of the coal pillar protection layer during water storage. Especially in the initially water-filled reservoir area, after the failure of the water-blocking structure of the protection layer, the water flow will impact the roadway structure downwards.

[0053] Please see Figure 2 , Figure 2This is a model of sudden water inrush into the coal pillar protective layer under the combined effects of excavation and reservoir impoundment. In step S2, based on the particle model, the response process of the coal pillar protective layer under the coupled conditions of water impoundment and excavation is simulated using the meshless particle method. This includes: dynamically updating the particle distribution in the excavation area using a particle inactivation algorithm to simulate the change in the thickness of the coal pillar protective layer; and calculating the interaction force between the reservoir water flow and the coal pillar protective layer based on the fluid-structure interaction contact algorithm. Specifically, this includes: ① Dynamic excavation modeling: To calculate the critical thickness of the coal pillar protective layer, different thicknesses of the coal pillar protective layer are considered in the numerical simulation. A multi-stage coal pillar protective layer model is established according to the pre-designed excavation sequence, with each stage corresponding to a different coal pillar protective layer thickness (e.g., initial 4.5m, 3.5m, ...). The particle birth and death algorithm is used to dynamically remove particles in the excavation area to simulate the reduction process of the coal pillar protective layer thickness; at the same time, fixed support boundary constraints are added to the excavation face in real time. For example, the initial excavation (reducing the coal pillar protective layer to 4.5m) is performed first, inactivating particles in the excavation area and generating particles to add support boundaries, and recalculating the damage process of the coal pillar protective layer under water pressure impact. Then, a second excavation is performed (reducing the coal pillar protective layer to 3.5m), inactivating particles in the excavation area, and recalculating the damage process of the coal pillar protective layer under water pressure impact. This process is then iterated repeatedly, repeating the excavation-damage analysis until the minimum coal pillar protective layer thickness for crack penetration is obtained, and the failure mode of the coal pillar protective layer at each stage is acquired. ② Multi-condition water pressure loading system: Different underground reservoir water levels are set to quantify the dynamic pressure distribution of water flow impacting the coal pillar protective layer, and then a water-rock interaction model is constructed to analyze the crack propagation and rupture process of the coal pillar protective layer during sudden water inrush. Through multi-condition comparison (e.g., water levels H1 / H2 / H3), a mapping relationship between water pressure, protective layer thickness, and failure type can be established to determine the critical thickness safety threshold of the coal pillar protective layer under different water pressures and different excavation processes.

[0054] In step 2, this disclosure establishes a multiphase coupled dynamic model of water inrush in the coal pillar protective layer considering "excavation unloading - sudden increase in water pressure". By introducing the SPH meshless method, it overcomes the problem of large deformation simulation interruption caused by mesh distortion in the finite element method (FEM). An interaction model including the coal pillar protective layer, reservoir, and boundary is established, and coupled calculations are performed within the framework of the SPH numerical algorithm. This can overcome the technical bottleneck of traditional mesh methods in simulating large deformation and water inrush in the coal pillar protective layer. It can accurately simulate the entire process of progressive damage, dynamic crack propagation, and rupture of the coal pillar protective layer under the combined action of excavation disturbance and water inrush pressure, and solve the technical defects of traditional methods in handling fluid-structure interaction and the co-evolution of large deformation.

[0055] In step S3, the number of damaged particles is counted in real time based on the stress state of the coal pillar protective layer particles to identify the crack propagation, penetration, and rupture processes. This step mainly involves numerical algorithms for water inrush and crack propagation in the coal pillar protective layer. These algorithms include: constitutive models, excavation birth and death particle method, crack propagation and damage identification statistical algorithms, and fluid-structure interaction contact algorithms. All these algorithms are uniformly implemented within the framework of smooth particle hydrodynamics numerical simulation. Specifically, these models include:

[0056] (1) Constitutive Model: This algorithm can be used to calculate the crack propagation and large deformation process of the coal pillar protective layer under excavation and water pressure. Before the coal pillar protective layer fractures, the cracks continue to propagate, and the overall protective layer remains basically static. After the cracks are connected, the water flow impacts and carries rock blocks in the roadway, at which point the coal pillar protective layer exhibits a broken particle flow motion state. Traditional constitutive models, such as the Drucker-Prager constitutive model, can only reflect the stress state of the coal pillar protective layer before it reaches yield, and cannot characterize the rate-dependent effect of the particle flow after fracture, i.e., the stress changes with the strain rate. Therefore, a rate-dependent constitutive model is proposed, which can realize the quasi-static failure process before the protective layer cracks are connected, and also characterize the particle flow motion process after the cracks are connected. The constitutive model is as follows:

[0057]

[0058] In the formula: For the total stress, p solid For the spherical stress tensor, The shear stress tensor is obtained using the Drucker-Prager constitutive model. τ y For the initiation stress of granular flow, μ is the shear strain rate. eff is the equivalent viscosity; m and n are constitutive model parameters.

[0059] (2) SPH (Synchronous Particle Hierarchy Process) excavation simulation: Dynamic excavation is achieved using the SPH method. The excavation area is pre-defined according to the engineering excavation plan. The initial excavation step generates a complete roadway model, which is discretized into particles and then input into the SPH numerical algorithm to calculate the dynamic process of water pressure impacting the coal pillar protective layer under this working condition. The excavation distance is determined according to the excavation plan, and the particles in the excavated roadway area are removed. After discretization and updating, the particles are input into the SPH numerical algorithm for calculation. The process is repeated until the specified excavation procedure is completed.

[0060] (3) Statistical algorithm for crack propagation and damage identification; In this algorithm, both the coal pillar protective layer and the water flow are calculated within a smooth particle hydrodynamic framework, and are treated as two independent objects in the calculation. When water pressure impacts the coal pillar protective layer, the improved fracture judgment criterion is used to determine whether crack propagation and rupture will occur in the protective layer. First, the stress of particle i in the coal pillar protective layer is calculated using the proposed constitutive model, and the maximum tensile stress σ of the particle is determined first. fmax With the maximum tensile strength σ t relation:

[0061] If σ fmax >σ t If the particle has already undergone tensile failure, it is marked as a tensile-damaged particle, and the number is counted in real time.

[0062] If σ fmax <σ t Then, it is further determined whether shear failure has occurred. If the Drucker-Prager yield function f is satisfied... shear If the value is 0, shear failure occurs, and these particles are labeled as shear damage particles, with their numbers counted in real time. The total number of damage particles is counted at each calculation step, and the sum of these counts yields the change in the total number of damage particles over time. This allows for real-time quantification and statistical analysis of the damage evolution process of the protective layer, and the calculation of the critical protective layer thickness. After the crack propagates and penetrates, the particles will move, generating a rate effect. Subsequent motion behavior can be characterized using the proposed rate-dependent constitutive model.

[0063] (4) Fluid-structure interaction contact algorithm: This algorithm establishes a calculation model for large deformation caused by water inrush and rupture of the coal pillar protective layer, considering the combined effects of excavation and water storage. The model adopts the SPH numerical simulation method, considering the interaction between the coal pillar protective layer and the water flow. The stress-strain response of the coal pillar protective layer is calculated using the proposed constitutive model, and the flow behavior of the water flow is calculated using the weak compressibility algorithm based on the NS equation. The support structure and terrain boundary are considered as static boundaries in the calculation. There are three main contact types: contact between the coal pillar protective layer and the water flow, contact between the coal pillar protective layer and the support structure, and contact between the support structure and the water flow. For consistent expression, the central particle is referred to as i, the particle region of the coal pillar protective layer is denoted as R, the particle region of the support and boundary is denoted as S, and the particle region of the water flow is denoted as W.

[0064] ① Centered on coal pillar protective layer particle i, the main contact relationships are: coal pillar protective layer particle in contact with particles of the same type, coal pillar protective layer particle in contact with water flow particles, and coal pillar protective layer particle in contact with support and boundary particles. The governing equation for coal pillar protective layer particle i is as follows:

[0065]

[0066] In the formula: ρ is the particle density; t is the calculation time; m is the particle mass; v is the particle velocity; x is the position coordinate of the base point; M is the smoothing kernel function; g is the gravitational acceleration; α and β represent the vector direction of stress, stress is a third-order tensor, and α and β can be taken in the x, y, and z directions respectively; R is the particle region of the coal pillar protection layer; S is the particle region of the support and boundary; W is the particle region of the water flow; σ αβ The stress tensor of the soil particles can be calculated using the proposed constitutive model. The deviatoric stress components of the boundary particles can be obtained through... Interpolation yields water particle pressure It can be obtained through state equations.

[0067] ② Centered on water flow particle i, the main contact relationships are: water flow particle contacts particles of the same type, water flow particle contacts coal pillar protective layer particles, and water flow particle contacts support structure particles. The governing equation for support particle i is as follows:

[0068]

[0069] ③ For support structure particles, the main contact relationships are: support structure particles contacting particles of the same type, support structure particles contacting coal pillar protective layer particles, and support structure particles contacting water flow particles. In this disclosure, support particles are treated as a fixed boundary, and their displacement and velocity are not updated in the calculation.

[0070] In step S3, this disclosure proposes a numerical simulation method for the dynamic process of coal pillar protective layer collapse and rupture under water pressure. The proposed constitutive model is used to calculate the stress-strain response of the coal pillar protective layer, and the SPH weakly compressible algorithm is used to calculate the water flow behavior. Through the calculation of inter-particle interaction forces using SPH, the evolution data of the displacement field, stress field, and damage field of the coal pillar protective layer are dynamically output, predicting the critical protective layer thickness, water inrush failure time, and rupture impact range. This achieves a full-process simulation of the coal pillar protective layer crack initiation, propagation, and water inrush channel formation under fluid-structure interaction. It can dynamically output the evolution data of the displacement field, stress field, and damage field of the coal pillar protective layer, predict the critical protective layer thickness, water inrush failure time, and rupture impact range, providing key indicators for engineering risk quantification.

[0071] Furthermore, this disclosure proposes a method for predicting the critical protective layer thickness during coal pillar excavation and a method for predicting the potential danger of water inrush caused by coal pillar excavation. By employing the proposed numerical simulation method, a suitable protective layer thickness is continuously selected through iterative numerical simulations. The continuity of cracks in the numerical simulation results indicates whether the protective layer has failed, thus determining the minimum protective layer thickness. The proposed numerical simulation method is used to simulate the failure path of the coal pillar protective layer under different working conditions, guiding the optimization of the coal pillar protective layer design. This predicts the critical protective layer thickness during coal pillar excavation, providing dynamic safety early warning and engineering decision support for underground reservoir excavation construction. It also assesses the danger and risk of water inrush during coal pillar excavation, providing a basis for developing advanced reinforcement schemes and emergency plans, and improving the disaster prevention and control capabilities of underground engineering.

[0072] In step S4, the critical protective layer thickness, water inrush failure time, and rupture impact range are generated based on the damage evolution data, and visualized data is output. Specifically, the field variables of each particle, such as stress, strain, displacement, velocity, and damage, are calculated using the smoothed particle hydrodynamics method. The obtained information is in the form of digital text information, which is converted into binary VTK files for visualization. The particle output for different partitions is controlled by particle type, enabling material output classification. Therefore, binary files containing the coal pillar protective layer, water flow, and boundary can be output separately. These files can be displayed in some general open-source software such as Paraview.

[0073] In practical applications, the reliability verification and application of the program calculation mainly include comparison of water flow impact tests, comparison of rock uniaxial compression crack propagation, simulation of the hydrodynamic process of coal pillar protective layer inrush, and prediction of critical thickness of coal pillar protective layer.

[0074] (1) Case 1: Comparison of water flow impact tests

[0075] To verify the reliability of the algorithm in simulating water flow behavior, a comparative water column collapse experiment was conducted. The rectangular water column had dimensions of 0.146m × 0.2m × 0.292m and was located on the left side of the water tank. Initially, the water column flowed to the right, with a particle spacing of 1.0mm and a total number of particles of 5,117,924. Figure 3 The numerical simulation results and experimental results of the water column collapse test at different times are presented and compared. Figure 3 As can be seen, the water surface line results obtained from the numerical simulation in this study are largely consistent with the experimental results, and the water flow patterns are roughly the same, especially at T=0.2s and T=0.4s, where the simulation results agree well with the experimental results. This indicates that the algorithm disclosed in this paper can reasonably predict the water flow process in the event of a sudden water inrush in the coal pillar protective layer.

[0076] (2) Case 2: Comparison of uniaxial compression crack propagation in rock

[0077] Numerical simulations of uniaxial compression were conducted to verify the reliability of the algorithm presented in calculating rock fracture propagation. Figure 4 It can be seen that the algorithm disclosed in this paper can capture the behavior of rock crack propagation relatively well.

[0078] (3) Case 3: Simulation of the sudden hydrodynamic process during tunnel excavation

[0079] A certain mining area employs a combined adit-inclined shaft development method. The mine's aquifers are mainly Quaternary loose aquifers and Mesozoic clastic fractured aquifers. Some areas contain newly constructed underground reservoirs with large water volumes, posing a risk of sudden water inrush during coal pillar excavation and reservoir impoundment. First, numerical models of the coal pillar protection layer, reservoir flow, and support structure boundaries are established based on the actual topography. Then, considering full impoundment conditions, the proposed method is used to calculate the dynamic response of the coal pillar protection layer and the crack propagation process, such as... Figure 5 and Figure 6 As shown, the algorithm in this study can effectively capture the crack propagation, rupture, and sudden hydrodynamic processes of coal pillar protective layer under the influence of reservoir water storage.

[0080] When the protective layer thickness is relatively large, such as 4.5m, Figure 5 As shown, the coal pillar protective layer will only experience crack propagation, and the cracks will not be continuous, so there will be no rupture and water inrush disaster, and the risk of water inrush disaster is relatively small.

[0081] When the protective layer thickness is relatively small, such as 2.5m, Figure 6 As shown, under the impact of water pressure, the coal pillar protective layer cracked and expanded rapidly. After the cracks were connected, the water pressure continued to impact and fracture the coal pillar protective layer, causing it to move into the tunnel and impacting the tunnel's infrastructure, threatening personnel safety. Meanwhile... Figure 7 The damage evolution process of the coal pillar protective layer with a protective layer thickness of 2.5m is presented.

[0082] (4) Case 4: Prediction of critical protective layer during tunnel excavation

[0083] like Figure 8 As shown, based on Case 3, the critical thickness of the coal pillar protective layer is further predicted. It is known that the protective layer thickness is between 4.5m and 2.5m. Calculations show that when the protective layer thickness is 2.6m, the coal pillar protective layer only experiences crack propagation, the cracks do not penetrate, and no sudden water inrush disaster will occur. Therefore, it can be determined that under a given water pressure condition, the critical thickness of the coal pillar protective layer is 2.6m.

[0084] Understandably, this disclosure can be applied to numerical simulation scenarios of the dynamic process of crack propagation and collapse of coal pillar protective layers under excavation and water pressure drive. It can simulate the entire process of crack initiation, propagation, and water inrush channel formation in coal pillar protective layers, considering fluid-structure interaction. It can dynamically output data on the evolution of displacement, stress, and damage fields of the coal pillar protective layer, predicting the critical thickness of the protective layer, the time of water inrush failure, and the range of rupture impact, providing key indicators for quantifying engineering risks. This disclosure can also be applied to dynamic modeling scenarios of coal pillar protective layers under the action of water pressure in underground reservoirs. Through a dynamic particle inactivation algorithm, it can characterize the real-time interaction process between excavation steps and the response of the coal pillar protective layer. Combined with indoor experiments, rock mechanics parameters can be directly obtained without the need for empirical parameter calibration. This disclosure can also be applied to scenarios of predicting and warning of water inrush disaster hazards in abandoned mine underground reservoirs. By pre-simulating the failure path of the coal pillar protective layer under different excavation and water storage schemes, it can guide the optimization of the coal pillar protective layer design. Combined with water inrush pressure early warning and critical thickness prediction of the protective layer, it can provide decision-making basis for underground reservoir safety assessment and emergency plan development.

[0085] Accordingly, this disclosure also provides a prediction system for large deformation caused by rupture and water inrush in the coal pillar protective layer of an underground reservoir, which can realize all the processes of the prediction method for large deformation caused by rupture and water inrush in the coal pillar protective layer of an underground reservoir in the above embodiments.

[0086] Please see Figure 9 , Figure 9 This is a schematic diagram of a preferred embodiment of a system for predicting large deformation due to rupture and water inrush in an underground reservoir's coal pillar protective layer, as disclosed in this disclosure. The system includes:

[0087] Modeling module 901: Used to generate a particle model containing coal pillar protection layer, reservoir water flow and support boundary based on preset particle precision;

[0088] Coupling module 902: Used to simulate the response process of the coal pillar protective layer under the coupled conditions of water storage and excavation using the meshless particle method, including:

[0089] A particle inactivation algorithm is used to dynamically update the particle distribution in the excavation area to simulate the change in the thickness of the coal pillar protective layer.

[0090] The interaction force between water flow and coal pillar protective layer is calculated based on the fluid-structure interaction contact algorithm.

[0091] Evolution Module 903: Used to count the number of damaged particles in real time based on the stress state of the coal pillar protective layer particles, and to identify the crack propagation, penetration and rupture process;

[0092] Output module 904: Used to generate critical protective layer thickness, water inrush failure time and rupture impact range based on damage evolution data, and output visualized data.

[0093] Preferably, the modeling module 901 is used to generate a particle model containing the coal pillar protective layer, reservoir water flow, and support boundaries based on a preset particle precision; specifically, it includes: ① Underground reservoir structure modeling: constructing an initial three-dimensional model using millimeter-level particle precision, covering the coal pillar protective layer and support boundaries, to achieve high-fidelity modeling; ② Coal pillar protective layer thickness design: the thickness of the coal pillar protective layer can be determined according to the actual design scheme, serving as a key water-blocking structure for the underground reservoir; ③ Reservoir model: establishing an underground reservoir and initial water flow model, the reservoir water level can be determined according to the actual reservoir operation scheme, simulating the impact process of underground reservoir water flow after the failure of the coal pillar protective layer during water storage. Especially in the initially water-filled reservoir area, after the failure of the protective layer water-blocking structure, the water flow will impact the roadway structure downwards.

[0094] The coupling module 902 is used to simulate the response process of the coal pillar protective layer under the coupled conditions of water storage and excavation using a particle model and a meshless particle method. This includes: dynamically updating the particle distribution in the excavation area using a particle deactivation algorithm to simulate the change in coal pillar protective layer thickness; and calculating the interaction force between the reservoir water flow and the coal pillar protective layer based on a fluid-structure interaction contact algorithm. Specifically, this includes: ① Dynamic excavation modeling: To calculate the critical thickness of the coal pillar protective layer, different coal pillar protective layer thicknesses are considered in the numerical simulation. A multi-stage coal pillar protective layer model is established according to the pre-designed excavation sequence, with each stage corresponding to a different coal pillar protective layer thickness (e.g., initial 4.5m, 3.5m, ...). The particle birth and death algorithm is used to dynamically remove particles in the excavation area to simulate the reduction process of the coal pillar protective layer thickness; simultaneously, fixed support boundary constraints are added to the excavation face in real time. For example, the first excavation is performed (coal pillar protective layer reduced to 4.5m), particles in the excavation area are deactivated and generated to add support boundaries, and the damage process of the coal pillar protective layer under water pressure impact is recalculated. Then, a second excavation is conducted (reducing the coal pillar protective layer to 3.5m), inactivating particles in the excavation area, and recalculating the damage process of the coal pillar protective layer under water pressure impact. This process is then iterated repeatedly, with the excavation-damage analysis continued until the minimum coal pillar protective layer thickness for crack penetration is obtained, and the failure modes of the coal pillar protective layer at each stage are acquired. ② Multi-condition water pressure loading system: Different underground reservoir water levels are set to quantify the dynamic pressure distribution of water flow impacting the coal pillar protective layer, thereby constructing a water-rock interaction model to analyze the crack propagation and rupture process of the coal pillar protective layer during sudden water inrush. Through multi-condition comparisons (such as water levels H1 / H2 / H3), a mapping relationship between water pressure, protective layer thickness, and failure type can be established to determine the critical thickness safety threshold of the coal pillar protective layer under different water pressures and excavation processes.

[0095] In this embodiment, this disclosure establishes a multiphase coupled dynamic model of water inrush in the coal pillar protective layer considering "excavation unloading - sudden increase in water pressure". By introducing the meshless SPH method, it overcomes the problem of large deformation simulation interruption caused by mesh distortion in the finite element method (FEM). A model including the interaction of the coal pillar protective layer, the reservoir, and the boundary is established. Coupled calculations are performed within the framework of the SPH numerical algorithm, which can overcome the technical bottleneck of traditional mesh methods in simulating large deformation and water inrush in the coal pillar protective layer. It can accurately simulate the entire process of progressive damage, dynamic crack propagation, and rupture of the coal pillar protective layer under the combined action of excavation disturbance and water inrush pressure, and solve the technical defects of traditional methods in handling fluid-structure interaction and the co-evolution of large deformation.

[0096] The evolution module 903 is used to count the number of damaged particles in real time based on the stress state of the coal pillar protective layer particles, and to identify the crack propagation, penetration, and rupture processes. This step mainly involves numerical algorithms for water inrush and crack propagation in the coal pillar protective layer. These algorithms include: constitutive models, excavation birth and death particle methods, crack propagation and damage identification statistical algorithms, and fluid-structure interaction contact algorithms. All these algorithms are uniformly implemented within the framework of smooth particle hydrodynamics numerical simulation. Specifically, these models include:

[0097] (1) Constitutive Model: This algorithm can be used to calculate the crack propagation and large deformation process of the coal pillar protective layer under excavation and water pressure. Before the coal pillar protective layer fractures, the cracks continue to propagate, and the overall protective layer remains basically static. After the cracks are connected, the water flow impacts and carries rock blocks in the roadway, at which point the coal pillar protective layer exhibits a broken particle flow motion state. Traditional constitutive models, such as the Drucker-Prager constitutive model, can only reflect the stress state of the coal pillar protective layer before it reaches yield, and cannot characterize the rate-dependent effect of the particle flow after fracture, i.e., the stress changes with the strain rate. Therefore, a rate-dependent constitutive model is proposed, which can realize the quasi-static failure process before the protective layer cracks are connected, and also characterize the particle flow motion process after the cracks are connected. The constitutive model is as follows:

[0098]

[0099] In the formula: For the total stress, p solid For the spherical stress tensor, The shear stress tensor is obtained using the Drucker-Prager constitutive model. τ y For the initiation stress of granular flow, μ is the shear strain rate. eff is the equivalent viscosity; m and n are constitutive model parameters.

[0100] (2) SPH (Synchronous Particle Hierarchy Process) excavation simulation: Dynamic excavation is achieved using the SPH method. The excavation area is pre-defined according to the engineering excavation plan. The initial excavation step generates a complete roadway model, which is discretized into particles and then input into the SPH numerical algorithm to calculate the dynamic process of water pressure impacting the coal pillar protective layer under this working condition. The excavation distance is determined according to the excavation plan, and the particles in the excavated roadway area are removed. After discretization and updating, the particles are input into the SPH numerical algorithm for calculation. The process is repeated until the specified excavation procedure is completed.

[0101] (3) Statistical algorithm for crack propagation and damage identification; In this algorithm, both the coal pillar protective layer and the water flow are calculated within a smooth particle hydrodynamic framework, and are treated as two independent objects in the calculation. When water pressure impacts the coal pillar protective layer, the improved fracture judgment criterion is used to determine whether crack propagation and rupture will occur in the protective layer. First, the stress of particle i in the coal pillar protective layer is calculated using the proposed constitutive model, and the maximum tensile stress σ of the particle is determined first. fmax With the maximum tensile strength σ t relation:

[0102] If σ fmax >σ t If the particle has already undergone tensile failure, it is marked as a tensile-damaged particle, and the number is counted in real time.

[0103] If σ fmax <σ t Then, it is further determined whether shear failure has occurred. If the Drucker-Prager yield function f is satisfied... shear If the value is 0, shear failure occurs, and these particles are labeled as shear damage particles, with their numbers counted in real time. The total number of damage particles is counted at each calculation step, and the sum of these counts yields the change in the total number of damage particles over time. This allows for real-time quantification and statistical analysis of the damage evolution process of the protective layer, and the calculation of the critical protective layer thickness. After the crack propagates and penetrates, the particles will move, generating a rate effect. Subsequent motion behavior can be characterized using the proposed rate-dependent constitutive model.

[0104] (4) Fluid-structure interaction contact algorithm: This algorithm establishes a calculation model for large deformation caused by water inrush and rupture of the coal pillar protective layer, considering the combined effects of excavation and water storage. The model adopts the SPH numerical simulation method, considering the interaction between the coal pillar protective layer and the water flow. The stress-strain response of the coal pillar protective layer is calculated using the proposed constitutive model, and the flow behavior of the water flow is calculated using the weak compressibility algorithm based on the NS equation. The support structure and terrain boundary are considered as static boundaries in the calculation. There are three main contact types: contact between the coal pillar protective layer and the water flow, contact between the coal pillar protective layer and the support structure, and contact between the support structure and the water flow. For consistent expression, the central particle is referred to as i, the particle region of the coal pillar protective layer is denoted as R, the particle region of the support and boundary is denoted as S, and the particle region of the water flow is denoted as W.

[0105] ① Centered on coal pillar protective layer particle i, the main contact relationships are: coal pillar protective layer particle in contact with particles of the same type, coal pillar protective layer particle in contact with water flow particles, and coal pillar protective layer particle in contact with support and boundary particles. The governing equation for coal pillar protective layer particle i is as follows:

[0106]

[0107] In the formula: ρ is the particle density; t is the calculation time; m is the particle mass; v is the particle velocity; x is the position coordinate of the base point; M is the smoothing kernel function; g is the gravitational acceleration; α and β represent the vector direction of stress, stress is a third-order tensor, and α and β can be taken in the x, y, and z directions respectively; R is the particle region of the coal pillar protection layer; S is the particle region of the support and boundary; W is the particle region of the water flow; σ αβ The stress tensor of the soil particles can be calculated using the proposed constitutive model. The deviatoric stress components of the boundary particles can be obtained through... Interpolation yields water particle pressure It can be obtained through state equations.

[0108] ② Centered on water flow particle i, the main contact relationships are: water flow particle contacts particles of the same type, water flow particle contacts coal pillar protective layer particles, and water flow particle contacts support structure particles. The governing equation for support particle i is as follows:

[0109]

[0110] ③ For support structure particles, the main contact relationships are: support structure particles contacting particles of the same type, support structure particles contacting coal pillar protective layer particles, and support structure particles contacting water flow particles. In this disclosure, support particles are treated as a fixed boundary, and their displacement and velocity are not updated in the calculation.

[0111] In this embodiment, this disclosure proposes a numerical simulation method for the dynamic process of coal pillar protective layer collapse and rupture under water pressure. The proposed constitutive model is used to calculate the stress-strain response of the coal pillar protective layer, and the SPH weakly compressible algorithm is used to calculate the water flow behavior. Through the calculation of SPH inter-particle interaction forces, the evolution data of the displacement field, stress field, and damage field of the coal pillar protective layer are dynamically output, predicting the critical protective layer thickness, water inrush failure time, and rupture impact range. This achieves a full-process simulation of the coal pillar protective layer crack initiation, propagation, and water inrush channel formation under fluid-structure interaction. It can dynamically output the evolution data of the displacement field, stress field, and damage field of the coal pillar protective layer, predict the critical protective layer thickness, water inrush failure time, and rupture impact range, providing key indicators for engineering risk quantification.

[0112] Furthermore, this disclosure proposes a method for predicting the critical protective layer thickness during coal pillar excavation and a method for predicting the potential danger of water inrush caused by coal pillar excavation. By employing the proposed numerical simulation method, a suitable protective layer thickness is continuously selected through iterative numerical simulations. The continuity of cracks in the numerical simulation results indicates whether the protective layer has failed, thus determining the minimum protective layer thickness. The proposed numerical simulation method is used to simulate the failure path of the coal pillar protective layer under different working conditions, guiding the optimization of the coal pillar protective layer design. This predicts the critical protective layer thickness during coal pillar excavation, providing dynamic safety early warning and engineering decision support for underground reservoir excavation construction. It also assesses the danger and risk of water inrush during coal pillar excavation, providing a basis for developing advanced reinforcement schemes and emergency plans, and improving the disaster prevention and control capabilities of underground engineering.

[0113] Output module 904 is used to generate critical protective layer thickness, water inrush failure time, and rupture impact range based on damage evolution data, and output visualized data. Specifically, the field variables of each particle, such as stress, strain, displacement, velocity, and damage, are calculated using the smoothed particle hydrodynamics method. The obtained information is in the form of digital text, which is converted into binary VTK files for visualization. The particle output of different partitions can be controlled by particle type to achieve material output classification. Therefore, binary files containing coal pillar protective layer, water flow, and boundary can be output separately. These files can be displayed in some general open-source software such as Paraview.

[0114] In specific implementation, the working principle, control process and technical effects of the underground reservoir coal pillar protective layer rupture and water inrush large deformation prediction system provided in this embodiment are the same as those of the underground reservoir coal pillar protective layer rupture and water inrush large deformation prediction method in the above embodiments, and will not be repeated here.

[0115] Please see Figure 10 , Figure 10 This is a schematic diagram of a preferred embodiment of a terminal device provided in this disclosure. The terminal device includes a processor 1001, a memory 1002, and a computer program stored in the memory 1002 and configured to be executed by the processor 1001. When the processor 1001 executes the computer program, it implements the method for predicting large deformation due to rupture and water inrush in underground reservoir coal pillar protective layer as described in any of the above embodiments.

[0116] Preferably, the computer program can be divided into one or more modules / units (such as computer program 1, computer program 2, ...), and the one or more modules / units are stored in the memory 1002 and executed by the processor 1001 to complete the present disclosure. The one or more modules / units can be a series of computer program instruction segments capable of performing specific functions, and the instruction segments are used to describe the execution process of the computer program in the terminal device.

[0117] The processor 1001 may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor, or the processor 1001 may be any conventional processor. The processor 1001 is the control center of the terminal device, connecting various parts of the terminal device through various interfaces and lines.

[0118] The memory 1002 mainly includes a program storage area and a data storage area. The program storage area can store the operating system, applications required for at least one function, etc., while the data storage area can store related data, etc. Furthermore, the memory 1002 can be a high-speed random access memory, or a non-volatile memory, such as a plug-in hard disk, a smart media card (SMC), a secure digital card (SD), and a flash card, or other volatile solid-state storage devices.

[0119] It should be noted that the aforementioned terminal devices may include, but are not limited to, processors and memory, as will be understood by those skilled in the art. Figure 10 The structural diagram is merely an example of the terminal device described above and does not constitute a limitation on the terminal device described above. It may include more or fewer components than shown in the diagram, or combine certain components, or use different components.

[0120] This disclosure also provides a computer-readable storage medium, which includes a stored computer program, wherein, when the computer program is executed, it controls the device where the computer-readable storage medium is located to perform the method for predicting large deformation due to rupture and water inrush in underground reservoir coal pillar protective layer as described in any of the above embodiments.

[0121] This disclosure also provides a computer program product, which includes a computer program or computer instructions. When the computer program or computer instructions are executed by a processor, they implement the method for predicting large deformation caused by rupture and water inrush in underground reservoir coal pillar protective layer as described in any of the above embodiments.

[0122] In summary, this disclosure overcomes the challenge of large deformation simulation interruption caused by mesh distortion in the finite element method (FEM) by introducing the meshless SPH method. A model integrating the coal pillar protective layer, reservoir, and boundary interactions is established, and coupled calculations are performed within the SPH numerical algorithm framework. This overcomes the technical bottleneck of traditional mesh methods in simulating large deformation and water inrush in the coal pillar protective layer. It can accurately simulate the entire process of progressive damage, dynamic crack propagation, and rupture of the coal pillar protective layer under the combined effects of excavation disturbance and water inrush pressure, solving the technical shortcomings of traditional methods in handling fluid-structure interaction and the co-evolution of large deformation. The proposed constitutive model is used to calculate the stress-strain response of the coal pillar protective layer, and the SPH weakly compressible algorithm is used to calculate the water flow behavior. By calculating the inter-particle interaction forces using SPH (Solid Phosphoric Hybridization), the system dynamically outputs the evolution data of the displacement, stress, and damage fields of the coal pillar protective layer. This allows for the prediction of the critical protective layer thickness, water inrush failure time, and rupture impact range. The system can simulate the entire process of crack initiation, propagation, and water inrush channel formation in the coal pillar protective layer under fluid-structure interaction. It can dynamically output the evolution data of the displacement, stress, and damage fields of the coal pillar protective layer, predicting the critical protective layer thickness, water inrush failure time, and rupture impact range, providing key indicators for quantifying engineering risks. Furthermore, by employing the proposed numerical simulation method, suitable protective layers are continuously and iteratively selected. Numerical simulations are conducted to determine the thickness of the protective layer. By analyzing whether cracks are continuous in the simulation results, it is possible to determine whether the protective layer has failed, identify the minimum thickness of the protective layer, and predict the critical protective layer thickness for coal pillar excavation. This provides dynamic safety early warning and engineering decision support for underground reservoir excavation. Furthermore, by employing the proposed numerical simulation method, the failure path of the coal pillar protective layer under different working conditions can be simulated, guiding the optimization of the coal pillar protective layer design. The risk and danger of sudden water inrush in the coal pillar protective layer during construction can be assessed, providing a basis for decision-making in formulating advanced reinforcement schemes and emergency plans, and improving the disaster prevention and control capabilities of underground engineering.

[0123] It should be noted that the system embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Furthermore, in the accompanying drawings of the system embodiments provided in this disclosure, the connection relationships between modules indicate that they have communication connections, which can be specifically implemented as one or more communication buses or signal lines. Those skilled in the art can understand and implement this without any creative effort.

[0124] The above description represents the preferred embodiments of this disclosure. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this disclosure, and these improvements and modifications are also considered to be within the scope of protection of this disclosure.

Claims

1. A method for predicting large deformation due to rupture and water inrush in the protective layer of an underground reservoir's coal pillar, characterized in that... include: A particle model containing coal pillar protection layer, reservoir water flow and support boundary is generated based on preset particle precision. Based on the particle model, the response process of the coal pillar protective layer under the coupled conditions of water storage and excavation is simulated by the meshless particle method, including: dynamically updating the particle distribution in the excavation area using a particle inactivation algorithm to simulate the thickness change of the coal pillar protective layer. The interaction force between reservoir water flow and coal pillar protective layer was calculated based on the fluid-structure interaction contact algorithm. The number of damaged particles is counted in real time based on the stress state of the particles in the coal pillar protective layer, and the process of crack propagation, penetration and rupture is identified. Based on damage evolution data, the critical protective layer thickness, water inrush failure time, and rupture impact range are generated, and visualized data is output.

2. The method for predicting large deformation due to rupture and water inrush in the coal pillar protective layer of an underground reservoir as described in claim 1, characterized in that, The preset particle precision is at the millimeter level, and the thickness of the coal pillar protective layer is preset with multiple sets of comparison values ​​for iterative calculation.

3. The method for predicting large deformation due to rupture and water inrush in the coal pillar protective layer of an underground reservoir as described in claim 1, characterized in that, In the fluid-structure interaction contact algorithm, the stress of the coal pillar protective layer particles is calculated using a rate-dependent constitutive model, and the expression of the constitutive model is as follows: in, For the total stress, p solid For the spherical stress tensor, Let τ be the shear stress tensor. y For the initiation stress of granular flow, μ is the shear strain rate. eff The viscosity is the equivalent viscosity, and m and n are constitutive model parameters.

4. The method for predicting large deformation due to rupture and water inrush in the coal pillar protective layer of an underground reservoir as described in claim 1, characterized in that, The method of real-time counting of damaged particles based on the stress state of the coal pillar protective layer particles specifically includes: If the maximum tensile stress of a particle exceeds its tensile strength, it is marked as a tensile-damaged particle. If a particle satisfies the Drucker-Prager yield criterion, it is marked as a shear-damaged particle. The total number of damage particles is counted in real time and damage field evolution data is generated.

5. The method for predicting large deformation due to rupture and water inrush in the coal pillar protective layer of an underground reservoir as described in claim 1, characterized in that, The critical protective layer thickness is determined through iterative simulation: the thickness of the coal pillar protective layer is cyclically reduced until the crack is penetrated, and the minimum thickness of the crack before penetration is taken as the critical value.

6. The method for predicting large deformation due to rupture and water inrush in the protective layer of an underground reservoir coal pillar as described in claim 1, characterized in that, The visualization data includes binary VTK format files of displacement field, stress field and damage field, which are used to display the dynamic evolution process in visualization tools.

7. A prediction system for large deformation due to rupture and water inrush in the protective layer of an underground reservoir coal pillar, characterized in that, include: Modeling module: Used to generate particle models containing coal pillar protection layers, reservoir water flow and support boundaries based on preset particle precision; Coupling module: used to simulate the response process of coal pillar protection layer under water storage-excavation coupled conditions based on the particle model using the meshless particle method, including: dynamically updating the particle distribution in the excavation area using a particle inactivation algorithm to simulate the thickness change of the coal pillar protection layer; and calculating the interaction force between water flow and coal pillar protection layer based on the fluid-structure interaction contact algorithm. Evolution module: Used to count the number of damaged particles in real time based on the stress state of the coal pillar protective layer particles, and to identify the crack propagation, penetration and rupture process; Output module: Used to generate critical protective layer thickness, water inrush failure time and rupture impact range based on damage evolution data, and output visualized data.

8. A terminal device, characterized in that, The method includes a processor and a memory, wherein the memory stores a computer program and the computer program is configured to be executed by the processor, wherein the processor executes the computer program to implement the method for predicting large deformation due to rupture and water inrush in underground reservoir coal pillar protective layer as described in any one of claims 1 to 6.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program, wherein when the device containing the computer-readable storage medium executes the computer program, it implements the method for predicting large deformation due to rupture and water inrush in underground reservoir coal pillar protective layer as described in any one of claims 1 to 6.

10. A computer program product, characterized in that, The computer program product includes a computer program or computer instructions, which, when executed by a processor, implement the method for predicting large deformation due to rupture and water inrush in underground reservoir coal pillar protective layer as described in any one of claims 1 to 6.

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