Roof pressure monitoring and early warning system for through retracement channel of coal face

Abstract

The invention discloses a roof pressure monitoring and early warning system for a through retracement channel of a coal face, and relates to the technical field of coal mine safety, and the system comprises a geological evaluation module which recognizes a stable region and an unstable region of a roof rock stratum; the roof lithology monitoring module is used for judging whether the roof rock stratum stability is changed or not through a geological radar and an acoustic emission instrument; the underground water monitoring module judges whether the stability of the roof rock stratum is changed or not according to the underground water level variable quantity; the roof pressure monitoring module is used for triggering a preliminary early warning mechanism when the roof pressure variation is greater than or equal to a preliminary early warning threshold value; the roof rock stratum analysis module uses monitoring data of the roof lithology monitoring module, the underground water monitoring module and the roof pressure monitoring module as evaluation indexes to evaluate the roof rock stratum stability, the subtle change of the roof rock stratum stability can be captured before the roof pressure is not obviously increased, and the early warning time is greatly advanced.

Description

Technical Field

[0001] The present invention relates to the technical field of coal mine safety, and in particular to a roof pressure monitoring and early warning system for a coal mining working face through-going withdrawal channel. Background Art

[0002] In the mining process of coal mines and other mines, the succession of coal mining faces is an important link in mine production. With the continuous advancement of the working face, the relocation and reversal of the fully mechanized mining face has become a key step for the mine to achieve high production and efficiency. However, after the fully mechanized mining face enters the final mining stage, the roof is broken and the side is spalled, and the surrounding rock pressure and deformation increase rapidly, posing a serious threat to the safe and efficient withdrawal of the working face. Especially when the working face is connected with the withdrawal channel, the problem of roof pressure is particularly prominent, which may lead to a series of problems such as roof sinking, coal wall spalling, and bottom drumming, seriously affecting the safe, efficient and rapid withdrawal of fully mechanized mining equipment.

[0003] In the Chinese invention application with application publication number CN114662530A, a method, device, system and storage medium for identifying roof pressure changes are disclosed, which relates to the field of coal mine operation safety protection. The method includes: collecting sound samples at the fully mechanized mining site; preliminarily screening the sound samples to obtain an initial sample library; preprocessing the sound sample data in the initial sample library to obtain a sample sound spectrum; extracting the feature vector corresponding to the sample sound spectrum to construct a feature vector library; training the feature vector library to obtain the best roof sound codebook and establish a recognition model library; extracting the feature vector of the sample to be tested, using the recognition model to identify the sample to be tested, calculating the distance between the feature vector of the sample to be tested and each codeword of the best roof sound codebook, judging the roof pressure change, and outputting an abnormal warning instruction.

[0004] In view of the above invention, the prior art still has the following deficiencies:

[0005] The complexity of geological structure, coal mining activities and dynamic changes in groundwater levels all have a significant impact on the stability of roof rock properties. Due to the continuous changes in roof rock properties under the influence of these multiple factors, the rock pressure increases. However, the existing roof pressure detection and early warning technology has failed to fully incorporate the profound impact of geological structure characteristics, specific conditions of coal mining and groundwater dynamics on roof rock properties during application. Therefore, in the early stage of abnormal pressure rise, there is a lack of effective early warning mechanism and it is difficult to take preventive measures in time. Summary of the invention

[0006] 1. Technical issues to be resolved

[0007] In view of the shortcomings of the prior art, the present invention provides a roof pressure monitoring and early warning system for a coal mining face through-withdrawal channel. By combining real-time monitoring data of roof rock properties, groundwater and roof pressure, a comprehensive analysis is conducted to evaluate the stability of the roof rock strata, the potential impact of groundwater and the ability of the roof pressure to withstand, thereby solving the problems mentioned in the background technology.

[0008] (II) Technical solution

[0009] To achieve the above objectives, the present invention is implemented through the following technical solutions: A roof pressure monitoring and early warning system for a coal mining face through-through withdrawal channel, comprising:

[0010] The geological assessment module collects geological information about the withdrawal channel through the coal mining face and its surrounding areas, draws a geological structure distribution map, and identifies stable and unstable areas of the roof rock based on roof rock mechanics testing and numerical simulation;

[0011] The roof rock property monitoring module monitors the roof rock property in the unstable area and determines whether the stability of the roof rock layer has changed through the reflected signal of the geological radar and the sound wave signal received by the acoustic transmitter;

[0012] The groundwater monitoring module monitors the dynamic changes of the groundwater level in real time, calculates the stress changes and displacements of the roof rock layers in the unstable area according to the changes in the groundwater level, and determines whether the stability of the roof rock layers has changed;

[0013] The roof pressure monitoring module monitors the roof pressure data in real time, calculates the change and standard deviation of the roof pressure, and triggers the preliminary warning mechanism when the change of the roof pressure is greater than the preliminary warning threshold, or when the standard deviation of the roof pressure is greater than the pressure fluctuation threshold. Conversely, when the stability of the roof rock formation changes, the roof rock formation analysis strategy is triggered;

[0014] The roof rock layer analysis module executes the roof rock layer analysis strategy, uses the monitoring data obtained by the roof rock property monitoring module, the groundwater monitoring module and the roof pressure monitoring module as evaluation indicators, calculates the stability evaluation value of the roof rock layer in the unstable area, and issues an early warning when the stability evaluation value of the roof rock layer is greater than the stability threshold.

[0015] Furthermore, drawing a geological structure distribution map includes:

[0016] Collect geological information of the withdrawal passage through the coal mining face and its surrounding areas from geological exploration reports, mine geological maps and coal seam occurrence maps, including but not limited to stratum lithology and geological structure, and establish a geological database;

[0017] Identify the geological structures of the withdrawal channel through the coal mining face and its surrounding areas, including but not limited to faults, folds, joints and fissures, through geological exploration, geophysical exploration and geological mapping;

[0018] Use geological mapping software to draw the stratigraphic lithology distribution map and the basic layer of the geological structure framework map based on the information in the geological database, overlay the data of geological exploration and geophysical exploration on the basic layer in the form of layers, and draw the geological structure lines of faults, folds, joints and fissures based on the geological exploration data to obtain the geological structure distribution map.

[0019] Further, identification of stable and unstable areas of the roof strata includes:

[0020] Collect rock samples from the roof rock layer in the abnormal geological structure area, test the compressive strength, tensile strength and shear strength mechanical properties, and determine the physical and mechanical property parameters of the roof rock layer based on the test results;

[0021] Obtain geological exploration data and test results of mechanical properties, use numerical simulation software to perform numerical simulation, establish a numerical model of the roof rock strata, evaluate the stability of different positions of the roof rock strata based on the simulation results of the numerical model of the roof rock strata, and identify stable and unstable areas of the roof rock strata.

[0022] Furthermore, the roof lithology monitoring module determines whether the stability of the roof rock formation has changed, including:

[0023] The reflected signal intensity, frequency and phase information of the reflected wave of the geological radar are obtained, and the change in the reflected signal intensity, the change in the frequency of the reflected wave and the change in the phase of the reflected wave are calculated. If it is detected that the change in the reflected signal intensity exceeds the preset threshold A, or the change in the frequency of the reflected wave exceeds the preset threshold B, or the change in the phase of the reflected wave exceeds the preset threshold C, it is determined that the stability of the roof rock layer has changed. Otherwise, no operation is performed.

[0024] Furthermore, the sound wave signal received by the acoustic transmitter is obtained, and the frequency change and amplitude change of the sound wave signal are calculated. If it is detected that the frequency change of the sound wave signal exceeds the preset threshold value D, or the amplitude change exceeds the preset threshold value E, it is determined that the stability of the roof rock layer has changed. Otherwise, no operation is performed.

[0025] Furthermore, the groundwater monitoring module determines whether the stability of the top rock layer has changed, including:

[0026] Obtain groundwater level data at different time points and calculate the groundwater level change: ΔH=H t -H0, where ΔH represents the change in groundwater level, H t represents the groundwater level at time t, H0 represents the initial water level;

[0027] According to the change of groundwater level, the stress change inside the top rock layer of the unstable area is calculated using the effective stress principle. The stress change is: Δσ=α*ΔP, where Δσ represents the stress change, α represents the effective stress coefficient, and the value range is between 0 and 1. ΔP represents the pore water pressure change, and the pore water pressure change is: ΔP=ρ w *g*ΔH, where ρ w represents the density of groundwater and g represents the acceleration due to gravity.

[0028] Furthermore, using the elastic mechanics theory, according to the physical and mechanical property parameters and stress variation of the roof rock layer, the displacement of the roof rock layer in the unstable area is calculated. The displacement is approximately expressed as: Among them, Δμ represents the displacement of the roof rock layer, E represents the elastic modulus, and h represents the thickness of the roof rock layer;

[0029] If it is detected that the stress change exceeds the preset threshold F, or the displacement change exceeds the preset threshold G, it is determined that the stability of the roof rock layer has changed. Otherwise, no operation is performed.

[0030] Furthermore, the stability evaluation value calculation process is as follows:

[0031] The monitoring data of the roof rock property monitoring module are obtained, including the change in the intensity of the reflected signal, the change in the frequency of the reflected wave, the change in the phase of the reflected wave, the change in the frequency of the acoustic wave signal, and the change in the amplitude; the monitoring data of the groundwater monitoring module are obtained, including the change in the stress inside the roof rock layer and the displacement of the roof rock layer; the monitoring data of the roof pressure monitoring module are obtained, including the change in the roof pressure and the standard deviation.

[0032] Furthermore, the monitoring data of the roof lithology monitoring module, groundwater monitoring module and roof pressure monitoring module are used as evaluation indicators to construct a stability evaluation matrix:

[0033]

[0034] Among them, a mn It is expressed as the importance of the mth monitoring indicator relative to the nth monitoring indicator, where m is the number of rows of matrix A and n is the number of columns of matrix A;

[0035] The weight of each monitoring indicator is calculated through the stability evaluation matrix. The calculation formula is as follows:

[0036]

[0037] Among them, ω j represents the weight of the jth monitoring indicator, j = 1, 2, …, N, N is the number of monitoring indicators, k is a constant, and 1≤k≤N.

[0038] Furthermore, the stability assessment value of the roof rock layer in the unstable area is calculated through the values ​​of each monitoring indicator and the corresponding weights. The calculation formula is as follows:

[0039]

[0040] Where Sv represents the stability evaluation value, V j Represents the value of the jth monitoring indicator.

[0041] (III) Beneficial effects

[0042] The present invention provides a roof pressure monitoring and early warning system for a coal mining working face through-through withdrawal channel, which has the following beneficial effects:

[0043] (1) The roof rock monitoring module can monitor the reflected signals and acoustic wave signals of the roof rock strata in the unstable area in real time through the installed geological radar, acoustic emission instrument and other equipment. It combines the monitoring data of the geological radar and acoustic emission instrument to analyze the stability of the roof rock strata from multiple dimensions. By comprehensively judging the changes in parameters such as the reflection signal intensity, frequency, phase, and the frequency and amplitude of the acoustic wave signal, it can more accurately identify the slight disturbance or damage to the roof rock strata.

[0044] (2) By real-time monitoring of the dynamic changes of the groundwater level and using the effective stress principle and elastic mechanics theory, the stress change and displacement inside the roof rock layer can be calculated, thereby predicting the changing trend of the stability of the roof rock layer. It can timely discover and warn of roof rock layer stability problems caused by water level changes, thereby improving the timeliness and accuracy of the warning, and helping to take timely preventive measures to avoid accidents.

[0045] (3) By real-time monitoring of roof pressure changes and comparing them with the preliminary warning threshold, the warning mechanism can be triggered in time at the early stage of abnormal roof pressure rise. When the roof pressure change is less than the preliminary warning threshold, further analysis of the standard deviation of the roof pressure can avoid underreporting and remind relevant personnel to pay attention to the roof status, so that there is enough time to prepare and take necessary preventive measures to avoid roof accidents.

[0046] (4) Due to the complex interaction between factors such as geological structure, coal mining and groundwater dynamics and the stability of the roof rock strata, by integrating the monitoring data of these factors, it is possible to capture subtle changes in the stability of the roof rock strata before the roof pressure rises significantly. This early warning method greatly advances the warning time, provides a valuable window period for taking preventive measures, and improves the accuracy and reliability of the early warning system. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1It is a structural schematic diagram of the roof pressure monitoring and early warning system of the present invention. DETAILED DESCRIPTION

[0048] 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.

[0049] See also Figure 1 The present invention provides a roof pressure monitoring and early warning system for a coal mining face through-through withdrawal channel, comprising: a geological assessment module, a roof lithology monitoring module, a groundwater monitoring module, a roof pressure monitoring module and a roof rock layer analysis module; wherein,

[0050] The geological assessment module draws a geological structure distribution map and identifies stable and unstable areas of the roof rock based on roof rock mechanics testing and numerical simulation;

[0051] Collect geological information on the withdrawal channel through the coal mining face and its surrounding areas from existing data such as geological exploration reports, mine geological maps, coal seam occurrence maps, etc., including but not limited to geological characteristics such as stratum lithology and geological structure, organize the collected geological data, and establish a geological database;

[0052] Through geological exploration, geophysical exploration (such as seismic exploration, electrical exploration, etc.) and geological mapping, identify the geological structures of the withdrawal channel through the coal mining face and its surrounding areas, including but not limited to faults, folds, joints, fissures and other structures that may affect the stability of the roof;

[0053] It should be noted that geological structures may change due to factors such as coal mining activities. Therefore, geological exploration, geophysical exploration (such as seismic exploration, electrical exploration, etc.) and geological mapping are used to obtain geological structures again to prevent changes.

[0054] Use professional geological mapping software, such as ArcGIS, MapGIS, etc., to draw basic layers such as stratigraphic lithology distribution map and geological structure framework map based on the information in the geological database, overlay the data of geological exploration and geophysical exploration on the basic layer in the form of layers, and draw geological structural lines such as faults, folds, joints, and fissures based on the geological exploration data to obtain the final geological structure distribution map;

[0055] Collect rock samples from the roof rock layer in the abnormal geological structure area, test the compressive strength, tensile strength, shear strength and other mechanical properties, and determine the physical and mechanical property parameters of the roof rock layer based on the test results;

[0056] Use professional numerical simulation software (such as FLAC3D, ANSYS, etc.) to perform numerical simulation. According to geological exploration data and mechanical property test results, establish a numerical model of the roof rock layer. According to the simulation results of the numerical model of the roof rock layer, evaluate the stability of different positions of the roof rock layer and identify the stable and unstable areas of the roof rock layer.

[0057] It should be noted that, according to the simulation results of the numerical model, the stability of the roof rock strata at different positions can be evaluated by analyzing the simulation results of displacement, stress, strain, etc. For example, displacement is an important indicator reflecting the degree of deformation of the roof rock strata. Through numerical simulation, the displacement distribution diagram of the roof rock strata under different working conditions can be obtained. By analyzing the displacement distribution diagram, areas with large displacement can be identified. These areas often indicate potential damage risks of the roof rock strata and are unstable areas; stress is another key factor in the stability of the roof rock strata. Through numerical simulation, the stress distribution diagram of the roof rock strata at different positions can be obtained. By analyzing the stress distribution diagram, stress concentration areas and stress release areas can be identified. Stress concentration areas are often prone to damage and are unstable areas, while stress release areas may form cavities or cracks, which are also unstable areas; strain is another important index reflecting the degree of deformation of the roof rock strata. Through numerical simulation, the strain distribution diagram of the roof rock strata at different positions can be obtained. By analyzing the strain distribution diagram, areas with large strain can be identified. These areas often indicate plastic deformation or damage risks of the roof rock strata and are unstable areas;

[0058] By collecting rock samples from the roof rock strata in the abnormal geological structure area and testing the mechanical properties, the geological assessment module can determine the physical and mechanical property parameters of the roof rock strata. Subsequently, professional numerical simulation software is used for numerical simulation. According to the geological exploration data and the mechanical property test results, a numerical model of the roof rock strata is established. By simulating the response of the roof rock strata under different working conditions, the stability of the roof rock strata at different positions can be evaluated, and the stable and unstable areas of the roof rock strata can be identified, providing a scientific basis for subsequent roof pressure monitoring and early warning.

[0059] The roof rock property monitoring module monitors the roof rock property in the unstable area and determines whether the stability of the roof rock layer has changed through the reflected signal of the geological radar and the sound wave signal received by the acoustic transmitter;

[0060] For roofs in unstable areas, roof rock monitoring equipment, such as geological radars and acoustic transmitters, is installed to collect real-time roof rock layer monitoring data, including the reflected signal intensity of the geological radar, the frequency and phase information of the reflected wave, and the sound wave signal received by the acoustic transmitter;

[0061] The change in the intensity of the reflected signal, the frequency and the phase information of the reflected wave are calculated by the reflected signal intensity of the geological radar. If the change in the intensity of the reflected signal exceeds the preset threshold value A, or the change in the frequency of the reflected wave exceeds the preset threshold value B, or the change in the phase of the reflected wave exceeds the preset threshold value C, it indicates that the roof rock layer may be disturbed or damaged, and it is determined that the stability of the roof rock layer has changed. Otherwise, no operation is performed.

[0062] The acoustic signal received by the acoustic transmitter is used to calculate the frequency change and amplitude change of the acoustic signal. If the frequency change of the acoustic signal exceeds the preset threshold value D, or the amplitude change exceeds the preset threshold value E, it indicates that micro-fractures or stress release may have occurred inside the roof rock formation, and the stability of the roof rock formation is determined to have changed. Otherwise, no operation is performed.

[0063] It should be noted that the preset threshold is set by collecting a large amount of reflection signal and sound wave signal data through laboratory simulation or field testing, analyzing these data to determine the normal fluctuation range of the reflection signal and sound wave signal under different conditions, and using statistical methods (such as mean, standard deviation, etc.) to process the collected data to determine the appropriate threshold;

[0064] The roof rock monitoring module can monitor the reflected signals and acoustic wave signals of the roof rock strata in unstable areas in real time through the installed geological radar, acoustic emission instrument and other equipment. It combines the monitoring data of the geological radar and acoustic emission instrument to analyze the stability of the roof rock strata from multiple dimensions. By comprehensively judging the changes in parameters such as the reflection signal intensity, frequency, phase, and the frequency and amplitude of the acoustic wave signal, it can more accurately identify slight disturbances or damage to the roof rock strata.

[0065] The groundwater monitoring module monitors the dynamic changes of the groundwater level in real time. According to the change of the groundwater level, it calculates the stress change inside the roof rock layer and the displacement of the roof rock layer in the unstable area to determine whether the stability of the roof rock layer has changed.

[0066] Set up groundwater monitoring wells or sensors at key locations in the withdrawal channel and its surrounding areas of the coal mining face to ensure that the dynamic changes of the groundwater level can be monitored in real time. Use groundwater monitoring equipment to record groundwater level data in real time and establish a groundwater level time series;

[0067] Compare the groundwater level data at different time points, analyze the changing trend and amplitude of the groundwater level, and calculate the groundwater level change: ΔH=H t -H0, where ΔH represents the change in groundwater level, H t represents the groundwater level at time t, H0 represents the initial water level;

[0068] According to the change of groundwater level, the stress change inside the top rock layer of the unstable area is calculated using the effective stress principle. The effective stress principle points out that the change of pore water pressure will affect the total stress state of the rock mass. The stress change is: Δσ=α*ΔP, where Δσ represents the stress change, α represents the effective stress coefficient (a coefficient reflecting the influence of pore pressure change on the stress state of the rock mass), and the value range is between 0 and 1. ΔP represents the change of pore water pressure. The pore water pressure change is: ΔP=ρ w *g*ΔH, where ρ w represents the density of groundwater, and g represents the acceleration due to gravity;

[0069] It should be noted that in practical applications, due to the lack of clear physical meaning and precise determination method, the effective stress coefficient is often determined by empirical methods. This method usually involves laboratory testing of porous media, and then fitting the value of the effective stress coefficient based on the test results. In the empirical method, the effective stress coefficient generally takes values ​​between 0 and 1;

[0070] Using the elastic mechanics theory, according to the physical and mechanical properties of the roof rock layer (such as elastic modulus, Poisson's ratio, etc.) and the stress change, the displacement of the roof rock layer in the unstable area is calculated. The displacement is approximately expressed as: Among them, Δμ represents the displacement of the roof rock layer, E represents the elastic modulus, Δσ represents the stress change, and h represents the thickness of the roof rock layer;

[0071] If the detected stress change exceeds the preset threshold F, or the displacement change exceeds the preset threshold G, it means that the water level change has caused damage to the roof rock layer, then it is determined that the stability of the roof rock layer has changed. Otherwise, no operation is performed;

[0072] By real-time monitoring of the dynamic changes of the groundwater level and using the effective stress principle and elastic mechanics theory, the stress change and displacement inside the roof rock stratum can be calculated, thereby predicting the changing trend of the stability of the roof rock stratum. It is possible to promptly discover and warn of roof rock stratum stability problems caused by water level changes, thereby improving the timeliness and accuracy of the warning, and helping to take timely preventive measures to avoid accidents.

[0073] The roof pressure monitoring module monitors the roof pressure data in real time, calculates the change and standard deviation of the roof pressure, and triggers the preliminary warning mechanism when the change of the roof pressure is greater than the preliminary warning threshold, or when the standard deviation of the roof pressure is greater than the pressure fluctuation threshold. Conversely, when the stability of the roof rock formation changes, the roof rock formation analysis strategy is triggered;

[0074] Install pressure sensors above the roof of the withdrawal channel and its surrounding areas of the coal mining face to ensure that the sensors can accurately measure the pressure on the roof, initialize the sensors, set the data collection frequency and preliminary warning threshold, and collect roof pressure data in real time through the pressure sensors;

[0075] The process of setting the initial warning threshold is as follows:

[0076] Collect a large amount of historical data on roof pressure. The historical data on roof pressure should cover the changes in roof pressure at different times and under different working conditions. Perform statistical analysis on the historical data, including calculating statistical quantities such as the average value, standard deviation, maximum value, and minimum value. Preliminary set the warning threshold based on the statistical quantities of the historical data. Add a fixed multiple (such as the standard deviation) to the average value of the roof pressure change as the preliminary warning threshold. Apply the preliminary set warning threshold to the simulation data or historical data for testing. If the warning occurs frequently or is inaccurate, adjust the preliminary warning threshold.

[0077] Calculate the roof pressure change using roof pressure data: ΔPd = Pd t -Pd0, where ΔPd represents the change in top plate pressure, Pd t represents the roof pressure at time t, Pd0 represents the initial roof pressure;

[0078] Compare the roof pressure change with the preset preliminary warning threshold. When the roof pressure change is greater than the preliminary warning threshold, the preliminary warning mechanism is triggered to remind relevant personnel to pay attention to the roof status through sound, light and other means, and prepare to take necessary preventive measures. When the roof pressure change is less than or equal to the preliminary warning threshold, calculate the standard deviation of the roof pressure: Among them, δ represents the standard deviation, represents the average value of the top plate pressure, i=1,2,…,N, N represents the number of data points;

[0079] Pre-set the pressure fluctuation threshold, compare the standard deviation of the roof pressure with the pressure fluctuation threshold, and trigger the preliminary warning mechanism when the roof pressure change is greater than the pressure fluctuation threshold. Use sound, light and other means to remind relevant personnel to pay attention to the roof status and prepare to take necessary preventive measures. When the roof pressure change is less than or equal to the pressure fluctuation threshold, determine whether the roof rock stability has changed. If so, trigger the roof rock analysis strategy, otherwise no operation will be performed.

[0080] The process of setting the pressure fluctuation threshold is as follows:

[0081] Collect pressure data. The pressure data should cover the pressure changes at different times and under different working conditions. Perform statistical analysis on the collected data and calculate the average, standard deviation, maximum, minimum and other statistical quantities of the pressure. Set the pressure fluctuation threshold according to the standard deviation of the pressure data. The standard deviation reflects the discreteness of the data, that is, the amplitude of the pressure fluctuation. Select a fixed multiple (such as 1.5 times, 2 times, etc.) multiplied by the standard deviation as the pressure fluctuation threshold. Apply the set pressure fluctuation threshold to simulation data or historical data for testing. If the warning occurs frequently or the warning is inaccurate, adjust the pressure fluctuation threshold.

[0082] By monitoring the change in roof pressure in real time and comparing it with the preliminary warning threshold, the warning mechanism can be triggered in time at the early stage of abnormal rise in roof pressure. When the change in roof pressure is less than the preliminary warning threshold, further analysis of the standard deviation of the roof pressure can avoid underreporting and remind relevant personnel to pay attention to the roof status, so that there is enough time to prepare and take necessary preventive measures to avoid roof accidents.

[0083] The roof rock layer analysis module executes the roof rock layer analysis strategy, uses the monitoring data obtained by the roof rock property monitoring module, the groundwater monitoring module and the roof pressure monitoring module as evaluation indicators, calculates the stability evaluation value of the roof rock layer in the unstable area, and issues an early warning when the stability evaluation value of the roof rock layer is greater than the stability threshold.

[0084] Acquire monitoring data of the roof rock property monitoring module, including the change in the intensity of the reflected signal, the change in the frequency of the reflected wave, the change in the phase of the reflected wave, the change in the frequency of the acoustic wave signal, and the change in the amplitude; acquire monitoring data of the groundwater monitoring module, including the change in stress inside the roof rock layer and the displacement of the roof rock layer; acquire monitoring data of the roof pressure monitoring module, including the change in roof pressure and standard deviation;

[0085] The monitoring data of the roof lithology monitoring module, groundwater monitoring module and roof pressure monitoring module are used as evaluation indicators to construct a stability evaluation matrix:

[0086]

[0087] Among them, a mn It is expressed as the importance of the mth monitoring indicator relative to the nth monitoring indicator, where m is the number of rows of matrix A and n is the number of columns of matrix A;

[0088] The weight of each monitoring indicator is calculated through the stability evaluation matrix. The calculation formula is as follows:

[0089]

[0090] Among them, ω j represents the weight of the jth monitoring indicator, j = 1, 2, ..., N, N is the number of monitoring indicators, k is a constant, and 1 ≤ k ≤ N;

[0091] The stability assessment value of the roof rock layer in the unstable area is calculated through the values ​​of each monitoring indicator and the corresponding weight. The calculation formula is as follows:

[0092]

[0093] Where Sv represents the stability evaluation value, V j represents the value of the jth monitoring indicator;

[0094] The stability threshold is set in advance. When the stability assessment value of the roof rock layer is greater than the stability threshold, an early warning is issued to remind relevant personnel to stay away from the unstable area and take necessary preventive measures. Otherwise, no operation is performed.

[0095] Due to the complex interaction between factors such as geological structure, coal mining and groundwater dynamics and the stability of the roof rock strata, by integrating the monitoring data of these factors, it is possible to capture subtle changes in the stability of the roof rock strata before the roof pressure rises significantly. This early warning method greatly advances the warning time, provides a valuable window period for taking preventive measures, and improves the accuracy and reliability of the early warning system.

[0096] In the application, the several formulas involved are all calculated by removing dimensions and taking their numerical values. The formula is a formula of the most recent real situation obtained by collecting a large amount of data and performing software simulation. The coefficients in the formula are set by technicians in this field according to actual conditions.

[0097] The above embodiments may be implemented in whole or in part by software, hardware, firmware or any other combination thereof. When implemented by software, the above embodiments may be implemented in whole or in part in the form of a computer program product. A person of ordinary skill in the art may appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein may be implemented in combination with electronic hardware, computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution.

[0098] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, and may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0099] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be covered by the protection scope of the present application.

Claims

1. A roof pressure monitoring and early warning system for a coal mining face through-through withdrawal channel, characterized in that: include: The geological assessment module collects geological information about the withdrawal channel through the coal mining face and its surrounding areas, draws a geological structure distribution map, and identifies stable and unstable areas of the roof rock based on roof rock mechanics testing and numerical simulation; The roof rock property monitoring module monitors the roof rock property in the unstable area and determines whether the stability of the roof rock layer has changed through the reflected signal of the geological radar and the sound wave signal received by the acoustic transmitter; The groundwater monitoring module monitors the dynamic changes of the groundwater level in real time, calculates the stress changes and displacements of the roof rock layers in the unstable area according to the changes in the groundwater level, and determines whether the stability of the roof rock layers has changed; The roof pressure monitoring module monitors the roof pressure data in real time, calculates the change and standard deviation of the roof pressure, and triggers the preliminary warning mechanism when the change of the roof pressure is greater than the preliminary warning threshold, or when the standard deviation of the roof pressure is greater than the pressure fluctuation threshold. Conversely, when the stability of the roof rock formation changes, the roof rock formation analysis strategy is triggered; The roof rock layer analysis module executes the roof rock layer analysis strategy, uses the monitoring data obtained by the roof rock property monitoring module, the groundwater monitoring module and the roof pressure monitoring module as evaluation indicators, calculates the stability evaluation value of the roof rock layer in the unstable area, and issues an early warning when the stability evaluation value of the roof rock layer is greater than the stability threshold.

2. A roof pressure monitoring and early warning system for a coal mining face through-through withdrawal channel according to claim 1, characterized in that: Mapping geological structures includes: Collect geological information of the withdrawal passage through the coal mining face and its surrounding areas from geological exploration reports, mine geological maps and coal seam occurrence maps, including but not limited to stratum lithology and geological structure, and establish a geological database; Identify the geological structures of the withdrawal channel through the coal mining face and its surrounding areas, including but not limited to faults, folds, joints and fissures, through geological exploration, geophysical exploration and geological mapping; Use geological mapping software to draw the stratigraphic lithology distribution map and the basic layer of the geological structure framework map based on the information in the geological database, overlay the data of geological exploration and geophysical exploration on the basic layer in the form of layers, and draw the geological structure lines of faults, folds, joints and fissures based on the geological exploration data to obtain the geological structure distribution map.

3. A roof pressure monitoring and early warning system for a coal mining face through-through withdrawal channel according to claim 2, characterized in that: Identifying stable and unstable areas of roof rock formations includes: Collect rock samples from the roof rock layer in the abnormal geological structure area, test the compressive strength, tensile strength and shear strength mechanical properties, and determine the physical and mechanical property parameters of the roof rock layer based on the test results; Obtain geological exploration data and test results of mechanical properties, use numerical simulation software to perform numerical simulation, establish a numerical model of the roof rock strata, evaluate the stability of different positions of the roof rock strata based on the simulation results of the numerical model of the roof rock strata, and identify stable and unstable areas of the roof rock strata.

4. A roof pressure monitoring and early warning system for a through-retraction channel of a coal mining face according to claim 1, characterized in that: The roof lithology monitoring module determines whether the stability of the roof rock formation has changed, including: The reflected signal intensity, frequency and phase information of the reflected wave of the geological radar are obtained, and the change in the reflected signal intensity, the change in the frequency of the reflected wave and the change in the phase of the reflected wave are calculated. If it is detected that the change in the reflected signal intensity exceeds the preset threshold A, or the change in the frequency of the reflected wave exceeds the preset threshold B, or the change in the phase of the reflected wave exceeds the preset threshold C, it is determined that the stability of the roof rock layer has changed. Otherwise, no operation is performed.

5. A roof pressure monitoring and early warning system for a through-retraction channel of a coal mining face according to claim 4, characterized in that: The sound wave signal received by the acoustic transmitter is obtained, and the frequency change and amplitude change of the sound wave signal are calculated. If it is detected that the frequency change of the sound wave signal exceeds the preset threshold value D, or the amplitude change exceeds the preset threshold value E, it is determined that the stability of the roof rock layer has changed. Otherwise, no operation is performed.

6. A roof pressure monitoring and early warning system for a through-retraction channel of a coal mining face according to claim 1, characterized in that: The groundwater monitoring module determines whether the stability of the top rock layer has changed, including: Obtain groundwater level data at different time points and calculate the groundwater level change: ΔH=H t -H0, where ΔH represents the change in groundwater level, H t represents the groundwater level at time t, H0 represents the initial water level; According to the change of groundwater level, the stress change inside the top rock layer of the unstable area is calculated using the effective stress principle. The stress change is: Δσ=α*ΔP, where Δσ represents the stress change, α represents the effective stress coefficient, and the value range is between 0 and 1. ΔP represents the pore water pressure change, and the pore water pressure change is: ΔP=ρ w *g*ΔH, where ρ w represents the density of groundwater and g represents the acceleration due to gravity.

7. A roof pressure monitoring and early warning system for a through-retraction channel of a coal mining face according to claim 6, characterized in that: Using elastic mechanics theory, according to the physical and mechanical properties and stress variation of the roof rock layer, the displacement of the roof rock layer in the unstable area is calculated. The displacement is approximately expressed as: Among them, Δμ represents the displacement of the roof rock layer, E represents the elastic modulus, and h represents the thickness of the roof rock layer; If it is detected that the stress change exceeds the preset threshold F, or the displacement change exceeds the preset threshold G, it is determined that the stability of the roof rock layer has changed. Otherwise, no operation is performed.

8. The roof pressure monitoring and early warning system for the through-retraction channel of a coal mining face according to claim 1, characterized in that: The calculation process of the stability assessment value is as follows: The monitoring data of the roof rock property monitoring module are obtained, including the change in the intensity of the reflected signal, the change in the frequency of the reflected wave, the change in the phase of the reflected wave, the change in the frequency of the acoustic wave signal, and the change in the amplitude; the monitoring data of the groundwater monitoring module are obtained, including the change in the stress inside the roof rock layer and the displacement of the roof rock layer; the monitoring data of the roof pressure monitoring module are obtained, including the change in the roof pressure and the standard deviation.

9. A roof pressure monitoring and early warning system for a through-retraction channel of a coal mining face according to claim 8, characterized in that: The monitoring data of the roof lithology monitoring module, groundwater monitoring module and roof pressure monitoring module are used as evaluation indicators to construct a stability evaluation matrix: Among them, a mn It is expressed as the importance of the mth monitoring indicator relative to the nth monitoring indicator, where m is the number of rows of matrix A and n is the number of columns of matrix A; The weight of each monitoring indicator is calculated through the stability evaluation matrix. The calculation formula is as follows: Among them, ω j represents the weight of the jth monitoring indicator, j = 1, 2, …, N, N is the number of monitoring indicators, k is a constant, and 1≤k≤N.

10. A roof pressure monitoring and early warning system for a through-retraction channel of a coal mining face according to claim 9, characterized in that: The stability assessment value of the roof rock layer in the unstable area is calculated through the values ​​of each monitoring indicator and the corresponding weight. The calculation formula is as follows: Where Sv represents the stability evaluation value, V j Represents the value of the jth monitoring indicator.

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