Precise positioning method of coal mine underground surrounding rock abnormal sound based on acoustic wave and microseismic combined monitoring

Abstract

The present application provides a kind of coal mine underground surrounding rock heteroacoustic sound accurate positioning method based on acoustic wave and microseismic joint monitoring, belong to coal mine safety mining field;Solve the problem that existing microseismic monitoring system cannot accurately position rock heteroacoustic sound;Including the following steps: in coal mine roadway, microseismic monitoring system and acoustic wave monitoring system are arranged;The parameters of microseismic monitoring system are set, the target roadway is monitored in a specific time period, and all microseismic events in the time period are obtained;The basic parameters of acoustic wave monitoring system are set, the acoustic wave frequency band interval is set as the frequency band that can be received by human ear, and the target roadway is monitored in a specific time period;The data collected by acoustic wave monitoring system at the same time and the effective microseismic events collected by microseismic monitoring system are compared, the microseismic events meeting the rock heteroacoustic sound condition are screened out, and the exact rock layer height of the heteroacoustic sound wave is positioned by microseismic monitoring system;The present application is applied to mine surrounding rock heteroacoustic monitoring.

Description

Technical Field

[0001] This invention provides a method for accurately locating abnormal noises in underground coal mine surrounding rock based on combined acoustic and microseismic monitoring, belonging to the field of coal mine safety mining technology. Background Technology

[0002] my country has abundant coal resources, but the geological structure of coal seams is complex and diverse, with differences in lithology among different rock strata. During the mining process, some mines experience excessive development of rock fissures, leading to abnormal noises from the surrounding rock. This has a significant impact on the safe production of the mine. Therefore, accurately locating abnormal noises caused by the surrounding rock in coal mines, eliminating potential dangers from these noises, or providing effective early warnings for areas affected by rock impacts are crucial guarantees for the safe and efficient mining of coal resources.

[0003] Under current technological conditions, the main methods for monitoring the damage to surrounding rock in coal mines are acoustic emission and microseismic monitoring technologies. These methods use highly sensitive sensors and data processing systems to record and analyze minute seismic activities to provide detailed information about underground activity. However, with advancements in coal mining technology, several shortcomings have emerged in practical applications. First, there are discrepancies between the predicted degree of rock strata fracture and the actual situation. Second, acoustic monitoring cannot be implemented to locate abnormal noise sources underground in real time. Furthermore, the on-site construction work is extensive, requiring a large number of personnel, the data obtained is uneven and prone to errors, and the cost is relatively high.

[0004] Some scholars have proposed a novel rock mass stability monitoring system and its application based on acoustic emission and microseismic technology (Article No. 1671-4172 (2008) 04-0032-04). This system utilizes waves and microseismic signals emitted by the rock mass itself after stress deformation and failure to monitor the stability of engineering rock masses. The disadvantages of this method are: 1. The monitoring frequency band is relatively broad, but the precision of the frequency range for specific acoustic waves of abnormal noises in the surrounding rock is insufficient. 2. The identification of specific monitoring objects is weak, and the data screening and extraction of abnormal noise acoustic waves cannot be accurate and effective. 3. It can only determine the location of the seismic source and the magnitude of the microseismic event energy, but cannot effectively identify the type of rock stratum from which the received wave emission source originates, or the actual development of rock fissures. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention proposes a precise method for locating abnormal noises in underground coal mine surrounding rock based on combined acoustic and microseismic monitoring. The aim is to classify and screen valid events monitored by the microseismic monitoring system, effectively identify events consistent with abnormal noises in the rock strata, and extract and save key data. This allows for precise location of the abnormal noises in the rock strata, determining the source location and providing a foundation for further research into their sound generation mechanisms. Real-time acoustic monitoring, combined with the microseismic monitoring system, helps prevent threats to mine safety caused by dynamic pressure on the mine roof or surrounding rock. Experimental calculations of the ground pressure and energy release in fractured rock strata can further provide a basis for selecting support strength and preventing rock outburst disasters.

[0006] The technical solution adopted in this invention is: a method for accurately locating abnormal noises in underground coal mine surrounding rock based on combined acoustic and microseismic monitoring, comprising the following steps:

[0007] S1: Install microseismic monitoring systems and acoustic monitoring systems in coal mine roadways;

[0008] S2: Set the parameters of the microseismic monitoring system, monitor the target roadway for a specific time period, acquire all microseismic events within that time period, perform preliminary screening, organize the valid microseismic events, and collect relevant data;

[0009] S3: Set the basic parameters of the acoustic monitoring system, set the acoustic frequency band to a band that can be received by the human ear, monitor the target tunnel for a specific time period, obtain all valid acoustic events within that time period, and collect relevant data;

[0010] S4: Compare the acoustic wave data collected by the acoustic wave monitoring system at the same time with the effective microseismic events collected by the microseismic monitoring system, screen out the microseismic events that meet the conditions for abnormal noise in the rock strata, and locate the exact height of the rock strata emitting the abnormal noise sound using the effective data collected by the microseismic monitoring system.

[0011] Furthermore, it also includes the following steps:

[0012] S5: Design a rock mechanics test for the rock strata that emitted abnormal sound waves as determined in step S4, prepare a rock core specimen, and use a sound wave acquisition instrument to collect the fracturing and crushing sound of the rock core specimen;

[0013] S6: Then perform uniaxial compression on the core specimen and collect relevant important data during the test;

[0014] S7: The acoustic wave data generated by the fracturing and crushing of rock core specimens collected in the laboratory test will be compared with the microseismic events that meet the conditions for abnormal noise in rock strata and have been screened in the microseismic monitoring system. Further screening will be conducted to identify relevant data in accurate and effective microseismic events that meet the conditions for abnormal noise caused by the fracturing of surrounding rock.

[0015] Furthermore, the microseismic monitoring system in step S1 includes seismic sensors and microseismic monitoring substations. The seismic sensors are connected to the microseismic monitoring substations via mine communication cables. The microseismic monitoring substations are connected to a ring network switch via network cables to transmit signals to a ground-based acquisition server, where the data is analyzed by the ground-based processing server.

[0016] Furthermore, the acoustic monitoring system in step S1 includes an acoustic receiving device, an acoustic detector, and a main controller. The acoustic receiving device is connected to the acoustic detector, the main controller, and the ground-based acquisition server via connecting cables.

[0017] Furthermore, the tunnel is divided into multiple monitoring sections, with a seismic sensor and an acoustic receiver installed in each section. A microseismic monitoring substation is installed at the tunnel exit, and at least one acoustic detector is installed inside the tunnel.

[0018] Furthermore, in step S4, by sequentially comparing the effective microseismic events collected by the microseismic monitoring system with the time, waveform, frequency, amplitude, and energy data of the abnormal sound waves collected by the acoustic monitoring system, microseismic events with abnormal sound waves in the rock strata are screened out.

[0019] Furthermore, by using proof by contradiction, abnormal sound waves that conform to the fracturing failure of surrounding rock can be effectively identified in the microseismic monitoring system. At the same time, the energy magnitude of these abnormal sound waves is further collected, and energy indicators are used for rockburst early warning.

[0020] Furthermore, the acoustic receiving device employs a contact sensor, which is installed at the top of the tunnel.

[0021] The advantages of this invention over the prior art are as follows:

[0022] 1. This invention can accurately screen valid microseismic events detected by the microseismic monitoring system and quickly collect data related to abnormal noises in the surrounding rock. This efficient data processing capability provides a solid foundation for subsequent analysis.

[0023] 2. This invention allows for the accurate location of rock strata experiencing compression-shear failure, and, combined with on-site monitoring data and experimental results, effectively determines the fracture characteristics of the roof strata. This process contributes to a deeper understanding of the mechanical behavior and potential instability risks of rock strata.

[0024] 3. This invention can infer the degree of damage caused by rock strata fractures, and thus assess their hazard level. Simultaneously, through uniaxial fracturing tests, the degree of ground pressure can be estimated, providing a scientific basis for the selection of tunnel support.

[0025] 4. The entire system is easy and quick to operate, has a high accuracy rate in identifying target events, and requires relatively few boreholes at the construction site, thereby improving work efficiency and reducing construction costs. Attached Figure Description

[0026] The present invention will be further described below with reference to the accompanying drawings:

[0027] Figure 1 Flowchart for combined acoustic and microseismic monitoring

[0028] Figure 2 This is a schematic diagram of the installation layout of the downhole monitoring system;

[0029] Figure 3 Equipment diagram for an acoustic wave monitoring system;

[0030] Figure 4 A schematic diagram of the waveforms monitored by the acoustic wave monitoring system:

[0031] In the diagram: 1 is the acoustic wave receiver, 2 is the seismic sensor, 3 is the acoustic wave detector, 4 is the tunnel, 5 is the microseismic monitoring substation, and 6 is the main control instrument. Detailed Implementation

[0032] like Figures 1 to 4 As shown, this invention provides a method for accurately locating abnormal noises in underground coal mine surrounding rock based on combined acoustic and microseismic monitoring, comprising the following steps:

[0033] S1: Install a microseismic monitoring system and an acoustic monitoring system in coal mine roadway 4;

[0034] The microseismic monitoring system includes a seismic sensor 2 and a microseismic monitoring substation 5. The seismic sensor 2 is connected to the microseismic monitoring substation 5 via a mine communication cable. The microseismic monitoring substation 5 is connected to a ring network switch via a network cable. The signal is transmitted to the ground acquisition server through the underground ring network. The ground processing server analyzes the data and compiles the corresponding results report.

[0035] The acoustic wave monitoring system includes an acoustic wave receiver 1, an acoustic wave detector 3, and a main controller 6. The acoustic wave receiver 1 is connected to the acoustic wave detector 3, the main controller 6, and a ground-based data acquisition server via connecting cables, thus completing the deployment of the monitoring system. The main controller 6 can process the detected acoustic waves and display the waveform, acoustic wave energy, etc.

[0036] Specifically, multiple monitoring sections are divided within roadway 4. A seismic sensor 2 and an acoustic receiver 1 are installed in each monitoring section. A microseismic monitoring substation 5 is installed at the exit of roadway 4. Figure 2As shown, the acoustic wave receiving device 1 can be a contact sensor, and the contact sensor is arranged on the top of the roadway 4. Multiple acoustic wave detectors 3 can be arranged in each roadway 4 according to the number of monitoring sections.

[0037] S2: Set the parameters of the microseismic monitoring system, monitor the target roadway 4 for a specific time period, acquire all microseismic events within that time period, perform preliminary screening, organize the valid microseismic events, and collect relevant data.

[0038] S3: Set the basic parameters of the acoustic wave detector 3, and set the acoustic wave frequency band to a band that can be received by the human ear, mainly including abnormal noises in the tunnel 4. Monitor the target tunnel 4 for a specific time period, obtain all valid acoustic wave events within that time period, and collect relevant data.

[0039] S4: The sound wave detector 3 collects data such as the time, waveform, frequency, and amplitude of the sound wave, and compares the data with the effective microseismic events collected by the microseismic monitoring system. Microseismic events that meet the conditions for abnormal noise in rock strata are selected. The exact height of the rock strata emitting the abnormal noise is located by using the effective data collected by the microseismic monitoring system.

[0040] In this step, the comparative study of sound wave and microseismic time data can start by focusing on the acquisition time to ensure it matches the approximate time period of the abnormal noise in the rock strata. Then, the waveforms of the sound waves and microseismic events within that time period are compared to identify which microseismic events produced abnormal noise. Further comparisons are then made using conditions such as sound wave energy and amplitude to screen out the precise microseismic events that produced abnormal noise in the rock strata.

[0041] S5: Design rock mechanics tests for rock strata at the corresponding height. On-site construction personnel will screen and extract rock blocks from the rock strata at the designated height. Because the rock blocks obtained from the on-site sampling are irregularly shaped and do not meet the test requirements, further processing of the rock block samples is necessary. The samples to be tested will be drilled, cut, and finely processed to meet the requirements of uniaxial fracturing tests. Simultaneously, acoustic wave receiving equipment will be prepared to collect the fracturing and breaking sounds of the specimens.

[0042] S6: The core specimens that have met the requirements are subjected to uniaxial compression. The core specimens exhibit obvious failure characteristics and acoustic phenomena. During the uniaxial compression failure process, cracking sounds are emitted from time to time. The core specimens eventually become unstable and fail, emitting a loud sound. Collect relevant important data during the test, including the stress during the uniaxial compression fracture process, the acoustic waveform and amplitude when cracks are generated, etc.

[0043] S7: The acoustic wave data generated by rock fracturing and breaking, collected in the laboratory test, will be compared with microseismic events that meet the conditions for abnormal rock strata noise, which have been screened in the microseismic monitoring system. Further screening will be conducted to identify relevant data from precise and effective microseismic events that match abnormal noise caused by surrounding rock fracturing. This method can also indirectly prove that the source of abnormal noise caused by rock strata compression-shear failure is the rock mass at the sampling height at the construction site.

[0044] By using proof by contradiction, abnormal sound waves consistent with rock fracturing failure can be effectively identified in subsequent microseismic monitoring systems. Simultaneously, the energy levels of these sound waves can be further collected. Energy indicators, compared to other indicators, better reflect the stability of the rock mass structure; therefore, using energy indicators for rockburst early warning is more effective. Yellow and red warning thresholds for energy indicators are determined based on field monitoring data analysis. Furthermore, the ultimate stresses exerted on rock blocks under fracturing failure through rock mechanics tests in the laboratory can provide valuable reference for selecting tunnel support during actual construction operations.

[0045] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for accurately locating abnormal noises in underground coal mine surrounding rock based on combined acoustic and microseismic monitoring, characterized in that: Includes the following steps: S1: Install microseismic monitoring systems and acoustic monitoring systems in coal mine roadways; S2: Set the parameters of the microseismic monitoring system, monitor the target roadway for a specific time period, acquire all microseismic events within that time period, perform preliminary screening, organize the valid microseismic events, and collect relevant data; S3: Set the basic parameters of the acoustic monitoring system, set the acoustic frequency band to a band that can be received by the human ear, monitor the target tunnel for a specific time period, obtain all valid acoustic events within that time period, and collect relevant data; S4: Compare the acoustic wave data collected by the acoustic wave monitoring system at the same time with the effective microseismic events collected by the microseismic monitoring system, screen out the microseismic events that meet the conditions for abnormal noise in the rock strata, and locate the exact height of the rock strata emitting the abnormal noise sound using the effective data collected by the microseismic monitoring system. In step S4, by sequentially comparing the effective microseismic events collected by the microseismic monitoring system with the time, waveform, frequency, amplitude, and energy data of the abnormal sound waves collected by the acoustic monitoring system, microseismic events with abnormal sound waves in the rock strata are screened out. S5: Design a rock mechanics test for the rock strata that emitted abnormal sound waves as determined in step S4, prepare a rock core specimen, and use a sound wave acquisition instrument to collect the fracturing and crushing sound of the rock core specimen; S6: Then perform uniaxial compression on the core specimen and collect relevant important data during the test; S7: The acoustic wave data generated by the fracturing and crushing of rock core specimens collected in the laboratory test will be compared with the microseismic events that meet the conditions for abnormal noise in rock strata and have been screened in the microseismic monitoring system. Further screening will be conducted to identify relevant data in accurate and effective microseismic events that meet the conditions for abnormal noise caused by the fracturing of surrounding rock.

2. The method for accurately locating abnormal noises in underground coal mine surrounding rock based on combined acoustic and microseismic monitoring, as described in claim 1, is characterized in that: The microseismic monitoring system in step S1 includes seismic sensors and microseismic monitoring substations. The seismic sensors are connected to the microseismic monitoring substations via mine communication cables. The microseismic monitoring substations are connected to a ring network switch via network cables to transmit signals to a ground-based acquisition server, where the data is analyzed by the ground-based processing server.

3. The method for accurately locating abnormal noises in underground coal mine surrounding rock based on combined acoustic and microseismic monitoring, as described in claim 1, is characterized in that: The acoustic monitoring system in step S1 includes an acoustic receiving device, an acoustic detector, and a main controller. The acoustic receiving device is connected to the acoustic detector, the main controller, and the ground-based acquisition server via connecting cables.

4. The method for accurately locating abnormal noises in underground coal mine surrounding rock based on combined acoustic and microseismic monitoring, as described in claim 3, is characterized in that: The tunnel is divided into multiple monitoring sections. In each monitoring section, a seismic sensor and an acoustic receiver are installed. A microseismic monitoring substation is set up at the exit of the tunnel, and at least one acoustic detector is set up in the tunnel.

5. The method for accurately locating abnormal noises in underground coal mine surrounding rock based on combined acoustic and microseismic monitoring, as described in claim 2, is characterized in that: By using proof by contradiction, abnormal sound waves that conform to the fracturing failure of surrounding rock can be effectively identified in the microseismic monitoring system. At the same time, the energy magnitude of these abnormal sound waves is further collected, and energy indicators are used for rockburst early warning.

6. The method for accurately locating abnormal noises in underground coal mine surrounding rock based on combined acoustic and microseismic monitoring, as described in claim 3, is characterized in that: The acoustic receiving device uses a contact sensor, which is installed on the top of the tunnel.

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