Analysis method suitable for stress wave propagation rule in coal rock medium

Abstract

The invention discloses an analysis method suitable for a stress wave propagation rule in a coal rock medium, and belongs to the technical field of coal mining. The invention discloses an analysis method suitable for a stress wave propagation rule in a coal rock medium. Comprising the following steps: determining physical and mechanical properties and parameters of coal rock, establishing a stress wave propagation theoretical model containing an internal structure and stress distribution characteristics of the coal rock, solving the model by adopting a finite element method and a discrete element method, and changing model parameters based on a verification result through comparison with actual seismic data or industrial test data. The method solves the problems that an existing analysis method is often difficult to comprehensively consider the influence of a complex internal structure of coal rock and non-uniform stress distribution on wave propagation, and limitation also exists when the interference effect of multi-type stress waves and complex boundary conditions are processed. According to the method, the complicated internal structure of the coal rock and the condition of non-uniform stress distribution are comprehensively considered, so that the propagation rule of the stress waves in the coal rock is more accurately predicted.

Description

Technical Field

[0001] The invention relates to the technical field of coal mining, and in particular to an analysis method suitable for the propagation law of stress waves in coal and rock media. Background Art

[0002] In coal mining and geological engineering, understanding the propagation characteristics of stress waves in coal and rock media is of great significance for ensuring operational safety and optimizing mining technology. The propagation law of stress waves directly affects the failure mode, energy dissipation and potential geological disaster risks of coal and rock. However, traditional analysis methods often find it difficult to fully consider the impact of the complex internal structure and non-uniform stress distribution of coal and rock on wave propagation. These methods are usually based on simplified assumptions and idealized models, ignoring the influence of factors such as natural cracks, bedding, pores and mineral composition. In addition, traditional methods also have limitations in dealing with the interference effects of multiple types of stress waves and complex boundary conditions, which limits their application in actual engineering.

[0003] Therefore, developing a stress wave propagation analysis method that can fully consider the complex internal structure and non-uniform stress distribution of coal rock is of great practical significance for improving the safety of coal mining and optimizing mining technology. Summary of the invention

[0004] The purpose of the present invention is to provide an analysis method suitable for the propagation law of stress waves in coal and rock media, which comprehensively considers the complex internal structure of coal and rock and the non-uniform stress distribution, and solves the model by means of numerical simulation to obtain more accurate information such as stress wave attenuation characteristics, velocity attenuation characteristics and energy dissipation characteristics. At the same time, the effectiveness of the model is verified by comparing with actual seismic data, thereby improving the prediction accuracy, better assessing potential safety risks, and solving the problems raised in the above-mentioned background technology.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] An analysis method for stress wave propagation law in coal and rock media includes the following steps:

[0007] S1. Determine the physical and mechanical properties and parameters of coal rock, including elastic modulus, Poisson's ratio, density, compressive strength and tensile strength, and identify natural cracks and bedding in coal rock, and evaluate the impact of these characteristics on the overall destruction and damage of coal rock;

[0008] S2. Establish a stress wave propagation theory model that includes the internal structure and stress distribution characteristics of coal and rock, model various types of stress waves generated during the impact coal breaking process, and set the boundary conditions, initial conditions, impact loads, and initial stress states of coal and rock;

[0009] S3, using the finite element method (FEM) and discrete element method (DEM) to solve the model, record the propagation process of stress waves in coal and rock, including the propagation speed, attenuation characteristics and energy dissipation of stress waves, and output the calculation results, and describe the interference effects of various types of stress waves;

[0010] S4. Verify the reliability of the proposed model in predicting stress wave propagation characteristics by comparing it with actual earthquake data or industrial test data;

[0011] S5. Based on the verification results, change the model parameters, re-perform numerical simulation, observe the changes in model output, evaluate the impact of different parameter changes on model output, and find out the key parameters and their sensitivity.

[0012] Preferably, the establishment of the stress wave propagation theoretical model comprises the following steps:

[0013] According to the actual geological data of coal and rock, a three-dimensional geometric model is established, which includes the geometric shape, cracks, bedding and internal structure of coal and rock;

[0014] Mesh the 3D geometric model and generate finite element or discrete element mesh.

[0015] Preferably, meshing the three-dimensional geometric model to generate a finite element or discrete element mesh includes:

[0016] Extracting first geological data of the actual coal rock, wherein the first geological data includes the number of coal rock layers, the thickness of each layer and the dip angle of the formation;

[0017] Comparing the number of coal and rock layers with a preset threshold value of the number of coal and rock layers;

[0018] Comparing the overall thickness of the coal rock with a preset overall thickness threshold;

[0019] When the number of coal rock layers exceeds a preset coal rock layer number threshold, and the overall thickness of the coal rock does not exceed a preset overall thickness threshold, the first geological data is used to obtain a geological evaluation coefficient; otherwise, the three-dimensional geometric model is meshed according to a preset initial mesh density to generate a finite element or discrete element mesh;

[0020] The geological evaluation coefficient is obtained by the following formula:

[0021]

[0022] Where G represents the geological evaluation coefficient; D represents the overall thickness of the coal rock; n represents the number of coal rock layers; H i represents the thickness of the i-th coal layer; A represents the formation dip; H c Indicates the preset reference value of the thickness of each coal layer; D yIndicates the preset overall thickness threshold; n y Indicates the preset coal and rock layer number threshold; H p It represents the average thickness corresponding to the n-layer coal rock;

[0023] Comparing the geological evaluation coefficient with a preset evaluation coefficient threshold;

[0024] When the geological evaluation coefficient is lower than a preset evaluation coefficient threshold, the three-dimensional geometric model is meshed according to a preset initial mesh density to generate a finite element or discrete element mesh;

[0025] When the geological evaluation coefficient is not lower than a preset evaluation coefficient threshold, the grid density is set, and the three-dimensional geometric model is gridded according to the set grid density to generate a finite element or discrete element grid.

[0026] Preferably, when the geological evaluation coefficient is not lower than a preset evaluation coefficient threshold, the grid density is set, including:

[0027] Extracting first geological data of the actual coal rock, wherein the first geological data includes the number of coal rock layers, the thickness of each layer and the dip angle of the formation;

[0028] Extracting second geological data of the actual coal rock, wherein the second geological data includes the number and width of cracks in each layer of coal rock;

[0029] Setting a grid density by using the first geological data and the second geological data in combination with a preset initial grid density;

[0030] The grid density is obtained by the following formula:

[0031]

[0032] Where P represents the grid density; P c represents the critical pressure; P0 represents the preset initial grid density; n represents the number of coal and rock layers; H i represents the thickness of the i-th coal layer; A represents the formation dip; H c represents the preset reference value of the thickness of each coal rock layer; m represents the number of cracks in the i-th coal rock layer; L j represents the crack width corresponding to the jth crack in the i-th coal rock layer; L b represents the standard deviation of the overall fracture width corresponding to the n-layer coal rock; L max Indicates the maximum crack width corresponding to the n-layer coal rock; L bmax Indicates the standard deviation of the crack width of the coal rock layer corresponding to the maximum crack width; L min Indicates the minimum crack width corresponding to the n-layer coal rock; L bminIt represents the standard deviation of the crack width of the cracks existing in the coal rock layer corresponding to the minimum crack width.

[0033] Preferably, the establishment of the stress wave propagation theoretical model further comprises the following steps:

[0034] Select one of the linear elastic constitutive relation, elastic-plastic constitutive relation and elastic-brittle constitutive relation to describe the mechanical behavior of coal rock, and input the physical and mechanical parameters of coal rock;

[0035] Set the boundary conditions of the model, including at least fixed boundary, free boundary and stress boundary;

[0036] Set the initial stress state of coal and rock, and obtain the initial stress distribution through in-situ stress test data;

[0037] The parameters are set according to the actual impact coal breaking process, including at least the size, direction and time history of the impact load, the impact force and the impact speed.

[0038] Preferably, the finite element method (FEM) and discrete element method (DEM) are used to solve the model, and the stress distribution inside the model is output, including compressive stress and tensile stress; the strain distribution inside the model is output to analyze the deformation; the displacement distribution inside the model is output to analyze the overall deformation of the structure; the energy loss analysis results of the stress wave during propagation are output, including friction dissipation and heat energy conversion; the dynamic response analysis results under impact load are output, including the propagation speed and attenuation characteristics of the stress wave; and the propagation data of the stress wave at different time points are output.

[0039] Preferably, the interference effect describing various types of stress waves is specifically:

[0040] Calculate the propagation and reflection of cylindrical compression waves in coal and rock, calculate the propagation and reflection of plane isochoric waves in coal and rock, calculate the propagation and attenuation of Rayleigh surface waves near the free surface, and calculate the propagation and reflection of Stoneley waves on discontinuous surfaces; in each time step, add up the contributions of all stress waves to obtain the total stress field distribution;

[0041] Analyze the superposition effect of different stress waves at the same location to determine whether constructive interference or destructive interference occurs.

[0042] Preferably, the validity and reliability of the proposed model are verified by comparing it with actual earthquake data or industrial test data, specifically:

[0043] Compare the stress wave waveforms obtained from numerical simulation with those in actual seismic data to check the similarity of the waveforms;

[0044] Compare the stress wave amplitudes in numerical simulations and actual data to evaluate the model's ability to predict the amplitudes;

[0045] Compare the frequency components in numerical simulations and actual data to check whether the model can accurately predict the spectral characteristics of stress waves;

[0046] Compare the stress wave propagation velocities in numerical simulations and actual data to evaluate the accuracy of the model's prediction of wave velocity;

[0047] Compare the stress wave attenuation characteristics in numerical simulations and actual data to check whether the model can accurately describe the wave attenuation process;

[0048] Compare the energy dissipation in numerical simulations and actual data to evaluate the model's ability to predict energy dissipation;

[0049] The coal-rock failure patterns in numerical simulations and actual data are compared to evaluate the model's ability to predict the failure mechanism.

[0050] Preferably, the verification of the validity and reliability of the proposed model by comparing with actual earthquake data or industrial test data also includes:

[0051] Calculate the mean and variance of numerical simulation results and actual data;

[0052] The correlation coefficient was used to evaluate the correlation between the numerical simulation results and the actual data;

[0053] Calculate the absolute error, relative error, and root mean square error to quantify the prediction accuracy of the model;

[0054] Draw time series graphs, waveform graphs, and spectrum graphs of numerical simulation results and actual data to intuitively display the comparison results.

[0055] Preferably, the method of changing the model parameters based on the verification results and re-performing the numerical simulation specifically comprises the following steps:

[0056] Run the benchmark model once and record its output as a reference;

[0057] Set a reasonable range of variation for each selected parameter;

[0058] By combining single-factor analysis with multi-factor analysis, the change in model output before and after each parameter change is calculated;

[0059] Record the impact of each parameter change on the model output;

[0060] Calculate the sensitivity index and rank the parameters in importance according to the sensitivity index;

[0061] Explain the reasons for the deviation of model output caused by parameter changes, and improve the model again based on the results of sensitivity analysis.

[0062] Compared with the prior art, the present invention has the following beneficial effects:

[0063] 1. The present invention establishes a three-dimensional geometric model that includes the internal structure and stress distribution characteristics of coal and rock, and performs grid division. The model takes into account the microstructures such as cracks, bedding and pores in detail, which can more accurately reflect the real situation of coal and rock, and can more accurately predict the propagation path and attenuation characteristics of stress waves in coal and rock, thereby improving the prediction accuracy of the model, optimizing the mining plan, reducing unnecessary damage, and improving engineering efficiency.

[0064] 2. The present invention obtains the initial stress distribution of coal rock by setting reasonable boundary conditions and initial stress state, and fully considers the influence of non-uniform stress distribution, accurately simulates the non-uniform stress distribution in coal rock, and can better evaluate potential safety risks, thereby improving operational safety and improving the reliability and practicality of the model.

[0065] 3. The present invention calculates the interference effects of different types of stress waves, analyzes their superposition effects at the same position, and determines whether constructive interference or destructive interference occurs, so as to more accurately predict the propagation behavior of stress waves in coal and rock and improve the prediction accuracy of the model.

[0066] 4. The present invention combines the advantages of the finite element method and the discrete element method, which are used to deal with continuous media and discontinuous media respectively, and comprehensively solve the stress wave propagation problem. It can deal with situations involving a large number of discontinuous surfaces and a large range of continuous media, thereby enhancing the applicability and flexibility of the model. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] Figure 1 is a flow chart of the analysis method of the present invention;

[0068] Figure 2 A flow chart is established for the stress wave propagation theoretical model of the present invention. DETAILED DESCRIPTION

[0069] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0070] In order to solve the problem that existing analysis methods often have difficulty in fully considering the influence of the complex internal structure of coal and rock and the non-uniform stress distribution on wave propagation, and also have limitations in dealing with the interference effect of multiple types of stress waves and complex boundary conditions, please refer to Figure 1-2 , this embodiment provides the following technical solutions:

[0071] An analysis method for stress wave propagation law in coal and rock media includes the following steps:

[0072] S1. Determine the physical and mechanical properties and parameters of coal rock, including elastic modulus, Poisson's ratio, density, compressive strength and tensile strength, and identify natural cracks and bedding in coal rock, and evaluate the impact of these characteristics on the overall destruction and damage of coal rock;

[0073] The elastic modulus, Poisson's ratio, density, compressive strength and tensile strength of coal rock are determined through uniaxial compression test, triaxial compression test, Brazilian splitting test and other methods. The natural cracks and bedding information in coal rock are identified and obtained through microscope and CT scanning technology.

[0074] S2. Establish a stress wave propagation theory model that includes the internal structure and stress distribution characteristics of coal and rock, model various types of stress waves generated during the impact coal breaking process, and set the boundary conditions, initial conditions, impact loads, and initial stress states of coal and rock;

[0075] S3, using the finite element method (FEM) and discrete element method (DEM) to solve the model, record the propagation process of stress waves in coal and rock, including the propagation speed, attenuation characteristics and energy dissipation of stress waves, and output the calculation results, and describe the interference effects of various types of stress waves;

[0076] S4. Verify the reliability of the proposed model in predicting stress wave propagation characteristics by comparing it with actual earthquake data or industrial test data;

[0077] S5. Based on the verification results, change the model parameters, re-perform numerical simulation, observe the changes in model output, evaluate the impact of different parameter changes on model output, and find out the key parameters and their sensitivity.

[0078] The establishment of the stress wave propagation theoretical model includes the following steps:

[0079] According to the actual geological data of coal and rock, Petre l software is used to establish a three-dimensional geometric model, including the geometric shape, cracks, bedding and internal structure of coal and rock;

[0080] Mesh the three-dimensional geometric model to generate finite element or discrete element meshes. For complex coal and rock structures, use unstructured meshes.

[0081] Specifically, the three-dimensional geometric model is meshed to generate a finite element or discrete element mesh, including:

[0082] Extracting first geological data of the actual coal rock, wherein the first geological data includes the number of coal rock layers, the thickness of each layer and the dip angle of the formation;

[0083] Comparing the number of coal and rock layers with a preset threshold value of the number of coal and rock layers;

[0084] Comparing the overall thickness of the coal rock with a preset overall thickness threshold;

[0085] When the number of coal rock layers exceeds a preset coal rock layer number threshold, and the overall thickness of the coal rock does not exceed a preset overall thickness threshold, the geological evaluation coefficient is obtained using the first geological data; otherwise, the three-dimensional geometric model is meshed according to a preset initial mesh density to generate a finite element or discrete element mesh;

[0086] The geological evaluation coefficient is obtained by the following formula:

[0087]

[0088] Where G represents the geological evaluation coefficient; D represents the overall thickness of the coal rock; n represents the number of coal rock layers; H i represents the thickness of the i-th coal layer; A represents the formation dip; H c Indicates the preset reference value of the thickness of each coal layer; D y Indicates the preset overall thickness threshold; n y Indicates the preset coal and rock layer number threshold; H p It represents the average thickness corresponding to the n-layer coal rock;

[0089] Comparing the geological evaluation coefficient with a preset evaluation coefficient threshold;

[0090] When the geological evaluation coefficient is lower than a preset evaluation coefficient threshold, the three-dimensional geometric model is meshed according to a preset initial mesh density to generate a finite element or discrete element mesh;

[0091] When the geological evaluation coefficient is not lower than a preset evaluation coefficient threshold, the grid density is set, and the three-dimensional geometric model is gridded according to the set grid density to generate a finite element or discrete element grid.

[0092] The technical effect of the above technical solution is: the technical solution can adaptively adjust the density of grid division according to the geological characteristics of coal rock (such as the number of coal rock layers, the thickness of each layer, the overall thickness and the formation dip). This adaptability ensures that the grid division can be optimized for specific geological conditions, thereby improving the accuracy and efficiency of the simulation. Through the introduction of the geological evaluation coefficient, the scheme can more accurately evaluate the geological complexity of coal rock. When the geological conditions of coal rock are relatively complex (such as many layers, large thickness changes, large formation dips, etc.), the geological evaluation coefficient will increase accordingly, thereby triggering a finer grid division to improve the accuracy of the simulation. On the contrary, for coal rock with relatively simple geological conditions, a coarser grid division is used to save computing resources. The scheme realizes effective control of the grid division density through the preset coal rock layer number threshold, the overall thickness threshold and the evaluation coefficient threshold. This control method enables computing resources to be dynamically allocated according to the geological complexity of coal rock, which not only avoids unnecessary resource waste, but also ensures the simulation accuracy of key areas. The technical solution is not only suitable for the simulation analysis of coal rock, but can also be extended to the simulation of other geological bodies with complex geological structures. By adjusting the preset thresholds and parameters, the solution can flexibly adapt to different geological conditions and simulation requirements. In the fields of coal and rock mining, underground engineering, etc., this technical solution can provide engineers with more accurate geological simulation results, thereby helping them make more scientific decisions. For example, in the process of coal and rock mining, by simulating the mechanical behavior of coal and rock, potential risks in the mining process can be predicted and corresponding preventive measures can be taken.

[0093] In summary, this technical solution achieves accurate simulation of coal and rock geological characteristics and optimal allocation of computing resources through the introduction of adaptive grid division and geological evaluation coefficients, providing strong support for research and engineering practice in related fields.

[0094] Specifically, when the geological evaluation coefficient is not lower than a preset evaluation coefficient threshold, the grid density is set, including:

[0095] Extracting first geological data of the actual coal rock, wherein the first geological data includes the number of coal rock layers, the thickness of each layer and the dip angle of the formation;

[0096] Extracting second geological data of the actual coal rock, wherein the second geological data includes the number and width of cracks in each layer of coal rock;

[0097] Setting a grid density by using the first geological data and the second geological data in combination with a preset initial grid density;

[0098] The grid density is obtained by the following formula:

[0099]

[0100] Where P represents the grid density; P c represents the critical pressure; P0 represents the preset initial grid density; n represents the number of coal and rock layers; H i represents the thickness of the i-th coal layer; A represents the formation dip; H c represents the preset reference value of the thickness of each coal rock layer; m represents the number of cracks in the i-th coal rock layer; L j represents the crack width corresponding to the jth crack in the i-th coal rock layer; L b represents the standard deviation of the overall fracture width corresponding to the n-layer coal rock; L max Indicates the maximum crack width corresponding to the n-layer coal rock; L bmax Indicates the standard deviation of the crack width of the coal rock layer corresponding to the maximum crack width; L min Indicates the minimum crack width corresponding to the n-layer coal rock; L bmin It represents the standard deviation of the crack width of the cracks existing in the coal rock layer corresponding to the minimum crack width.

[0101] The technical effect of the above technical solution is: the technical solution not only considers the basic geological data of coal rock (such as the number of coal rock layers, the thickness of each layer and the formation inclination), but also introduces more detailed geological data such as the number of fractures and the width of fractures. This comprehensive consideration makes the setting of the grid density closer to the actual geological situation and improves the accuracy and authenticity of the simulation. By combining the first geological data and the second geological data, the scheme can more accurately evaluate the geological complexity of coal rock. When the geological evaluation coefficient is not lower than the preset threshold, the grid density set according to these comprehensive data can more finely reflect the internal structure and mechanical properties of coal rock, thereby improving the accuracy and reliability of the simulation. The grid density setting in the technical solution is a dynamic process, which is adjusted in real time according to the actual geological data of coal rock. This dynamic adjustment mechanism ensures that the grid division can respond to the complexity and variability of coal rock in a timely manner, and improves the flexibility and adaptability of the simulation. Although the scheme considers more geological factors in the setting of the grid density, it does not increase unnecessary computational burden. On the contrary, by reasonably setting the grid density, the scheme can optimize the allocation of computing resources and improve computing efficiency while ensuring the simulation accuracy. Since the scheme comprehensively considers various geological factors of coal and rock, and dynamically adjusts the grid density according to these factors, the simulation results are closer to the actual geological conditions. This reliability is of great significance for decision-making in the fields of coal and rock mining, underground engineering, etc., and can reduce potential risks and improve engineering safety. This technical solution is not only suitable for the simulation analysis of coal and rock, but can also be extended to the simulation of other geological bodies with similar geological structures and characteristics. By adjusting the preset initial grid density and related parameters, the scheme can flexibly adapt to different geological conditions and simulation requirements.

[0102] In summary, this technical solution achieves accurate simulation of coal and rock geological characteristics and optimal allocation of computing resources by comprehensively considering various geological factors of coal and rock and dynamically adjusting the grid density. This technical solution not only improves the accuracy and reliability of the simulation, but also enhances its scalability and applicability, providing strong support for research and engineering practice in related fields.

[0103] Select one of the linear elastic constitutive relation, elastoplastic constitutive relation and elastic-brittle constitutive relation to describe the mechanical behavior of coal rock, and input the physical and mechanical parameters of coal rock, such as elastic modulus, Poisson's ratio, density, compressive strength and tensile strength;

[0104] Setting the boundary conditions of the model, including at least fixed boundary, free boundary and stress boundary, wherein the fixed boundary can simulate the tunnel wall and the free boundary can simulate the free surface;

[0105] Set the initial stress state of coal and rock, obtain the initial stress distribution through in-situ stress test data, and input it into the model;

[0106] The parameters are set according to the actual impact coal breaking process, including at least the size, direction and time history of the impact load, the impact force and the impact speed.

[0107] The finite element method (FEM) and discrete element method (DEM) are used to solve the model, import the three-dimensional geometric model and mesh, set the material properties, boundary conditions and initial conditions, apply impact loads, run numerical simulations, and record the propagation process of stress waves in coal and rock.

[0108] The stress wave propagation of continuous media and discontinuous media is analyzed respectively, and the stress distribution inside the model is output, including compressive stress and tensile stress; the strain distribution inside the model is output to analyze the deformation; the displacement distribution inside the model is output to analyze the overall deformation of the structure; the energy loss analysis results of the stress wave during propagation are output, including friction dissipation and heat energy conversion; the dynamic response analysis results under impact load are output, including the propagation speed and attenuation characteristics of the stress wave; and the propagation data of the stress wave at different time points are output.

[0109] Describe the interference effects of various types of stress waves, specifically:

[0110] Calculate the propagation and reflection of cylindrical compression waves in coal and rock, calculate the propagation and reflection of plane isochoric waves in coal and rock, calculate the propagation and attenuation of Rayleigh surface waves near the free surface, and calculate the propagation and reflection of Stoneley waves on discontinuous surfaces; in each time step, add up the contributions of all stress waves to obtain the total stress field distribution;

[0111] Analyze the superposition effect of different stress waves at the same location to determine whether constructive interference or destructive interference occurs.

[0112] The effectiveness and reliability of the proposed model are verified by comparing it with actual earthquake data or industrial test data. Specifically:

[0113] Compare the stress wave waveforms obtained from numerical simulation with those in actual seismic data to check the similarity of the waveforms;

[0114] Compare the stress wave amplitudes in numerical simulations and actual data to evaluate the model's ability to predict the amplitude; compare the frequency components in numerical simulations and actual data to check whether the model can accurately predict the spectral characteristics of stress waves; compare the stress wave propagation velocities in numerical simulations and actual data to evaluate the model's accuracy in predicting wave velocity; compare the stress wave attenuation characteristics in numerical simulations and actual data to check whether the model can accurately describe the wave attenuation process; compare the energy dissipation in numerical simulations and actual data to evaluate the model's ability to predict energy dissipation; compare the coal and rock failure modes in numerical simulations and actual data to evaluate the model's ability to predict failure mechanisms.

[0115] The effectiveness and reliability of the proposed model are verified by comparing it with actual earthquake data or industrial test data, including:

[0116] Calculate the mean and variance of numerical simulation results and actual data;

[0117] The correlation coefficient was used to evaluate the correlation between the numerical simulation results and the actual data;

[0118] Calculate the absolute error, relative error, and root mean square error to quantify the prediction accuracy of the model;

[0119] Draw time series graphs, waveform graphs, and spectrum graphs of numerical simulation results and actual data to intuitively display the comparison results.

[0120] Based on the verification results, the model parameters are changed and the numerical simulation is repeated, which specifically includes the following steps:

[0121] Run the benchmark model once and record its output as a reference;

[0122] Set a reasonable range for each selected parameter, elastic modulus range 5GPa to 20GPa, Poisson's ratio range 0.15 to 0.40, density range 1800kg / m 3 Up to 2600kg / m 3, compressive strength ranges from 10MPa to 50MPa, tensile strength ranges from 0.5MPa to 5MPa, crack density ranges from 0.01 to 0.2, impact load ranges from 50kN to 200kN, impact velocity ranges from 1m / s to 10m / s, impact time history ranges from 0.01s to 0.1s, friction coefficient ranges from 0.2 to 0.6, thermal conductivity ranges from 0.5W / (m·K) to 2.0W / (m·K);

[0123] By combining single-factor analysis with multi-factor analysis, the change in model output before and after each parameter change is calculated;

[0124] Record the impact of each parameter change on the model output;

[0125] Calculate the sensitivity index and rank the parameters in importance according to the sensitivity index;

[0126] Explain the reasons for the deviation of model output caused by parameter changes, and improve the model again based on the results of sensitivity analysis.

[0127] Working principle: First, determine the physical and mechanical properties and parameters of coal rock, identify the natural cracks and bedding in coal rock, and evaluate the impact of these characteristics on the overall destruction and damage of coal rock. Then, establish a three-dimensional geometric model containing the internal structure and stress distribution characteristics of coal rock, and perform meshing, select the appropriate constitutive relationship to describe the mechanical behavior of coal rock, and set boundary conditions, initial stress state and impact load.

[0128] The finite element method and discrete element method are used to solve the model, record the propagation process of stress waves in coal and rock, including propagation speed, attenuation characteristics and energy dissipation, and output the results of stress distribution, strain distribution, displacement distribution, etc. By calculating the interference effect of different types of stress waves and analyzing their superposition effect at the same position, it is determined whether constructive interference or destructive interference occurs.

[0129] Finally, the numerical simulation results are compared with actual earthquake data or industrial test data to verify the effectiveness and reliability of the model. Based on the verification results, the model parameters are changed, the numerical simulation is repeated, the changes in model output are observed, the impact of different parameter changes on model output is evaluated, the key parameters and their sensitivity are identified, and the model is optimized.

[0130] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. The terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0131] While the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that many changes, modifications, substitutions and variations can be made to the embodiments without departing from the principles and spirit of the invention.

Claims

1. An analysis method for stress wave propagation law in coal and rock media, characterized in that: The following steps are involved: S1. Determine the physical and mechanical properties and parameters of coal rock, including elastic modulus, Poisson's ratio, density, compressive strength and tensile strength, identify natural cracks and bedding in coal rock, and evaluate the impact of natural cracks and bedding on the overall destruction and damage of coal rock; S2. Establish a stress wave propagation theory model that includes the internal structure and stress distribution characteristics of coal and rock, model various types of stress waves generated during the impact coal breaking process, and set the boundary conditions, initial conditions, impact loads, and initial stress states of coal and rock; S3. Use the finite element method and discrete element method to solve the model, record the propagation process of stress waves in coal and rock, including the propagation speed, attenuation characteristics and energy dissipation of stress waves, output the calculation results, and describe the interference effects of various types of stress waves; S4. Verify the reliability of the proposed model in predicting stress wave propagation characteristics by comparing it with actual earthquake data or industrial test data; S5. Based on the verification results, change the model parameters, re-perform numerical simulation, observe the changes in model output, evaluate the impact of different parameter changes on model output, and find out the key parameters and sensitivities.

2. The method for analyzing the propagation law of stress waves in coal and rock media according to claim 1, characterized in that: The establishment of the stress wave propagation theoretical model comprises the following steps: According to the actual geological data of coal and rock, a three-dimensional geometric model is established, which includes the geometric shape, cracks, bedding and internal structure of coal and rock; Mesh the 3D geometric model and generate finite element or discrete element mesh.

3. The method for analyzing the propagation law of stress waves in coal and rock media according to claim 2, characterized in that: Mesh the 3D geometric model and generate finite element or discrete element meshes, including: Extracting first geological data of the actual coal rock, wherein the first geological data includes the number of coal rock layers, the thickness of each layer and the dip angle of the formation; Comparing the number of coal and rock layers with a preset threshold value of the number of coal and rock layers; Comparing the overall thickness of the coal rock with a preset overall thickness threshold; When the number of coal rock layers exceeds a preset coal rock layer number threshold, and the overall thickness of the coal rock does not exceed a preset overall thickness threshold, the geological evaluation coefficient is obtained using the first geological data; otherwise, the three-dimensional geometric model is meshed according to a preset initial mesh density to generate a finite element or discrete element mesh; The geological evaluation coefficient is obtained by the following formula: Where G represents the geological evaluation coefficient; D represents the overall thickness of the coal rock; n represents the number of coal rock layers; H i represents the thickness of the i-th coal layer; A represents the formation dip; H c Indicates the preset reference value of the thickness of each coal layer; D y Indicates the preset overall thickness threshold; n y Indicates the preset coal and rock layer number threshold; H p It represents the average thickness corresponding to the n-layer coal rock; Comparing the geological evaluation coefficient with a preset evaluation coefficient threshold; When the geological evaluation coefficient is lower than a preset evaluation coefficient threshold, the three-dimensional geometric model is meshed according to a preset initial mesh density to generate a finite element or discrete element mesh; When the geological evaluation coefficient is not lower than a preset evaluation coefficient threshold, the grid density is set, and the three-dimensional geometric model is gridded according to the set grid density to generate a finite element or discrete element grid.

4. The method for analyzing the propagation law of stress waves in coal and rock media according to claim 3, characterized in that: When the geological evaluation coefficient is not lower than the preset evaluation coefficient threshold, the grid density is set, including: Extracting first geological data of the actual coal rock, wherein the first geological data includes the number of coal rock layers, the thickness of each layer and the dip angle of the formation; Extracting second geological data of the actual coal rock, wherein the second geological data includes the number and width of cracks in each layer of coal rock; Setting a grid density by using the first geological data and the second geological data in combination with a preset initial grid density; The grid density is obtained by the following formula: Where P represents the grid density; P c represents the critical pressure; P0 represents the preset initial grid density; n represents the number of coal and rock layers; H i represents the thickness of the i-th coal layer; A represents the formation dip; H c represents the preset reference value of the thickness of each coal rock layer; m represents the number of cracks in the i-th coal rock layer; L j represents the crack width corresponding to the jth crack in the i-th coal rock layer; L b represents the standard deviation of the overall fracture width corresponding to the n-layer coal rock; L max Indicates the maximum crack width corresponding to the n-layer coal rock; L bmax Indicates the standard deviation of the crack width of the coal rock layer corresponding to the maximum crack width; L min Indicates the minimum crack width corresponding to the n-layer coal rock; L bmin It represents the standard deviation of the crack width of the cracks existing in the coal rock layer corresponding to the minimum crack width.

5. The method for analyzing the propagation law of stress waves in coal and rock media according to claim 2, characterized in that: The establishment of the stress wave propagation theoretical model also includes the following steps: Select one of the linear elastic constitutive relation, elastic-plastic constitutive relation and elastic-brittle constitutive relation to describe the mechanical behavior of coal rock, and input the physical and mechanical parameters of coal rock; Set the boundary conditions of the model, including at least fixed boundary, free boundary and stress boundary; Set the initial stress state of coal and rock, and obtain the initial stress distribution through in-situ stress test data; The parameters are set according to the actual impact coal breaking process, including at least the size, direction and time history of the impact load, the impact force and the impact speed.

6. The method for analyzing the propagation law of stress waves in coal and rock media according to claim 5, characterized in that: The finite element method and discrete element method are used to solve the model, and the stress distribution inside the model is output, including compressive stress and tensile stress; the strain distribution inside the model is output to analyze the deformation; the displacement distribution inside the model is output to analyze the overall deformation of the structure; Output the energy loss analysis results of stress waves during propagation, including friction dissipation and heat energy conversion; Output the dynamic response analysis results under impact load, including the propagation speed and attenuation characteristics of stress waves; Output stress wave propagation data at different time points.

7. The method for analyzing the propagation law of stress waves in coal and rock media according to claim 6, characterized in that: The interference effects of various types of stress waves are described as follows: Calculate the propagation and reflection of cylindrical compression waves in coal and rock, calculate the propagation and reflection of plane isochoric waves in coal and rock, calculate the propagation and attenuation of Rayleigh surface waves near the free surface, and calculate the propagation and reflection of Stoneley waves on discontinuous surfaces; in each time step, add up the contributions of all stress waves to obtain the total stress field distribution; Analyze the superposition effect of different stress waves at the same location to determine whether constructive interference or destructive interference occurs.

8. The method for analyzing the propagation law of stress waves in coal and rock media according to claim 7, characterized in that: The effectiveness and reliability of the proposed model are verified by comparing it with actual earthquake data or industrial test data. Specifically: Compare the stress wave waveforms obtained from numerical simulation with those in actual seismic data to check the similarity of the waveforms; Compare the stress wave amplitudes in numerical simulations and actual data to evaluate the model's ability to predict the amplitudes; Compare the frequency components in numerical simulations and actual data to check whether the model can accurately predict the spectral characteristics of stress waves; Compare the stress wave propagation velocities in numerical simulations and actual data to evaluate the accuracy of the model's prediction of wave velocity; Compare the stress wave attenuation characteristics in numerical simulations and actual data to check whether the model can accurately describe the wave attenuation process; Compare the energy dissipation in numerical simulations and actual data to evaluate the model's ability to predict energy dissipation; The coal-rock failure patterns in numerical simulations and actual data are compared to evaluate the model's ability to predict the failure mechanism.

9. The method for analyzing the propagation law of stress waves in coal and rock media according to claim 8, characterized in that: The effectiveness and reliability of the proposed model are verified by comparing it with actual earthquake data or industrial test data, including: Calculate the mean and variance of numerical simulation results and actual data; The correlation coefficient was used to evaluate the correlation between the numerical simulation results and the actual data; Calculate the absolute error, relative error, and root mean square error to quantify the prediction accuracy of the model; Draw time series graphs, waveform graphs, and spectrum graphs of numerical simulation results and actual data to intuitively display the comparison results.

10. The method for analyzing the propagation law of stress waves in coal and rock media according to claim 9, characterized in that: Based on the verification results, the model parameters are changed and the numerical simulation is repeated, which specifically includes the following steps: Run the benchmark model once and record the output for reference; Set a reasonable range of variation for each selected parameter; By combining single-factor analysis with multi-factor analysis, the change in model output before and after each parameter change is calculated; Record the impact of each parameter change on the model output; Calculate the sensitivity index and rank the parameters in importance according to the sensitivity index; Explain the reasons for the deviation of model output caused by parameter changes, and improve the model again based on the results of sensitivity analysis.

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