A roof pressure monitoring and early warning system for a through retreat passage of a coal mining face

Abstract

The application discloses a roof pressure monitoring and early warning system of a through retreat channel of a coal mining face, and relates to the technical field of coal mine safety, which comprises: a geological evaluation module, which identifies stable and unstable areas of a roof stratum; a roof lithology monitoring module, which judges whether the stability of the roof stratum changes through a geological radar and an acoustic emission instrument; a groundwater monitoring module, which judges whether the stability of the roof stratum changes according to a groundwater level change amount; a roof pressure monitoring module, which triggers a preliminary early warning mechanism when a roof pressure change amount is greater than or equal to a preliminary early warning threshold; and a roof stratum analysis module, which takes monitoring data of the roof lithology monitoring module, the groundwater monitoring module and the roof pressure monitoring module as evaluation indexes to evaluate the stability of the roof stratum. The application can capture subtle changes in the stability of the roof stratum before the roof pressure significantly rises, thus greatly advancing the early warning time.

Description

Technical Field

[0001] This invention relates to the field of coal mine safety technology, specifically to a roof pressure monitoring and early warning system for a coal mining face through-traverse and retreat passage. Background Technology

[0002] In the mining process of coal mines and other mining operations, the succession of coal faces is a crucial link in mine production. As the working face advances, the relocation and replacement of the fully mechanized mining face becomes a key step for achieving high production and efficiency. However, after the fully mechanized mining face enters the final mining stage, roof fracturing and wall spalling become severe, 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 and the withdrawal passage are connected, the problem of roof pressure is particularly prominent, which may lead to a series of problems such as roof subsidence, coal wall spalling, and floor heave, seriously affecting the safe, efficient, and rapid withdrawal of fully mechanized mining equipment.

[0003] Chinese invention application CN114662530A discloses a method, apparatus, system, and storage medium for identifying roof pressure changes, relating to the field of coal mine operation safety protection. The method includes: collecting sound samples from the fully mechanized mining site; performing preliminary screening of the sound samples to obtain an initial sample library; preprocessing the sound sample data in the initial sample library to obtain sample sound spectra; extracting feature vectors corresponding to the sample sound spectra to construct a feature vector library; training the feature vector library to obtain an optimal roof sound codebook and establishing a recognition model library; extracting feature vectors 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 in the optimal roof sound codebook, judging roof pressure changes, and outputting an abnormal warning command.

[0004] In summary, the existing technology still has the following shortcomings:

[0005] The complexity of geological structures, coal seam mining activities, and dynamic changes in groundwater levels all significantly impact the stability of roof lithology. The continuous changes in roof lithology under these multiple factors lead to increased strata pressure. However, existing roof pressure detection and early warning technologies fail to fully incorporate the profound impact of geological structural characteristics, specific coal seam mining conditions, and groundwater dynamics on roof lithology. Consequently, in the early stages of abnormal pressure increases, there is a lack of effective early warning mechanisms, making it difficult to take timely preventative measures. Summary of the Invention

[0006] (a) Technical problems to be solved

[0007] To address the shortcomings of existing technologies, this invention provides a roof pressure monitoring and early warning system for the retraction passage of a coal mining face. By combining real-time monitoring data of roof lithology, groundwater, and roof pressure, a comprehensive analysis is conducted to assess the stability of the roof strata, the potential impact of groundwater, and the roof's ability to withstand pressure, thus solving the problems mentioned in the background technology.

[0008] (II) Technical Solution

[0009] To achieve the above objectives, the present invention provides the following technical solution: a roof pressure monitoring and early warning system for a coal mining face retraction passage, comprising:

[0010] The geological assessment module collects geological information on the coal mining face's access and retreat channels and its surrounding areas, draws geological structure distribution maps, and identifies stable and unstable areas of the roof strata based on roof rock mechanics tests and numerical simulations.

[0011] The roof lithology monitoring module monitors the roof lithology in unstable areas and determines whether the stability of the roof strata has changed by using the reflected signals from the ground-penetrating radar and the acoustic signals received by the acoustic transmitter.

[0012] The groundwater monitoring module monitors the dynamic changes of groundwater level in real time, calculates the stress changes and displacement of the top rock layer in unstable areas based on the groundwater level changes, and determines whether the stability of the top rock layer has changed.

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

[0014] The roof strata analysis module executes the roof strata analysis strategy, using the monitoring data obtained from the roof lithology monitoring module, groundwater monitoring module, and roof pressure monitoring module as evaluation indicators to calculate the stability assessment value of the roof strata in unstable areas. When the stability assessment value of the roof strata exceeds the stability threshold, an early warning is issued.

[0015] Furthermore, mapping the distribution of geological structures includes:

[0016] Collect geological information on the coal mining face access and its surrounding areas from geological exploration reports, mine geological maps and coal seam occurrence maps, including but not limited to stratigraphy, lithology and geological structure, and establish a geological database.

[0017] Geological exploration, geophysical exploration and geological mapping methods are used to identify the geological structures of the coal mining face's access and retreat channels and its surrounding areas, including but not limited to faults, folds, joints and fissures.

[0018] Using geological mapping software, based on information from the geological database, a base layer of strata and lithology distribution map and geological structure framework map is drawn. Data from geological exploration and geophysical exploration are overlaid on the base layer in the form of layers. Based on the geological exploration data, geological structural lines of faults, folds, joints and fissures are drawn to obtain a geological structure distribution map.

[0019] Furthermore, identifying stable and unstable regions of the overlying strata includes:

[0020] Rock samples were collected from the top strata of the anomalous geological structure area to test the compressive strength, tensile strength and shear strength mechanical properties. Based on the test results, the physical and mechanical property parameters of the top strata were determined.

[0021] Geological exploration data and mechanical property test results are obtained, numerical simulation software is used to conduct numerical simulation, a numerical model of the roof strata is established, and the stability of the roof strata at different locations is evaluated based on the simulation results of the roof strata numerical model, and stable and unstable regions of the roof strata are identified.

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

[0023] The system acquires the intensity, frequency, and phase information of the reflected signal from the ground-penetrating radar. It calculates the changes in the intensity, frequency, and phase of the reflected signal. If the change in the intensity of the reflected signal exceeds a preset threshold A, or the change in the frequency exceeds a preset threshold B, or the change in the phase exceeds a preset threshold C, it determines that the stability of the roof strata has changed. Otherwise, no operation is performed.

[0024] Furthermore, the acoustic wave signal received by the acoustic transmitter is acquired, and the frequency change and amplitude change of the acoustic wave signal are calculated. If the frequency change of the acoustic wave signal exceeds the preset threshold D, or the amplitude change exceeds the preset threshold 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 overlying rock strata has changed, including:

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

[0027] Based on the groundwater level change, the stress change within the top strata of the unstable zone 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 (ranging from 0 to 1), and ΔP represents the pore water pressure change: ΔP = ρ w *g*ΔH, where ρ w ρ represents the density of groundwater, and g represents the acceleration due to gravity.

[0028] Furthermore, using the theory of elasticity, based on the physical and mechanical properties and stress changes of the roof strata, the displacement of the roof strata in the unstable region is calculated. The displacement is approximately expressed as: Where Δμ represents the displacement of the top rock layer, E represents the elastic modulus, and h represents the thickness of the top rock layer;

[0029] If the detected 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 strata has changed; otherwise, no operation is performed.

[0030] Furthermore, the stability assessment value is calculated as follows:

[0031] Acquire monitoring data from the roof lithology monitoring module, including changes in reflected signal intensity, frequency, and phase of reflected waves, as well as changes in the frequency and amplitude of acoustic signals. Acquire monitoring data from the groundwater monitoring module, including changes in stress within the roof strata and displacement of the roof strata. Acquire monitoring data from the roof pressure monitoring module, including changes in roof pressure and standard deviation.

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

[0033]

[0034] Among them, a mn This represents the importance of the m-th monitoring indicator relative to the n-th monitoring indicator, where m is the number of rows in matrix A and n is the number of columns in matrix A.

[0035] The weight of each monitoring indicator is calculated using a stability assessment matrix, as shown in the following formula:

[0036]

[0037] Where, ω j Let represent the weight of the j-th monitoring indicator, where j = 1, 2, ..., N, N is the number of monitoring indicators, k is a constant, and 1 ≤ k ≤ N.

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

[0039]

[0040] Where Sv represents the stability evaluation value, V j This represents the value of the j-th monitoring indicator.

[0041] (III) Beneficial Effects

[0042] This invention provides a roof pressure monitoring and early warning system for a coal mining face through-traverse and retreat passage, which has the following beneficial effects:

[0043] (1) The roof lithology monitoring module can monitor the reflection signals and acoustic signals of the roof strata in unstable areas in real time through the installed ground radar, acoustic transmitter and other equipment. By combining the monitoring data of ground radar and acoustic transmitter, the stability of the roof strata can be analyzed from multiple dimensions. By comprehensively judging the changes in parameters such as the intensity, frequency and phase of the reflection signal and the frequency and amplitude of the acoustic signal, the module can more accurately identify the small disturbances or damages of the roof strata.

[0044] (2) By monitoring the dynamic changes of groundwater level in real time, and using the effective stress principle and elasticity theory, the stress change and displacement of the roof rock layer can be calculated, thereby predicting the trend of roof rock layer stability. It can promptly detect and warn of roof rock layer stability problems caused by water level changes, improve the timeliness and accuracy of early warning, and help to take timely preventive measures to avoid accidents.

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

[0046] (4) Due to the complex interaction between factors such as geological structure, coal seam mining and groundwater dynamics and the stability of the roof strata, by integrating the monitoring data of these factors, subtle changes in the stability of the roof strata can be captured 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. Attached Figure Description

[0047] Figure 1This is a schematic diagram of the roof pressure monitoring and early warning system of the present invention. Detailed Implementation

[0048] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0049] Please see Figure 1 This invention provides a roof pressure monitoring and early warning system for a coal mining face's through-passage retreat channel, comprising: a geological assessment module, a roof lithology monitoring module, a groundwater monitoring module, a roof pressure monitoring module, and a roof strata analysis module; wherein,

[0050] The geological assessment module draws a geological structure distribution map and identifies stable and unstable regions of the roof strata based on roof rock mechanical testing and numerical simulation.

[0051] Geological information on the coal mining face access and its surrounding area is collected from existing data such as geological exploration reports, mine geological maps, and coal seam occurrence maps. This includes, but is not limited to, geological features such as stratigraphy, lithology, and geological structure. The collected geological data is then organized to establish a geological database.

[0052] Geological exploration, geophysical exploration (such as seismic exploration, electrical exploration, etc.) and geological mapping are used to identify the geological structures of the coal mining face’s access and retreat channels 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 re-observe the geological structure and prevent changes from occurring.

[0054] Using professional geological mapping software, such as ArcGIS and MapGIS, based on information from the geological database, basic layers such as stratigraphic and lithological distribution maps and geological structural framework maps are drawn. Geological exploration and geophysical exploration data are overlaid on the basic layers in the form of layers. Based on the geological exploration data, geological structural lines such as faults, folds, joints, and fissures are drawn to obtain the final geological structural distribution map.

[0055] Rock samples were collected from the top strata of the anomalous geological structure area, and mechanical properties such as compressive strength, tensile strength, and shear strength were tested. Based on the test results, the physical and mechanical property parameters of the top strata were determined.

[0056] Numerical simulations are performed using professional numerical simulation software (such as FLAC3D, ANSYS, etc.). Based on geological exploration data and mechanical property test results, a numerical model of the roof strata is established. Based on the simulation results of the roof strata numerical model, the stability of the roof strata at different locations is evaluated, and stable and unstable regions of the roof strata are identified.

[0057] It should be noted that, based on the simulation results of the numerical model, the stability of the roof strata at different locations can be assessed by analyzing the simulation results of displacement, stress, and strain. For example, displacement is an important indicator reflecting the degree of deformation of the roof strata. Through numerical simulation, displacement distribution maps of the roof strata under different working conditions can be obtained. Analyzing the displacement distribution maps can identify areas with large displacements, which often indicate potential failure risks to the roof strata and are considered unstable areas. Stress is another key factor in the stability of the roof strata. Through numerical simulation, stress distribution maps of the roof strata at different locations can be obtained. Analyzing the stress distribution maps can identify stress concentration areas and stress release areas. Stress concentration areas are often prone to failure and are considered unstable areas, while stress release areas may form cavities or cracks, and are also considered unstable areas. Strain is another important index reflecting the degree of deformation of the roof strata. Through numerical simulation, strain distribution maps of the roof strata at different locations can be obtained. Analyzing the strain distribution maps can identify areas with large strains, which often indicate plastic deformation or failure risks to the roof strata and are considered unstable areas.

[0058] By collecting rock samples from the roof strata in areas with abnormal geological structures and testing their mechanical properties, the geological assessment module can determine the physical and mechanical property parameters of the roof strata. Subsequently, using professional numerical simulation software, numerical simulations are performed. Based on the geological exploration data and the mechanical property test results, a numerical model of the roof strata is established. By simulating the roof strata response under different working conditions, the stability of the roof strata at different locations can be evaluated, and stable and unstable regions of the roof strata can be identified, providing a scientific basis for subsequent roof pressure monitoring and early warning.

[0059] The roof lithology monitoring module monitors the roof lithology in unstable areas and determines whether the stability of the roof strata has changed by using the reflected signals from the ground-penetrating radar and the acoustic signals received by the acoustic transmitter.

[0060] For roofs in unstable areas, install roof lithology monitoring equipment, such as ground-penetrating radar and acoustic transmitters, to collect roof rock strata monitoring data in real time, including the intensity of reflected signals from ground-penetrating radar, the frequency and phase information of reflected waves, and the acoustic wave signals received by the acoustic transmitters.

[0061] By using the reflected signal intensity, frequency, and phase information of the ground-penetrating radar, the changes in reflected signal intensity, frequency, and phase are calculated. If the changes in reflected signal intensity exceed a preset threshold A, or the changes in frequency exceed a preset threshold B, or the changes in phase exceed a preset threshold C, it indicates that the roof strata may have been disturbed or damaged, and the stability of the roof strata is determined to have changed. Otherwise, no operation is performed.

[0062] The acoustic wave signal received by the acoustic transmitter is used to calculate the frequency change and amplitude change of the acoustic wave signal. If the frequency change of the acoustic wave signal exceeds the preset threshold D, or the amplitude change exceeds the preset threshold E, it indicates that micro-fractures or stress release may have occurred inside the roof rock layer. In this case, the stability of the roof rock layer 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 reflected signal and sound wave signal data through laboratory simulation or field testing, analyzing the data to determine the normal fluctuation range of reflected 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 lithology monitoring module, through the installation of equipment such as ground-penetrating radar and acoustic transmitters, can monitor the reflected signals and acoustic signals of the roof strata in unstable areas in real time. By combining the monitoring data of ground-penetrating radar and acoustic transmitters, the stability of the roof strata can be analyzed from multiple dimensions. By comprehensively judging the changes in parameters such as the intensity, frequency, and phase of the reflected signal, as well as the frequency and amplitude of the acoustic signal, it can more accurately identify minor disturbances or damage to the roof strata.

[0065] The groundwater monitoring module monitors the dynamic changes in groundwater level in real time. Based on the changes in groundwater level, it calculates the stress changes and displacement of the top rock layer in unstable areas to determine whether the stability of the top rock layer has changed.

[0066] Groundwater monitoring wells or sensors are installed at key locations in the coal mining face access and surrounding areas to ensure that the dynamic changes of groundwater level can be monitored in real time. Groundwater level data is recorded in real time through groundwater monitoring equipment to establish a groundwater level time series.

[0067] By comparing groundwater level data at different time points, we can analyze the trend and magnitude of groundwater level changes and calculate the change in groundwater level: ΔH = H t -H0, where ΔH represents the change in groundwater level, H t H represents the groundwater level at time t, and H0 represents the initial water level.

[0068] Based on changes in groundwater level, the stress variation within the top strata of the unstable zone is calculated using the effective stress principle. The effective stress principle states that changes in pore water pressure affect the total stress state of the rock mass. The stress variation is: Δσ = α * ΔP, where Δσ represents the stress variation, α represents the effective stress coefficient (a coefficient reflecting the influence of pore pressure changes on the stress state of the rock mass), with a value between 0 and 1, and ΔP represents the change in pore water pressure: ΔP = ρ w *g*ΔH, where ρ w The density of groundwater is represented by g, 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 methods, the effective stress coefficient is often determined by empirical methods. This method usually involves laboratory testing of porous media, and then fitting the effective stress coefficient value based on the test results. In empirical methods, the effective stress coefficient is generally taken between 0 and 1.

[0070] Using the theory of elasticity, based on the physical and mechanical properties of the roof strata (such as elastic modulus, Poisson's ratio, etc.) and stress changes, the displacement of the roof strata in the unstable region is calculated. The displacement is approximately expressed as: Where Δμ represents the displacement of the top rock layer, E represents the elastic modulus, Δσ represents the stress change, and h represents the thickness of the top rock layer;

[0071] If the detected stress change exceeds the preset threshold F, or the displacement change exceeds the preset threshold G, it indicates that the water level change has damaged the roof rock layer, and the stability of the roof rock layer is determined to have changed; otherwise, no operation is performed.

[0072] By monitoring the dynamic changes in groundwater level in real time and utilizing the effective stress principle and elasticity theory, it is possible to calculate the stress changes and displacements within the roof strata, thereby predicting the trend of roof strata stability changes. This allows for timely detection and early warning of roof strata stability problems caused by water level changes, improving the timeliness and accuracy of early warnings and facilitating timely preventative measures to avoid accidents.

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

[0074] Pressure sensors are installed above the roof of the coal mining face through the retreat passage and its surrounding area to ensure that the sensors can accurately measure the pressure on the roof. The sensors are initialized, the data acquisition frequency and the preliminary warning threshold are set, and the roof pressure data is collected in real time through the pressure sensors.

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

[0076] Collect a large amount of historical data on roof pressure, which should cover roof pressure changes under different times and working conditions. Perform statistical analysis on the historical data, including calculating statistical quantities such as average, standard deviation, maximum, and minimum values. Based on the statistical quantities of the historical data, initially set the warning threshold by adding a fixed multiple (such as the standard deviation) to the average value of the roof pressure change as the initial warning threshold. Apply the initially set warning threshold to simulated data or historical data for testing. If warnings occur frequently or are inaccurate, adjust the initial warning threshold.

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

[0078] The change in roof pressure is compared with a preset preliminary warning threshold. When the change in roof pressure exceeds the preliminary warning threshold, the preliminary warning mechanism is triggered, alerting relevant personnel to the roof condition through sound, light, and electricity, and prompting them to prepare for necessary preventative measures. When the change in roof pressure is less than or equal to the preliminary warning threshold, the standard deviation of the roof pressure is calculated. Where δ represents the standard deviation, The average value of the pressure on the top plate is represented by i = 1, 2, ..., N, where N represents the number of data points.

[0079] A pressure fluctuation threshold is preset, and the standard deviation of the roof pressure is compared with the pressure fluctuation threshold. When the change in roof pressure is greater than the pressure fluctuation threshold, a preliminary early warning mechanism is triggered, and relevant personnel are alerted to the roof condition through sound, light, and electricity, and they are prepared to take necessary preventive measures. When the change in roof pressure is less than or equal to the pressure fluctuation threshold, it is determined whether the stability of the roof rock layer has changed. If it has changed, the roof rock layer analysis strategy is triggered; otherwise, no operation is performed.

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

[0081] Collect pressure data, which should cover pressure changes under different times and operating conditions. Perform statistical analysis on the collected data to calculate the average, standard deviation, maximum, and minimum pressure values. Set a pressure fluctuation threshold based on the standard deviation of the pressure data. The standard deviation reflects the dispersion of the data, i.e., the amplitude of pressure fluctuations. 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 simulated or historical data for testing. If warnings occur frequently or are inaccurate, adjust the pressure fluctuation threshold.

[0082] By monitoring the changes in roof pressure in real time and comparing them with the preliminary warning threshold, the early warning mechanism can be triggered in the early stages of abnormal roof pressure rise. When the changes in roof pressure are less than the preliminary warning threshold, the standard deviation of the roof pressure can be further analyzed to avoid missed reports and remind relevant personnel to pay attention to the roof condition, thus giving them enough time to prepare and take necessary preventive measures to avoid roof accidents.

[0083] The roof strata analysis module executes the roof strata analysis strategy, using the monitoring data obtained from the roof lithology monitoring module, groundwater monitoring module, and roof pressure monitoring module as evaluation indicators to calculate the stability assessment value of the roof strata in unstable areas. When the stability assessment value of the roof strata exceeds the stability threshold, an early warning is issued.

[0084] Acquire monitoring data from the roof lithology monitoring module, including changes in reflected signal intensity, frequency of reflected waves, phase of reflected waves, frequency of acoustic signals, and amplitude; acquire monitoring data from the groundwater monitoring module, including stress changes within the roof strata and displacement of the roof strata; and acquire monitoring data from the roof pressure monitoring module, including roof pressure changes and standard deviation.

[0085] Monitoring data from the roof lithology monitoring module, groundwater monitoring module, and roof pressure monitoring module were used as evaluation indicators to construct a stability assessment matrix:

[0086]

[0087] Among them, a mn This represents the importance of the m-th monitoring indicator relative to the n-th monitoring indicator, where m is the number of rows in matrix A and n is the number of columns in matrix A.

[0088] The weight of each monitoring indicator is calculated using a stability assessment matrix, as shown in the following formula:

[0089]

[0090] Where, ω j Let represent the weight of the j-th monitoring indicator, where 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 strata in the unstable area is calculated by using the values ​​of each monitoring indicator and their corresponding weights. The calculation formula is as follows:

[0092]

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

[0094] A stability threshold is preset. When the stability assessment value of the roof strata exceeds the stability threshold, an early warning is issued, prompting relevant personnel to stay away from the unstable area and take necessary preventive measures. Otherwise, no operation is performed.

[0095] Because of the complex interactions between factors such as geological structure, coal seam mining, and groundwater dynamics and the stability of the roof strata, by integrating the monitoring data of these factors, subtle changes in the stability of the roof strata can be detected before the roof pressure rises significantly. This early warning method greatly advances the warning time, provides a valuable window of opportunity for taking preventive measures, and improves the accuracy and reliability of the early warning system.

[0096] In the application, the various formulas mentioned are all calculated by removing dimensions and taking their numerical values. The formulas are derived from software simulations based on a large amount of collected data to obtain the most recent real-world results. The coefficients in the formulas are set by those skilled in the art according to the actual situation.

[0097] The above embodiments can be implemented, in whole or in part, by software, hardware, firmware, or any other combination thereof. When implemented in software, the above embodiments can be implemented, in whole or in part, as a computer program product. Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, and combinations thereof. Whether these functions are implemented 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 separate. The components shown as units may or may not be physical units; they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment, depending on actual needs.

[0099] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application.

Claims

1. A roof pressure monitoring and early warning system for a coal mining face through-traverse and retreat passage, characterized in that: include: The geological assessment module collects geological information on the coal mining face's access and retreat channels and its surrounding areas, draws geological structure distribution maps, and identifies stable and unstable areas of the roof strata based on roof rock mechanics tests and numerical simulations. The roof lithology monitoring module monitors the roof lithology in unstable areas and determines whether the stability of the roof strata has changed by using the reflected signals from the ground-penetrating radar and the acoustic signals received by the acoustic transmitter. The groundwater monitoring module monitors the dynamic changes of groundwater level in real time, calculates the stress changes and displacement of the top rock layer in unstable areas based on the groundwater level changes, and determines whether the stability of the top rock layer has changed. The roof pressure monitoring module monitors roof pressure data in real time, calculates the change and standard deviation of roof pressure, and triggers the preliminary warning mechanism when the change in roof pressure exceeds the preliminary warning threshold or the standard deviation of roof pressure exceeds the pressure fluctuation threshold. Conversely, when the stability of the roof rock strata changes, the roof rock strata analysis strategy is triggered. The roof strata analysis module executes the roof strata analysis strategy, acquires monitoring data from the roof lithology monitoring module, including changes in reflected signal intensity, frequency changes in reflected waves, phase changes in reflected waves, frequency changes in acoustic signals, and amplitude changes; acquires monitoring data from the groundwater monitoring module, including stress changes within the roof strata and displacement of the roof strata; and acquires monitoring data from the roof pressure monitoring module, including roof pressure changes and standard deviation. Monitoring data from the roof lithology monitoring module, groundwater monitoring module, and roof pressure monitoring module were used as evaluation indicators to construct a stability assessment matrix: ； in, Represented as the first m The monitoring indicator is relative to the first n The importance of each monitoring indicator m For matrix A the number of rows, n For matrix A The number of columns; The weight of each monitoring indicator is calculated using a stability assessment matrix, as shown in the following formula: ； in, This represents the weight of the j-th monitoring indicator. , N To monitor the number of indicators, k It is a constant, and ; The stability assessment value of the roof strata in the unstable area is calculated by using the values ​​of each monitoring indicator and their corresponding weights. The calculation formula is as follows: ； in, Sv Indicates the stability assessment value. This represents the value of the j-th monitoring indicator; an early warning is issued when the stability assessment value of the roof strata exceeds the stability threshold.

2. The roof pressure monitoring and early warning system for a coal mining face through-traverse and retreat passage according to claim 1, characterized in that: Drawing a map of geological structures includes: Collect geological information on the coal mining face access and its surrounding areas from geological exploration reports, mine geological maps and coal seam occurrence maps, including but not limited to stratigraphy, lithology and geological structure, and establish a geological database. Geological exploration, geophysical exploration and geological mapping methods are used to identify the geological structures of the coal mining face's access and retreat channels and its surrounding areas, including but not limited to faults, folds, joints and fissures. Using geological mapping software, based on information from the geological database, a base layer of strata and lithology distribution map and geological structure framework map is drawn. Data from geological exploration and geophysical exploration are overlaid on the base layer in the form of layers. Based on the geological exploration data, geological structural lines of faults, folds, joints and fissures are drawn to obtain a geological structure distribution map.

3. The roof pressure monitoring and early warning system for a coal mining face through-traverse and retreat passage according to claim 2, characterized in that: Identifying stable and unstable regions of the roof strata includes: Rock samples were collected from the top strata of the anomalous geological structure area to test the compressive strength, tensile strength and shear strength mechanical properties. Based on the test results, the physical and mechanical property parameters of the top strata were determined. Geological exploration data and mechanical property test results are obtained, numerical simulation software is used to conduct numerical simulation, a numerical model of the roof strata is established, and the stability of the roof strata at different locations is evaluated based on the simulation results of the roof strata numerical model, and stable and unstable regions of the roof strata are identified.

4. The roof pressure monitoring and early warning system for a coal mining face through-traverse and retreat passage according to claim 1, characterized in that: The roof lithology monitoring module determines whether the stability of the roof strata has changed, including: The system acquires the reflected signal intensity, frequency, and phase information of the ground-penetrating radar, calculates the changes in reflected signal intensity, frequency, and phase, and determines if the change in reflected signal intensity exceeds a preset threshold. A Or the frequency change of the reflected wave exceeds a preset threshold. B Or the phase change of the reflected wave exceeds a preset threshold. C If the stability of the top strata changes, it is determined that the stability has changed; otherwise, no operation is performed.

5. The roof pressure monitoring and early warning system for a coal mining face through-traverse and retreat passage according to claim 4, characterized in that: Acquire the acoustic wave signal received by the acoustic transmitter, calculate the frequency change and amplitude change of the acoustic wave signal, and if the frequency change of the acoustic wave signal exceeds a preset threshold... D Or the change in amplitude exceeds a preset threshold. E If the stability of the top strata changes, it is determined that the stability has changed; otherwise, no operation is performed.

6. The roof pressure monitoring and early warning system for a coal mining face through-traverse and retreat passage according to claim 1, characterized in that: The groundwater monitoring module determines whether the stability of the roof strata has changed, including: Obtain groundwater level data at different time points and calculate the changes in groundwater level: ,in, This indicates the change in groundwater level. This represents the groundwater level at time t. Indicates the initial water level; Based on the changes in groundwater level, the stress changes within the top strata of the unstable region are calculated using the effective stress principle. The stress changes are as follows: ,in, Indicates the amount of stress change. α This represents the effective stress coefficient, with a value ranging from 0 to 1. This represents the change in pore water pressure. ,in, This indicates the density of groundwater. g It represents the acceleration due to gravity.

7. The roof pressure monitoring and early warning system for a coal mining face through-traverse and retreat passage according to claim 6, characterized in that: Using the theory of elasticity, based on the physical and mechanical properties and stress changes of the roof strata, the displacement of the roof strata in the unstable region is calculated. The displacement is approximately expressed as: ,in, This indicates the displacement of the top strata. E Indicates the elastic modulus. h Indicates the thickness of the top strata; If the detected 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 strata has changed; otherwise, no operation is performed.

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