Loading structure optimization method based on stress wave analysis in open bench blasting

Abstract

The invention discloses a loading structure optimization method based on stress wave analysis in open bench blasting. The method comprises the following steps: S1, performing rock mass blasting and stress wave theoretical analysis, researching a rock mass blasting rock breaking process and a breaking mechanism, deducing rock mass blasting mechanisms under different coupling media, and analyzing the influence of different coupling media on the blasting effect; and S2, calculating the initial delay detonation time according to the delay detonation rock blasting principle, and determining the optimal delay detonation time through numerical simulation calculation and field test demonstration. According to the method, a method combining theoretical analysis, numerical simulation and field test is comprehensively applied, a scientific and systematic charging structure optimization scheme is provided for open bench blasting, wide applicability and popularization value are achieved, progress of the open bench blasting technology can be promoted, and sustainable development of the mining industry is promoted.

Description

Technical Field

[0001] The present invention relates to the technical field of open-pit step blasting, and in particular to a charge structure optimization method based on stress wave analysis in open-pit step blasting. Background Art

[0002] In open-pit bench blasting operations, the charge structure plays a key role in blasting effectiveness. Traditional charge structures often struggle to achieve ideal blasting results in complex geological conditions, leading to problems such as large blast piles, numerous foundations, and strong blasting vibrations. These issues not only increase mining costs but also pose a threat to the surrounding environment and personnel safety.

[0003] Currently, commonly used axially spaced charge structures are affected by the axial decoupling coefficient and the physical and mechanical properties of the spacer medium, resulting in differences in their blasting mechanical effects. For example, when conventional air-spaced charge blasting is used in open-pit coal mines, the development of rock joints and fissures and differences in rock strata properties can lead to undesirable effects such as insufficient bench blast pile settlement, excessive large blocks, and numerous root formations. Furthermore, there is a lack of precise and effective methods for determining appropriate detonation times and charge structures. Existing hypotheses for calculating delayed detonation times suffer from difficulties in obtaining parameters and inaccurate calculation results. Therefore, a scientific and effective method is needed to optimize charge structure, improve blasting effectiveness, and reduce blasting hazards. To this end, we propose a charge structure optimization method for open-pit bench blasting based on stress wave analysis. Summary of the Invention

[0004] The purpose of the present invention is to solve the shortcomings of the prior art and to propose a charge structure optimization method based on stress wave analysis in open-pit step blasting.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: A method for optimizing charge structure in open-pit bench blasting based on stress wave analysis comprises the following steps: S1. Conduct theoretical analysis of rock blasting and stress waves, study the rock breaking process and crushing mechanism of rock blasting, deduce the rock blasting mechanism under different coupling media, and analyze the influence of different coupling media on blasting effect; S2. Calculate the initial delayed blasting time based on the delayed blasting rock breaking principle, and determine the optimal delayed blasting time through numerical simulation and field test verification; S3. Introduce a water-medium spaced charge structure and determine the optimal unit consumption for blasting in open-pit mines through field tests; S4. Based on the optimal unit consumption, use numerical simulation software to establish three-dimensional models of different water-medium spaced charge structures, analyze the rock stress change curve, damage range, and the proportion of free surface tensile crack area, and select the optimal water-medium spaced charge structure; S5. Design a field comparison test plan for water medium interval charge blasting and air medium interval charge blasting, conduct field comparison tests, collect vibration signals, use software to analyze the blasting block size distribution, foundation and dust concentration, and evaluate the blasting effect.

[0006] Preferably, in the rock blasting and stress wave theoretical analysis in step S1, the rock blasting and rock breaking process includes the radial compression stage of the rock mass by the explosion stress wave, the stage of the reflected tensile wave causing uplift and promoting crack development, the stage of the explosion gas destroying the rock mass and throwing rock fragments.

[0007] Preferably, in the rock blasting and stress wave theoretical analysis in step S1, the rock blasting and crushing mechanism includes the explosion gas product expansion pressure failure theory, the stress wave reflection and stretching failure theory, and the stress wave and explosion gas expansion pressure combined failure theory.

[0008] Preferably, in step S1, the analysis of rock blasting mechanism under different coupling media includes the derivation and analysis of initial parameters of explosion shock waves, initial pressure of blast hole wall and quasi-static stress field under air and water media.

[0009] Preferably, in step S3, the optimal unit consumption suitable for blasting the water medium interval charging structure in open-pit mines is determined through field tests. While keeping other blasting parameters unchanged, the water medium interval length and the unit consumption of explosives are changed, the blasting effect is observed, the blasting pile size distribution and foundation condition data are recorded, and the optimal unit consumption is determined by analyzing the test data.

[0010] Preferably, in step S4, a three-dimensional model of different water medium spaced charge structures is established using numerical simulation software, in which the rock mass adopts the RHT constitutive model, the explosive adopts the MAT008 material, and the state equation adopts EOS002.

[0011] Preferably, in step S5, in the on-site comparative test plan, the step height, blasthole diameter, explosive type, detonator category, drilling form, hole depth, extra depth, chassis resistance line, blasthole spacing, row spacing, filling length, unit explosive consumption, interval length, single hole charge, charge structure, hole layout method, and delay time are clearly defined.

[0012] Preferably, in step S5, the software is used to analyze the blasting fragmentation distribution, which is to import the blasting pile image collected on site into Split-Desktop software, and obtain the rock block proportion data of different fragmentation ranges by marking reference objects, depicting rock block outlines, etc., and calculate the powder block rate, utilization rate and large block rate.

[0013] Preferably, in step S5, the dust concentration is analyzed by gray-scaling and rendering the collected dust images using MATLAB, and the difference in dust concentration generated by water-medium interval charge blasting and air-medium interval charge blasting is evaluated by analyzing the gray-scale level and color distribution of the images.

[0014] Compared with the prior art, the present invention has the following beneficial effects: 1. In the present invention, through in-depth analysis of stress waves, combined with different delayed blasting rock breaking principles and numerical simulation technology, it is possible to accurately optimize the charge structure, improve the blasting and crushing effect, make the blast pile more uniform, reduce the large block rate and foundation, reduce the secondary crushing cost, and improve mining efficiency.

[0015] 2. The present invention employs a water-based intermittent charging structure, which not only reduces explosive consumption and saves costs, but also reduces blasting dust pollution, protecting the environment and the health of on-site personnel. Furthermore, by rationally designing a delayed detonation time, blasting vibration is effectively reduced, minimizing the impact on the surrounding environment and buildings, and improving the safety of blasting operations.

[0016] 3. In the present invention, a method combining theoretical analysis, numerical simulation and field tests is comprehensively used to provide a scientific and systematic charging structure optimization scheme for open-pit step blasting, which has wide applicability and promotion value, can promote the advancement of open-pit step blasting technology and promote the sustainable development of the mining industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a logic block diagram of a charge structure optimization method based on stress wave analysis in open-pit step blasting proposed by the present invention. DETAILED DESCRIPTION

[0018] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0019] Reference Figure 1 A charge structure optimization method based on stress wave analysis in open-pit bench blasting includes the following steps: S1. Conduct theoretical analysis of rock blasting and stress waves, study the rock breaking process and crushing mechanism of rock blasting, deduce the rock blasting mechanism under different coupling media, and analyze the influence of different coupling media on blasting effect; S2. Calculate the initial delayed blasting time based on the delayed blasting rock breaking principle, and determine the optimal delayed blasting time through numerical simulation and field test verification; S3. Introduce a water-medium spaced charge structure and determine the optimal unit consumption for blasting in open-pit mines through field tests; S4. Based on the optimal unit consumption, use numerical simulation software to establish three-dimensional models of different water-medium spaced charge structures, analyze the rock stress change curve, damage range, and the proportion of free surface tensile crack area, and select the optimal water-medium spaced charge structure; S5. Design a field comparison test plan for water medium interval charge blasting and air medium interval charge blasting, conduct field comparison tests, collect vibration signals, use software to analyze the blasting block size distribution, foundation and dust concentration, and evaluate the blasting effect.

[0020] In step S1, in the rock blasting and stress wave theoretical analysis, the rock blasting and rock breaking process includes the radial compression stage of the explosion stress wave on the rock mass, the stage of the reflected tensile wave causing uplift and promoting crack development, the stage of the explosion gas destroying the rock mass and throwing rock fragments.

[0021] In step S1, in the rock blasting and stress wave theoretical analysis, the rock blasting and crushing mechanisms include the explosion gas product expansion pressure failure theory, the stress wave reflection and tensile failure theory, and the stress wave and explosion gas expansion pressure combined failure theory.

[0022] In step S1, the analysis of rock blasting mechanism under different coupling media includes the derivation and analysis of the initial parameters of the explosion shock wave, the initial pressure of the blast hole wall, and the quasi-static stress field under air and water media.

[0023] In step S3, the optimal unit consumption suitable for blasting the water medium interval charging structure in the open-pit mine is determined through field tests. While keeping other blasting parameters unchanged, the water medium interval length and the unit consumption of explosives are changed, the blasting effect is observed, the blast pile size distribution and foundation condition data are recorded, and the optimal unit consumption is determined by analyzing the test data.

[0024] In step S4, a three-dimensional model of different water medium interval charge structures is established using numerical simulation software. In the model, the rock mass adopts the RHT constitutive model, the explosive adopts the MAT008 material, and the state equation adopts the EOS002.

[0025] In step S5, in the on-site comparative test plan, the step height, blasthole diameter, explosive type, detonator category, drilling form, hole depth, extra depth, chassis resistance line, blasthole spacing, row spacing, filling length, unit explosive consumption, interval length, single hole charge, charge structure, hole layout method, and delay time are clearly defined.

[0026] In step S5, software is used to analyze the blasting fragmentation distribution. The blast pile image collected on site is imported into Split-Desktop software. By marking reference objects and outlining rock fragments, data on the proportion of rock fragments in different fragmentation ranges is obtained, and the powder fragment rate, utilization rate, and large fragment rate are calculated.

[0027] In step S5, the dust concentration is analyzed by grayscale and rendering the collected dust images using MATLAB. By analyzing the grayscale level and color distribution of the images, the difference in dust concentration generated by water-medium interval charge blasting and air-medium interval charge blasting is evaluated.

[0028] Working principle: Collect rock mechanical parameters at the engineering site, including density, elastic modulus, compressive strength, tensile strength, etc., as well as performance parameters of explosives, such as detonation velocity and explosion pressure.

[0029] Based on the rock-breaking process and fragmentation mechanism of rock blasting, relevant theoretical formulas are used to calculate the initial parameters of the explosion shock wave, the initial pressure on the blasthole wall, and the quasi-static stress field in different coupling media. For example, when calculating the initial parameters of the explosion shock wave in air, approximate calculations are performed in stages based on its expansion characteristics. For water, the calculation is derived based on its physical and mechanical properties and conservation equations.

[0030] A comparative analysis of the differences in blasting effects between air and water as uncoupled charge media identifies the advantages of water media and provides a theoretical basis for subsequent charge structure optimization.

[0031] Based on the geological conditions and blasting requirements of the project site, select an appropriate delayed blasting rock-breaking hypothesis to calculate the initial delayed blasting time. For example, in an open-pit mine, based on the development of rock joints and fissures and rock properties, the wall-pushing formula based on the rock collision hypothesis was used to calculate the inter-row delay time. The semi-theoretical formula proposed by the Changsha Research Institute of Mining and Metallurgy was used to calculate the inter-hole delay time.

[0032] Field tests were conducted at an open-pit mine using water-interval charge structures with varying unit charges. While other blasting parameters remained constant, only the water-interval length and unit charge were varied. The blasting results were observed, and data such as the blast pile size distribution and foundation conditions were recorded. Through analysis of the test data, the optimal unit charge for water-interval charge blasting in this open-pit mine was determined.

[0033] Using ANSYS / LS-DYNA numerical simulation software, we established three-dimensional models of different water-interval charge structures based on the determined optimal unit consumption. During the modeling process, we rationally set parameters such as model size, meshing, material model, and equation of state. For example, the RHT constitutive model was used for the rock mass model, MAT008 material for the explosive, and EOS002 for the equation of state.

[0034] The established model was simulated and calculated to analyze the rock stress variation curves, rock damage range, and free surface tensile crack area ratio at the bottom of the blasthole, the middle of the lower charge, and the upper position of the blasthole. By comparing the calculation results of different models, the optimal water-medium spaced charge structure was selected.

[0035] Based on the numerical simulation results and the actual project situation, a field comparison test plan for water-medium interval charge blasting and air-medium interval charge blasting was designed. The plan detailed various blasting parameters, including step height, blasthole diameter, explosive type, detonator type, drilling form, hole depth, over-depth, chassis resistance line, blasthole spacing, row spacing, packing length, unit explosive consumption, interval length, single-hole charge, charge structure, hole layout, and delay time control.

[0036] During the field test, blasting operations were carried out according to the designed plan. During the blasting process, a TC-4850 blasting vibration meter was used to collect vibration signals generated by blasting different medium interval charges, recording data such as vibration velocity, frequency, and duration. Simultaneously, photographs were taken of the blast pile to provide image data for subsequent fragmentation analysis.

[0037] Split-Desktop fragmentation analysis software is used to analyze the fragmentation of blast piles. Images of the blast pile collected on-site are imported into the software. By marking reference objects and outlining the rock fragments, data on the percentage of rock fragments within different fragmentation ranges is obtained. Based on this data, the powder fragment rate, utilization rate, and large fragment rate are calculated to assess the uniformity and rationality of the blast fragmentation.

[0038] The collected dust images were grayscaled and rendered using MATLAB. By analyzing the grayscale levels and color distribution of the images, the difference in dust concentration generated by water- and air-interval charge blasting was evaluated, and the dust reduction effect of water-interval charge blasting was determined.

[0039] Based on the analysis results of vibration signals, explosive pile size and dust concentration, the blasting effects of different charge structures were comprehensively evaluated, and the advantages of the optimized charge structure in improving blasting fragmentation effect, reducing blasting vibration and reducing dust pollution were verified.

[0040] In summary, the present invention, through in-depth analysis of stress waves, combined with different delayed blasting rock breaking principles and numerical simulation technologies, can accurately optimize the charging structure, improve the blasting crushing effect, make the blasting pile more uniform, reduce the large block rate and foundation, reduce the secondary crushing cost, and improve the mining efficiency; the use of water medium interval charging structure can not only reduce the unit consumption of explosives and save costs, but also reduce blasting dust pollution, protect the environment and the health of on-site personnel. At the same time, by reasonably designing the delayed blasting time, the blasting vibration is effectively reduced, the impact on the surrounding environment and buildings is reduced, and the safety of the blasting operation is improved; the comprehensive use of theoretical analysis, numerical simulation and field test methods provides a scientific and systematic charging structure optimization scheme for open-pit step blasting, which has wide applicability and promotion value, can promote the progress of open-pit step blasting technology, and promote the sustainable development of the mining industry.

[0041] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A charge structure optimization method based on stress wave analysis in open-pit bench blasting, characterized in that: The following steps are involved: S1. Conduct theoretical analysis of rock blasting and stress waves, study the rock breaking process and crushing mechanism of rock blasting, deduce the rock blasting mechanism under different coupling media, and analyze the influence of different coupling media on blasting effect; S2. Calculate the initial delayed blasting time based on the delayed blasting rock breaking principle, and determine the optimal delayed blasting time through numerical simulation and field test verification; S3. Introduce a water-medium spaced charge structure and determine the optimal unit consumption for blasting in open-pit mines through field tests; S4. Based on the optimal unit consumption, use numerical simulation software to establish three-dimensional models of different water-medium spaced charge structures, analyze the rock stress change curve, damage range, and the proportion of free surface tensile crack area, and select the optimal water-medium spaced charge structure; S5. Design a field comparison test plan for water medium interval charge blasting and air medium interval charge blasting, conduct field comparison tests, collect vibration signals, use software to analyze the blasting block size distribution, foundation and dust concentration, and evaluate the blasting effect.

2. The method for optimizing charge structure based on stress wave analysis in open-pit bench blasting according to claim 1, characterized in that: In the rock blasting and stress wave theoretical analysis in step S1, the rock blasting and rock breaking process includes the radial compression stage of the rock mass by the explosion stress wave, the stage of uplift caused by the reflected tensile wave and the promotion of crack development, the stage of destruction of the rock mass by the explosion gas and the throwing of rock fragments.

3. The method for optimizing charge structure based on stress wave analysis in open-pit bench blasting according to claim 1, characterized in that: In the rock blasting and stress wave theoretical analysis in step S1, the rock blasting and crushing mechanisms include the explosion gas product expansion pressure failure theory, the stress wave reflection and stretching failure theory, and the stress wave and explosion gas expansion pressure combined failure theory.

4. The method for optimizing charge structure based on stress wave analysis in open-pit bench blasting according to claim 1, characterized in that: In step S1, the analysis of rock blasting mechanism under different coupling media includes the derivation and analysis of initial parameters of explosion shock waves, initial pressure of blast hole wall and quasi-static stress field under air and water media.

5. The method for optimizing charge structure based on stress wave analysis in open-pit bench blasting according to claim 1, characterized in that: In step S3, the optimal unit consumption suitable for blasting the water medium interval charging structure in the open-pit mine is determined through field tests. While keeping other blasting parameters unchanged, the water medium interval length and the unit consumption of explosives are changed, the blasting effect is observed, the blast pile size distribution and foundation condition data are recorded, and the optimal unit consumption is determined by analyzing the test data.

6. The method for optimizing charge structure based on stress wave analysis in open-pit bench blasting according to claim 1, characterized in that: In step S4, a three-dimensional model of different water medium spaced charge structures is established using numerical simulation software, in which the rock mass adopts the RHT constitutive model, the explosive adopts the MAT008 material, and the state equation adopts the EOS002.

7. The method for optimizing charge structure based on stress wave analysis in open-pit bench blasting according to claim 1, characterized in that: In step S5, in the on-site comparative test plan, the step height, blasthole diameter, explosive type, detonator category, drilling form, hole depth, over-depth, chassis resistance line, blasthole spacing, row spacing, filling length, unit explosive consumption, interval length, single hole charge, charge structure, hole layout method, and delay time are clearly defined.

8. The method for optimizing charge structure based on stress wave analysis in open-pit bench blasting according to claim 1, characterized in that: In step S5, software is used to analyze the blasting fragmentation distribution. The blasting pile image collected on site is imported into Split-Desktop software. By marking reference objects and outlining rock blocks, data on the proportion of rock blocks in different size ranges is obtained, and the powder block rate, utilization rate and large block rate are calculated.

9. The method for optimizing charge structure based on stress wave analysis in open-pit bench blasting according to claim 1, characterized in that: In step S5, the dust concentration is analyzed by gray-scaling and rendering the collected dust images using MATLAB. By analyzing the gray-scale level and color distribution of the images, the difference in dust concentration generated by water-medium interval charge blasting and air-medium interval charge blasting is evaluated.

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