A method for blasting in a combined size aperture blasthole in a hard, fractured rock formation

Abstract

The application discloses a kind of large and small aperture combined blasthole blasting method of hard jointed rock stratum blast area, specifically relates to the technical field of open-pit mine rock mass blasting, comprising the following steps: the working face is divided into zones;Determine the hole net parameter and delay time of working face, and the hole arrangement mode is that the blasthole row close to the free face of step is the first row, the blastholes of adjacent two rows are equidistant staggered arrangement, the blasthole aperture of each row is same, the blasthole of first row and second row is large aperture blasthole, and the blasthole from second row to last row is large aperture blasthole and small aperture blasthole interval arrangement;The blasthole is filled with charge, and the detonator is placed in the hard rock layer area of blasthole, according to the partial blasthole is detonated according to cross-row diagonal line of detonation route;After blasting, collect, collate and analyze blasting data, and optimize hole net parameter and delay time.The application can reduce explosive specific consumption, improve blasting effect, improve explosive energy utilization efficiency, and then improve the efficiency of shovel loading.

Description

Technical Field

[0001] This invention relates to the field of open-pit mine rock blasting technology, and in particular to a method for blasting blasting holes of different diameters in blasting areas containing hard rock strata. Background Technology

[0002] With the rapid development of the national economy, the demand for energy in the economy and society is increasing, and the scale of mineral resource development and utilization is also expanding. Many factors constrain the speed of mineral resource development and utilization, and blasting efficiency is one of the key factors. Blasting efficiency mainly includes two aspects: blasting scale and blasting quality.

[0003] As mining production scale continues to expand, blasting scale is also increasing. Generally, open-pit blasting with a single explosive charge of 50 tons or more is referred to as large-scale open-pit blasting. The development of borehole layout and borehole network parameter design for large-scale open-pit blasting is relatively recent, with weak theoretical foundations and limited practical experience. Therefore, the borehole network parameter design for large-scale blasting often relies on the experience of designers, improving upon traditional blasting designs. However, in actual production, this leads to blasting quality problems such as numerous large chunks, high root-base ratios, long flyrock distances, and large blasting vibrations. The cause of these problems lies in insufficient research into the energy transfer mechanism of explosions and low energy utilization efficiency. In small-scale blasting, the small explosive charge per blast means these problems are not obvious. Occasionally, large chunks or root-base elements (where the internal rock clamping effect is significant, and the explosive release energy fails to overcome the clamping effect, leaving unblasted rock) may occur, but their impact on loading efficiency is limited. However, in large-scale blasting, a series of problems such as large chunks and root-base elements are amplified, severely affecting loading efficiency and hindering mining plans.

[0004] Furthermore, to reduce costs and increase efficiency in large-scale blasting, the geological conditions of the blasting area should be fully considered during the blasting design. Among the many geological conditions, the state of the rock strata in the blasting area is a crucial factor affecting the blasting effect. A common rock stratum affecting blasting is hard-rock interbedded rock. Large-scale blasting itself has a weak theoretical foundation and limited practical experience; therefore, blasting designs specifically for hard-rock interbedded rock are even less common in large-scale blasting, resulting in unsatisfactory blasting effects, with large hard rock fragments severely impacting blasting efficiency. Summary of the Invention

[0005] The purpose of this invention is to provide a method for blasting blast holes of different sizes in blasting areas containing hard rock strata, in order to solve the problems existing in the prior art, reduce the consumption of explosives, improve the blasting effect, increase the energy utilization efficiency of explosives, and thus improve the blasting efficiency.

[0006] To achieve the above objectives, the present invention provides the following solution:

[0007] This invention provides a method for blasting boreholes of varying diameters in a blasting zone containing hard rock strata, comprising the following steps:

[0008] Step 1: Divide the working face into zones according to the hardness and water-porosity ratio of the lithology, and draw profile diagrams of different lithologies;

[0009] Step 2: Based on the length and width of the working face and the mine's previous blasting data, combined with the different lithological profiles in Step 1, preliminarily determine the borehole network parameters and delay time for different lithological working faces. The borehole layout is set with the row of boreholes closest to the free surface of the bench as the first row, and then sequentially set to the last row. The boreholes in adjacent rows are arranged at equal intervals and staggered. The boreholes in the borehole network parameters include large-diameter boreholes and small-diameter boreholes. The borehole diameters of each row are the same. Among them, the boreholes in the first and second rows are large-diameter boreholes, and the boreholes from the second row to the last row are arranged with large-diameter boreholes and small-diameter boreholes alternately.

[0010] Step 3: Based on the site conditions and the hole network parameters determined in Step 2, use easily identifiable markers to lay out the holes and perform drilling. After drilling is completed, check the quality of the blast holes.

[0011] Step 4: Based on the different lithological profiles drawn in Step 1, the boreholes are filled with explosive charges. The detonating charge is placed in the hard rock layer of the borehole and detonated according to the predetermined detonation sequence. For some boreholes, the detonation is carried out according to the diagonal detonation route across rows.

[0012] Step 5: After the blasting is completed, collect, organize and analyze the data on blasting vibration, root ratio, large block ratio, blast pile shape, fly rock distance and forward thrust distance, and optimize the hole mesh parameters and delay time in Step 2. Adjust the implementation plan of the working face according to the optimized parameters and carry out blasting operation again.

[0013] Preferably, in step 2, the diameter of the large-diameter borehole is 152 mm, and the diameter of the small-diameter borehole is 133 mm.

[0014] Preferably, in step 1, if all rock strata on the working face have f = 4 to 6, it is a soft rock area; if the rock strata on the working face have f = 8 to 10, it is a hard rock area, where f is the rock hardness according to Protodyakonov hardness; if the proportion of water holes after drilling on the working face is less than 5%, it is a waterless area; if the proportion of water holes after drilling on the working face is greater than 5%, it is a water-bearing area.

[0015] Preferably, if the working face is a soft rock area, in step 2, the row spacing of the blast holes is 7.5m, the hole spacing is 8.5m, the delay time between holes within a row is 47ms, and the delay time between rows is 77ms; if the working face is a hard rock area, in step 2, the row spacing of the blast holes is 7m, the hole spacing is 8m, the delay time between holes within a row is 24ms, and the delay time between rows is 71ms.

[0016] Preferably, the detonating charge in step 4 is No. 2 rock emulsion explosive. If the working face is a waterless area, the main explosive is ammonium nitrate oil explosive; if the working face is a watery area, the main explosive is mixed emulsion explosive.

[0017] Preferably, in step 2, the inclination angle of the first row of blast holes is 80°, the inclination angle of the last row of blast holes is 80°, and the inclination direction of the first row of blast holes and the inclination direction of the last row of blast holes are the same as the inclination direction of the free surface of the step.

[0018] The present invention achieves the following technical effects compared to the prior art:

[0019] This invention provides a method for blasting areas containing hard rock strata using a combination of large and small diameter boreholes. Based on the dimensions of the working face, the lithology, and the ratio of water holes, and incorporating data from previous blasting operations, the working face is meticulously divided and scientifically designed. The first and second rows of boreholes are all large-diameter, increasing the energy output of the front row and reducing uneven block size. Furthermore, the boreholes from the second row to the last row are arranged with alternating large and small diameter boreholes, reducing the amount of explosives required, lowering explosive consumption per unit, and improving excavation and loading efficiency, thereby achieving cost reduction and efficiency improvement. This approach improves efficiency and reduces the overall cost of blasting operations. In large-diameter blast holes, the detonating charge is placed at the bottom for reverse detonation, while in small-diameter blast holes, it is placed in the middle for intermediate detonation. This improves blasting effectiveness and increases the efficiency of explosive energy utilization. After blasting, statistical analysis of blasting quality evaluation parameters, along with optimization of blasting parameters based on the analysis results, allows for a deeper understanding of explosive energy, increases the control rate of blasting quality, reduces energy waste, and improves the efficiency of explosive energy utilization. The optimized blasting effect can then approach the ideal blasting effect. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the drilling inclination and charge position of the combined borehole method for blasting strata containing hard rock inclusions according to the present invention.

[0022] Figure 2 This is a schematic diagram of the borehole layout for the combined borehole size configuration in the blasting method for rock strata containing hard inclusions, according to the present invention.

[0023] In the diagram: 101 - Large-diameter borehole; 102 - Small-diameter borehole; 103 - Diagonal detonation line between rows; 104 - Detonation line between boreholes; 105 - Detonating charge; 106 - Detonator line; 107 - Main explosive; 108 - Step free surface; 109 - Hard rock layer area. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] The purpose of this invention is to provide a method for blasting blast holes of different sizes in blasting areas containing hard rock strata, in order to solve the problems existing in the prior art, reduce the consumption of explosives, improve the blasting effect, increase the energy utilization efficiency of explosives, and thus improve the blasting efficiency.

[0026] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] Embodiments of the present invention provide a method for blasting boreholes of varying diameters in a blasting zone containing hard rock strata, comprising the following steps:

[0028] Step 1: Divide the working face into zones based on lithological hardness and the ratio of water to pore size, and draw different lithological profiles. If the f = 4-6 for all rock layers in the working face, it is a soft rock zone; if the f = 8-10 for the rock layers in the working face, it is a hard rock zone, where f represents the lithological hardness according to Protodyakonov hardness. If the water pore ratio after drilling is less than 5%, it is a waterless zone; if the water pore ratio after drilling is greater than 5%, it is a water-bearing zone. Therefore, the working face is divided into soft rock waterless zone, hard rock waterless zone, soft rock water-bearing zone, and hard rock water-bearing zone based on lithological hardness and the ratio of water to pore size. Based on the length and width of the working face, the different lithologies and water pore ratios, and combined with the data from previous blasting operations, the working face is finely divided and scientifically designed.

[0029] Step 2: Based on the length and width of the working face and previous blasting data from the mine, combined with the different lithological profiles from Step 1, preliminarily determine the borehole parameters and delay time for working faces of different lithologies, such as... Figure 2As shown, the borehole layout uses the row of boreholes closest to the free surface 108 of the step as the first row, and continues sequentially to the last row. The boreholes in adjacent rows are arranged at equal intervals and alternately. The borehole parameters in the borehole network include large-diameter boreholes 101 and small-diameter boreholes 102. Each row has the same borehole diameter. The first and second rows consist of large-diameter boreholes 101. From the second row to the last row, large-diameter boreholes 101 and small-diameter boreholes 102 are arranged alternately. The diameter of the large-diameter borehole 101 is 152 mm, and the diameter of the small-diameter borehole 102 is 133 mm. Both the first and second rows contain large-diameter boreholes 101. This design increases the energy of the front row and reduces the problem of uneven block size. The arrangement of the boreholes from the second to the last row, with large-diameter boreholes 101 and small-diameter boreholes 102 alternating, reduces the amount of explosives required, lowers the consumption of explosives per unit, and improves excavation and loading efficiency, thereby achieving cost reduction and efficiency improvement and lowering the overall cost of blasting operations. If the working face is a soft rock area, the row spacing of the boreholes is 7.5m, the hole spacing is 8.5m, the delay time between holes within a row is 47ms, and the delay time between rows is 77ms. If the working face is a hard rock area, the row spacing of the boreholes is 7m, the hole spacing is 8m, the delay time between holes within a row is 24ms, and the delay time between rows is 71ms. The borehole spacing is determined based on the borehole diameter, generally 30 to 60 times the diameter, with the specific multiple selected according to the lithology of the working face. The slope crest distance is determined based on the minimum resistance line, which is the distance between the borehole center and the free surface. In this embodiment, the minimum resistance line that the 105 detonating charge can overcome is 3.5 to 4.5 meters, the slope crest distance is 2.5 to 3 meters, and the step height is 15 meters. The calculation process for the parameters of the base resistance line, borehole spacing, row spacing, over-depth, and filling length is as follows:

[0030] 1. Chassis resistance line W

[0031] (1) According to the maximum resistance that the medicine pack can overcome.

[0032] W = (25~45)d = 2.5~4.5m

[0033] In the formula: d - diameter of the medicine pack, taken as 0.1m.

[0034] (2) According to the drilling rig safety operation conditions

[0035] W≥Hctga+c=15×ctg70°+2.5=7.95m

[0036] In the formula: H is the step height, 15m;

[0037] A is the slope angle of the working step, 70°;

[0038] C represents the safe distance of 2-3m from the front row of blast holes to the top of the slope; the design value is 2.5m.

[0039] Based on the above calculation results, W = 7.95m.

[0040] 2. Hole spacing a

[0041] a=k×R(30~60)×0.152=4.56~9.12m

[0042] In the formula: k is a multiple, and R is the larger borehole diameter. This invention includes boreholes with diameters of 133mm and 152mm. Since this invention is based on improving the energy efficiency of explosives, the larger borehole diameter, 152mm, is chosen. The borehole spacing is selected as 8m.

[0043] 3. Row spacing b

[0044] b = (1.1~1.2)W = 6.6~7.2m

[0045] In the formula: W is the chassis resistance line (the distance from the bottom of the first row of gun holes to the bottom of the free face), and 1.1 to 1.2 are multiples.

[0046] Choose a row spacing of 7m.

[0047] 4. Ultra-deep h

[0048] h=(0.15~0.35)×W=0.90~2.10m

[0049] In the formula: W is the chassis resistance line, and 0.15 to 0.35 are multiples.

[0050] The design determines the ultra-deep depth of the rock step to be h = 1.0~1.5m.

[0051] 5. Filling length Ld

[0052] 25×R≥Ld≥30×R

[0053] In the formula, R is the large aperture, and 25 and 30 are multiples thereof.

[0054] The design specifies that the filling length Ld is 4m.

[0055] Step 3: Based on the site conditions and the hole network parameters determined in Step 2, use easily identifiable markers to lay out and drill holes. After drilling is completed, check the quality of the blast holes. During the drilling and inspection process, observe the drilling conditions of the blast holes in a timely manner and mark the water holes.

[0056] Step 4: Based on the different rock strata profiles drawn in Step 1, the boreholes are filled with explosive charges. The detonating charge is placed in the hard rock layer 109 of the borehole and detonated according to the predetermined detonation sequence. For some boreholes, the detonation follows a diagonal detonation path spanning multiple rows. Figure 2The diagonally arranged initiation wires 103 and 104 shown detonate from the upper left corner, with energy propagating towards the lower right corner. During the blasting process, the shaded area experiences two shearing failures: the first occurs when the stress wave from the first detonating hole propagates to the lower right, and the second occurs when the stress wave from the subsequent detonating hole propagates to the upper left. These two failures completely overcome the binding effect of the bottom rock, resulting in a better blasting effect. Figure 1 As shown, the detonating charge is placed in the hard rock layer of the blast hole. Utilizing the high detonation velocity and high heat of explosion of the detonating charge, the hard rock layer is broken, improving the blasting effect and increasing the energy utilization efficiency of the explosive. The detonating charge 105 is No. 2 rock emulsion explosive. For working faces in waterless areas, regardless of whether the rock is soft or hard, ammonium nitrate explosive (AMO) is used as the main explosive 107. For working faces in water-bearing areas, regardless of whether the rock is soft or hard, pre-made emulsion explosive is used as the main explosive 107. Preferably, for occasional water holes in waterless areas, water can be pumped out, and then AMO can be loaded. However, for numerous water holes in water-bearing areas, there are problems with the number of holes, their depth, and the large volume of water. Pumping out water would reduce construction efficiency, making it impossible to complete the blasting operation within the specified time. Therefore, for water holes in water-bearing areas, pre-made emulsion explosive is loaded.

[0057] Step 5: After the blasting is completed, collect, organize and analyze the data on blasting vibration, root ratio, large block ratio, blast pile shape, fly rock distance and forward thrust distance, and optimize the hole mesh parameters and delay time in Step 2. Adjust the implementation plan of the working face according to the optimized parameters and carry out blasting operation again.

[0058] Collecting blasting vibration data can monitor whether blasting vibration causes damage to mine buildings and slopes. Blasting vibration monitoring equipment can be deployed around the mine buildings to measure the frequency and velocity of vibration. If the peak value of blasting vibration at the test point 80m away from the blasting area exceeds 5cm / s, the blasting vibration can be reduced by increasing the delay time between the holes in the blasting blast.

[0059] The statistical foundation rate is mainly used to monitor the geological conditions of the blasting area and provide a geological basis for the next blasting design. The presence of foundation residue indicates that the energy released by the explosive has not overcome the clamping effect at the bottom of the rock. Based on experience, increasing the extra depth can effectively reduce foundation formation. If foundation residue exists, the extra depth can be appropriately increased within the range of 0.9–2.1 m to reduce foundation formation.

[0060] In evaluating blasting effectiveness, the large-block ratio is a core parameter. Generally, a large-block ratio of 3%-5% for a single blast can be considered a good blasting effect. If the large-block ratio is too high, it can be reduced by decreasing the spacing between the blast holes.

[0061] The blast pile configuration includes the maximum height, maximum width, and horizontal distance from the center of the explosive charge to the maximum height. In open-pit deep-hole blasting, the blast pile configuration significantly impacts loading and transportation efficiency. An excessively high blast pile can affect the safe operation of excavators, while an excessively low blast pile can reduce the efficiency of loaders.

[0062] The distance of flying rocks is related to the terrain, geology, explosive charge parameters and climate conditions. A flying rock distance greater than 50 meters is generally considered to be an unreasonable design of the minimum resistance line, which can easily cause safety hazards. The distance between the first row of blast holes and the free surface can be increased.

[0063] The forward thrust distance indicates the work done by the explosive energy on the rock. The forward thrust distance is generally between 10 and 15 meters. If the forward thrust distance exceeds 15 meters, the explosive energy does a large amount of work on the rock and the rock is broken up thoroughly. In subsequent blasting, the hole spacing can be appropriately increased to reduce explosive consumption.

[0064] Further optimization, based on the comprehensive evaluation parameters of blasting quality, if the peak blasting vibration at a test point 80m from the blasting zone exceeds 5cm / s, the inter-hole delay time is increased by 5ms to allow the stress wave to be fully released, reducing the superposition effect and thus reducing blasting vibration. If there is no foundation, few large fragments, and far-reaching flyrock, the distance between the first row of blast holes and the free surface can be increased by 0.5-1m. A longer forward thrust indicates greater energy, and the hole spacing can be increased by 0.5m to allow the explosive energy to be fully released, reducing the energy consumption per unit and proceeding to the next blast. If a foundation is formed, many large fragments, close-reaching flyrock, and a short forward thrust indicate insufficient energy, the hole spacing can be reduced by 0.5m to increase the energy consumption per unit and proceed to the next blast. After blasting, statistical analysis is performed on the blasting quality evaluation parameters. Based on the analysis results, the delay time and hole mesh parameters of the working face under this lithology are optimized. This can further understand the explosion energy, improve the control rate of blasting quality, reduce blasting energy waste, improve the energy utilization efficiency of explosives, and improve the blasting effect of the next blasting test on the same working face with the same lithology, so that the optimized blasting effect is close to the ideal blasting effect.

[0065] In a further preferred embodiment of the present invention, in step 2, the inclination angle of the first row of blast holes is 80°, the inclination angle of the last row of blast holes is 80°, and the inclination direction of the first row of blast holes and the inclination direction of the last row of blast holes are the same as the inclination direction of the free surface of the step. The inclination angle of the first row of blast holes is 80°, which can reduce the problem of too many large blocks on the free surface. The inclination angle of the last row of blast holes is 80°, which can prevent excessive energy from causing the rear row to pull apart and affecting the design of the next blasting.

[0066] Example 1

[0067] This embodiment provides a method for blasting blasting areas containing hard rock strata with a combination of large and small boreholes. This embodiment was implemented at the 580-565 hard rock anhydrous working face in the South Open-pit Coal Mine. The rock strata at the 580-565 working face are mainly composed of mudstone and sandstone. The blasting bench height is 15m, and 38 boreholes are drilled. Five 152mm boreholes are drilled per row, with a charge height of 12.5m, a packing height of 4m, and an over-depth of 1.5m. Five 133mm boreholes are drilled per row, with a charge height of 12m, a packing height of 4m, and an over-depth of 1m. The first and last rows of boreholes have an 80° inclination. The delay time of the digital electronic detonator is 24ms between boreholes and 71ms between rows. The row spacing of the boreholes is 7m, and the hole spacing is 8m. The detonating charge 105 is composed of No. 2 rock emulsion explosive wound with digital electronic detonator wire 106, with a diameter of 110mm, and is placed in the sandstone layer of the borehole. Before the blast, three vibration monitoring devices were fixed with plaster at distances of 20m, 40m, and 80m from the blast zone, respectively. Calculations showed that the explosive consumption per unit volume was 190g / cm³. 3 After confirming safety at the scene, the device was detonated and a video of the detonation was recorded.

[0068] After blasting, vibration data was exported, images of the blast pile were taken, and the images were processed and uploaded to wipfrag software for large block percentage statistics. On-site personnel measured the forward thrust and flyrock distance. Due to the massive volume of the blast, after excavation and loading, an on-site survey and statistical analysis of the large blocks and foundation conditions within the blast pile were conducted.

[0069] Observations of the blasting photos show that the experimental area effectively suppressed burr formation. Combined with photos of the blast pile and statistics on large blocks on the front free face, the large block rate was only 5%, effectively reducing the generation of large blocks on the free face. After excavation and loading, there were no obvious large blocks or foundation residues inside, indicating good experimental results. After blasting, the blast zone extended forward by 12-15m, the flyrock distance was approximately 37-42m, the rear settlement was approximately 1.5-2.5m, there was no backburst, and the blast pile height was 17m. All data are superior to previous blasting results, indicating an ideal blasting effect.

[0070] Based on the above information, it can be concluded that this embodiment significantly improves the blasting effect and achieves higher energy utilization efficiency of explosives while reducing the consumption of explosives per unit. Calculations show that this invention saves 18% of explosives, increases loading efficiency by 25%, and reduces the overall cost of blasting operations.

[0071] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A method for blasting blast holes of varying diameters in a blasting zone containing hard rock strata, characterized in that: The steps include the following: Step 1: Divide the working face into zones according to the hardness of the rock and the proportion of water and pores, and draw cross-sectional diagrams of different rock layers. If the f=4 to 6 of all rock layers in the working face, it is a soft rock zone; if the f=8 to 10 of the rock layers in the working face, it is a hard rock zone, where f is the Protodyakonov coefficient of the rock; if the proportion of water pores after drilling is less than 5% in the working face, it is a waterless zone; if the proportion of water pores after drilling is greater than 5% in the working face, it is a water-bearing zone. Step 2: Based on the length and width of the working face and the mine's previous blasting data, combined with the different lithological profiles in Step 1, preliminarily determine the borehole network parameters and delay time for different lithological working faces. The borehole layout is set with the row of boreholes closest to the free surface of the bench as the first row, and then sequentially set to the last row. The boreholes in adjacent rows are arranged at equal intervals and staggered. The boreholes in the borehole network parameters include large-diameter boreholes and small-diameter boreholes. The borehole diameters of each row are the same. Among them, the boreholes in the first and second rows are large-diameter boreholes, and the boreholes from the second row to the last row are arranged with large-diameter boreholes and small-diameter boreholes alternately. Step 3: Based on the site conditions and the hole network parameters determined in Step 2, use easily identifiable markers to lay out the holes and perform drilling. After drilling is completed, check the quality of the blast holes. Step 4: Based on the different rock strata profiles drawn in Step 1, the boreholes are filled with explosives. The detonating charge is placed in the hard rock layer of the borehole and detonated according to the predetermined detonation sequence. For some boreholes, the detonation is carried out along a diagonal detonation route. The detonating charge is No. 2 rock emulsion explosive. If the working face is a dry area, the main explosive is ammonium nitrate oil explosive; if the working face is a wet area, the main explosive is a mixed emulsion explosive. Step 5: After the blasting is completed, collect, organize and analyze the data on blasting vibration, root ratio, large block ratio, blast pile shape, fly rock distance and forward thrust distance, and optimize the hole mesh parameters and delay time in Step 2. Adjust the implementation plan of the working face according to the optimized parameters and carry out blasting operation again.

2. The method for blasting blast holes of varying diameters in a blasting zone containing hard rock strata according to claim 1, characterized in that: In step 2, the diameter of the large-diameter blast hole is 152 mm, and the diameter of the small-diameter blast hole is 133 mm.

3. The method for blasting blast holes of varying diameters in a blasting zone containing hard rock strata according to claim 1, characterized in that: If the working face is a soft rock area, in step 2, the row spacing of the blast holes is 7.5m, the hole spacing is 8.5m, the delay time between holes within a row is 47ms, and the delay time between rows is 77ms; if the working face is a hard rock area, in step 2, the row spacing of the blast holes is 7m, the hole spacing is 8m, the delay time between holes within a row is 24ms, and the delay time between rows is 71ms.

4. The method for blasting blast holes of varying diameters in a blasting zone containing hard rock strata according to claim 1, characterized in that: In step 2, the inclination angle of the first row of blast holes is 80°, and the inclination angle of the last row of blast holes is 80°. The inclination directions of the first row of blast holes and the last row of blast holes are the same as the inclination direction of the free surface of the step.

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