A tunnel blasting simulation method and system for karst areas

Abstract

The present invention discloses a tunnel blasting simulation method and system for karst areas, which relates to the field of tunnel blasting simulation. The method comprises: establishing a three-dimensional geological model of the karst area, generating the initial geostress distribution law through numerical simulation; generating refined initial geostress field data; calculating the stress wave intensity and time series data generated by the explosion; obtaining stress wave propagation data; calculating the degree of surrounding rock damage and the initial position and direction of the crack; simulating the surrounding rock crack propagation process, and calculating the crack penetration probability and propagation speed near the cave in combination with cave characteristic parameters; analyzing the surrounding rock stability and damage evolution trend in the cave area; optimizing the explosive blast source term parameters and stress wave propagation boundary conditions, and generating tunnel blasting simulation results in the karst area. By accurately simulating the influence of caves on stress wave propagation, the present invention provides strong support for optimizing blasting plans and improving construction safety and efficiency, and has important guiding significance for tunnel engineering under complex geological conditions.

Description

Technical Field

[0001] The present invention belongs to the technical field of tunnel blasting simulation, and in particular relates to a tunnel blasting simulation method and system for karst areas. Background Art

[0002] Applying initial in-situ stress is a critical step in tunnel blasting simulations in karst areas. This application must accurately reflect the stress state before tunnel excavation to ensure simulation accuracy. However, the complex geological conditions in karst areas, coupled with the presence of karst caves, result in a non-uniform distribution of initial in-situ stress. Stress concentration is significant near karst caves, requiring more sophisticated application of the initial in-situ stress. Inaccurate application of the initial in-situ stress can lead to significant deviations in subsequent blasting simulation results, failing to accurately reflect the stress wave propagation and surrounding rock damage during the blasting process. Simulating explosive blasting is a technical challenge in establishing the source term for the blasting process. The propagation of stress waves and blasting gases generated by explosive blasting in the surrounding rock is significantly affected by karst caves. The presence of karst caves alters the propagation path and intensity of stress waves, leading to reflection, refraction, and scattering of stress waves near karst caves. These phenomena complicate the propagation of stress waves, making them difficult to accurately simulate. Furthermore, the flow behavior of blasting gases in karst caves differs from that in intact surrounding rock, further complicating simulation. When simulating stress wave propagation and surrounding rock damage, the impact of caves on the blasting process requires special attention. The propagation of stress waves near caves can lead to stress concentration effects, significantly increasing the degree of damage to the surrounding rock near the caves. However, the shape, size, and distribution of caves have different effects on stress wave propagation and surrounding rock damage, which requires detailed analysis of different cave characteristics during the simulation process. In addition, the damage mechanism of surrounding rock under the action of stress waves is complex, including processes such as crack generation, expansion, and penetration, which are more intense near caves. Therefore, it is necessary to accurately capture these damage mechanisms during the simulation process to ensure the reliability of the simulation results. Summary of the Invention

[0003] To solve the above-mentioned technical problems, the present invention proposes a tunnel blasting simulation method and system for karst areas. By accurately simulating the influence of karst caves on stress wave propagation, high-precision simulation of the tunnel blasting process in karst areas is achieved, which provides strong support for optimizing blasting plans and improving construction safety and efficiency. It has important guiding significance for tunnel engineering under complex geological conditions.

[0004] To achieve the above-mentioned object, the present invention provides a tunnel blasting simulation method for karst areas, comprising: establishing a three-dimensional geological model of the karst area, extracting characteristic parameters of cave distribution, shape and size, and generating initial ground stress distribution law through numerical simulation;

[0005] Based on the initial geostress distribution law, combined with the stress concentration correction coefficient of the cave area and the surrounding rock mechanical parameters, generate refined initial geostress field data;

[0006] Set the explosive explosion source term and calculate the stress wave intensity and time series data generated by the explosion;

[0007] A wave equation solver is used to simulate the reflection, refraction, and scattering of stress waves near caves to obtain stress wave propagation data.

[0008] Calculate the surrounding rock damage degree and the initial crack position and direction based on the stress wave propagation data and in combination with the surrounding rock damage mechanics model;

[0009] Simulate the crack propagation process of the surrounding rock and calculate the crack penetration probability and propagation speed near the cave in combination with the cave characteristic parameters;

[0010] Generate surrounding rock damage distribution maps and analyze surrounding rock stability and damage evolution trends in the cave area based on initial geostress field data;

[0011] Based on the damage evolution trend, the explosive source term parameters and stress wave propagation boundary conditions are optimized to generate tunnel blasting simulation results in the karst area.

[0012] Optionally, establishing a three-dimensional geological model of the karst area includes: constructing a three-dimensional geological body model based on geological exploration data using the Kriging interpolation method, extracting the cave boundaries through a threshold segmentation method, and dividing the grid units to establish a numerical simulation calculation domain.

[0013] Optionally, generating refined initial geostress field data includes: applying a stress concentration correction coefficient to the initial geostress in the area near the cave, and smoothing stress values ​​exceeding a threshold value by an interpolation algorithm.

[0014] Optionally, setting the explosive explosion source item includes: calculating time series data of stress wave intensity attenuation over time based on explosive equivalent, detonation method and detonation gas flow characteristics.

[0015] Optionally, simulating stress wave propagation includes defining cave boundary conditions in a wave equation solver, and calculating propagation paths of stress wave reflection, refraction, and scattering in combination with elastic modulus, density, and Poisson's ratio parameters.

[0016] Optionally, calculating the degree of surrounding rock damage includes: determining the initial position of the crack and extracting the propagation direction based on time series data of stress wave intensity values ​​in combination with a damage factor model.

[0017] Optionally, simulating the surrounding rock crack propagation process includes: analyzing the stress state at the crack tip using the maximum circumferential stress criterion, and predicting the crack penetration probability and propagation speed in combination with the cave spacing and shape parameters.

[0018] Optionally, analyzing the surrounding rock stability includes: superimposing the surrounding rock damage distribution map with the initial ground stress field, combining the crack density and stress concentration area data, and determining the surrounding rock instability risk level.

[0019] Optionally, optimizing the explosive source parameters includes adjusting the charge amount and detonation sequence according to the surrounding rock damage evolution trend, and setting free boundary and fixed boundary conditions to correct the simulation results.

[0020] On the other hand, to achieve the above-mentioned purpose, the present invention also provides a tunnel blasting simulation system for karst areas, comprising: a three-dimensional geological modeling module, an initial geostress field generation module, an explosive explosion simulation module, a stress wave propagation simulation module, a surrounding rock damage calculation module, a crack propagation simulation module, a surrounding rock stability analysis module, and a blasting simulation optimization module;

[0021] The three-dimensional geological modeling module is used to establish a three-dimensional geological model of the karst area, extract characteristic parameters of cave distribution, shape and size, and generate initial geostress distribution law through numerical simulation;

[0022] The initial geostress field generation module is used to generate refined initial geostress field data based on the initial geostress distribution law, combined with the stress concentration correction coefficient of the cave area and the surrounding rock mechanical parameters;

[0023] The explosive explosion simulation module is used to set the explosive explosion source term and calculate the stress wave intensity and time series data generated by the explosion;

[0024] The stress wave propagation simulation module is used to simulate the reflection, refraction and scattering phenomena of stress waves near the cave using a wave equation solver to obtain stress wave propagation data;

[0025] The surrounding rock damage calculation module is used to calculate the surrounding rock damage degree and the initial crack position and direction based on the stress wave propagation data in combination with the surrounding rock damage mechanics model;

[0026] The crack propagation simulation module is used to simulate the crack propagation process of the surrounding rock and calculate the crack penetration probability and propagation speed near the cave in combination with the cave characteristic parameters;

[0027] The surrounding rock stability analysis module is used to generate a surrounding rock damage distribution map and analyze the surrounding rock stability and damage evolution trend in the cave area in combination with the initial ground stress field data;

[0028] The blasting simulation optimization module is used to optimize the explosive source term parameters and stress wave propagation boundary conditions based on the damage evolution trend to generate blasting simulation results for tunnels in karst areas.

[0029] Technical effect of the present invention: The present invention discloses a tunnel blasting simulation method and system for karst areas. First, a three-dimensional geological model is established based on geological exploration data, characteristic parameters of the cave are extracted, and the non-uniform initial ground stress distribution is obtained through numerical simulation. Then, the explosive explosion source term is set to simulate the propagation characteristics of the stress wave near the cave, and the degree of surrounding rock damage and the crack propagation process are calculated. By analyzing the stability of the surrounding rock and the damage evolution trend, the blasting parameter setting is optimized. The present invention realizes high-precision simulation of the tunnel blasting process in the karst area by accurately simulating the influence of the cave on the propagation of stress waves, which provides strong support for optimizing the blasting plan and improving construction safety and efficiency, and has important guiding significance for tunnel engineering under complex geological conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of this application. The exemplary embodiments and descriptions of this application are intended to explain this application and do not constitute an improper limitation on this application. In the accompanying drawings:

[0031] Figure 1 This is a flow chart of a tunnel blasting simulation method for karst areas according to an embodiment of the present invention;

[0032] Figure 2 The figure is a schematic structural diagram of a tunnel blasting simulation system for karst areas according to an embodiment of the present invention. DETAILED DESCRIPTION

[0033] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0034] It should be noted that the steps shown in the flowcharts of the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and that, although a logical order is shown in the flowcharts, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0035] like Figure 1 As shown, this embodiment provides a tunnel blasting simulation method for karst areas, including:

[0036] Establish a three-dimensional geological model of the karst area, extract the characteristic parameters of cave distribution, shape and size, and generate the initial ground stress distribution law through numerical simulation;

[0037] Based on the initial geostress distribution law, combined with the stress concentration correction coefficient of the cave area and the surrounding rock mechanical parameters, generate refined initial geostress field data;

[0038] Set the explosive explosion source term and calculate the stress wave intensity and time series data generated by the explosion;

[0039] A wave equation solver is used to simulate the reflection, refraction, and scattering of stress waves near caves to obtain stress wave propagation data.

[0040] Calculate the surrounding rock damage degree and the initial crack position and direction based on the stress wave propagation data and in combination with the surrounding rock damage mechanics model;

[0041] Simulate the crack propagation process of the surrounding rock and calculate the crack penetration probability and propagation speed near the cave in combination with the cave characteristic parameters;

[0042] Generate surrounding rock damage distribution maps and analyze surrounding rock stability and damage evolution trends in the cave area based on initial geostress field data;

[0043] Based on the damage evolution trend, the explosive source term parameters and stress wave propagation boundary conditions are optimized to generate tunnel blasting simulation results in the karst area.

[0044] Furthermore, establishing a three-dimensional geological model of the karst area includes: constructing a three-dimensional geological body model based on geological exploration data using the Kriging interpolation method, extracting the cave boundary through the threshold segmentation method, and dividing the grid units to establish a numerical simulation calculation domain.

[0045] Specifically, 3D modeling can use Kriging interpolation to process discrete point data, building a geological model based on this data. For example, in a limestone region, a 3D geological model containing multi-layered lithologic structures was generated by processing 120 drill hole data points, clearly demonstrating the spatial distribution of karst cave zones. When identifying karst cave boundaries, threshold segmentation is often used to extract cave contours. In one engineering case, a density threshold method was used to successfully identify clusters of karst caves ranging in diameter from 0.5 to 5 meters, and their shape parameters, including their orientation and extension, were obtained. Meshing is a key step in numerical simulation. In a specific karst cave cluster area, a tetrahedral mesh was used to segment the complex geological volume, with the mesh refined around the caves, generating approximately 200,000 mesh elements to ensure computational accuracy. The anisotropic characteristics of the rock mass must be considered when calculating non-uniform stress fields. Finite element analysis in one case revealed stress concentration in the cave roof, with the maximum principal stress reaching three times the in-situ rock stress, indicating a risk of instability in the area. The outliers in the stress distribution are processed using cubic spline interpolation, achieving a smooth transition in the stress field. In a cave cluster example, interpolation correction eliminates singular values ​​in the calculated results, making the stress distribution more consistent with the actual situation.

[0046] Furthermore, generating refined initial geostress field data includes applying a stress concentration correction coefficient to the initial geostress in the area near the cave, and smoothing stress values ​​exceeding a threshold value by an interpolation algorithm.

[0047] Specifically, for a karst region, when the surrounding rock is moderately weathered limestone, its elastic modulus is approximately 20 GPa, its Poisson's ratio is 0.28, and its uniaxial compressive strength is 60 MPa. These parameters directly influence stress distribution characteristics. For example, a larger elastic modulus results in faster stress transmission and more pronounced stress concentration. The stress threshold should be determined based on engineering practice and a safety factor. In the aforementioned example, 70% of the uniaxial compressive strength, or 42 MPa, can be used as the stress threshold. When the calculated stress exceeds this value, stress field smoothing is required. Using the Kriging interpolation algorithm to smooth the stress field effectively eliminates sudden stress fluctuations and achieves a more reasonable stress distribution. The range of the non-uniform stress field distribution must be determined based on the influence of the cave. Three times the diameter of the cave is used as the boundary of the influence range. For the aforementioned 10-meter diameter cave, the influence range is 30 meters. Within this range, a mesh is created, with the mesh size gradually finer from the outside inward. The mesh size near the cave can be 0.5 meters, while the mesh size at the periphery can be 2 meters. Setting boundary conditions is crucial in finite element calculations. Gravity stress is applied vertically, while horizontal stress is applied based on measured geostress values. For a cave at a depth of 100 meters, vertical stress is approximately 2.7 MPa, while horizontal stress can reach 4 to 6 MPa. Identifying areas of stress concentration requires focusing on the cave's vault and floor.

[0048] Furthermore, setting the explosive explosion source term includes: calculating the time series data of the stress wave intensity attenuating over time based on the explosive equivalent, the detonation method and the flow characteristics of the explosive gas flow.

[0049] Specifically, the explicit dynamic finite element method is used to calculate the stress wave distribution. During the simulation process, the time step is set to one microsecond to ensure the stability of the calculation. The reflection, refraction and superposition effects of the waves in different media are analyzed through the propagation law of stress waves. For example, at the boundary of the cave, due to the difference in medium impedance, obvious stress wave reflection and diffraction phenomena will occur. The judgment of the stress wave concentration area is mainly based on the stress wave amplitude and duration. At characteristic locations such as the top and bottom of the cave, stress wave focusing often occurs, resulting in local stress concentration. For example, when the local stress exceeds twice the average value of the surrounding area, it can be determined as a stress concentration area. The time series data of these areas need to be recorded and analyzed in detail to provide a basis for engineering design and safety assessment.

[0050] Furthermore, simulating stress wave propagation includes defining cave boundary conditions in a wave equation solver, and calculating the propagation paths of stress wave reflection, refraction, and scattering by combining elastic modulus, density, and Poisson's ratio parameters.

[0051] Specifically, when dividing the grid in the simulation domain, it is necessary to select an appropriate grid size based on the geometric characteristics of the cave. For a cave with a diameter of 10 meters, the grid size can be set to 0.5 meters, which can ensure the calculation accuracy while taking into account the calculation efficiency. The setting of the initial stress wave field usually uses a Gaussian function to describe the waveform, and the amplitude and frequency of the waveform need to match the actual engineering situation. The reflection and refraction of stress waves on the cave wall is a key research object. When the incident wave reaches the surface of the cave, part of the energy is reflected, and part of the energy continues to propagate and is scattered multiple times inside the cave. By recording the spatiotemporal evolution of the wave field, the propagation path of the stress wave around the cave can be obtained.

[0052] Furthermore, the calculation of the surrounding rock damage degree includes: judging the initial crack position and extracting the propagation direction based on the time series data of the stress wave intensity value in combination with the damage factor model.

[0053] Specifically, stress wave propagation path data reflects the changing characteristics of stress waves in the cave region. By analyzing the amplitude and frequency characteristics of the waveform curve, a series of intensity values ​​at different moments is obtained. For example, during the propagation of a certain cave project, the stress wave intensity gradually decays from an initial 100 MPa to 50 MPa, exhibiting a typical exponential decay characteristic. The mechanical model of the surrounding rock mass must account for its anisotropy and heterogeneity, and a damage factor is introduced into the model to characterize the degree of damage. For example, in a limestone cave, the rock mass has a compressive strength of 80 MPa. When the stress wave intensity exceeds 40 MPa, microcracks begin to appear, and the damage intensity increases nonlinearly. The damage intensity distribution is directly related to the crack initiation location, and the stress intensity factor is used to determine the crack propagation direction. In actual engineering, the cave roof and sidewalls are often areas of stress concentration. When the damage intensity exceeds 0.6, through-going cracks are highly likely to form in these areas. The intensity value adjustment uses a cubic spline interpolation algorithm to ensure numerical stability.

[0054] Furthermore, the simulation of the surrounding rock crack propagation process includes: using the maximum circumferential stress criterion to analyze the stress state at the crack tip, combining the spacing and shape parameters of the caves, and predicting the crack penetration probability and propagation speed.

[0055] Specifically, crack propagation algorithms are important tools for studying crack development in surrounding rock. Commonly used methods include the maximum circumferential stress criterion and the maximum energy release rate criterion. Taking the maximum circumferential stress criterion as an example, crack propagation begins when the circumferential stress at the crack tip reaches a critical value. In practical applications, stress monitoring points can be placed at the crack tip to record the stress evolution over time and obtain crack propagation path data. Cave characteristic parameters include cave size, shape, and distribution density. For example, in a limestone region, underground caves have an average diameter of 3 meters and are distributed in an elliptical shape, with cave spacing of approximately 15 meters. By analyzing the spatial relationship between the crack propagation path and the caves, the crack penetration probability can be calculated. When the penetration probability in an area with dense cave clusters reaches 0.8, exceeding the preset threshold of 0.6, interpolation and adjustment of the cave characteristic parameters in that area are required. The crack propagation rate is closely related to the stress state and rock mass properties of the surrounding rock. For example, in a mining area, the surrounding rock is primarily composed of granite. An initial crack length of 0.5 meters is observed. Under dynamic load, the crack growth rate gradually increases from 0.1 meters per second to 0.5 meters per second. By plotting the velocity distribution, the changes in crack growth speed can be visualized.

[0056] Furthermore, the analysis of surrounding rock stability includes: superimposing the surrounding rock damage distribution map with the initial ground stress field, combining the crack density and stress concentration area data to determine the surrounding rock instability risk level.

[0057] Furthermore, the optimization of explosive source parameters includes adjusting the charge amount and detonation sequence according to the evolution trend of surrounding rock damage, and setting free boundary and fixed boundary conditions to correct the simulation results.

[0058] Specifically, under the complex geological conditions of karst areas, millisecond delayed detonation technology was employed, with the detonation time difference between adjacent blastholes set to 25 milliseconds, effectively controlling vibrations in the surrounding rock mass. Regarding boundary conditions, a free boundary was set at the tunnel excavation face, while fixed constraints were applied to the remaining boundaries to simulate real-world geological conditions. Stress wave propagation analysis revealed that stress concentration areas in the surrounding rock primarily occur at the cave roof and sidewalls. Actual case studies show that the stress concentration factor at the cave roof reaches 2.5, far exceeding the critical value of 1.8. Combined with crack growth data, it was found that when the stress concentration factor at the top exceeds 2.0, microcracks begin to extend and connect, forming through-hole fractures. Analysis of surrounding rock properties indicates that in areas with cave development, the compressive strength of the rock mass generally decreases by 30%. During stress wave propagation, these weakened areas are prone to stress concentration. For example, in a tunnel cave area, the original rock mass compressive strength was 80 MPa, but this was reduced to 56 MPa due to dissolution, leading to new crack propagation under the action of stress waves. By optimizing blasting parameters, surrounding rock damage was controlled while ensuring excavation efficiency. Practice has proven that using smooth blasting technology, which reduces the charge in peripheral holes by 40%, effectively controls overexcavation and surrounding rock disturbance. Simultaneously, adjusting the detonation network and adopting a two-way central delayed detonation scheme can reduce blasting vibration by 25%. Damage evolution analysis shows that surrounding rock damage tends to spread from shallow to deep, and from the periphery inward. In areas with developed caves, damage depth can reach up to 2 meters beyond the excavation outline. By adjusting blasting parameters, damage depth was controlled to less than 1 meter, significantly improving the surrounding rock's self-stabilization capacity. Final simulation results demonstrate that the optimized blasting scheme both ensures excavation efficiency and effectively controls surrounding rock damage.

[0059] like Figure 2 As shown, this embodiment also provides a tunnel blasting simulation system for karst areas, including: a three-dimensional geological modeling module, an initial geostress field generation module, an explosive explosion simulation module, a stress wave propagation simulation module, a surrounding rock damage calculation module, a crack propagation simulation module, a surrounding rock stability analysis module, and a blasting simulation optimization module;

[0060] The three-dimensional geological modeling module is used to establish a three-dimensional geological model of the karst area, extract characteristic parameters of cave distribution, shape and size, and generate initial geostress distribution law through numerical simulation;

[0061] The initial geostress field generation module is used to generate refined initial geostress field data based on the initial geostress distribution law, combined with the stress concentration correction coefficient of the cave area and the surrounding rock mechanical parameters;

[0062] The explosive explosion simulation module is used to set the explosive explosion source term and calculate the stress wave intensity and time series data generated by the explosion;

[0063] The stress wave propagation simulation module is used to simulate the reflection, refraction and scattering phenomena of stress waves near the cave using a wave equation solver to obtain stress wave propagation data;

[0064] The surrounding rock damage calculation module is used to calculate the surrounding rock damage degree and the initial crack position and direction based on the stress wave propagation data in combination with the surrounding rock damage mechanics model;

[0065] The crack propagation simulation module is used to simulate the crack propagation process of the surrounding rock and calculate the crack penetration probability and propagation speed near the cave in combination with the cave characteristic parameters;

[0066] The surrounding rock stability analysis module is used to generate a surrounding rock damage distribution map and analyze the surrounding rock stability and damage evolution trend in the cave area in combination with the initial ground stress field data;

[0067] The blasting simulation optimization module is used to optimize the explosive source term parameters and stress wave propagation boundary conditions based on the damage evolution trend to generate blasting simulation results for tunnels in karst areas.

[0068] The present invention discloses a tunnel blasting simulation method and system for karst areas. First, a three-dimensional geological model is established based on geological exploration data, characteristic parameters of karst caves are extracted, and the non-uniform initial ground stress distribution is obtained through numerical simulation. Then, the explosive explosion source term is set to simulate the propagation characteristics of stress waves near the karst caves, and the degree of surrounding rock damage and the crack propagation process are calculated. By analyzing the stability of the surrounding rock and the damage evolution trend, the blasting parameter setting is optimized. By accurately simulating the influence of karst caves on stress wave propagation, the present invention realizes high-precision simulation of the tunnel blasting process in karst areas, provides strong support for optimizing blasting plans and improving construction safety and efficiency, and has important guiding significance for tunnel engineering under complex geological conditions.

[0069] The above are merely preferred embodiments of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A tunnel blasting simulation method for karst areas, characterized in that: include: Establish a three-dimensional geological model of the karst area, extract the characteristic parameters of cave distribution, shape and size, and generate the initial ground stress distribution law through numerical simulation; Based on the initial geostress distribution law, combined with the stress concentration correction coefficient of the cave area and the surrounding rock mechanical parameters, generate refined initial geostress field data; Set the explosive explosion source term and calculate the stress wave intensity and time series data generated by the explosion; Setting the explosive source term includes: calculating the time series data of stress wave intensity decaying with time based on the explosive equivalent, detonation method and detonation gas flow characteristics; A wave equation solver is used to simulate the reflection, refraction, and scattering of stress waves near the cave to obtain stress wave propagation data. Stress wave propagation simulation includes defining cave boundary conditions in the wave equation solver and calculating the propagation paths of stress wave reflection, refraction, and scattering by combining elastic modulus, density, and Poisson's ratio parameters. Based on the stress wave propagation data and in combination with the surrounding rock damage mechanics model, the surrounding rock damage degree and the initial crack position and direction are calculated; the calculation of the surrounding rock damage degree includes: based on the time series data of the stress wave intensity value and in combination with the damage factor model, determining the initial crack position and extracting the propagation direction; Simulate the crack propagation process of the surrounding rock and calculate the crack penetration probability and propagation speed near the cave in combination with the cave characteristic parameters; Generate surrounding rock damage distribution maps and analyze surrounding rock stability and damage evolution trends in the cave area based on initial geostress field data; Based on the damage evolution trend, the explosive source term parameters and stress wave propagation boundary conditions are optimized to generate tunnel blasting simulation results in the karst area.

2. The tunnel blasting simulation method for karst areas according to claim 1, characterized in that: Establishing a three-dimensional geological model of the karst area includes: constructing a three-dimensional geological model based on geological exploration data using the Kriging interpolation method, extracting the cave boundaries through the threshold segmentation method, and dividing the grid units to establish a numerical simulation calculation domain.

3. The tunnel blasting simulation method for karst areas according to claim 1, characterized in that: Generating refined initial geostress field data includes: applying a stress concentration correction coefficient to the initial geostress in the area near the cave, and smoothing the stress values ​​exceeding the threshold through an interpolation algorithm.

4. The tunnel blasting simulation method for karst areas according to claim 1, characterized in that: The simulation of surrounding rock crack propagation process includes: using the maximum circumferential stress criterion to analyze the stress state at the crack tip, combining the spacing and shape parameters of the caves, and predicting the crack penetration probability and propagation speed.

5. The tunnel blasting simulation method for karst areas according to claim 1, characterized in that: Analyzing the surrounding rock stability includes: superimposing the surrounding rock damage distribution map with the initial ground stress field, combining the crack density and stress concentration area data to determine the surrounding rock instability risk level.

6. The tunnel blasting simulation method for karst areas according to claim 1, characterized in that: Optimizing the explosive source parameters includes adjusting the charge and detonation sequence according to the evolution trend of surrounding rock damage, and setting free boundary and fixed boundary conditions to correct the simulation results.

7. A system for simulating tunnel blasting in karst areas according to any one of claims 1 to 6, characterized in that: include: 3D geological modeling module, initial geostress field generation module, explosive blast simulation module, stress wave propagation simulation module, surrounding rock damage calculation module, crack propagation simulation module, surrounding rock stability analysis module and blasting simulation optimization module; The three-dimensional geological modeling module is used to establish a three-dimensional geological model of the karst area, extract characteristic parameters of cave distribution, shape and size, and generate initial geostress distribution law through numerical simulation; The initial geostress field generation module is used to generate refined initial geostress field data based on the initial geostress distribution law, combined with the stress concentration correction coefficient of the cave area and the surrounding rock mechanical parameters; The explosive explosion simulation module is used to set the explosive explosion source term and calculate the stress wave intensity and time series data generated by the explosion; The stress wave propagation simulation module is used to simulate the reflection, refraction and scattering phenomena of stress waves near the cave using a wave equation solver to obtain stress wave propagation data; The surrounding rock damage calculation module is used to calculate the surrounding rock damage degree and the initial crack position and direction based on the stress wave propagation data in combination with the surrounding rock damage mechanics model; The crack propagation simulation module is used to simulate the crack propagation process of the surrounding rock and calculate the crack penetration probability and propagation speed near the cave in combination with the cave characteristic parameters; The surrounding rock stability analysis module is used to generate a surrounding rock damage distribution map and analyze the surrounding rock stability and damage evolution trend in the cave area in combination with the initial ground stress field data; The blasting simulation optimization module is used to optimize the explosive source term parameters and stress wave propagation boundary conditions based on the damage evolution trend to generate blasting simulation results for tunnels in karst areas.

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