Quantitative analysis method for blasting cracking mode of jointed rock mass

Abstract

The invention discloses a quantitative analysis method for a jointed rock mass blasting cracking mode, which comprises the following steps: establishing a jointed rock mass blasting stress wave propagation theoretical model, deducing a propagation equation of stress waves in a jointed rock mass, and determining stress wave reflection, transmission and superposition rules; a jointed rock mass blasting numerical model is constructed based on ANSYS / LS-DYNA software, material parameters and state equations of rocks, joints, explosives and air are determined, an RHT damage model is adopted for the rocks and the joints, an MATHIGHEXPLOSIONBURN model is adopted for the explosives and combined with an EOSJWL state equation, and an EOSLINEARPOLYNOMIAL state equation is adopted for the air. According to the method, theoretical derivation, numerical simulation and image quantitative analysis are combined, and quantitative analysis of the blasting cracking mode of the jointed rock mass is achieved. The engineering cost can be effectively reduced, and the blasting effect and the construction safety are improved.

Description

Technical Field

[0001] This invention relates to the field of rock blasting technology, and in particular to a quantitative analysis method for cracking modes in jointed rock mass blasting. Background Technology

[0002] In large-scale engineering projects such as water conservancy and hydropower, and mining, the blasting excavation of jointed rock masses is a critical construction step. Joints, as naturally occurring fissures in rock masses, significantly affect the propagation of blast stress waves and the rock mass blasting cracking mode, thereby impacting construction efficiency, cost, and safety. Currently, research on the blasting cracking mode of jointed rock masses is primarily qualitative, lacking systematic quantitative analysis methods. This makes it difficult to accurately reveal the influence of joint parameters on blasting cracking, resulting in a lack of scientific basis for blasting parameter design in engineering projects and easily leading to problems such as excessively high block ratios, dust pollution, or uneven rock mass damage. Therefore, a quantitative analysis method for the blasting cracking mode of jointed rock masses is urgently needed to provide technical support for engineering practice. Summary of the Invention

[0003] The purpose of this invention is to address the shortcomings of existing technologies by proposing a quantitative analysis method for the blasting cracking mode of jointed rock masses.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: A quantitative analysis method for the cracking mode of jointed rock mass blasting includes the following steps: S1. Establish a theoretical model for the propagation of explosive stress waves in jointed rock mass, derive the propagation equation of stress waves in jointed rock mass, and clarify the laws of stress wave reflection, transmission and superposition. S2. Construct a numerical model for jointed rock mass blasting based on ANSYS / LS-DYNA software, and determine the material parameters and equations of state for rock, joints, explosives and air. The RHT damage model is used for rock and joints, the MAT_HIGH_EXPLOSION_BURN model combined with the EOS_JWL equation of state is used for explosives, and the EOS_LINEAR_POLYNOMIAL equation of state is used for air. S3. Mesh the numerical model, set the overall mesh size to 0.02m, refine the mesh for the boreholes and joints, and apply normal constraints and non-reflection boundary conditions around the model. S4. Set up different joint parameter conditions, including joint-hole spacing, joint width, number of joint layers, joint dip angle, joint density and joint elastic modulus, and carry out blasting numerical simulation to obtain the damage diagram of each condition over time. S5. Use ImageJ software to process the historical damage map. First, perform image preprocessing and noise reduction, and then perform binarization through thresholding to distinguish the damaged area from the undamaged area. S6. Based on the binarized image, statistically analyze the damage area between the joint and the borehole, the area behind the joint, and the crack propagation length and damage area at both ends of the joint. S7. Based on statistical data, analyze the influence of different joint parameters on the blasting cracking mode of jointed rock mass, and realize the quantitative analysis of the blasting cracking mode.

[0005] Preferably, in step S1, when deriving the stress wave propagation equation, the rock is regarded as an elastic medium. Based on the generalized Hooke's law and elasticity theory, the motion equation of elastic wave propagation is established. The wave equation is solved by Laplace transform to obtain the relationship between stress wave propagation and time, distance and joint parameters.

[0006] Preferably, in step S2, the RHT model parameters include density, elastic shear modulus, erosion plastic strain, equation of state parameters, failure surface parameters, uniaxial tensile strength, relative shear strength, relative tensile strength, Rhodes angle correlation coefficient, compaction pressure, crushing pressure, and porosity index, and the RHT model parameters for rocks and joints are set according to the actual rock mass characteristics.

[0007] Preferably, in step S4, the joint-to-bore distance is set to 0.4m, 0.7m, 1m, and 1.3m; the joint width is set to 0.02m, 0.05m, 0.08m, and 0.11m; the number of joint layers is set to 1, 2, 3, and 4 layers with a 0.025m interval between each layer; the joint dip angle is set to 30°, 45°, 60°, and 90°; the joint density is set to 2300kg / m³, 2100kg / m³, 1900kg / m³, and 1700kg / m³; and the joint elastic modulus is set to 16.27GPa, 13.77GPa, 11.27GPa, and 8.77GPa.

[0008] Preferably, in step S5, the image preprocessing uses enhancement processing to achieve the best visualization effect, the noise reduction processing uses a mean filter to remove irrelevant details in the image, and the threshold cutting analyzes the gray-level distribution of the image through gray-level histogram analysis, and scans and marks each pixel as an object or background to achieve image cutting.

[0009] Preferably, in step S6, when calculating the damage area of ​​the region between the joint and the borehole and the region behind the joint, the region is divided with the joint as the boundary. The region between the joint and the borehole is the region from the center of the borehole to the wave-facing side of the joint, and the region behind the joint is the wave-back side of the joint. The crack propagation length at both ends of the joint is obtained by measuring the distance from the borehole to the crack endpoints at both ends of the joint and taking the average value. The crack damage area is directly calculated using the area measurement function built into ImageJ software.

[0010] Preferably, in step S7, the quantitative analysis indicators include the growth rate of damage area in the region between the joint and the borehole, the attenuation rate of damage area in the region behind the joint, the change rate of crack propagation length at both ends of the joint, and the change rate of crack damage area. By comparing the indicator data under different joint parameter conditions, the influence of each parameter on the blasting cracking mode is clarified.

[0011] Preferably, in step S4, when conducting numerical simulation of blasting, the detonation point is set at the middle of the explosive, the simulation time lasts for 0.8 ms, to ensure that the complete rock mass blasting damage process is obtained, and each working condition is simulated at least 3 times, and the average value is taken as the final duration damage data.

[0012] Preferably, in step S7, when analyzing the influence of the joint and borehole spacing on the blasting cracking mode, if the joint and borehole spacing increases from 0.4m to 1.3m, the damage area between the joint and borehole gradually increases and decreases significantly in the range of 1m to 1.3m, the crack propagation length at both ends of the joint gradually increases, and the crack damage area gradually decreases, then it is determined that the increase in the joint and borehole spacing causes the range of cracks generated by the explosive to first increase and then decrease, and the joint's ductility to crack propagation is weakened.

[0013] Compared with the prior art, the beneficial effects of the present invention are: This invention achieves quantitative analysis of the cracking modes in jointed rock mass blasting by combining theoretical derivation, numerical simulation, and image-based quantitative analysis. It systematically reveals the influence of joint parameters on blasting cracking, providing a scientific basis for the design of engineering parameters for jointed rock mass blasting, effectively reducing engineering costs, minimizing environmental pollution, and improving blasting efficiency and construction safety, thus possessing significant engineering application value. Attached Figure Description

[0014] Figure 1 This is a flowchart of a quantitative analysis method for the blasting cracking mode of jointed rock mass proposed in this invention. Detailed Implementation

[0015] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0016] Reference Figure 1 A quantitative analysis method for the blasting cracking mode of jointed rock mass includes the following steps: S1. Establish a theoretical model for the propagation of explosive stress waves in jointed rock mass, derive the propagation equation of stress waves in jointed rock mass, and clarify the laws of stress wave reflection, transmission and superposition. S2. Construct a numerical model for jointed rock mass blasting based on ANSYS / LS-DYNA software, and determine the material parameters and equations of state for rock, joints, explosives and air. The RHT damage model is used for rock and joints, the MAT_HIGH_EXPLOSION_BURN model combined with the EOS_JWL equation of state is used for explosives, and the EOS_LINEAR_POLYNOMIAL equation of state is used for air. S3. Mesh the numerical model, set the overall mesh size to 0.02m, refine the mesh for the boreholes and joints, and apply normal constraints and non-reflection boundary conditions around the model. S4. Set up different joint parameter conditions, including joint-hole spacing, joint width, number of joint layers, joint dip angle, joint density and joint elastic modulus, and carry out blasting numerical simulation to obtain the damage diagram of each condition over time. S5. Use ImageJ software to process the historical damage map. First, perform image preprocessing and noise reduction, and then perform binarization through thresholding to distinguish the damaged area from the undamaged area. S6. Based on the binarized image, statistically analyze the damage area between the joint and the borehole, the area behind the joint, and the crack propagation length and damage area at both ends of the joint. S7. Based on statistical data, analyze the influence of different joint parameters on the blasting cracking mode of jointed rock mass, and realize the quantitative analysis of the blasting cracking mode.

[0017] In step S1, when deriving the stress wave propagation equation, the rock is regarded as an elastic medium. Based on the generalized Hooke's law and elasticity theory, the motion equation of elastic wave propagation is established. The wave equation is solved by Laplace transform to obtain the relationship between stress wave propagation and time, distance and joint parameters.

[0018] In step S2, the RHT model parameters include density, elastic shear modulus, erosion plastic strain, equation of state parameters, failure surface parameters, uniaxial tensile strength, relative shear strength, relative tensile strength, Rhodes angle correlation coefficient, compaction pressure, crushing pressure, and porosity index. The RHT model parameters for rocks and joints are set according to the actual rock mass characteristics.

[0019] In step S4, the joint-to-bore distance is set to 0.4m, 0.7m, 1m, and 1.3m; the joint width is set to 0.02m, 0.05m, 0.08m, and 0.11m; the number of joint layers is set to 1, 2, 3, and 4 layers with a 0.025m interval between each layer; the joint dip angle is set to 30°, 45°, 60°, and 90°; the joint density is set to 2300kg / m³, 2100kg / m³, 1900kg / m³, and 1700kg / m³; and the joint elastic modulus is set to 16.27GPa, 13.77GPa, 11.27GPa, and 8.77GPa.

[0020] In step S5, image preprocessing uses enhancement processing to achieve the best visualization effect, noise reduction processing uses a mean filter to remove irrelevant details in the image, and threshold cutting analyzes the gray-level distribution of the image through gray-level histogram analysis, and scans and marks each pixel as an object or background to achieve image cutting.

[0021] In step S6, when calculating the damage area in the region between the joint and the borehole and the region behind the joint, the region is divided with the joint as the boundary. The region between the joint and the borehole is the region from the center of the borehole to the wave-facing side of the joint, and the region behind the joint is the region on the back wave side of the joint. The crack propagation length at both ends of the joint is obtained by measuring the distance from the borehole to the crack endpoints at both ends of the joint and taking the average value. The crack damage area is directly calculated using the area measurement function built into ImageJ software.

[0022] In step S7, the quantitative analysis indicators include the growth rate of damage area in the region between the joint and the borehole, the attenuation rate of damage area in the region behind the joint, the change rate of crack propagation length at both ends of the joint, and the change rate of crack damage area. By comparing the indicator data under different joint parameter conditions, the influence of each parameter on the blasting cracking mode is clarified.

[0023] In step S4, when conducting numerical simulation of blasting, the detonation point is set to be located in the middle of the explosive, and the simulation time lasts for 0.8 ms to ensure that the complete rock mass blasting damage process is obtained. Each working condition is simulated at least 3 times, and the average value is taken as the final duration damage data.

[0024] In step S7, when analyzing the influence of the joint and borehole spacing on the blasting cracking mode, if the joint and borehole spacing increases from 0.4m to 1.3m, the damage area between the joint and borehole gradually increases and decreases significantly in the range of 1m to 1.3m, the crack propagation length at both ends of the joint gradually increases, and the crack damage area gradually decreases, then it is determined that the increase in the joint and borehole spacing causes the range of cracks generated by the explosive to first increase and then decrease, and the joint's ductility to crack propagation is weakened.

[0025] This invention achieves quantitative analysis of the cracking modes in jointed rock mass blasting by combining theoretical derivation, numerical simulation, and image-based quantitative analysis. It systematically reveals the influence of joint parameters on blasting cracking, providing a scientific basis for the design of engineering parameters for jointed rock mass blasting, effectively reducing engineering costs, minimizing environmental pollution, and improving blasting efficiency and construction safety, thus possessing significant engineering application value.

[0026] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A quantitative analysis method for the cracking mode of jointed rock mass blasting, characterized in that, Includes the following steps: S1. Establish a theoretical model for the propagation of explosive stress waves in jointed rock mass, derive the propagation equation of stress waves in jointed rock mass, and clarify the laws of stress wave reflection, transmission and superposition. S2. Construct a numerical model for jointed rock mass blasting based on ANSYS / LS-DYNA software, and determine the material parameters and equations of state for rock, joints, explosives and air. The RHT damage model is used for rock and joints, the MAT_HIGH_EXPLOSION_BURN model combined with the EOS_JWL equation of state is used for explosives, and the EOS_LINEAR_POLYNOMIAL equation of state is used for air. S3. Mesh the numerical model, set the overall mesh size to 0.02m, refine the mesh for the boreholes and joints, and apply normal constraints and non-reflection boundary conditions around the model. S4. Set up different joint parameter conditions, including joint-hole spacing, joint width, number of joint layers, joint dip angle, joint density and joint elastic modulus, and carry out blasting numerical simulation to obtain the damage diagram of each condition over time. S5. Use ImageJ software to process the historical damage map. First, perform image preprocessing and noise reduction, and then perform binarization through thresholding to distinguish the damaged area from the undamaged area. S6. Based on the binarized image, statistically analyze the damage area in the region between the joint and the borehole, the region behind the joint, and the crack propagation length and damage area at both ends of the joint. S7. Based on statistical data, analyze the influence of different joint parameters on the blasting cracking mode of jointed rock mass, and realize the quantitative analysis of the blasting cracking mode.

2. The quantitative analysis method for the blasting cracking mode of jointed rock mass according to claim 1, characterized in that, In step S1, when deriving the stress wave propagation equation, the rock is regarded as an elastic medium. Based on the generalized Hooke's law and elasticity theory, the motion equation of elastic wave propagation is established. The wave equation is solved by Laplace transform to obtain the relationship between stress wave propagation and time, distance and joint parameters.

3. The quantitative analysis method for the blasting cracking mode of jointed rock mass according to claim 1, characterized in that, In step S2, the RHT model parameters include density, elastic shear modulus, erosion plastic strain, equation of state parameters, failure surface parameters, uniaxial tensile strength, relative shear strength, relative tensile strength, Rhodes angle correlation coefficient, compaction pressure, crushing pressure, and porosity index. The RHT model parameters for rocks and joints are set according to the actual rock mass characteristics.

4. The quantitative analysis method for the blasting cracking mode of jointed rock mass according to claim 1, characterized in that, In step S4, the joint-to-bore distance is set to 0.4m, 0.7m, 1m, and 1.3m; the joint width is set to 0.02m, 0.05m, 0.08m, and 0.11m; the number of joint layers is set to 1, 2, 3, and 4 layers with a 0.025m interval between each layer; the joint dip angle is set to 30°, 45°, 60°, and 90°; the joint density is set to 2300kg / m³, 2100kg / m³, 1900kg / m³, and 1700kg / m³; and the joint elastic modulus is set to 16.27GPa, 13.77GPa, 11.27GPa, and 8.77GPa.

5. The quantitative analysis method for the blasting cracking mode of jointed rock mass according to claim 1, characterized in that, In step S5, image preprocessing uses enhancement processing to achieve the best visualization effect, noise reduction processing uses a mean filter to remove irrelevant details in the image, and threshold cutting analyzes the gray-level distribution of the image through gray-level histogram analysis, and scans and marks each pixel as an object or background to achieve image cutting.

6. The quantitative analysis method for the blasting cracking mode of jointed rock mass according to claim 1, characterized in that, In step S6, when calculating the damage area between the joint and the borehole and the area behind the joint, the area is divided with the joint as the boundary. The area between the joint and the borehole is the area from the center of the borehole to the wave-facing side of the joint, and the area behind the joint is the area on the back wave side of the joint. The crack propagation length at both ends of the joint is obtained by measuring the distance from the borehole to the crack endpoints at both ends of the joint and taking the average value. The crack damage area is directly calculated using the area measurement function built into ImageJ software.

7. The quantitative analysis method for the blasting cracking mode of jointed rock mass according to claim 1, characterized in that, In step S7, the quantitative analysis indicators include the growth rate of damage area between joint and borehole, the attenuation rate of damage area behind joint, the change rate of crack propagation length at both ends of joint, and the change rate of crack damage area. By comparing the indicator data under different joint parameter conditions, the influence of each parameter on the blasting cracking mode is clarified.

8. The quantitative analysis method for the blasting cracking mode of jointed rock mass according to claim 1, characterized in that, In step S4, when conducting numerical simulation of blasting, the detonation point is set to be located in the middle of the explosive, and the simulation time lasts for 0.8 ms to ensure that the complete rock mass blasting damage process is obtained. Each working condition is simulated at least 3 times, and the average value is taken as the final duration damage data.

9. The quantitative analysis method for the blasting cracking mode of jointed rock mass according to claim 1, characterized in that, In step S7, when analyzing the influence of the joint and borehole spacing on the blasting cracking mode, if the joint and borehole spacing increases from 0.4m to 1.3m, the damage area between the joint and borehole gradually increases and decreases significantly in the range of 1m to 1.3m, the crack propagation length at both ends of the joint gradually increases, and the crack damage area gradually decreases, then it is determined that the increase in the joint and borehole spacing causes the range of cracks generated by the explosive to first increase and then decrease, and the joint's ductility to crack propagation is weakened.

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