Rock burst working face roof blasting effect inspection method

Abstract

The invention discloses a rock burst working face roof blasting effect inspection method, and belongs to the technical field of coal mining rock burst prevention and control. The data comprises micro-seismic monitoring data, mine pressure monitoring data and influence factors influencing a working face; 2, analyzing data; analyzing the micro-seismic monitoring data to obtain a micro-seismic event activity trend and a micro-seismic event working face trend distribution rule; analyzing the mine pressure monitoring data to obtain the overall average level of the daily average pressure and the periodic weighting step pitch of the support in the corresponding impact dangerous area of the panel stope face; 3, the blasting effect is inspected; according to the method, the blank of the method for testing the effect of the roof blasting roof breaking measure is filled, a scientific, accurate and systematic means is provided for evaluating the effect of roof blasting in coal mining, and the uncertainty caused by experience and rough judgment in the past is avoided.

Description

Technical Field

[0001] The invention relates to the technical field of rock burst prevention and control in coal mining, and in particular to a method for testing the blasting effect of a roof of a rock burst working face. Background Art

[0002] In the field of coal mining, rock burst is a serious disaster that poses a huge threat to safe production. In order to reduce the impact of rock burst, roof blasting and roof breaking measures are often adopted. However, in previous practices, there is a lack of effective methods to accurately test the effect of roof blasting. The impact hazard level in different areas objectively reflects the influence of geological factors on the length of the roof cantilever beam, the bending deformation energy of the roof, and the degree of stress concentration. At the same time, the mining speed will also have an effect on the bending deformation energy and stress concentration of the roof.

[0003] Traditional inspection methods often rely on limited monitoring data and empirical judgments, which are highly subjective and uncertain. In the past, it was difficult to fully and deeply understand the changes in the internal structure and stress distribution of the roof rock layer caused by blasting by only observing the surface phenomena of the roof or simple stress measurements. Due to the lack of accurate and systematic effect inspection methods, it is impossible to discover problems in the blasting plan in time, resulting in unsatisfactory roof blasting effects, and the inability to effectively reduce the bearing capacity of the roof, change its structure and mechanical properties, thereby increasing the risk of rock burst and affecting the normal mining and production efficiency of coal mines. In addition, the lack of effective inspection methods also restricts the optimization and improvement of blasting parameters, making it difficult to achieve the best blasting effect, and also causing waste of resources and increased costs. Summary of the invention

[0004] In order to solve the problems of the prior art, the present invention provides a method for testing the blasting effect of the roof of a rock burst working face, comprising the following steps:

[0005] Step 1: Get data.

[0006] The data include: microseismic monitoring data, mine pressure monitoring data and influencing factors affecting the working face;

[0007] Step 2: Analyze the data.

[0008] The microseismic monitoring data is analyzed to obtain the activity trend of microseismic events and the distribution law of microseismic events on the working face.

[0009] The mine pressure monitoring data was analyzed to obtain the overall average level of the daily average support pressure and periodic pressure step distance in the corresponding impact danger area of ​​the panel mining face;

[0010] Step 3: Inspection of blasting effect;

[0011] The roof blasting effect is evaluated based on the analysis results of microseismic monitoring data and mine pressure monitoring data;

[0012] If the monitoring data and analysis results after the blasting show that the activity trend of microseismic events is low-frequency and low-energy, the distribution pattern of microseismic events on the working face has changed favorably, and the overall average level indicators of the daily average pressure of the supports and the expected pressure step distance in the corresponding impact danger area have improved significantly, it means that the blasting has achieved the expected effect and subsequent construction can continue according to the current blasting plan, otherwise the data should be optimized.

[0013] Furthermore, the process of obtaining data in step 1 includes:

[0014] Collect historical microseismic monitoring data and historical mine pressure monitoring data of all working faces in the panel area where the coal mining working face adopts blasting roof breaking measures and has been mined out;

[0015] The influencing factors affecting the working face include: the coal seam thickness H in the working face area where mining has been completed, the working face length L, the working face width W, the range R of different impact danger areas, the daily mining speed V of the working face where mining has been completed, the bulk density Y of the mined coal seam and the working face recovery rate η.

[0016] Furthermore, in step 2, the microseismic event activity trend analysis process includes:

[0017] The total energy, total frequency and maximum energy of microseismic events under different impact hazard area ranges R and different pushing and mining speeds are calculated according to the coal seam thickness H, working face length L, working face width W, bulk density Y of the mined coal seam and working face recovery rate η parameters in the corresponding area. The average microseismic energy and frequency released per 10,000 tons of coal at different pushing and mining speeds in the mined working face within different impact hazard area ranges R are obtained, and the overall average results of the maximum energy of the disk area, the microseismic energy and frequency released per 10,000 tons of coal are obtained.

[0018] Furthermore, in step 2, the process of analyzing the distribution law of microseismic events on the working surface includes:

[0019] The distribution law of microseismic events along the working face direction effectively reflects the influence range of the advanced stress caused by the length of the cantilever beam of the working face roof. Based on the known position coordinates of the two end points of the cut-eye and the microseismic event, the Heron's formula is used to calculate the straight-line distance h between the microseismic event and the cut-eye. The straight-line distance h between the microseismic event and the cut-eye is subtracted from the cumulative mining length L of the working face. Similarly, the distance between the microseismic event and the working face within the impact danger area range R of different mined working faces is calculated to obtain the overall average result of the panel area. The result is the overall average influence range of the advanced stress in the corresponding impact danger area of ​​the panel area.

[0020] Furthermore, the mine pressure monitoring data analysis process in step 2 includes:

[0021] Statistical analysis was conducted on the daily average pressure and periodic pressure step length of the working face supports in different impact hazard areas R of the mined working face in the panel area, and the overall average level of the daily average pressure and periodic pressure step length of the supports in the corresponding impact hazard areas of the panel area was obtained;

[0022] Statistical analysis methods are used to conduct statistical and comparative analysis on the average daily pressure and periodic pressure step of the support before and after blasting. Drawing software is used to draw a cloud diagram of the maximum end resistance of the support, which can show the changes and distribution patterns of the maximum end resistance of the support before and after blasting.

[0023] Furthermore, in step 3, during the inspection of the blasting effect, if the maximum energy of the current mining face, the microseismic energy and frequency released per 10,000 tons of coal, the advanced impact range of microseismic events, the daily average pressure of the supports in the corresponding impact danger area of ​​the mining face, and the periodic pressure step are greater than the overall level of the disk area, it indicates that the blasting effect has not met expectations, and the blasting parameters need to be adjusted, and the overlying key rock strata need to be accurately obtained through core drilling, the amount of explosives increased, and the blasting hole arrangement optimized until the ideal blasting effect is achieved.

[0024] Beneficial effects of the present invention:

[0025] 1. This application fills the gap in the effectiveness test method of roof blasting and roof breaking measures, and provides a scientific, accurate and systematic means for evaluating the effectiveness of roof blasting in coal mining, avoiding the uncertainty caused by relying on experience and rough judgment in the past.

[0026] 2. It can accurately quantify the stress changes and energy release after roof blasting, clearly reflect the degree of change in the roof rock structure and mechanical properties caused by blasting, and provide strong data support for optimizing subsequent blasting plans. It effectively makes up for the shortcomings of traditional inspection methods, and comprehensively considers the stress state, stability and energy changes of the roof through comprehensive monitoring of microseismic and mine pressure, thus improving the reliability of blasting effect evaluation.

[0027] 3. Timely discover problems and deficiencies in blasting roof breaking measures, adjust blasting parameters in a targeted manner, avoid rock burst accidents caused by poor blasting effects, and ensure safe production in coal mines. It provides a standardized and normalized roof blasting effect inspection model for the coal mining industry, promoting technical exchanges and industry development. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A schematic flow chart of the detection method provided by the present invention;

[0029] Figure 2 This is a schematic diagram for predicting the influence range of the advance stress provided by the present invention. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] See also Figure 1-2 The present invention provides a method for testing the blasting effect of the roof of a rock burst working face, comprising the following steps:

[0032] Step 1: Data collection:

[0033] Before acquiring data, the detection system is arranged first. Among them, the microseismic monitoring system and mine pressure monitoring system are reasonably arranged in the rock burst working face and surrounding areas.

[0034] The sensors of the microseismic monitoring system should be installed according to scientific spacing and layout to ensure comprehensive and accurate monitoring of microseismic events on the working face and surrounding rock formations; the pressure sensors of the mine pressure monitoring system should be installed on each support of the working face to achieve real-time and continuous monitoring of the support pressure.

[0035] (1) Collect historical microseismic monitoring data and historical mine pressure monitoring data of all working faces in the panel area where the coal mining working face adopts blasting roof breaking measures and has been mined out.

[0036] (2) According to the geological description of the working face and the impact hazard assessment report, the coal seam thickness H, working face length L, working face width W, range of different impact hazard areas R (none, weak, medium, strong), daily mining speed V of the working face that has been mined, bulk density Y of the mined coal seam, and working face recovery rate η are obtained.

[0037] Step 2: Data analysis and processing:

[0038] (1) Microseismic monitoring data analysis

[0039] Analysis of the activity trend of microseismic events: Microseismic monitoring can effectively capture the tiny vibration signals generated by rock fracture, thereby objectively reflecting the activity state and stress concentration of the overlying roof rock layer. The total energy, total frequency and maximum energy of microseismic events in different impact danger area ranges R (none, weak, medium, strong) and at different mining speeds are deeply analyzed. Among them, the impact danger area range and mining speed are known. According to the corresponding impact danger area range and different mining speeds, the maximum energy Emax, total energy ∑E and total frequency ∑N of microseismic events are summarized. Combined with the relevant parameters such as the coal seam thickness H, working face length L, working face width W, bulk density Y of the mined coal seam and working face recovery rate η in the corresponding area, the average microseismic energy and frequency released per 10,000 tons of coal in the mined working face in different impact danger area ranges R (none, weak, medium, strong) and at different mining speeds are calculated, and the overall average results of the maximum energy of the disk area and the microseismic energy and frequency released per 10,000 tons of coal are obtained.

[0040] Among them, the maximum energy Emax, total energy ∑E and total frequency ∑N of microseismic events are summarized under different pushing and mining speeds in the corresponding impact danger area calculated in the above steps, the total coal output of the working face Q = H×L×W×Y×η, the maximum energy of the disk area is the maximum energy Emax of the microseismic events calculated in the above, the microseismic energy E released per 10,000 tons of coal = total energy ∑E / coal output Q, and the microseismic frequency N released per 10,000 tons of coal = total frequency ∑N / coal output Q.

[0041] Analysis of the distribution law of microseismic events on the working face: The distribution law of microseismic events on the working face effectively reflects the influence range of the advanced stress caused by the length of the cantilever beam on the top plate of the working face. Given that the position coordinates of the two end points of the cut-eye and the microseismic event are known, the Heron formula can be used to calculate the straight-line distance h between the microseismic event and the cut-eye (first calculate the lengths AB, AC, BC of the three sides of the triangle formed by the coordinate points of the microseismic event and the coordinate points of the two end points of the cut-eye, calculate the semi-perimeter p = (AB + AC + BC) / 2, and the area of ​​the triangle formed The straight-line distance between the microseismic event and the cut-eye is h=2S / |AB|. Subtract the cumulative mining length d of the working face from the straight-line distance h between the microseismic event and the cut-eye, and calculate the distance between the microseismic event and the working face within the impact hazard area range R (none, weak, medium, strong) of the different recovered working faces in turn, and obtain the overall average result of the disk area. The result is the overall average influence range of the lead stress in the corresponding impact hazard area of ​​the disk area. In the actual monitoring of rock burst mines, by accurately calculating the distance between the microseismic event and the cut-eye, the influence range of the lead stress is accurately grasped, which provides a key reference basis for subsequent mining operations and effectively quantifies the pressure relief effect of blasting top breaking. At the same time, the analysis of the trend of microseismic activity in different impact hazard areas has deepened the understanding of stress changes in the process of coal seam mining, so that the blasting top breaking plan can be optimized in a targeted manner to improve mining efficiency and safety. The schematic diagram is as follows Figure 1 (2) Analysis of mine pressure monitoring data

[0042] The blasting roof breaking measure will destroy the integrity of the overlying rock layer on the roof, reduce the bearing capacity of the roof, and effectively change the structure and mechanical properties of the roof. The daily average pressure and periodic pressure step length of the working face support can objectively reflect the stress state and stability changes of the roof after blasting roof breaking. Statistical analysis was carried out on the daily average pressure and periodic pressure step length of the working face support in different impact hazard areas R (none, weak, medium, strong) of the recovered working face in the panel area, and the overall average level of the daily average pressure and periodic pressure step length of the support in the corresponding impact hazard area of ​​the panel area was obtained.

[0043] Step 3: Comprehensive inspection and evaluation of blasting effect

[0044] Comprehensive microseismic monitoring data and mine pressure monitoring data are used to comprehensively and systematically evaluate the roof blasting effect. If the maximum energy of the current mining face, the microseismic energy and frequency released per 10,000 tons of coal, the advanced impact range of microseismic events, the average daily pressure of the face support and the periodic pressure step are less than or equal to the overall level of the panel area, it means that the roof blasting has achieved the expected effect and the current blasting plan can be maintained for subsequent construction; on the contrary, if the above indicators are greater than the overall level of the panel area, it means that the blasting effect has not met expectations and the blasting parameters need to be adjusted, such as accurately obtaining the overlying key rock layer through drilling and coring, increasing the charge amount, optimizing the blasting hole layout, etc., until the ideal blasting effect is achieved.

[0045] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for testing the blasting effect of the roof of a rock burst working face, characterized in that: The following steps are involved: Step 1: Get data. The data include: microseismic monitoring data, mine pressure monitoring data and influencing factors affecting the working face; Step 2: Analyze the data. The microseismic monitoring data is analyzed to obtain the activity trend of microseismic events and the distribution law of microseismic events on the working face. The mine pressure monitoring data was analyzed to obtain the overall average level of the daily average support pressure and periodic pressure step distance in the corresponding impact danger area of ​​the panel mining face; Step 3: Inspection of blasting effect; The roof blasting effect is evaluated based on the analysis results of microseismic monitoring data and mine pressure monitoring data; If the monitoring data and analysis results after the blasting show that the activity trend of microseismic events is low-frequency and low-energy, the distribution pattern of microseismic events on the working face has changed favorably, and the overall average level indicators of the daily average pressure of the supports and the periodic pressure step distance in the corresponding impact danger area have improved significantly, it means that the blasting has achieved the expected effect and subsequent construction can continue according to the current blasting plan, otherwise the data should be optimized.

2. The method for testing the blasting effect of the roof of a rock burst working face according to claim 1, characterized in that: The process of obtaining data in step 1 includes: Collect historical microseismic monitoring data and historical mine pressure monitoring data of all working faces in the panel area where the coal mining working face adopts blasting roof breaking measures and has been mined out; The influencing factors affecting the working face include: the coal seam thickness H in the working face area where mining has been completed, the working face length L, the working face width W, the range R of different impact danger areas, the daily mining speed V of the working face where mining has been completed, the bulk density Y of the mined coal seam and the working face recovery rate η.

3. The method for testing the blasting effect of the roof of a rock burst working face according to claim 2, characterized in that: In step 2, the microseismic event activity trend analysis process includes: The total energy, total frequency and maximum energy of microseismic events under different impact hazard area ranges R and different pushing and mining speeds are calculated according to the coal seam thickness H, working face length L, working face width W, bulk density Y of the mined coal seam and working face recovery rate η parameters in the corresponding area. The average microseismic energy and frequency released per 10,000 tons of coal at different pushing and mining speeds in the mined working face within different impact hazard area ranges R are obtained, and the overall average results of the maximum energy of the disk area, the microseismic energy and frequency released per 10,000 tons of coal are obtained.

4. The method for testing the blasting effect of the roof of a rock burst working face according to claim 1, characterized in that: In step 2, the process of analyzing the distribution law of microseismic events along the working face includes: Based on the known coordinates of the two end points of the cut-eye and the position of the microseismic event, the Heron's formula is used to calculate the straight-line distance h between the microseismic event and the cut-eye. The straight-line distance h between the microseismic event and the cut-eye is subtracted from the cumulative mining length L of the working face. Similarly, the distance between the microseismic event and the working face within the impact danger area range R of different recovered working faces is calculated to obtain the overall average result of the panel area. The result is the overall average influence range of the advanced stress in the corresponding impact danger area of ​​the panel area.

5. The method for testing the blasting effect of the roof of a rock burst working face according to claim 1, characterized in that: The mine pressure monitoring data analysis process in step 2 includes: Statistical analysis was conducted on the daily average pressure and periodic pressure step length of the working face supports in different impact hazard areas R of the mined working face in the panel area, and the overall average level of the daily average pressure and periodic pressure step length of the supports in the corresponding impact hazard areas of the panel area was obtained; Statistical analysis methods are used to conduct statistical and comparative analysis on the average daily pressure and periodic pressure step of the support before and after blasting. Drawing software is used to draw a cloud diagram of the maximum end resistance of the support, which can show the changes and distribution patterns of the maximum end resistance of the support before and after blasting.

6. The method for testing the blasting effect of the roof of a rock burst working face according to claim 1, characterized in that: In step 3, during the inspection of the blasting effect, if the maximum energy of the current mining face, the microseismic energy and frequency released per 10,000 tons of coal, the advanced impact range of microseismic events, the daily average pressure of the support in the corresponding impact danger area of ​​the mining face, and the periodic pressure step are greater than the overall level of the disk area, it indicates that the blasting effect has not met expectations, and the blasting parameters need to be adjusted. The overlying key rock strata should be accurately obtained through drilling and coring, the amount of explosives should be increased, and the blasting hole layout should be optimized until the ideal blasting effect is achieved.

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