Method for evaluating pressure relief effect of coal seam roof blasting

Abstract

The application provides a coal seam roof blasting pressure relief effect evaluation method, comprising: detecting at each detection area to obtain a first apparent resistivity and a first rock layer loose degree before pressure relief; blasting the area to be blasted; detecting the blasted area at each detection area to obtain a second apparent resistivity and a second rock layer loose degree after pressure relief; obtaining a blasting pressure relief efficiency evaluation result at each detection area according to the first apparent resistivity and the second apparent resistivity at each detection area; obtaining a blasting loose degree efficiency evaluation result at each detection area according to the first rock layer loose degree and the second rock layer loose degree at each detection area; and obtaining a roof blasting pressure relief effect evaluation result according to the blasting pressure relief efficiency evaluation result and the blasting loose degree efficiency evaluation result at each detection area. The technical scheme of the application effectively solves the problem of poor accuracy of roof pressure relief effect evaluation after blasting in related technologies.

Description

Technical Field

[0001] This invention relates to the field of coal mine safety technology, and more specifically, to a method for evaluating the pressure relief effect of coal seam roof blasting. Background Technology

[0002] Due to the unique geological environment and complex geological structure of the coal seam, the hard roof is difficult to collapse, posing a significant threat to the safe mining of the working face. To disrupt the continuity of the hard roof, reduce stress concentration at the working face, facilitate timely roof collapse after mining, and increase the venting potential of the top coal, pre-splitting blasting is implemented to relieve pressure on the roof. The roof pressure relief efficiency after blasting is evaluated.

[0003] A related technology provides a method for evaluating the pressure relief effect of coal seam blasting. This evaluation method involves deploying a microseismic monitoring system and several microseismic sensors underground in the coal mine. It utilizes the location information and energy release intensity of blasting events in the test boreholes through microseismic monitoring, and then evaluates the pressure relief effect of the blasting using a constructed comprehensive evaluation method.

[0004] A microseismic monitoring system was used to compare and analyze data before and after depressurization. Simultaneously, the established evaluation method was used to analyze the roof depressurization effect after blasting. This involves processing and analyzing the vibration wave signals, which are easily affected by the coal seam environment and underground production. Furthermore, the vibration signals are easily affected by the face mining, complicating filtering and noise reduction work and resulting in poor accuracy in evaluating the roof depressurization effect after blasting. Summary of the Invention

[0005] The main objective of this invention is to provide a method for evaluating the pressure relief effect of coal seam roof blasting, so as to solve the problem of poor accuracy in evaluating the pressure relief effect of the roof after blasting in related technologies.

[0006] To achieve the above objectives, the present invention provides a method for evaluating the pressure relief effect of coal seam roof blasting, comprising: before roof blasting, setting multiple blasting holes at equal intervals along a preset direction in the area to be blasted; setting multiple detection areas at equal intervals along the preset direction, with one detection area set at each blasting hole and at least one detection area set at a preset distance from each blasting hole; probing at each detection area to obtain a first apparent resistivity and a first rock stratum looseness before pressure relief; blasting the area to be blasted; probing the blasted area at each detection area to obtain a second apparent resistivity and a second rock stratum looseness after pressure relief; obtaining a blasting pressure relief efficiency evaluation result for each detection area based on the first and second apparent resistivity; obtaining a blasting loosening efficiency evaluation result for each detection area based on the first and second rock stratum looseness; and obtaining an evaluation result of the roof blasting pressure relief effect based on the blasting pressure relief efficiency evaluation result and the blasting loosening efficiency evaluation result for each detection area.

[0007] Furthermore, the steps for obtaining the evaluation results of the roof blasting pressure relief effect based on the evaluation results of the blasting pressure relief efficiency and the blasting loosening efficiency at each detection area include: establishing a comprehensive evaluation model for the blasting pressure relief effect based on the evaluation results of the blasting pressure relief efficiency and the blasting loosening efficiency at each detection area; evaluating the results obtained from the comprehensive evaluation model for the blasting pressure relief effect to obtain the evaluation results of the roof blasting pressure relief effect.

[0008] Further, the step of obtaining the explosion relief efficiency evaluation result for each detection area based on the first and second apparent resistivity at each detection area includes: calculating the explosion relief efficiency for each detection area based on the first and second apparent resistivity according to the following formula: Among them, M i The burst pressure relief efficiency at each detection area. The first apparent resistivity, Let i be the second apparent resistivity, where i is a positive integer; determine M. i Does it satisfy: M min <M i <M max , of which M min To achieve the minimum explosive pressure relief efficiency, M max To achieve the maximum explosive pressure relief efficiency, when M is determined i Satisfy: M min <M i <M max At that time, according to M i The results of the blasting depressurization efficiency were obtained.

[0009] Further, the steps for obtaining the blasting loosening efficiency evaluation result for each detection area based on the first and second rock strata loosening at each detection area include: using a transient electromagnetic instrument to obtain the first area before blasting and the second area after blasting for each detection area; obtaining the score corresponding to each measuring line in each detection area based on multiple measuring lines within each detection area and the relationship between the first and second areas; obtaining the weight of the second rock strata loosening at each measuring line in each detection area relative to the second area based on the second rock strata loosening at each measuring line in each detection area; and obtaining the blasting loosening efficiency evaluation result based on the weight of the second rock strata loosening at each measuring line in each detection area relative to the second area of ​​the detection area it belongs to and the score corresponding to each measuring line.

[0010] Furthermore, the steps for obtaining the score corresponding to each measurement line in each detection area based on the multiple measurement lines within each detection area and the relationship between the first area and the second area include: setting a full score of A points, where A is a positive integer, and determining the relationship between the first area and the second area using the following formula to obtain the score corresponding to each measurement line in each detection area: Where i is a positive integer, d i The score s for each measurement line in each detection area. i Let s be the first area. ’ i This is the second area.

[0011] Furthermore, the steps for obtaining the blasting loosening efficiency evaluation result based on the weight of the second rock layer loosening at each measuring line in each detection area to the second area of ​​the detection area and the score corresponding to each measuring line include: analyzing the weight of the second rock layer loosening at each measuring line in each detection area to the second area of ​​the detection area and the score corresponding to each measuring line according to the following formula to obtain the blasting loosening efficiency evaluation result for each detection area: Among them, W i Evaluation results of blasting loosening efficiency at each detection area, u i The weight of the second rock stratum looseness at each survey line in each detection area is given by the weight of the second area of ​​the detection area, where u1 + u2 + ... + u i +……+u n =1, n is greater than or equal to i, and i and n are both positive integers.

[0012] Furthermore, the comprehensive evaluation model for the blasting pressure relief effect is obtained through the following formula: Where U is the comprehensive evaluation matrix of the comprehensive evaluation model for the blasting pressure relief effect, and V a-b The feature vector represents the weight between the blasting pressure relief efficiency evaluation result and the blasting loosening efficiency evaluation result at each detection area. ab represents the rock strata from the final roof blasting pressure relief to the intermediate roof blasting pressure relief, and Y represents the measured score of the blasting pressure relief efficiency evaluation result and the blasting loosening efficiency evaluation result.

[0013] Furthermore, the weighting of the blasting decompression efficiency evaluation result and the blasting loosening efficiency evaluation result at each detection area is as follows: Among them, M i M i For M i Relative to M i The importance of M i W i For M i Compared to W iThe importance of W i M i For W i Relative to M i The importance of W i W i For W i Compared to W i The importance of the explosion is determined by the following formula: Y = (Q1, Q2), where Y is the measured score, Q1 is the explosion decompression efficiency evaluation result, and Q2 is the explosion loosening efficiency evaluation result.

[0014] Furthermore, between the steps of evaluating the blasting pressure relief efficiency and blasting loosening efficiency at each detection area and establishing a comprehensive evaluation model for the blasting pressure relief effect, the coal seam roof blasting pressure relief effect evaluation method also includes: quantifying and classifying the blasting pressure relief efficiency and blasting loosening efficiency at each detection area into { , , ..., , ..., }, where n is greater than or equal to i, and i and n are both positive integers. The larger n is, the greater the value of n. The lower the evaluation level, the better; the final evaluation result for the roof blasting pressure relief effect is: T max =max{ , , ..., , ..., }, when T max =max At that time, we obtain the same as corresponding The evaluation method for the pressure relief effect of coal seam roof blasting also includes: when Less than At the same time, at least one of the following parameters can be changed: the location of the blast hole, the angle of the blast hole, and the amount of explosive charge inside the blast hole.

[0015] Furthermore, the step of setting a blasting hole at a predetermined interval along a predetermined direction in the inner edge of the area to be blasted before the roof blasting includes: setting a blasting hole at a predetermined interval along a predetermined direction on the sidewalls of the upper and lower roadways in the inner edge of the area to be blasted before the roof blasting, thus dividing the blasting holes in the upper and lower roadways into upper and lower groups.

[0016] The method for evaluating the pressure relief effect of coal seam roof blasting using the technical solution of this invention includes: before roof blasting, setting multiple blasting holes at equal intervals along a preset direction in the area to be blasted; setting multiple detection areas at equal intervals along a preset direction, with one detection area set at each blasting hole and at least one detection area set at a preset distance from each blasting hole; detecting at each detection area and obtaining the first apparent resistivity and the first rock stratum looseness before pressure relief; blasting the area to be blasted; detecting the blasted area at each detection area and obtaining the second apparent resistivity and the second rock stratum looseness after pressure relief; obtaining the blasting pressure relief efficiency evaluation result for each detection area based on the first and second apparent resistivity; obtaining the blasting loosening efficiency evaluation result for each detection area based on the first and second rock stratum looseness; and obtaining the evaluation result of the roof blasting pressure relief effect based on the blasting pressure relief efficiency evaluation result and the blasting loosening efficiency evaluation result for each detection area. The evaluation results of the roof blasting pressure relief effect obtained through the above-mentioned method for evaluating the roof blasting pressure relief effect do not require processing and analysis of vibration wave signals, are unaffected by the coal seam occurrence environment and underground production, and do not need to consider the influence of working face mining on vibration signals, thus avoiding the trouble caused by filtering and noise reduction work. This improves the accuracy of the evaluation of the roof blasting pressure relief effect. Therefore, the technical solution of this application effectively solves the problem of poor accuracy in evaluating the roof blasting pressure relief effect in related technologies. Attached Figure Description

[0017] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0018] Figure 1 A flowchart illustrating an embodiment of the method for evaluating the pressure relief effect of coal seam roof blasting according to the present invention is shown;

[0019] Figure 2 It shows the use of Figure 1 A cross-sectional view of the coal seam roof blasting pressure relief effect evaluation method, which involves arranging blasting holes in the area to be blasted.

[0020] Figure 3 It shows the use of Figure 1 The evaluation method for the pressure relief effect of coal seam roof blasting involves a perspective view of the arrangement of blasting holes in the area to be blasted.

[0021] Figure 4 It shows Figure 1 A schematic diagram illustrating the use of a transient electromagnetic instrument for detecting the effect of coal seam roof blasting pressure relief;

[0022] Figure 5 It shows Figure 1 A cross-sectional view of the method for evaluating the pressure relief effect of coal seam roof blasting when using a transient electromagnetic instrument for detection.

[0023] The above figures include the following reference numerals:

[0024] 1. Working face; 10. Area to be blasted; 2. Detection area; 3. Blasting hole; 4. Measuring line; 5. Upper roadway; 6. Lower roadway. Detailed Implementation

[0025] 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. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. 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.

[0026] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0027] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0028] like Figures 1 to 5As shown, the method for evaluating the pressure relief effect of coal seam roof blasting in this embodiment includes: Step S01, before roof blasting, multiple blasting holes 3 are set at equal intervals along a preset direction in the area 10 to be blasted; Step S02, multiple detection areas 2 are set at equal intervals along a preset direction, one detection area 2 is set at each blasting hole 3, and at least one detection area 2 is set at a preset distance from each blasting hole 3; Step S03, detection is performed at each detection area 2, and the first apparent resistivity and the first rock looseness before pressure relief are obtained; Step S04, the area 10 to be blasted is blasted; Step S05, at each detection area 2, the pressure relief effect is evaluated by blasting multiple detection areas 2. Step S06: Based on the first and second apparent resistivity of each detection area 2, the blasting pressure relief efficiency evaluation result of each detection area 2 is obtained; Step S07: Based on the first and second apparent resistivity of each detection area 2, the blasting loosening efficiency evaluation result of each detection area 2 is obtained; Step S08: Based on the blasting pressure relief efficiency evaluation result and the blasting loosening efficiency evaluation result of each detection area 2, the roof blasting pressure relief effect is evaluated.

[0029] The method for evaluating the pressure relief effect of coal seam roof blasting using the technical solution of this embodiment includes: before roof blasting, setting multiple blasting holes 3 at equal intervals along a preset direction in the area 10 to be blasted; setting multiple detection areas 2 at equal intervals along a preset direction, with one detection area 2 set at each blasting hole 3 and at least one detection area 2 set at a preset distance from each blasting hole 3; detecting at each detection area 2 and obtaining the first apparent resistivity and the first rock looseness before pressure relief; blasting the area 10 to be blasted; and detecting at each detection area 2. The blasting area is probed, and the second apparent resistivity and second stratum looseness after pressure relief are obtained. Based on the first and second apparent resistivity at each detection area 2, the blasting pressure relief efficiency evaluation result for each detection area 2 is obtained. Based on the first and second stratum looseness at each detection area 2, the blasting looseness efficiency evaluation result for each detection area 2 is obtained. Based on the blasting pressure relief efficiency evaluation result and the blasting looseness efficiency evaluation result for each detection area 2, the roof blasting pressure relief effect evaluation result is obtained. In the process of obtaining the roof blasting pressure relief effect evaluation result through the above-mentioned coal seam roof blasting pressure relief effect evaluation method, there is no need to process and analyze the vibration wave signal, it is not affected by the coal seam occurrence environment and underground working production, and there is no need to consider the vibration signal being easily affected by the mining of the working face 1, avoiding the trouble brought about by filtering and noise reduction work. In this way, the accuracy of the roof pressure relief effect evaluation after blasting can be improved. Therefore, the technical solution of this embodiment effectively solves the problem of poor accuracy in the evaluation of the roof pressure relief effect after blasting in related technologies. In this embodiment, a transient electromagnetic instrument is used to perform detection at two locations in each detection area. This makes the transient electromagnetic instrument simple to operate, provides accurate results, and allows for rock strata detection at a depth of up to 150m. Furthermore, the transient electromagnetic instrument is highly sensitive to the resistivity of the surrounding rock medium, enabling it to accurately identify the evolution of the surrounding rock structure from an intact to a fragmented state. Moreover, the transient electromagnetic instrument provides non-destructive testing of the surrounding rock in roadways, with high detection efficiency, high accuracy, and minimal impact on normal mine production activities.

[0030] like Figures 1 to 5 As shown, the steps for obtaining the evaluation results of the roof blasting pressure relief effect based on the evaluation results of the blasting pressure relief efficiency and blasting loosening efficiency at each detection area 2 include: establishing a comprehensive evaluation model for the blasting pressure relief effect based on the evaluation results of the blasting pressure relief efficiency and blasting loosening efficiency at each detection area 2; evaluating the results obtained from the comprehensive evaluation model for the blasting pressure relief effect to obtain the evaluation results of the roof blasting pressure relief effect. In this way, when evaluating the blasting pressure relief effect through the comprehensive evaluation model, the relationship between various blasting effect evaluation indicators can be grasped more comprehensively. Furthermore, the evaluation results of the roof blasting pressure relief effect can be used as a basis for adjusting roof blasting weakening measures, optimizing roof blasting pressure relief parameters, and promoting roof collapse.

[0031] According to the collected hydrogeological data of the rock strata, the area where the roof was blasted and depressurized has good water content, which is helpful in distinguishing between the intact and fractured states of the rock strata when using a transient electromagnetic instrument. For rock strata rich in water or containing pore water, the transient electromagnetic instrument results show a low-resistivity area; for dry areas without water, the transient electromagnetic instrument results show a high-resistivity area.

[0032] Based on the determined properties and apparent resistivity of the roof strata of working face 1, and after reviewing relevant literature and conducting on-site investigations, the rock strata in the blasting decompression area, from bottom to top, consist of mudstone, medium sandstone, fine sandstone, and siltstone. Combining the pre-blasting decompression survey results with literature data, the apparent resistivity range of the rock strata was determined. The apparent resistivity was found to be 20–25 for mudstone, 28–42 for medium sandstone, 28–45 for fine sandstone, and 22–32 for siltstone.

[0033] like Figures 1 to 5 As shown, the steps for obtaining the explosion pressure relief efficiency evaluation result for each detection area 2 based on the first and second apparent resistivity at each detection area 2 include: calculating the explosion pressure relief efficiency for each detection area 2 based on the first and second apparent resistivity at each detection area 2 according to the following formula: Among them, M i The burst pressure relief efficiency at 2 locations in each detection area. The first apparent resistivity, Let i be the second apparent resistivity, where i is a positive integer; determine M. i Does it satisfy: M min <M i <M max , of which M min To achieve the minimum explosive pressure relief efficiency, M max To achieve the maximum explosive pressure relief efficiency, when M is determined i Satisfy: M min <M i <M max At that time, according to M i The results of the blasting depressurization efficiency were obtained.

[0034] According to the user manual for transient electromagnetic instruments, the first apparent resistivity... Approximately 35-55 Between, the second apparent resistivity Approximately 10-20 between.

[0035]

[0036]

[0037] The calculation results from the above formula show that the reasonable range for evaluating the blasting pressure relief efficiency of each detection area 2 using the apparent resistivity index is [42.86%, 81.82%]. Further, the steps for obtaining the blasting loosening efficiency evaluation result for each detection area 2 based on the first and second rock stratum looseness include: using a transient electromagnetic instrument to obtain the first area of ​​each detection area 2 before blasting and the second area after blasting; obtaining the score corresponding to each measuring line 4 of each detection area 2 based on the relationship between the multiple measuring lines 4 within each detection area 2 and the first and second areas; obtaining the weight of the second rock stratum looseness at each measuring line 4 of each detection area 2 relative to the second area based on the second rock stratum looseness; and obtaining the blasting loosening efficiency evaluation result based on the weight of the second rock stratum looseness at each measuring line 4 of each detection area 2 relative to the second area of ​​the detection area 2 it belongs to and the score corresponding to each measuring line 4. In this way, by using a transient electromagnetic instrument to evaluate the pressure relief effect of blasting on the roof of the coal seam, the area to be blasted can be monitored remotely without damage, without affecting the normal production activities of the mine.

[0038] Based on the burst pressure relief efficiency M at 2 locations in each detection area i The data was organized according to the numbering of blast hole 3, serving as a control group. Data from the monitoring was analyzed using transient electromagnetic instrument data processing software, ultimately yielding an image showing the change in apparent resistivity of the rock strata with increasing probe depth. The processed data images were numbered according to their distance from working face 1, and the first area, first apparent resistivity, and second apparent resistivity of the detection area 2 were recorded respectively.

[0039] It should be noted that the degree of looseness of the rock strata after blasting can serve as an important indicator for evaluating the pressure relief effect of roof blasting. The distribution characteristics and degree of looseness of the roof rock strata before and after roof blasting determine the blasting quality. Simultaneously, the distribution of the blasted blocks also affects the detection results of transient electromagnetic instruments. Based on the detection principle of transient electromagnetic instruments, they are more sensitive to low-resistivity regions. Assuming the underground rock strata are not aquifers, the cavity after blasting will not contain water or other substances, and the apparent resistivity of the blasted area will be high. If water is present, or if there is an aquifer near the blasted area, the blasted area will exhibit low resistivity.

[0040] The degree of looseness of the blocks after rock blasting is determined by the loosening coefficient, which is generally 1.2-1.5 for rocks. This coefficient varies considerably with lithology. Therefore, the degree of looseness of the fractured roof after depressurization by blasting is determined by the on-site personnel. The evaluation criteria can be initially divided into categories based on the degree of looseness. The five stages are shown below:

[0041]

[0042] The loosening coefficient after rock blasting was used to evaluate the blasting pressure relief effect on site. The evaluation criteria were mainly based on the range of the ratio of the first area to the second area of ​​the transient electromagnetic low resistance zone before and after blasting around the blast hole.

[0043] like Figures 1 to 5 As shown, utilizing the sensitivity of transient electromagnetic detection of the transient electromagnetic field in the blasting area 10, monitoring is conducted before and after blasting in each detection area to clarify the apparent resistivity of the rock strata near the blast hole 3 and the range of low-resistivity regions. Based on the multiple measuring lines 4 within each detection area 2 and the relationship between the first area and the second area, the steps to obtain the score corresponding to each measuring line 4 in each detection area 2 include: setting a full score of A points, where A is a positive integer, and determining the relationship between the first area and the second area using the following formula to obtain the score corresponding to each measuring line 4 in each detection area 2: Where i is a positive integer, d i The score s for each measurement line 4 in each detection area 2. i Let s be the first area. ’ i This is the second area.

[0044] like Figures 1 to 5 As shown, the steps to obtain the blasting loosening efficiency evaluation result based on the weight of the second rock layer loosening at each measuring line 4 of each detection area 2 relative to the second area of ​​the detection area 2 and the score corresponding to each measuring line 4 include: analyzing the weight of the second rock layer loosening at each measuring line 4 of each detection area 2 relative to the second area of ​​the detection area 2 and the score corresponding to each measuring line 4 according to the following formula to obtain the blasting loosening efficiency evaluation result for each detection area 2: Among them, W i Evaluation results of blasting loosening efficiency at two locations in each detection area, u i The weight of the second rock stratum looseness at each survey line 4 in each detection area 2 is given by the weight of the second area in that detection area 2, where u1 + u2 + ... + u i +……+u n =1, n is greater than or equal to i, and i and n are both positive integers. The evaluation results W of the blasting loosening efficiency at two locations in each detection area are used. i The data was organized according to the numbering of blast holes 3, forming a detection group. Transient electromagnetic instruments were used to analyze the monitored data using data processing software, ultimately obtaining an image showing the change in apparent resistivity of the rock strata with increasing detection depth. The processed data images were numbered according to their distance from the working face 1, and the second area, first rock stratum looseness, and second rock stratum looseness of the detection area 2 were recorded respectively.

[0045] The evaluation results of the blasting loosening efficiency at two locations in each testing area can be evaluated and scored using the method shown in Table 1 below.

[0046] Table 1

[0047]

[0048] According to the specifications for transient electromagnetic instruments, a reduction in apparent resistivity after rock blasting to less than half of the normal apparent resistivity value of the rock strata is required to meet the basic requirements for roof weakening. In other words, the greater the difference between the two values, the higher the score and the lower the degree of weakening.

[0049] When evaluating the decompression effect of blasting based on the degree of loosening after blasting, five measuring lines are used for evaluation and scoring at each cross-section. The full score is set as A = 10 points. The lower the score, the lower the degree of loosening and the worse the blasting effect. For specific scoring criteria, please refer to [reference needed]. The following scores were obtained:

[0050]

[0051] like Figures 1 to 5 As shown, the comprehensive evaluation model for the blasting pressure relief effect is obtained through the following formula: Where U is the comprehensive evaluation matrix of the comprehensive evaluation model for the blasting pressure relief effect, and V a-b This is a feature vector representing the weight between the blasting pressure relief efficiency evaluation result and the blasting loosening efficiency evaluation result at each detection area 2. Here, ab represents the rock strata from the final roof blasting pressure relief to the intermediate roof blasting pressure relief, and Y represents the measured score of both the blasting pressure relief efficiency evaluation result and the blasting loosening efficiency evaluation result. During the evaluation process, the comprehensive evaluation model for blasting pressure relief effect combines the evaluators' previous evaluation experience to quantify and classify each evaluation indicator, perform weight analysis, and then, through a series of calculations, finally obtain a quantitative evaluation level for the step blasting effect.

[0052] like Figures 1 to 5 As shown, the weights between the blasting decompression efficiency evaluation results and the blasting loosening efficiency evaluation results at each detection area 2 are as follows: Among them, M i M i For M i Relative to M i The importance of M i W i For M i Compared to W i The importance of W i M i For W i Relative to M i The importance of W i Wi For W i Compared to W i The importance of.

[0053] The scale table designed based on the evaluators' previous evaluation experience is shown in Table 2.

[0054] Table 2

[0055]

[0056] The method for filling out the table is to compare the importance of each indicator pairwise using a scaling table. In the case of M... i W i When performing weighted analysis, the factors affecting the on-site blasting pressure relief efficiency are analyzed (M). i Importance relative to W i The value is 2, therefore M i and W i The weights are shown in Table 3 below.

[0057] Table 3

[0058]

[0059] Normalizing the judgment matrix yields

[0060]

[0061] Normalizing the above equation, we obtain the eigenvectors of the weights:

[0062] V a-b =[0.667, 0.333]

[0063] The measured score is obtained by the following formula: Y = Q1, Q2, where Y is the measured score, Q1 is the evaluation result of the blasting pressure relief efficiency, and Q2 is the evaluation result of the blasting loosening efficiency.

[0064] like Figures 1 to 5 As shown, between the steps of evaluating the blasting pressure relief efficiency and blasting loosening efficiency at each detection area 2 and establishing a comprehensive evaluation model for the blasting pressure relief effect, the coal seam roof blasting pressure relief effect evaluation method further includes: quantifying and classifying the blasting pressure relief efficiency and blasting loosening efficiency at each detection area 2 into { , , ..., , ..., }, where n is greater than or equal to i, and i and n are both positive integers. The larger n is, the greater the value of n. The lower the evaluation level, the better; the final evaluation result for the roof blasting pressure relief effect is: T max =max{ , , ..., , ..., }, when T max =max At that time, we obtain the same as corresponding The evaluation method for the pressure relief effect of coal seam roof blasting also includes: when Less than At the same time, at least one parameter among the following can be changed: the position of blasting hole 3, the angle of blasting hole 3, and the amount of explosive charge inside blasting hole 3. This modifies the method for evaluating the pressure relief effect of coal seam roof blasting, thereby improving the accuracy of the evaluation of the pressure relief effect of the roof after blasting.

[0065] Based on the evaluators' previous evaluation experience, a scale table and levels were designed, and each evaluation indicator was quantified and graded to establish an indicator level grading table, as shown in Table 4 below.

[0066] Table 4

[0067]

[0068] like Figures 1 to 5 As shown, the step of setting a blasting hole 3 at a predetermined interval along a predetermined direction in the inner edge of the area to be blasted 10 before the roof blasting includes: setting a blasting hole 3 at a predetermined interval along a predetermined direction on the side walls of the upper roadway 5 and the lower roadway 6 in the inner edge of the area to be blasted 10 before the roof blasting, thus dividing the blasting holes 3 on the upper roadway 5 and the lower roadway 6 into upper and lower groups.

[0069] Before depressurizing the blasting area 10, the first step is to determine the extent of the blasting area 10 in front of the working face 1.

[0070] Due to the special occurrence environment of the coal seam, the hard roof, and its tendency to impact, roof overhang is likely to occur during the mining of working face 1, threatening the safe production of working face 1. In order to destroy the integrity of the roof, weaken the roof strength, and cut off the stress transmission path of the roof, the roof pre-splitting blasting measure is adopted to reduce the stress concentration of the hard roof in front of working face 1 and ensure the safe production of working face 1.

[0071] In this embodiment, the area to be blasted 10 is selected 200m-300m in front of the working face 1, with a set of blasting holes 3 set every 10m. To accurately evaluate the pressure relief effect of the roof blasting, transient electromagnetic detection is used with a detection depth of 50m. Three measuring points are set on each of the upper and lower roadways 6, spaced 5m apart. Each measuring point has five measuring lines 4, and the area where these five measuring lines 4 are located is the detection area, with angles ranging from 30° to 90°. Each measuring point is measured once before and after blasting, requiring a total of 12 measuring points and 60 measuring lines 4.

[0072] The pre-splitting blasting holes 3 in the upper roadway 5 and lower roadway 6 are arranged in a fan shape along the dip direction. The thick, high-strength rock strata 200-300m in front of the pre-splitting working face 1 form the basic roof, supporting the roof. The pre-splitting range of the roof is 100m, with a group of two boreholes arranged every 10m. The construction parameters of the blasting holes 3 in the upper roadway 5 and lower roadway 6 are shown in Table 5. After the pre-splitting blasting of the roof is completed, a transient electromagnetic instrument is used to probe the area 10 to be blasted.

[0073] Table 5

[0074]

[0075] In this embodiment, blasting was performed on the roof of a working face 1 in the Kuangou Coal Mine, from 5770m of the upper roadway to 780m of the lower roadway 6. Transient electromagnetic instruments were used for monitoring and quantitative evaluation of the blasting pressure relief effect. Monitoring results showed that after blasting, roof fractures developed significantly, and the apparent resistivity of the rock strata decreased substantially. The blasting effect was even better on the medium sandstone at a position 15.8m above working face 1. Furthermore, increasing the angle of the blasting hole 3 can significantly improve the pressure relief effect on the rock strata above the lower roadway 6. Based on the analysis of the pressure relief effect of the coal seam roof blasting, increasing the length of the blasting hole 3 is more conducive to the fracturing of the roof siltstone and allows for efficient and rapid monitoring of the pressure relief area, providing a basis for adjusting roof blasting weakening measures.

[0076] The transient electromagnetic instrument used in this embodiment is the YCS200(A) manufactured by Wuhan University of Geosciences Huarui. It is mainly used for geological structure detection, water-bearing (including) detection, and surface engineering exploration around underground coal mine roadways. The equipment mainly consists of a mining intrinsically safe transient electromagnetic instrument main unit, a YCS60F mining explosion-proof and intrinsically safe transient electromagnetic instrument transmitter, a receiving coil, and a transmitting coil.

[0077] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this invention; the directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0078] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0079] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0080] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for evaluating the pressure relief effect of coal seam roof blasting, characterized in that, include: Before the top plate is blasted, multiple blasting holes (3) are set at equal intervals along a preset direction in the area to be blasted (10). Multiple detection areas (2) are set at equal intervals along the preset direction. One detection area (2) is set at each of the blast holes (3). At least one detection area (2) is set at each of the blast holes (3) at a preset distance. Detection was performed at each of the detection areas (2) to obtain the first apparent resistivity and the first rock layer looseness before depressurization; The area to be blasted (10) is blasted; The blasting area is detected at each of the detection areas (2), and the second apparent resistivity and the second rock layer looseness after depressurization are obtained; Based on the first apparent resistivity and the second apparent resistivity at each of the detection areas (2), the evaluation result of the bursting pressure relief efficiency at each of the detection areas (2) is obtained; Based on the first rock layer looseness and the second rock layer looseness at each of the detection areas (2), the blasting looseness efficiency evaluation result at each of the detection areas (2) is obtained; Based on the evaluation results of the blasting pressure relief efficiency and the evaluation results of the blasting loosening efficiency at each of the detection areas (2), the evaluation results of the blasting pressure relief effect of the roof are obtained; The step of obtaining the evaluation result of the roof blasting pressure relief effect based on the evaluation results of the blasting pressure relief efficiency and the evaluation results of the blasting loosening efficiency at each of the detection areas (2) includes: establishing a comprehensive evaluation model of the blasting pressure relief effect based on the evaluation results of the blasting pressure relief efficiency and the evaluation results of the blasting loosening efficiency at each of the detection areas (2); evaluating the results obtained by the comprehensive evaluation model of the blasting pressure relief effect to obtain the evaluation result of the roof blasting pressure relief effect; The steps for obtaining the blasting loosening efficiency evaluation result for each detection area (2) based on the first rock layer loosening degree and the second rock layer loosening degree at each detection area (2) include: using a transient electromagnetic instrument to obtain the first area before blasting and the second area after blasting for each detection area (2); obtaining the score corresponding to each measuring line (4) of each detection area (2) based on the multiple measuring lines (4) in each detection area (2) and the relationship between the first area and the second area; obtaining the weight of the second rock layer loosening degree at each measuring line (4) of each detection area (2) relative to the second area based on the second rock layer loosening degree at each measuring line (4) of each detection area (2); and obtaining the blasting loosening efficiency evaluation result based on the weight of the second rock layer loosening degree at each measuring line (4) of each detection area (2) relative to the second area of ​​the detection area (2) where it is located and the score corresponding to each measuring line (4). The comprehensive evaluation model for the blasting pressure relief effect is obtained through the following formula: ； Wherein, U is the comprehensive evaluation matrix of the comprehensive evaluation model of the blasting pressure relief effect, Va-b is the feature vector of the weight between the blasting pressure relief efficiency evaluation result and the blasting loosening efficiency evaluation result at each detection area (2), ab is the rock layer from the final roof blasting pressure relief to the middle roof blasting pressure relief, and Y is the measured score of the blasting pressure relief efficiency evaluation result and the blasting loosening efficiency evaluation result; The weights between the explosion decompression efficiency evaluation result and the explosion loosening efficiency evaluation result at each of the detection areas (2) are as follows: ； Wherein, Mi is the blasting decompression efficiency at each of the detection areas (2), Wi is the blasting loosening efficiency evaluation result at each of the detection areas (2), MiMi is the importance of Mi relative to Mi, MiWi is the importance of Mi relative to Wi, WiMi is the importance of Wi relative to Mi, and WiWi is the importance of Wi relative to Wi; The measured score is obtained using the following formula: Y = (Q1, Q2) Wherein, Y is the measured score, Q1 is the evaluation result of the blasting pressure relief efficiency, and Q2 is the evaluation result of the blasting loosening efficiency.

2. The method for evaluating the pressure relief effect of coal seam roof blasting according to claim 1, characterized in that, The steps for obtaining the burst pressure relief efficiency evaluation result for each of the detection areas (2) based on the first apparent resistivity and the second apparent resistivity at each of the detection areas (2) include: The first apparent resistivity and the second apparent resistivity at each of the detection areas (2) are calculated according to the following formula to obtain the burst pressure relief efficiency at each of the detection areas (2): ； Among them, the For the first apparent resistivity, the Let i be the second apparent resistivity, where i is a positive integer; Determine the M i Does it satisfy: M min <M i <M max , wherein, the M min To minimize the explosive decompression efficiency, M max To maximize the explosive decompression efficiency. When M is determined i Satisfy: M min <M i <M max At that time, according to the M i The results of the blasting depressurization efficiency were obtained.

3. The method for evaluating the pressure relief effect of coal seam roof blasting according to claim 2, characterized in that, The steps for obtaining the score corresponding to each measurement line (4) of each detection area (2) based on the multiple measurement lines (4) within each detection area (2) and the relationship between the first area and the second area include: The maximum score is set to A, where A is a positive integer. The relationship between the first area and the second area is determined by the following formula to obtain the score corresponding to each measurement line (4) of each detection area (2): ； Where i is a positive integer, and d i For each test line (4) corresponding to each of the detection regions (2), the s i For the first area, s ’ i This is the second area.

4. The method for evaluating the pressure relief effect of coal seam roof blasting according to claim 3, characterized in that, The steps for obtaining the blasting loosening efficiency evaluation result based on the weight of the second rock layer loosening at each measuring line (4) of each detection area (2) relative to the second area of ​​the detection area (2) where it is located and the score corresponding to each measuring line (4) include: The following formula is used to analyze the weight of the second rock layer looseness at each measuring line (4) of each detection area (2) relative to the second area of ​​the detection area (2) where it is located, and the score corresponding to each measuring line (4), so as to obtain the blasting looseness efficiency evaluation result at each detection area (2): ； Wherein, the u i The weight of the second rock stratum looseness at each measuring line (4) of each of the detection areas (2) is given by the weight of the second area of ​​the detection area (2) in which it is located, where u1+u2+……+u i +……+u n =1, where n is greater than or equal to i, and both i and n are positive integers.

5. The method for evaluating the pressure relief effect of coal seam roof blasting according to claim 1, characterized in that, Between the steps of evaluating the blasting pressure relief efficiency and the blasting loosening efficiency at each of the detection areas (2) and establishing a comprehensive evaluation model for the blasting pressure relief effect, the method for evaluating the blasting pressure relief effect of the coal seam roof further includes: The quantification and grading are based on the evaluation results of the blasting decompression efficiency and the evaluation results of the blasting loosening efficiency at each of the detection areas (2) as follows: , , ..., , ..., }, wherein n is greater than or equal to i, to ensure that the evaluation results of the blasting decompression efficiency and the evaluation results of the blasting looseness efficiency at each detection area (2) are within the quantitative classification, i and n are both positive integers, and the larger n is, the greater the evaluation results of the blasting decompression efficiency and the blasting looseness efficiency at each detection area (2) are within the quantitative classification. The lower the rating; The final evaluation result of the roof blasting pressure relief effect is: T max =max{ , , ..., , ..., }, when T max =max At that time, the result is the same as described. The corresponding ; Wherein, ti is the top plate blasting and decompression effect of each of the detection areas (2); The method for evaluating the pressure relief effect of coal seam roof blasting also includes: When the Smaller than the At the same time, at least one of the following parameters can be changed: the position of the blast hole (3), the angle of the blast hole (3), and the amount of explosive charge in the blast hole (3).

6. The method for evaluating the pressure relief effect of coal seam roof blasting according to claim 1, characterized in that, The step of setting a blast hole (3) at a predetermined interval along the inner edge of the area to be blasted (10) before the top plate is blasted includes: On the sidewalls of the upper roadway (5) and lower roadway (6) in the area to be blasted (10) before the roof blasting, a blasting hole (3) is set at a predetermined distance along the predetermined direction, dividing the blasting holes (3) on the upper roadway (5) and lower roadway (6) into upper and lower groups.

Images