A method for predicting blasting fragmentation

Abstract

The present invention provides a method for predicting the size of blasting fragments, which is used for blasting engineering blasting data collection. During the blasting process, the formation of fragments is formed by the development of a large number of interlaced cracks, and each crack will form the surface of two adjacent rock blocks. By taking the laboratory measurement of joints and fissures as a reference, an adjustment coefficient is established based on the size formed by the intersection of the crack surfaces, and then the actual blasting fragments are predicted to obtain the percentage of fragments that meet the requirements, so as to solve the problem that the current blasting fragments are still uneven and irregular, resulting in a generally low blasting rate, thereby affecting the blasting process and restricting work production and economic benefits.

Description

Technical Field

[0001] The invention belongs to the technical field of blasting engineering blasting data collection, and in particular relates to a method for predicting blasting fragmentation. Background Art

[0002] With the rapid development of my country's economy and technology, facing the increasingly scarce resources, the exploration and exploitation of deep resources in the country will inevitably be carried out in the future. Facing the deep environment, the underground rock problem must be solved. At present, blasting technology has been widely used in rock engineering. The type of explosives, the diameter of the blasthole, the depth of the blasthole, the method of detonation and geological conditions will affect the fragmentation produced by blasting. How to scientifically and rationally use the explosive energy is one of the key technical issues to effectively break the rock mass into suitable fragments. Predicting the size distribution of blasting fragments by scientific means is conducive to guiding the optimization design of blasting plans and improving blasting efficiency.

[0003] In engineering, many experts and scholars have done a lot of research on blasting fragments. The existing methods are based on theoretical research or model research, and then determine the best blasting plan by comparing the results of field tests. Or conduct sampling tests on site, compare and analyze the advantages and disadvantages of various blasting plans, select reasonable blasting parameters, and optimize the blasting plan. Zou Dingxiang and others used the unit surface energy theory as the basis for destruction to study the fragmentation of rock mass caused by different stress wave energy values, which basically reflected the nature of blasting, but the test caused more large pieces. Zhou Chuanbo and others combined engineering field tests, used significance tests and regression methods to study the influencing factors of blasting fragment size distribution.

[0004] At present, there are still uneven and irregular phenomena in the blasting fragments, which leads to a generally low blasting rate, thus affecting the blasting process and restricting work production and economic benefits. Summary of the invention

[0005] Therefore, the technical problem to be solved by the present invention is to provide a method for predicting blasting fragmentation, which can solve the problem that the current blasting fragments are still uneven and irregular, resulting in a generally low blasting rate, thereby affecting the blasting process and restricting work production and economic benefits.

[0006] In order to solve the above problems, the present invention provides a method for predicting blasting fragmentation, which is used for blasting engineering blasting data collection. The prediction method comprises the following steps:

[0007] Step 1: In the target rock mass area, multiple rock specimens are drilled at equal distances L from the central blast source. The sampling depth is 0.5m to 1m in the rock layer. The drilling diameter of each rock specimen is 50mm and the drilling height is 100mm. Each rock specimen is numbered.

[0008] Step 2: Conduct impact mechanics experiments on each rock specimen. Place the rock specimens after the test in an open glass container. Soak and rinse them with a neutral detergent at an ambient temperature of 25°C. Wipe the washed rock specimens clean and dry them. Ventilate and cool the dried rock specimens.

[0009] Step 3: Scan the rock specimen in multiple directions with a scanner, process the scanned image to obtain a grayscale image, filter the grayscale image to remove noise, and convert all lines in the grayscale image into a color plane image with multiple chromaticity values;

[0010] Step 4: Perform data statistics on the lines in the acquired color plane image and define each line as m i , then the total number of cracks M in the color plane image of all rock specimens is as shown in formula (1):

[0011]

[0012] Step 5: Based on the cracks of different lengths obtained from the color plane images of all rock specimens, set the first crack, the second crack and the third crack, where the total number of the first crack is recorded as m i1 , the total number of cracks of the second crack is recorded as m i2 , the total number of cracks of the third crack is recorded as m i3 According to multiple groups of tests, the relationship between the sum of the number of cracks of the first crack and the number of cracks of the second crack and the sum of the number of cracks of the first crack, the number of cracks of the second crack and the number of cracks of the third crack is established to establish the correlation matching coefficient U of the rock specimen to form a qualified block volume, as shown in formula (2):

[0013]

[0014] Step 6: Establish the matching relationship between the blasting block ratio and the corresponding blasting charge Q and blasting radius R, as shown in formula (3):

[0015]

[0016] Where, N is the proportion of blasting block size; C is the rock wave impedance correction coefficient, ranging from 0.01 to 1; Q is the blasting charge in the blasting area, kg; K is the adjustment coefficient related to the explosive performance, ranging from 1 to 2.82; R is the blasting radius of the blasting area, m; U is the relevant matching coefficient;

[0017] The matching relationship between the blasting block size ratio and the corresponding blasting charge Q and blasting radius R is obtained based on the calculation, and the parameters are adjusted according to the predicted effect to achieve the target blasting.

[0018] Optionally, step 2 further includes: loading the rock specimen using a SHPB impact bar dynamic test, with the impact gas pressure set to 0.1-1.5 MPa and the confining pressure set to 1-2 MPa;

[0019] The pH value of neutral detergent is 6-8.

[0020] Optionally, the scanner in step three is a CT scanner.

[0021] Optionally, in step five, the first crack size is less than 25 mm in length, the second crack size is 25 mm-75 mm in length, and the third crack size is greater than 75 mm in length.

[0022] Beneficial Effects

[0023] A method for predicting blasting fragmentation provided in an embodiment of the present invention, in the blasting process of the present invention, the formation of fragmentation is formed by the development of a large number of interlaced cracks, and each crack will form the surface of two adjacent rock blocks. Through indoor experiments, the impact of blasting energy is simulated by the dynamic experiment of the impact pressure rod, the total number of rock cracks is analyzed by CT scanning technology, the distribution of blasting fragmentation is analyzed and predicted from the perspective of the change of the rock cracks itself, the number of interlaced cracks is measured, and the distribution of blasting fragmentation size is predicted in combination with the physical properties of the rock itself. It has the characteristics of simple operation, fast calculation, and applicable effect, and then guides the optimization of blasting operations and realizes high-efficiency and high-quality blasting work. Among them, scientific blasting is one of the key technologies for forming suitable fragments, in order to improve blasting efficiency and ensure the balanced development of production. The present invention is not only conducive to establishing a blasting research system, guiding the optimization of blasting operations, and realizing high-efficiency and high-quality blasting work, but also can further guide the efficiency of blasting operations, and can make the blasting industry further move towards precision and completeness. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a flow chart of a prediction method according to an embodiment of the present invention;

[0025] Figure 2 FIG. 4 is a schematic diagram of a scanner scanning according to an embodiment of the present invention. DETAILED DESCRIPTION

[0026] See also Figure 1 to Figure 2 According to an embodiment of the present invention, a method for predicting blasting block size is shown in FIG. Figure 1 , used for blasting engineering blasting data collection, the prediction method includes the following steps:

[0027] Step 1: In the target rock mass area, multiple rock specimens are drilled at an equal distance increment L from the central blast source position, with a sampling depth of 0.5m to 1m in the rock layer. The drilling diameter of each rock specimen is 50mm, the drilling height is 100mm, and each rock specimen is numbered;

[0028] Step 2: Each rock specimen is loaded by the SHPB impact bar dynamic test, the impact gas pressure is set to 0.1-1.5 MPa, the confining pressure is set to 1-2 MPa, and the rock specimen after the test is placed in an open glass container, wherein the size of the open container is greater than 50 mm in diameter and greater than 150 mm in height, and the rock specimen after the test is placed in the open container;

[0029] The open container is at a standard ambient temperature of 25°C. Add a neutral detergent with a pH of 6-8 to the container, submerge the top of the rock specimen, soak for 2 minutes, then take it out and clean the surface of the rock specimen with a cotton pad or dust-proof brush. Put it in a constant temperature blast drying oven to dry; take out the dried rock specimen, place it in a cool and ventilated place for 1 hour, and cool it down;

[0030] Please refer to Figure 2 ,Step 3: Scan the rock specimen in multiple directions by using a CT scanner, that is, rotate counterclockwise along the vertical direction Y of the rock specimen, and scan at 0° (vertical direction Y), 30°, 45°, 60°, and 75° (horizontal direction X), respectively, process the scanned image to obtain a grayscale image, filter the grayscale image to remove noise, and convert all lines in the grayscale image into color plane images with different chromaticity values;

[0031] Step 4: Perform data statistics on the lines in the acquired color plane image and define each line as m i , then the total number of cracks M in the color plane image of all rock specimens is as shown in formula (1):

[0032]

[0033] Step 5: Based on the cracks of different lengths obtained from the color plane images of all rock specimens, the first crack, the second crack and the third crack are set. The first crack is a small crack, the second crack is a medium crack, and the third crack is a large crack. Among them, the length of the crack is less than 25 mm and the total number of cracks is recorded as m. i1 ; The length of 25mm-75mm is medium crack, and the total number of cracks is recorded as m i2 , the length of cracks greater than 75mm is considered a large crack, and the total number of cracks is recorded as m i3According to the relationship between the total number of small and medium cracks and the total number of cracks in multiple groups of tests, the relevant matching coefficient U of the rock specimen to form a qualified block volume is established, as shown in formula (2):

[0034]

[0035] Step 6: Establish the matching relationship between the blasting block ratio and the corresponding blasting charge Q and blasting radius R, as shown in formula (3):

[0036]

[0037] Where, N is the proportion of blasting block size; C is the rock wave impedance correction coefficient, ranging from 0.01 to 1; Q is the blasting charge in the blasting area, kg; K is the adjustment coefficient related to the explosive performance, ranging from 1 to 2.82; R is the blasting radius of the blasting area, m; U is the relevant matching coefficient;

[0038] According to the calculation, the matching relationship between the blasting block size ratio and the corresponding blasting charge Q and blasting radius R is obtained, and the parameters are adjusted according to the predicted effect to achieve the target blasting. Among them, N is the blasting block size ratio. In the present invention, the blasting block size ratio is small and medium blasting, that is, the qualified blasting block size ratio is greater than 70%, which is an indicator of qualified blasting.

[0039] In the blasting process of the present invention, the block size is formed by the development of a large number of interlaced cracks, and each crack will form the surface of two adjacent rock blocks. Through indoor experiments, the impact of blasting energy is simulated by the dynamic experiment of impact pressure rod, the total number of rock cracks is analyzed by CT scanning technology, the number of interlaced cracks is determined, and the distribution of blasting block size is predicted in combination with the physical properties of the rock itself, thereby guiding and optimizing the blasting operation and achieving high-efficiency and high-quality blasting work. It can further guide the efficiency of blasting operations and make the blasting industry further move towards precision and completeness.

[0040] In the blasting of the present invention, when the size of about 1 / 3 of the rock blocks in the first blasting does not meet the requirements, it is very likely that a large number of secondary blasting will be carried out. At this time, the blasting effect is poor. Therefore, the control value is set when the proportion of qualified blasting blocks is greater than 70% to ensure that the blasting effect reaches the expected goal.

[0041] Embodiment 1:

[0042] Step 1: At a distance of 10m from the central blast source, a group of rock specimens were drilled at 5m increments, i.e. 10m, 15m, and 20m. There were 9 granite rock specimens in total, with 3 specimens in each group. Cylindrical rock specimens with a diameter of 50mm and a height of 100mm were made. The specimens were loaded using the SHPB impact pressure bar dynamic experiment, using a 100mm large diameter rod, the impact gas pressure was set to 1MPa, and the confining pressure was 2MPa.

[0043] Step 2: Select a 500ml open glass container and place the rock specimen in the open container. At 25°C, add a neutral detergent with a pH of 6-8 to the open container, submerge the top of the rock specimen, soak for 2 minutes, then take it out and wipe the surface of the rock specimen with a cotton pad or dust-proof brush. Place it in a DHG-9140A vertical constant temperature blast drying oven for drying. Take out the dried rock specimen, place it in a cool and ventilated place for 1 hour, and cool it down.

[0044] Step 3: Use a scanner to scan the rock specimen in different directions, process the scanned images to obtain grayscale images, filter the grayscale images to remove noise, and convert all lines in the grayscale images into color plane images with different chromaticity values.

[0045] Step 4: Statistical analysis of the lines in the color plane images of all rock specimens, see Table 1, and define each line as m i , then the total number of cracks in the color plane images of all rock specimens is:

[0046] Table 1 Number of cracks in the image

[0047]

[0048] Substituting the above data into formula (1), we obtain M=114.

[0049] Step 5: Statistical graph of the number of small cracks less than 25 mm in length m i1 , the number of medium cracks with a length of 25-75 mm m i2 , the number of large cracks with a length greater than 75 mm m i3 , see Table 2:

[0050] Table 2 Crack distribution number

[0051]

[0052] Substituting the above data into formula (2), we obtain U=0.6582.

[0053] Step 6: According to the on-site blasting design, the blasting charge is 20×10 3 kg. Based on the empirical formula for blasting, the blasting radius is estimated to be 27m.

[0054] The matching relationship between the blasting block ratio and the corresponding blasting charge Q and blasting radius R is established as shown in formula (3):

[0055]

[0056] Where, C is the rock wave impedance correction constant, which is 0.025; Q is the blasting charge in the blasting area, which is 20×10 3 kg; K is the adjustment coefficient related to the performance of explosives, which is taken as 1.2; R is the blasting radius of the blasting area, which is taken as 27m; U is the correlation matching coefficient, which are 0.6582 respectively.

[0057] Substituting the above data into formula (3), the final calculated blasting block size ratio is N=0.7391, that is, the blasting block size qualification rate is 73.91%, and there is no need for secondary blasting, indicating that the blasting effect requirements are met.

[0058] Embodiment 2:

[0059] Step 1: At a distance of 10m from the central blast source, a group of rock specimens were drilled at 5m increments, i.e. 10m, 15m, and 20m, respectively. There were 9 sandstone rock specimens in total, with 3 specimens in each group. Cylindrical rock specimens with a diameter of 50mm and a height of 100mm were made. The specimens were loaded using the SHPB impact pressure rod dynamic experiment, using a 100mm large diameter rod, the impact gas pressure was set to 0.6MPa, and the confining pressure was 1MPa.

[0060] Step 2: Select a 500ml open glass container and place the rock specimen in the open container. At 25℃, add a neutral detergent with a pH of 6-8 to the open container, submerge the top of the rock specimen, soak for 2 minutes, take it out, and wipe the surface of the specimen with a cotton pad or dust-proof brush. Put it in the DHG-9140A vertical constant temperature blast drying oven for drying. Take out the dried specimen, place it in a cool and ventilated place for 1 hour, and cool it down.

[0061] Step 3: Use a scanner to scan the rock specimen in different directions, process the scanned images to obtain grayscale images, filter the grayscale images to remove noise, and convert all lines in the grayscale images into color plane images with different chromaticity values.

[0062] Step 4: Perform data statistics on the lines in the image, see Table 3, and define each line as m i , then the total number of cracks in all images is:

[0063] Table 3 Number of cracks in the image

[0064]

[0065] Substituting the above data into formula (1), we obtain M=111.

[0066] Step 5: Statistical graph of the number of small cracks less than 25 mm in length m i1 , the number of medium cracks with a length of 25-75 mm m i2 , the number of large cracks with a length greater than 75 mm mi3 , see Table 4:

[0067] Table 4 Crack distribution number

[0068]

[0069] Substituting the above data into formula (2), we obtain U=0.6725.

[0070] Step 6: According to the on-site blasting design, the blasting charge is 20×10 3 kg. Based on the empirical formula for blasting, the blasting radius is estimated to be 27m.

[0071] The matching relationship between the blasting block size ratio and the corresponding blasting charge Q and blasting radius R is established as shown in formula (3):

[0072]

[0073] Where, C is the rock wave impedance correction constant, which is 0.807; Q is the blasting charge in the blasting area, which is 15×10 3 kg; K is the adjustment coefficient related to the performance of explosives, which is taken as 1.5; R is the blasting radius of the blasting area, which is taken as 25m; L is the correlation matching coefficient, which are 0.6725 respectively.

[0074] Substituting the above data into formula (3), the final calculated blasting block size ratio is N=0.9431, that is, the blasting block size qualification rate is 94.31%, and the difference between the expected value and the target value of the blasting block size is less than 6%, indicating that the blasting effect is excellent.

[0075] In the blasting process of the present invention, the block size is formed by the development of a large number of interlaced cracks, and each crack will form the surface of two adjacent rock blocks. By taking the joints and fissures measured in the laboratory as a reference, an adjustment coefficient is established based on the block size formed by the intersection of the crack surfaces, and then the actual blasting block size is predicted to obtain the percentage of block size that meets the requirements. This guides the optimization of blasting engineering and achieves high-efficiency and high-quality blasting work.

[0076] It is easy for those skilled in the art to understand that, under the premise of no conflict, the above-mentioned advantageous methods can be freely combined and superimposed.

Claims

1. A method for predicting blasting fragmentation, characterized in that: The method for collecting and predicting blasting data for blasting engineering includes the following steps: Step 1: In the target rock mass area, multiple rock specimens are drilled at equal distances L from the central blast source. The sampling depth is 0.5m to 1m in the rock layer. The drilling diameter of each rock specimen is 50mm and the drilling height is 100mm. Each rock specimen is numbered. Step 2: Conduct impact mechanics experiments on each rock specimen. Place the rock specimens after the test in an open glass container. Soak and rinse them with a neutral detergent at an ambient temperature of 25°C. Wipe the washed rock specimens clean and dry them. Ventilate and cool the dried rock specimens. Step 3: Scan the rock specimen in multiple directions with a scanner, process the scanned image to obtain a grayscale image, filter the grayscale image to remove noise, and convert all lines in the grayscale image into a color plane image with multiple chromaticity values; Step 4: Perform data statistics on the lines in the acquired color plane image and define each line as m i , then the total number of cracks M in the color plane image of all rock specimens is as shown in formula (1): Step 5: Based on the total number of cracks obtained from the color plane images of all rock specimens, set the first crack, the second crack, and the third crack, where the total number of first cracks is recorded as m i1 , the total number of cracks of the second crack is recorded as m i2 , the total number of cracks of the third crack is recorded as m i3 According to multiple groups of tests, the relationship between the sum of the number of cracks of the first crack and the number of cracks of the second crack and the sum of the number of cracks of the first crack, the number of cracks of the second crack and the number of cracks of the third crack is established to establish the correlation matching coefficient U of the rock specimen to form a qualified block volume, as shown in formula (2): Step 6: Establish the matching relationship between the blasting block ratio and the corresponding blasting charge Q and blasting radius R as shown in formula (3): Where, N is the proportion of blasting block size; C is the rock wave impedance correction coefficient, ranging from 0.01 to 1; Q is the blasting charge in the blasting area, kg; K is the adjustment coefficient related to the explosive performance, ranging from 1 to 2.82; R is the blasting radius of the blasting area, m; U is the relevant matching coefficient; The matching relationship between the blasting block size ratio and the corresponding blasting charge Q and blasting radius R is obtained based on the calculation, and the parameters are adjusted according to the predicted effect to achieve the target blasting.

2. The method for predicting blasting fragmentation according to claim 1, characterized in that: Step 2 also includes: loading the rock specimen using the SHPB impact bar dynamic test, with the impact gas pressure set to 0.1-1.5 MPa and the confining pressure set to 1-2 MPa; The pH value of neutral detergent is 6-8.

3. The method for predicting blasting fragmentation according to claim 1, characterized in that: The scanner in step three is a CT scanner.

4. The method for predicting blasting fragmentation according to claim 1, characterized in that: In step 5, the first crack size is less than 25 mm in length, the second crack size is 25 mm-75 mm in length, and the third crack size is greater than 75 mm in length.

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