Coal seam working face radio wave reflection imaging method based on error analysis

Abstract

The invention discloses a coal seam working face radio wave reflection imaging method based on error analysis, and the method comprises the steps: enabling a radio wave transmitting device and a radio wave receiving device to move in a roadway at one side of a coal seam working face for multiple times, obtaining actual measurement field intensity values at different positions, and obtaining an actual measurement abnormal body reflection wave field intensity value through calculation; the method comprises the following steps: establishing a coordinate system to grid the area of a coal seam working face, obtaining the position coordinate of each grid, further obtaining the distance between each grid and the position of a receiving device corresponding to receiving obviously different field intensity values, and then substituting the distances of different grids and different set attenuation coefficients into a formula to obtain a theoretical anomalous body reflected wave field intensity value; and finally, determining an absolute value obtained by subtracting the actually measured abnormal body reflected wave field intensity value from the theoretical abnormal body reflected wave field intensity value as an error value. And setting a threshold value, selecting a position with an error value smaller than the threshold value, and finally determining the position as an abnormal body area and imaging, thereby providing a quantitative and visual exploration result for mine radio wave reflection exploration.

Description

Technical Field

[0001] This invention relates to an imaging method for radio wave reflection exploration in mine working face roadways, specifically a radio wave reflection imaging method for coal seam working faces based on error analysis. Background Technology

[0002] In modern coal mine exploration, accurate and efficient acquisition of underground geological information is crucial for improving mining efficiency and ensuring operational safety. Traditional exploration methods, such as geological drilling and seismic exploration, while providing mine geological data, are generally costly, time-consuming, and complex, especially in mine environments where their limitations become more pronounced. In stark contrast, mine radio wave exploration is a non-contact method with advantages such as lightweight equipment and simple operation. In practice, this technology has greatly improved work efficiency and convenience, gradually becoming an important method in the field of coal mine exploration. Radio wave transmission exploration has been extensively applied and researched. Although significant progress has been made in theory, instrumentation, and application, some problems remain unresolved. Radio wave transmission exploration primarily utilizes the attenuation coefficient of transmitted radio waves from coal seams for linear tomography. When strike or near-strike structures exist within the coal seam working face, the weak signal response of transmitted radio waves often results in insufficient resolution and limited positioning accuracy.

[0003] To address the issue of accuracy in detecting strike structures within coal mine working faces using radio wave exploration probes, some experts and scholars have proposed the concept of radio wave reflection exploration and conducted experiments and practices, achieving good application results. However, current data processing in mine radio wave reflection exploration remains at the qualitative research stage, lacking quantitative imaging methods. Therefore, this invention aims to provide a new method that utilizes coal seam radio wave reflection data for imaging, offering quantitative and visualized exploration results for mine radio wave reflection exploration, thereby contributing to the development of mine geological transparency. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a method for radio wave reflection imaging of coal seam working faces based on error analysis. It utilizes radio wave reflection data from coal seams and obtains the error value by subtracting the measured field strength value from the theoretical field strength value. Finally, it determines the anomaly region through error analysis imaging, providing quantitative and visualized exploration results for mine radio wave reflection exploration, thereby contributing to the development of mine geological transparency.

[0005] To achieve the above objectives, the technical solution adopted by this invention is: a method for radio wave reflection imaging of coal seam working faces based on error analysis, comprising the following steps: Step 1: Obtain measured field strength data: In the roadway on one side of the coal seam working face to be imaged, a radio wave transmitter and a radio wave receiver are set up along the roadway direction. At the current location, the radio wave transmitter excites radio waves, and the radio wave receiver measures the measured field strength value at the current location. Then, the radio wave transmitter and the radio wave receiver are moved the same distance along the roadway, and the measured field strength value at the current location is measured again. This process is repeated until the measured field strength values ​​at different locations of the coal seam working face to be explored are obtained. Step 2: Calculate the measured field strength of the reflected wave from the anomalous body: Compare the measured field strength values ​​obtained at each location in Step 1, select the measured field strength values ​​that are significantly different from those at other locations, and subtract the average value of the measured field strength values ​​from the other locations to obtain the measured field strength of the reflected wave from the anomalous body. Step 3: Calculate the reflected wave intensity of the theoretical anomaly: Based on the theory of reflected radio wave propagation, obtain the calculation formula for the reflected wave intensity of the theoretical anomaly. Set any distance r and attenuation coefficient β to obtain the reflected wave intensity of the theoretical anomaly. Step 4, Error Imaging: The absolute value of the difference between the measured reflected wave intensity value of the anomalous body obtained in Step 2 and the theoretical reflected wave intensity value of the anomalous body obtained in Step 3 is determined as the error value; a threshold is set, and the theoretical reflected wave intensity value of the anomalous body at different positions within the imaging range is calculated by adjusting the distance r and the attenuation coefficient β within the imaging range, thereby obtaining the error value at different positions; the positions with error values ​​less than the threshold are selected, and finally determined as the anomalous body region and imaged.

[0006] Furthermore, the distance between the radio wave transmitting device and the radio wave receiving device is d; and the position information of the radio wave transmitting device and the radio wave receiving device is determined for each detection.

[0007] Furthermore, in step two, a coordinate system is established with the direction of the tunnel as the X-axis and the perpendicular direction of the tunnel as the Y-axis; let the measured field strength value be H(x n ), x n Let Avg[H(x)] be the x-axis coordinates at different locations; let the average value be Avg[H(x)]. n The measured intensity of the reflected wave field from the anomalous body is: H R (x n ) = H(x n )-Avg[H(x n )] Among them, H R (x n () represents the measured intensity of the reflected wave field from the anomalous body.

[0008] Furthermore, in step three, based on the theory of reflected radio wave propagation, for any distance r and attenuation coefficient β, the theoretical anomalous body reflected wave field strength value is: H T= H0-8.68lnr-8.68βr In the formula: H T denoted as , where r is the propagation path length of the radio waves reflected from the anomaly, H0 is the field strength of the radio wave transmitting source, and β is the attenuation coefficient of the field strength of the radio waves propagating in the coal seam. If we set the reflection point of the anomalous body at any location on the working face of the coal seam to be imaged, then we have: In the formula, r i x is the propagation path length from the transmitting device to the i-th imaging grid and back to the receiving device; i and y i Let x be the x and y coordinates of the i-th imaging grid. j x is the x-coordinate of the launching device. k The x-axis represents the receiving device.

[0009] Furthermore, in step four, if the radio wave attenuation coefficient β of the coal seam is arbitrarily given... s and the Y-axis coordinate y at any position i, The theoretical anomalous body reflected wave field strength value H is calculated according to step three. Ti Where i is the number of imaging points; and the formula for the error value is: In the formula, H Ti H represents the intensity of the reflected wave field from the theoretical anomalous body. R (x n () represents the measured intensity of the reflected wave field from the anomalous body.

[0010] Furthermore, step four, which involves determining and imaging the anomalous body region, specifically includes: The spatial grid within the imaging range of the coal seam working face is divided into grids with a lateral interval of [value missing]. The vertical interval is This divides the space within the imaging range into i rectangular imaging points; Assuming any imaging point within the imaging range is a reflection point of the radio wave, the propagation distance of the reflected radio wave is calculated based on the spatial relationship between the positions of the radio wave transmitter, the radio wave receiver, and the reflection point. ; Assume the attenuation coefficient of radio waves at the coal seam working face is ; where β minThe initial value of the attenuation coefficient is given by s, the number of changes is given by β, and the amount of change is given by β in each change. This is determined by the parameter combination (r). i ,β s A set of error values ​​was calculated: Repeat the above steps to obtain the error values ​​corresponding to all imaging points, thereby completing the reflection radio wave imaging calculation based on error analysis; Based on the above error imaging results, a threshold is set, and the locations in each imaging point with error values ​​less than the threshold are identified as anomalous regions. The corresponding (r) values ​​for these regions are then obtained. i ,β s ), to complete the identification of abnormal body regions.

[0011] Compared with existing technologies, this invention maintains the same distance between the radio wave transmitting and receiving devices, moves the device multiple times along one side of the coal seam working face in the roadway, and obtains measured field strength values ​​at different locations. Then, it selects the measured field strength values ​​that are significantly different from other locations and calculates the measured anomalous body reflected wave field strength value. Next, it establishes a formula for calculating the theoretical anomalous body reflected wave field strength value and establishes a coordinate system to grid the coal seam working face region, obtaining the position coordinates of each grid. This allows it to obtain the distance between each grid and the receiving device location corresponding to the significantly different field strength values. Finally, it calculates the distances between different grids. Substituting r and different set attenuation coefficients β into the calculation formula for the theoretical anomaly reflected wave intensity, the theoretical anomaly reflected wave intensity is obtained. Finally, the absolute value of the difference between the measured anomaly reflected wave intensity and the theoretical anomaly reflected wave intensity is determined as the error value. A threshold is set, and the error values ​​calculated by different grids and attenuation coefficients are used to select the locations where the error value is less than the threshold. These locations are then identified as anomaly regions and imaged. This method can obtain relatively accurate anomaly regions and locations, and is simple to implement. It provides quantitative and visualized exploration results for mine radio wave reflection exploration, thereby contributing to the development of mine geological transparency. Attached Figure Description

[0012] Figure 1 This is a diagram illustrating the process of collecting field strength data at the coal seam working face according to an embodiment of the present invention.

[0013] Figure 2 This is a schematic diagram of the principle of radio wave reflection imaging at the coal seam working face in an embodiment of the present invention.

[0014] Figure 3 This is a schematic diagram of a known anomaly model in an embodiment of the present invention.

[0015] Figure 4 This is the error analysis imaging result of an embodiment of the present invention. Detailed Implementation

[0016] The present invention will be further described below.

[0017] To verify the effectiveness of the embodiments of the present invention, known anomaly ranges and locations are first established within the working face of the coal seam to be imaged, as shown below. Figure 3 As shown, imaging processing is then performed using the method described in this embodiment of the invention, such as... Figure 1 As shown, it includes the following steps: Step 1: Obtain measured field strength data: In the roadway on one side of the coal seam to be imaged, a radio wave transmitter and a radio wave receiver are deployed along the roadway direction. At the current location, the radio wave transmitter excites radio waves, and the radio wave receiver measures the measured field strength value at the current location. Then, the radio wave transmitter and the radio wave receiver are moved the same distance along the roadway, and the measured field strength value at the current location is measured again. This process is repeated until the measured field strength values ​​at different locations of the coal seam to be explored are obtained. The distance between the radio wave transmitter and the radio wave receiver is d. The position information of the radio wave transmitter and the radio wave receiver is determined for each detection.

[0018] Step 2: Calculate the measured reflected wave field intensity value of the anomalous body: Compare the measured field intensity values ​​obtained at each location in Step 1, select the measured field intensity value that is significantly different from the others, and subtract the average value of the measured field intensity values ​​from the other locations to obtain the measured reflected wave field intensity value of the anomalous body. Specifically, establish a coordinate system with the X-axis along the tunnel direction and the Y-axis perpendicular to the tunnel direction; let the measured field intensity value be H(x n ), x n Let Avg[H(x)] be the x-axis coordinates at different locations; let the average value be Avg[H(x)]. n The measured intensity of the reflected wave field from the anomalous body is: H R (x n ) = H(x n )-Avg[H(x n )] Among them, H R (x n () represents the measured intensity of the reflected wave field from the anomalous body.

[0019] The principle described above is as follows: When there are no anomalies in the coal seam face at the receiving location, the receiving device receives the field strength value of the direct radio wave propagating from the roadway; when there are anomalies in the coal seam face at the receiving location, the receiving device receives the field strength value of the direct wave field strength and the sum of the reflected wave field strength generated by the anomaly. By subtracting the average field strength value obtained when there are anomalies from the average field strength value at each location when there are no anomalies, the reflected wave field strength value generated by the geological anomaly in the coal seam face can be obtained.

[0020] Step 3: Calculate the reflected wave intensity of the theoretical anomalous body: Based on the theory of reflected radio wave propagation, for any distance r and attenuation coefficient β, the reflected wave intensity of the theoretical anomalous body is: H T= H0-8.68lnr-8.68βr In the formula: H T denoted as , where r is the propagation path length of the radio waves reflected from the anomaly, H0 is the field strength of the radio wave transmitting source, and β is the attenuation coefficient of the field strength of the radio waves propagating in the coal seam. Set the reflection point of the anomalous body at any location on the working face of the coal seam to be imaged, such as... Figure 2 As shown, we have: In the formula, r i x is the propagation path length from the transmitting device to the i-th imaging grid and back to the receiving device; i and y i Let x be the x and y coordinates of the i-th imaging grid. j x is the x-coordinate of the launching device. k The x-axis represents the receiving device.

[0021] Step 4, Error Imaging: The absolute value of the difference between the measured reflected wave intensity value of the anomaly obtained in Step 2 and the theoretical reflected wave intensity value of the anomaly obtained in Step 3 is determined as the error value. Specifically, it is: [The text abruptly ends here, so the translation stops as well.] s and the Y-axis coordinate y at any position i, The theoretical anomalous body reflected wave field strength value H is calculated according to step three. Ti Where i is the number of imaging points; and the formula for the error value is: In the formula, H Ti H represents the intensity of the reflected wave field from the theoretical anomalous body. R (x n () represents the measured intensity of the reflected wave field from the anomalous body.

[0022] A threshold is set, and the theoretical reflected wave intensity values ​​of the anomalous body at different locations within the imaging range are calculated by adjusting the distance r and the attenuation coefficient β, thereby obtaining the error values ​​at different locations. Locations with error values ​​less than the threshold are selected and ultimately identified as anomalous body regions for imaging. The principle is as follows: when the error value ε is large, it indicates that the selected distance r and attenuation coefficient β differ significantly from the actual situation; when the error value ε is small, it indicates that the selected distance r and attenuation coefficient β are closer to the actual situation. Therefore, as long as the location with the smaller error value is obtained, it can be identified as an anomalous body region. The specific process is as follows: The spatial grid within the imaging range of the coal seam working face is divided into grids with a lateral interval of [value missing]. The vertical interval is This divides the space within the imaging range into i rectangular imaging points, such as... Figure 2 The black square shown.

[0023] Assuming any imaging point within the imaging range is a reflection point of the radio wave, the propagation distance of the reflected radio wave is calculated based on the spatial relationship between the positions of the radio wave transmitter, the radio wave receiver, and the reflection point. ; Assume the attenuation coefficient of radio waves at the coal seam working face is ; where β min The initial value of the attenuation coefficient is 0.01 dB / m; s is the number of changes, and β is the amount of change in each change, specifically 0.001 dB / m; the changes are performed using the above formula until β... s The value stops changing when it reaches 0.1 dB / m; determined by the parameter combination (r) i ,β s A set of error values ​​was calculated: Repeat the above steps to obtain the error values ​​corresponding to all imaging points, a total of n error values, and sum them to obtain the sum of all error values, thereby completing the reflection radio wave imaging calculation based on error analysis; Based on the above error imaging results, the average value is calculated by summing all error values ​​and determining the number of error values. 20% of the average value is set as a threshold. Locations with error values ​​less than this threshold in each imaging point are identified as anomalous regions, and the corresponding (r) values ​​for these regions are obtained. i ,β s )like Figure 4 As shown, the imaging and identification of the abnormal body region is completed.

[0024] The imaging results were compared with known anomalous body regions and locations, and the two were found to be quite similar, indicating that the method of the present invention can effectively identify the range and location of anomalous bodies, and the method is relatively simple to implement.

[0025] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for radio wave reflection imaging of coal seam working faces based on error analysis, characterized in that, Includes the following steps: Step 1: Obtain measured field strength data: In the roadway on one side of the coal seam working face to be imaged, a radio wave transmitter and a radio wave receiver are set up along the roadway direction. At the current location, the radio wave transmitter excites radio waves, and the radio wave receiver measures the measured field strength value at the current location. Then, the radio wave transmitter and the radio wave receiver are moved the same distance along the roadway, and the measured field strength value at the current location is measured again. This process is repeated until the measured field strength values ​​at different locations of the coal seam working face to be explored are obtained. Step 2: Calculate the measured field strength of the reflected wave from the anomalous body: Compare the measured field strength values ​​obtained at each location in Step 1, select the measured field strength values ​​that are significantly different from those at other locations, and subtract the average value of the measured field strength values ​​from the other locations to obtain the measured field strength of the reflected wave from the anomalous body. Step 3: Calculate the reflected wave intensity of the theoretical anomaly: Based on the theory of reflected radio wave propagation, obtain the calculation formula for the reflected wave intensity of the theoretical anomaly. Set any distance r and attenuation coefficient β to obtain the reflected wave intensity of the theoretical anomaly. Step 4, Error Imaging: The absolute value of the difference between the measured reflected wave intensity value of the anomalous body obtained in Step 2 and the theoretical reflected wave intensity value of the anomalous body obtained in Step 3 is determined as the error value; a threshold is set, and the theoretical reflected wave intensity value of the anomalous body at different positions within the imaging range is calculated by adjusting the distance r and the attenuation coefficient β within the imaging range, thereby obtaining the error value at different positions; the positions with error values ​​less than the threshold are selected, and finally determined as the anomalous body region and imaged.

2. The method for radio wave reflection imaging of coal seam working faces based on error analysis according to claim 1, characterized in that, The distance between the radio wave transmitting device and the radio wave receiving device is d; and the position information of the radio wave transmitting device and the radio wave receiving device is determined for each detection.

3. The method for radio wave reflection imaging of coal seam working faces based on error analysis according to claim 1, characterized in that, In step two, a coordinate system is established with the X-axis along the tunnel direction and the Y-axis perpendicular to the tunnel direction; the measured field strength value is set to H(x). n ), x n Let Avg[H(x)] be the x-axis coordinates at different locations; let the average value be Avg[H(x)]. n The measured intensity of the reflected wave field from the anomalous body is: H R (x n ) = H(x n )-Avg[H(x n )] Among them, H R (x n () represents the measured intensity of the reflected wave field from the anomalous body.

4. The radio wave reflection imaging method for coal seam working faces based on error analysis according to claim 1, characterized in that, In step three, based on the theory of reflected radio wave propagation, for any distance r and attenuation coefficient β, the theoretical anomalous body reflected wave field strength value is: H T= H0-8.68lnr-8.68βr Where: H T denoted as , where r is the propagation path length of the radio waves reflected from the anomaly, H0 is the field strength of the radio wave transmitting source, and β is the attenuation coefficient of the field strength of the radio waves propagating in the coal seam. If we set the reflection point of the anomalous body at any location on the working face of the coal seam to be imaged, then we have: In the formula, r i x is the propagation path length from the transmitting device to the i-th imaging grid and back to the receiving device; i and y i Let x be the x and y coordinates of the i-th imaging grid. j x is the x-coordinate of the launching device. k The x-axis represents the receiving device.

5. The radio wave reflection imaging method for coal seam working faces based on error analysis according to claim 4, characterized in that, In step four, if the radio wave attenuation coefficient β of the coal seam is arbitrarily given... s and the Y-axis coordinate y at any position i, The theoretical anomalous body reflected wave field strength value H is calculated according to step three. Ti Where i is the number of imaging points; and the formula for the error value is: In the formula, H Ti H represents the intensity of the reflected wave field from the theoretical anomalous body. R (x n () represents the measured intensity of the reflected wave field from the anomalous body.

6. The blowout prevention device for gas drainage boreholes in outburst-prone coal seams according to claim 5, characterized in that, Step four, determining the anomalous body region and imaging it, specifically involves: The spatial grid within the imaging range of the coal seam working face is divided into grids with a lateral interval of [value missing]. The vertical interval is This divides the space within the imaging range into i rectangular imaging points; Assuming any imaging point within the imaging range is a reflection point of the radio wave, the propagation distance of the reflected radio wave is calculated based on the spatial relationship between the positions of the radio wave transmitter, the radio wave receiver, and the reflection point. Assume the attenuation coefficient of radio waves at the coal seam working face is ; where β min Here, s is the initial value of the attenuation coefficient, β is the number of changes, and β is the amount of change each time. By parameter combination (r) i ,β s A set of error values ​​was calculated: Repeat the above steps to obtain the error values ​​corresponding to all imaging points, thereby completing the reflection radio wave imaging calculation based on error analysis; Based on the above error imaging results, a threshold is set, and the locations in each imaging point with error values ​​less than the threshold are identified as anomalous regions. The corresponding (r) values ​​for these regions are then obtained. i ,β s ), to complete the identification of abnormal body regions.

Images