Advanced detection system and method with electrical method

Abstract

The application discloses a kind of advanced detection system and method of electrical method with excavation, system includes receiving array, transmitting array, receiving substation and transmitting substation;Receiving array is connected to the receiving substation;Receiving array is composed of multiple measuring electrodes located on a measuring line;Measuring electrode is equidistantly laid along measuring line;Measuring line is laid along the direction of roadway;Transmitting array is connected to the transmitting substation;The transmitting array at least includes 6 power supply electrodes;At least three power supply electrodes are laid along the direction of measuring line of receiving array, at least two power supply electrodes are perpendicular to the direction of measuring line;At least one power supply electrode is laid on the roadway wall opposite to the first position.The application realizes the prediction of the orientation of abnormal body in front of the excavation face, realizes the distance prediction of abnormal body in front of the excavation face;The distance and orientation information of the abnormal body obtained by prediction are used as prior information, to constrain the inversion imaging of abnormal body in front of the excavation face, overcome the problem of weak anomaly identification difficulty.

Description

Technical Field

[0001] This invention relates to a method for detecting water hazards in mines, belonging to the field of mine water control, and specifically to a tunneling electrical method for advanced detection and a method thereof. Background Technology

[0002] Underground mining of energy resources such as coal and metal ores, as well as the construction of underground engineering projects such as tunnels and subways, all face geological hazards such as collapses, subsidence, mudslides, and water inrushes, which seriously threaten the lives of construction workers and cause huge property losses. The main causes of geological hazards are unstable geological structures, faults and fault fracture zones, karst collapse columns, and other hidden unstable structures and water-bearing geological structures. The purpose of advanced detection is to identify unfavorable geological bodies ahead of deeply buried underground tunnels in advance to prevent the occurrence of sudden geological hazards.

[0003] Most coal mines in my country have extremely complex hydrogeological conditions, and the threat of water hazards hinders the intelligent construction of coal mines. Therefore, transparent geological information on water hazard risks is urgently needed to safeguard mines. With the vigorous development of intelligent coal mine construction, the contradiction of "mining-excavation imbalance" is becoming increasingly prominent, and the development of rapid tunneling technology is unstoppable. The need for transparent geological information on water hazard risks in tunneling operations is also becoming increasingly urgent. Electromagnetic exploration methods in mines have unique advantages in detecting low-resistivity anomalies caused by water hazards and have been widely used in advanced detection of tunneling faces, achieving good geological results.

[0004] The main methods for advanced detection of water hazards at tunneling faces are transient electromagnetic methods and DC resistivity methods.

[0005] When using transient electromagnetic (TEM) detection technology in mine roadways, it is easily affected by metallic interference within the roadway. To overcome this problem, roadway-hole TEM detection technology and borehole-based TEM detection technology have been gradually developed. Both methods involve inserting a receiving probe into the borehole to avoid metallic interference within the roadway. Simultaneously, the observation point is closer to potential water hazards, allowing for the acquisition of stronger anomalous signals, thereby improving detection accuracy. The borehole-based TEM method utilizes a probe with an integrated transmitting and receiving design, further developing into a "long-distance tunneling, long-exploration" TEM detection technology. By combining geophysical exploration and directional drilling, it solves the problem of making geological information about potential water hazards transparent during rapid roadway excavation. However, this method requires combination with directional drilling to achieve long-distance TEM detection ahead of the working face, which is technically challenging and costly.

[0006] The DC resistivity method for advance detection in tunnels is less affected by metallic interference within the tunnel and is easy to implement, making it a common method for detecting water hazards at tunneling faces. Compared to other advance detection methods, the DC resistivity method offers advantages such as flexible and varied device configurations, high sensitivity to low-resistivity anomalies, and high resolution, making it suitable for detecting highly hazardous hydrogeological structures such as water accumulation in empty areas, water-bearing faults, water-rich rock strata, and karst collapse columns. However, this method involves deploying survey lines in the tunnel behind the tunneling face to detect water hazards ahead of the tunneling face, resulting in a relatively weak anomaly response. In the decades since its introduction, various observation methods such as the three-point method, five-point method, seven-point method, and focusing method have been proposed, but the three-point method remains the most widely used in practical engineering. Numerical simulation results show that when conducting borehole electrical resistivity tomography (EDT) advance detection, the observation point is closer to the potential water hazard, and the observation data is more sensitive to the abnormal resistivity changes caused by the potential water hazard, which can significantly enhance the abnormal response to the potential water hazard. However, since DC resistivity tomography exploration requires the electrodes to have good grounding conditions, conventional borehole electrical resistivity tomography has difficulty overcoming the conductive coupling problem between the electrodes and the borehole wall. Therefore, borehole electrical resistivity tomography advance detection is still in the theoretical and methodological research stage.

[0007] Electromagnetic exploration methods in mines are an important means of making geological information on water hazard risks transparent. However, when applied to advance detection during tunneling, they still face technical bottlenecks such as limited observation space and difficulties in identifying weak anomalies. In order to achieve transparency of geological information on water hazard risks in advance at the tunneling face and provide efficient geological support for rapid tunneling, the establishment of an advance detection system and method based on electromagnetic methods during tunneling is urgent and cannot be delayed. Summary of the Invention

[0008] This invention primarily addresses the technical problems of limited observation space and difficulty in identifying weak anomalies in existing technologies for on-the-fly electrical resistivity tomography (EDT) advanced detection, providing an EDT system and method. This method uses a three-dimensional transmission array with different directional combinations to predict the distance and orientation of anomalies ahead of the tunnel face. Furthermore, the predicted distance and orientation information is used as prior information to perform constrained inversion imaging of the anomalies ahead of the tunnel face, improving the imaging resolution of anomalies ahead of the tunnel face.

[0009] The technical solution adopted by this invention to solve its technical problem is: On one hand, the present invention provides a tunneling electrical resistivity tomography (TET) advanced detection system, comprising a receiving array, a transmitting array, a receiving substation, and a transmitting substation; wherein: The receiving array is connected to the receiving substation; the receiving array consists of multiple measuring electrodes M located on a measuring line. i r composition, i r =1, 2, ...,Nr , Nr The total number of measuring electrodes; the measuring electrodes are evenly spaced along the measuring line; the measuring line is laid out along the roadway direction; the total number of measuring electrodes is Nr =1+ l / Dp The measuring electrodes are numbered in order of distance from the working face, from closest to furthest, with larger numbers for greater distances, and are designated as M1, M2, M3, ..., M... Nr ; The transmitting array is connected to the transmitting substation; the transmitting array includes at least 6 power supply electrodes A. i s , i s =1, 2, ..., Ns , Ns This represents the total number of power supply electrodes. Ns ≥6; Among them, at least three power supply electrodes are arranged along the measuring line direction of the receiving array, and are respectively labeled A1, A2 and A3 in order of distance from the tunneling face from near to far. The spacing between these three power supply electrodes and the spacing between adjacent measuring electrodes are... Dp Equal; at least two power supply electrodes are perpendicular to the survey line direction and symmetrically arranged with A1 as the center, and are respectively denoted as A4 and A5 in order from left to right; at least one power supply electrode is arranged on the roadway wall opposite to the position of A1, and is denoted as A6; The distance between measuring electrode M1 and power supply electrode A3 and the distance between adjacent measuring electrodes Dp equal.

[0010] On the other hand, the present invention provides a method for advance detection using electrical resistivity tomography (EDT) in tunneling, which, based on the aforementioned advance detection system for EDT in tunneling, specifically includes the following steps: Step 1: Deploy the under-tunnel electrical resistivity tomography (EDT) advanced detection system and record the deployment information; Step 2: Use the under-excavation electrical resistivity tomography (EDT) advance detection system to collect under-excavation electrical resistivity tomography (EDT) data; Step 3: In the observation data obtained in Step 2, the observation data of the tunneling electrical resistivity advance detection system at the same location are processed to obtain the apparent resistivity data corresponding to each power supply electrode of the tunneling electrical resistivity advance detection system at different locations. Step 4: Eliminate background influence on the apparent resistivity data of power supply electrodes A1, A2, A3, A4, A5 and A6 at different locations of the under-excavation electrical resistivity detection system to obtain pure abnormal response data of power supply electrodes A1, A2, A3, A4, A5 and A6 at different locations. Step 5: Using the pure anomalous apparent resistivity data corresponding to the power supply electrodes A1, A2 and A3 at different positions obtained in Step 4, predict the distance of the anomalous body in front of the tunneling face. Step 6: Using the pure anomalous apparent resistivity data corresponding to the power supply electrodes A1, A4, A5, and A6 at different positions obtained in Step 4, predict the left-right and up-down positions of the anomalous body in front of the tunneling working face.

[0011] Compared with the prior art, the beneficial effects of the present invention are as follows: By deploying three-dimensional transmission arrays with different directional combinations and comparing the abnormal response intensities corresponding to power supply electrodes at different locations, the problem of limited observation space for advance detection during tunneling was overcome without increasing the number of survey lines, enabling the prediction of the orientation of anomalies in front of the tunneling face. Using apparent resistivity data from different detection locations, the distance to anomalies in front of the tunneling face was predicted by fitting the power supply electrode positions to the corresponding apparent resistivity extreme points. Furthermore, the predicted distance and orientation information of the anomalies were used as prior information to perform constrained inversion imaging of the anomalies in front of the tunneling face, overcoming the difficulty of identifying weak anomalies and improving the imaging resolution of anomalies in front of the tunneling face. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of an electrical resistivity tomography (EDT) advanced detection system. Figure 2 The apparent resistivity curves of A1, A2, and A3 at the 0m excavation position; Figure 3 The apparent resistivity curves of A1, A2, and A3 at the 10m excavation position; Figure 4 The apparent resistivity curves of A1, A2, and A3 at the 20m excavation position; Figure 5 The apparent resistivity curves of A1, A2, and A3 at the 30m excavation position; Figure 6 The apparent resistivity curves of A1, A2, and A3 at the 40m excavation position; Figure 7 A curve fitting the position of the power supply electrode to the position of the apparent resistivity extreme point; Figure 8 The apparent resistivity curves of A1, A4, and A5 at the 0m excavation position; Figure 9 The apparent resistivity curves of A1, A4, and A5 at the 10m excavation position; Figure 10 The apparent resistivity curves of A1, A4, and A5 at the 20m excavation position; Figure 11 The apparent resistivity curves of A1, A4, and A5 at the 30m excavation position; Figure 12The apparent resistivity curves of A1, A4, and A5 at the 40m excavation position; Figure 13 This is the result of inversion imaging based on the electrical resistivity tomography method during excavation. Detailed Implementation

[0013] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0014] This invention primarily addresses the technical problems of limited observation space and difficulty in identifying weak anomalies in existing technologies for on-the-fly electrical resistivity tomography (EDT) advanced detection, providing an EDT system and method. This method uses a three-dimensional transmission array with different directional combinations to predict the distance and orientation of anomalies ahead of the tunnel face. Furthermore, the predicted distance and orientation information is used as prior information to perform constrained inversion imaging of the anomalies ahead of the tunnel face, improving the imaging resolution of anomalies ahead of the tunnel face.

[0015] Example 1 This embodiment presents an in-situ electrical resistivity tomography (EDT) advanced detection system, such as... Figure 1 As shown, the tunneling electrical method advanced detection system mainly consists of receiving array 1, transmitting array 2, receiving substation 3, and transmitting substation 4.

[0016] Receiver array 1 is connected to receiving substation 3. Receiver array 1 consists of multiple measuring electrodes M located on a single measuring line. i r composition, i r =1, 2, ..., Nr , Nr This represents the total number of measuring electrodes. The measuring electrodes are evenly spaced along the survey line, with a spacing of 2m or less between adjacent electrodes. Dp ≤10m. Survey lines are laid out along the direction of the roadway, with a survey line length of... l ≥100m. The total number of measuring electrodes is Nr =1+ l / Dp The measuring electrodes were numbered in order of distance from the working face, from closest to furthest, with larger numbers for greater distances, and were designated as M1, M2, M3, ..., M... Nr .

[0017] Transmitter array 2 is connected to transmitter substation 4. Transmitter array 2 contains at least 6 power supply electrodes A. i s , i s =1, 2, ..., Ns , Ns This represents the total number of power supply electrodes. Ns≥6. At least three power supply electrodes are arranged along the measuring line direction of the receiving array, and are designated A1, A2, and A3 respectively in order of distance from the tunneling face from near to far. The spacing between these three power supply electrodes is the same as the spacing between adjacent measuring electrodes. Dp Equal; at least two power supply electrodes are perpendicular to the survey line direction and symmetrically arranged with A1 as the center. They are denoted as A4 and A5 respectively from left to right. The distance between these two power supply electrodes is limited by the tunnel size and is generally required to be no less than 2m; at least one power supply electrode is arranged on the tunnel wall opposite to the position of A1 and is denoted as A6.

[0018] The distance between measuring electrode M1 and power supply electrode A3 and the distance between adjacent measuring electrodes Dp equal.

[0019] Example 2 This embodiment presents a tunneling electrical resistivity tomography (ERT) method for advance detection. This method is based on the tunneling electrical resistivity tomography (ERT) system given in Embodiment 1, and specifically includes the following steps: Step 1: Deploy the under-excavation electrical resistivity tomography (EDT) advanced detection system and record the deployment information.

[0020] The under-excavation electrical resistivity tomography (EPT) system of Example 1 is deployed at a distance from the tunneling face. R At position 0, 4m≤ R 0≤10m. The entire electrical resistivity tomography (EDT) advance detection system moves forward with the tunnel excavation, with a moving step distance of [missing information]. R 1, 10m≤ R 1≤20m. Step distance. R 1 is generally the distance between adjacent measuring electrodes. Dp The distance must be an integer multiple of the specified value. During the movement, the distance from A1 to the tunneling face must always be maintained at a constant value. R 0 remains unchanged. (Keep) R Keeping it constant at 0 ensures that the impact of tunnel cavities and mining-induced damage on the detection results is basically consistent during each advance detection, making it easier to eliminate this impact by using ratio correction methods in the future.

[0021] The positions of the under-excavation electrical resistivity tomography (EDT) system are numbered according to their distance from the starting position of the tunneling operation, with larger numbers for greater distances. The current position of the EDT system is recorded as follows: i The origin of the coordinate system is the starting position of the tunneling, and the coordinate system is the direction of tunneling. x In the axial direction, record the coordinate positions of the power supply electrode and the measuring electrode. Record the position information of the tunneling electrical resistivity tomography (EPTM) advanced detection system in tabular form, including the location number of the ETM advanced detection system, the distance from the ETM advanced detection system to the tunneling start position, the distance from the ETM advanced detection system to the tunneling face, the power supply electrode number and its corresponding coordinate position, and the measuring electrode number and its corresponding coordinate position.

[0022] Step 2: Use the tunneling electrical resistivity tomography (ERT) advanced detection system to collect ERT data.

[0023] During the acquisition of electrical resistivity tomography (EDT) data, the power supply electrodes are switched in turn according to their numerical order. When the... i s While each power supply electrode transmits a signal, all measuring electrodes acquire voltage signals. After all power supply electrodes have completed one round of signal transmission, a complete set of observation data is obtained.

[0024] A complete set of observation data includes Ns × Nr Each data record contains, in sequence, the location number of the tunneling electrical resistivity tomography (EPT) advanced detection system, the power supply electrode number and its corresponding coordinates, the measurement electrode number and its corresponding coordinates, the transmitting current, and the receiving voltage. The data records are arranged in ascending order of power supply electrode number and measurement electrode number.

[0025] The under-tunnel electrical resistivity tomography (EDT) system continuously collects data at each location, with a total of [number] cycles. n c ≥5 times, which facilitates the improvement of data stability by averaging multiple observations from the same location.

[0026] Step 3: In the observation data obtained in Step 2, the observation data of the tunneling electrical resistivity advance detection system at the same location are processed to obtain the apparent resistivity data corresponding to each power supply electrode of the tunneling electrical resistivity advance detection system at different locations.

[0027] Specifically, for multiple sets of observation data collected cyclically at the same location by the under-excavation electrical resistivity tomography (EMT) advanced detection system, the received voltage in each data record is first divided by the transmitted current to normalize the received voltage; then, the normalized received voltages with the same power supply electrode number and measurement electrode number in multiple sets of observation data are superimposed to calculate the average voltage; finally, the calculated average voltage is converted into apparent resistivity data.

[0028] Specifically, in the location i No. c The voltage data obtained from the second cycle is recorded as follows: U ic Current data is recorded as I ic . U ic and I ic All are one-dimensional arrays with a length of . Ns × Nr Normalized received voltage The under-excavation electrical resistivity tomography (EDT) advanced detection system is used in location...i go through n c The average voltage value obtained from the second cycle U i The calculation formula is as follows:

[0029] Corresponding apparent resistivity value ρ i The calculation formula is as follows:

[0030] In the formula, K This is the device coefficient, which is related to the observation device used and the coordinate positions of the transmitting and measuring electrodes.

[0031] Specifically, when using a single-pole-single-pole observation device, r AM This represents the distance between the transmitting electrode A and the receiving electrode M, and is a device coefficient. K AM The format is as follows:

[0032] When using a monopole-dipole observation device, r AM The distance between the transmitting electrode A and the receiving electrode M is represented by... r AN This represents the distance between the transmitting electrode A and the receiving electrode N, and is a device coefficient. K AMN The format is as follows:

[0033] When using a dipole-dipole observation device, r AM The distance between the transmitting electrode A and the receiving electrode M is represented by... r AN The distance between the transmitting electrode A and the receiving electrode N is represented by r. BM The distance between the transmitting electrode B and the receiving electrode M is represented by... r BN This represents the distance between the transmitting electrode B and the receiving electrode N, and is a device coefficient. K ABMN The format is as follows: .

[0034] Step 4: Background influence elimination is performed on the apparent resistivity data of power supply electrodes A1, A2, A3, A4, A5 and A6 at different locations of the tunneling electrical resistivity tomography (TMT) advanced detection system to obtain pure abnormal response data of power supply electrodes A1, A2, A3, A4, A5 and A6 at different locations.

[0035] The detection data includes background influences such as random noise, coal-bearing strata, roadway cavities, roadway side anomalies, and mining-induced damage at the tunneling face. These background influences can be categorized into three types: the first type has a random amplitude, mainly including random noise; the second type has an amplitude that depends only on the position of the power supply electrode and the offset distance between the measuring electrode and the power supply electrode, mainly including coal-bearing strata, roadway cavities, and mining-induced damage at the tunneling face; and the third type has an amplitude that is limited to the vicinity of a fixed location in the roadway, mainly including roadway side anomalies.

[0036] For the first type of influencing factors, methods such as outlier removal and smoothing filtering are used to eliminate the influence of random noise. For the second type of influencing factors, a method of equal offset ratio correction between current and historical detection results is used to eliminate the influence of coal-bearing strata, roadway cavities, and mining-induced damage at the tunneling face. For the third type of influencing factors, a method of ratio correction between adjacent locations and the receiving point is used to eliminate the influence of lateral anomalies.

[0037] By using the above-mentioned smoothing filtering and quadratic ratio correction methods, different types of background influences are eliminated, thereby enabling the extraction of pure abnormal responses in front of the tunneling face.

[0038] Step 5: Using the pure anomalous apparent resistivity data corresponding to electrodes A1, A2, and A3 at different locations obtained in Step 4 from the under-excavation electrical resistivity prediction system, predict the distance to the anomalous body ahead of the tunneling face. Details are as follows: The under-excavation electrical resistivity tomography (EDT) advanced detection system will be used at the location i The pure anomalous apparent resistivity data corresponding to the power supply electrodes A1, A2, and A3 are recorded as follows: , , Plot the corresponding apparent resistivity curves and observe whether the three apparent resistivity curves overlap.

[0039] like , , The three corresponding apparent resistivity curves basically overlap, indicating that the anomaly ahead of the tunneling face is far away and outside the effective detection range of the under-tunnel electrical resistivity detection system. At this point, we continue to analyze the pure anomaly apparent resistivity data corresponding to the power supply electrodes A1, A2, and A3 at the next location. , , The corresponding apparent resistivity curves are obtained until the three apparent resistivity curves separate from each other.

[0040] like , , The three corresponding apparent resistivity curves are separated, indicating the presence of an anomaly ahead of the tunneling face, within the effective detection range of the under-tunnel electrical resistivity tomography (EDT) advance detection system. Assume the coordinates of the anomaly are... x Take at least two sets of spatially consecutive detection data, with the spatial locations numbered as follows: i , i +1, at this time, the coordinate positions of the power supply electrodes A1, A2, and A3 along the survey line are arranged in ascending order, as follows: , , , , , The coordinates of the extreme points of the corresponding apparent resistivity curve along the survey line are as follows: , , , , , .

[0041] Calculate each power supply electrode to The distance is in the following form: X =[0, , , , , ]; Calculate the distance between each power supply electrode and its corresponding extreme point on the apparent resistivity curve, in the following form: D =[ , , , , , ]; by X The horizontal axis is... D Using the vertical axis as the ordinate, we perform curve fitting using the following formula:

[0042] In the above formula, A is the slope obtained by fitting, and B is the intercept obtained by fitting.

[0043] when D When =0, , This represents the abnormal body to The distance.

[0044] The formula for predicting the coordinate position of the anomaly in front of the tunneling face at the current tunneling location is as follows: ; The formula for predicting the distance from the anomaly to the tunneling face is as follows: .

[0045] Step 6: Using the pure anomalous apparent resistivity data corresponding to electrodes A1, A4, A5, and A6 at different locations obtained in Step 4, predict the left-right and up-down positions of the anomalous body ahead of the tunneling face. The specific operation is as follows: (1) Prediction of left and right directions; Using the pure anomalous apparent resistivity data corresponding to the power supply electrodes A1, A4, and A5 at different locations obtained in step 4, the left and right orientations of the anomalous body in front of the tunneling face are predicted, as follows: The under-excavation electrical resistivity tomography (EDT) advanced detection system will be used at the location i The pure anomalous apparent resistivity data corresponding to the power supply electrodes A1, A4, and A5 are recorded as follows: , , Plot the corresponding apparent resistivity curves and observe whether the three apparent resistivity curves overlap.

[0046] like , , The three corresponding apparent resistivity curves basically overlap, indicating that the anomaly ahead of the tunneling face is far away and outside the effective detection range of the under-tunnel electrical resistivity tomography (EDT) advance detection system. At this point, we continue analyzing the next location. , , The corresponding apparent resistivity curves are used until the apparent resistivity curves corresponding to power supply electrode A1 separate from the apparent resistivity curves corresponding to power supply electrodes A4 and A5.

[0047] like The corresponding apparent resistivity curve and and The corresponding apparent resistivity curves are separated, indicating the presence of an anomaly ahead of the tunneling face, within the effective detection range of the electrical resistivity tomography (EDT) advance detection system. Further, it is determined... and Do the two corresponding apparent resistivity curves overlap?

[0048] like and If the two corresponding apparent resistivity curves basically overlap, it indicates that the anomaly is located directly in front of the tunneling face.

[0049] like and The two corresponding apparent resistivity curves are separated from each other. Further, the magnitude of the abnormal amplitude of the two sets of apparent resistivity data is determined.

[0050] if The abnormal amplitude is greater than The abnormal amplitude indicates that the abnormal body is closer to the power supply electrode A4, which is located to the left front of the tunneling face; if The abnormal amplitude is greater than The abnormal amplitude indicates that the abnormal body is closer to the power supply electrode A5, which is located in the right front of the tunneling face.

[0051] (2) Prediction of vertical and horizontal orientation.

[0052] Using the pure anomalous apparent resistivity data of A1, A2, and A6 at different locations obtained by the under-excavation electrical resistivity prediction system in step 4, the vertical and horizontal positions of the anomalous body in front of the tunnel face are predicted. Taking A1 and A2 located on the tunnel floor and A6 located on the tunnel roof as an example, the details are as follows: The under-excavation electrical resistivity tomography (EDT) advanced detection system will be used at the location i The pure anomalous apparent resistivity data corresponding to times A1, A2, and A6 are recorded as follows: , , Plot the corresponding apparent resistivity curves and observe whether the three apparent resistivity curves overlap.

[0053] like , , The three corresponding apparent resistivity curves basically overlap, indicating that the anomaly ahead of the tunneling face is far away and outside the effective detection range of the under-tunnel electrical resistivity tomography (EDT) advance detection system. At this point, we continue analyzing the next location. , , The corresponding apparent resistivity curves are used until the apparent resistivity curve corresponding to power supply electrode A2 separates from the apparent resistivity curves corresponding to power supply electrodes A1 and A6.

[0054] like The corresponding apparent resistivity curve and and The corresponding apparent resistivity curves are separated, indicating the presence of an anomaly ahead of the tunneling face, within the effective detection range of the electrical resistivity tomography (EDT) advance detection system. Further, it is determined... and Do the two corresponding apparent resistivity curves overlap?

[0055] like and If the two corresponding apparent resistivity curves basically overlap, it indicates that the anomaly is located directly in front of the tunneling face.

[0056] like and The two corresponding apparent resistivity curves are separated from each other. Further, the magnitude of the abnormal amplitude of the two sets of apparent resistivity data is determined.

[0057] if The abnormal amplitude is greater than The abnormal amplitude indicates that the abnormal body is closer to the power supply electrode A1, and it is located slightly below and in front of the tunneling face; if The abnormal amplitude is greater than The abnormal amplitude indicates that the abnormal body is closer to the power supply electrode A6, and it is located slightly above and in front of the tunneling face.

[0058] Example 3 This embodiment, based on the result of the method in Embodiment 2, further includes the following steps: Step 7: Constrained inversion imaging of anomalies in front of the tunneling working face.

[0059] Multiple sets of continuous, spatially synchronized electrical resistivity tomography (EDS) advance detection data are used to invert and image anomalies ahead of the tunnel face. Simultaneously, the anomaly prediction information obtained in steps 5 and 6 is used as prior information to constrain the inversion process. Details are as follows: Current position of the under-excavation electrical resistivity tomography (EDT) advanced detection system i Starting from position j, backtrack to position j, ensuring At the same time, position i and location j The distance between them shall not exceed 100m.

[0060] Read multiple sets of continuous detection data from the under-tunnel electrical resistivity tomography (EDT) system at different spatial locations, ρ t =[ ρ j , ρ j+1 , ..., ρ i ].

[0061] Using the distance and orientation prediction information of the anomaly in front of the tunneling face obtained in steps 5 and 6, an initial model m0 is established.

[0062] The model calculation formula for constrained inversion imaging is as follows:

[0063] In the formula m i This is the resistivity model obtained from the inversion, where α is the model correction coefficient. βW is the regularization parameter. d For data weights, W m For model weights, ρ m To simulate detection data, Let be the Jacobian matrix. The value of α is generally in the range of 0 ≤ α < 1. β The range of values ​​is generally 0 ≤ β ≤20.

[0064] During the inversion process, prior condition constraints are applied through m0. m0 contains prior information such as the distance and orientation of the anomaly in front of the tunneling working face, which can constrain the resistivity inversion process and thus improve the imaging resolution of the anomaly in front of the tunneling working face.

[0065] Through the constrained inversion process, the resistivity imaging results of the underground medium in front of the tunnel face are obtained.

[0066] Example 4 This embodiment, based on the method of Embodiment 3, further includes the following steps: Step 8, Risk Warning.

[0067] Based on the constrained inversion imaging results of the anomaly in front of the tunnel face, water hazard risk warnings are issued by analyzing the changing characteristics of the low-resistivity anomaly area in front of the tunnel face during the tunneling process. When the range of the low-resistivity anomaly area becomes increasingly focused and the magnitude of the low-resistivity anomaly increases, it is inferred that there is a potential water hazard in front of the tunnel face, requiring drilling verification and relevant treatment measures.

[0068] To verify the feasibility and effectiveness of this invention, the following experiment was designed for verification: like Figure 1 As shown, a low-resistivity anomaly exists in front of the tunneling face. The distance from the tunneling electrical method advanced detection system to the tunneling face is fixed at 5m, the electrode spacing between adjacent measuring electrodes is 5m, the measuring line length is 200m, the spacing between adjacent power supply electrodes along the measuring line direction is 5m, and the spacing between adjacent power supply electrodes perpendicular to the measuring line direction is 2m. The observation system moves forward once every 10m.

[0069] When the tunneling electrical resistivity tomography (EPR) advanced detection system first detected the anomaly, it was located 50m directly in front of the tunneling face. The position of the tunneling face at this time was recorded as 0m. Figures 2-6 The figure shows the apparent resistivity curves of electrodes A1, A2, and A3 at continuous spatial locations for the under-excavation electrical resistivity detection system. As the tunnel advances, the distance between the under-excavation electrical resistivity detection system and the anomaly decreases, leading to larger deviations in the apparent resistivity curves corresponding to A1, A2, and A3, smaller apparent resistivity extremes, and a decreasing distance from the apparent resistivity extreme points to the tunneling face.

[0070] Taking the coordinate position of A3 at 10m of tunneling as the starting point, the distance from each power supply electrode to that position was calculated, and the results are as follows: X =[0, 5, 10, 15, 20, 25, 30, 35, 40] Calculate the distance between each power supply electrode and its corresponding extreme point on the apparent resistivity curve, in the following form: D =[132.5, 122.5, 112.5, 102.5, 92.5, 82.5, 67.5, 57.5, 42.5] by X The horizontal axis is... D Using the vertical axis as the ordinate, perform curve fitting, such as... Figure 7 As shown. The fitting formula is as follows: D = 3X + 162.5 When D=0, X=54. After tunneling 10m, the actual distance between A3 and the anomaly is 50m, while the predicted distance is 54m. The predicted result is close to the actual result.

[0071] Will Figure 1 The abnormal body is placed 50m ahead of the tunnel face and 5m to the left, and the position of the tunnel face at this time is recorded as 0m. Figures 8-12 The figure shows the apparent resistivity curves of electrodes A1, A4, and A5 at continuous spatial locations for the under-excavation electrical resistivity detection system. As the tunnel advances, the distance between the under-excavation electrical resistivity detection system and the anomaly decreases, leading to larger deviations in the apparent resistivity curves corresponding to A1, A4, and A5. After 10m of excavation, the apparent resistivity of A4 is generally smaller than that of A1 and A5, indicating the largest anomaly amplitude. This suggests that the anomaly is closest to A4, and it is inferred that the anomaly is located to the left front of the working face, consistent with the actual situation.

[0072] Figure 13 The inversion imaging results are obtained when using anomaly distance and orientation prediction information as constraints. As can be seen from the figure, as the tunneling face advances, the location and distribution range of the low-resistivity anomaly area in front of the tunneling face deviate less and less from the actual situation of the anomaly, until the two basically coincide.

[0073] This embodiment overcomes the problem of limited observation space for advance detection during tunneling by deploying three-dimensional transmission arrays with different directional combinations and comparing the abnormal response intensity corresponding to power supply electrodes at different positions, without increasing the number of survey lines, and realizes the prediction of the orientation of anomalies in front of the tunneling working face. By using the apparent resistivity data at different detection positions and the fitting relationship between the power supply electrode position and the corresponding apparent resistivity extreme point position, the distance of anomalies in front of the tunneling working face is predicted. Furthermore, the predicted distance and orientation information of the anomalies are used as prior information to perform constrained inversion imaging of anomalies in front of the tunneling working face, overcoming the problem of difficulty in identifying weak anomalies and improving the imaging resolution of anomalies in front of the tunneling working face.

Claims

1. A tunneling electrical resistivity tomography (EPT) advanced detection system, characterized in that, It includes a receiving array (1), a transmitting array (2), a receiving substation (3), and a transmitting substation (4); wherein: The receiving array (1) is connected to the receiving substation (3); the receiving array (1) consists of multiple measuring electrodes M located on a measuring line. i r composition, i r =1, 2, ..., Nr , Nr The total number of measuring electrodes; the measuring electrodes are evenly spaced along the measuring line; the measuring line is laid out along the roadway direction; the total number of measuring electrodes is Nr =1+ l / Dp , l The measuring electrodes are numbered in order of distance from the working face, from closest to furthest, with larger numbers for greater distances, and are designated as M1, M2, M3, ..., M... Nr ; The transmitting array (2) is connected to the transmitting substation (4); the transmitting array (2) includes 6 power supply electrodes A i s , i s =1, 2, ..., Ns , Ns This represents the total number of power supply electrodes. Ns =6; Among them, at least three power supply electrodes are arranged along the measuring line direction of the receiving array, and are respectively labeled A1, A2 and A3 in order of distance from the tunneling face from near to far. The spacing between these three power supply electrodes and the spacing between adjacent measuring electrodes are... Dp Equal; at least two power supply electrodes are perpendicular to the survey line direction and symmetrically arranged with A1 as the center, and are respectively denoted as A4 and A5 in order from left to right; at least one power supply electrode is arranged on the roadway wall opposite to the position of A1, and is denoted as A6; The distance between measuring electrode M1 and power supply electrode A3 and the distance between adjacent measuring electrodes Dp equal.

2. The under-drilling electrical resistivity tomography (EDT) advanced detection system as described in claim 1, characterized in that, The distance between adjacent measuring electrodes is 2m≤ Dp ≤10m, survey line length l ≥100m; The distance between the two power supply electrodes A4 and A5 is not less than 2m.

3. A method for advance detection using electrical resistivity tomography (EDT), characterized in that, The under-drilling electrical resistivity tomography (EDT) advanced detection system according to claim 1 or 2 specifically includes the following steps: Step 1: Deploy the under-tunnel electrical resistivity tomography (EDT) advanced detection system and record the deployment information; Step 2: Use the under-excavation electrical resistivity tomography (EDT) advance detection system to collect under-excavation electrical resistivity tomography (EDT) data; Step 3: In the observation data obtained in Step 2, the observation data of the tunneling electrical resistivity advance detection system at the same location are processed to obtain the apparent resistivity data corresponding to each power supply electrode of the tunneling electrical resistivity advance detection system at different locations. Step 4: Eliminate background influence on the apparent resistivity data of power supply electrodes A1, A2, A3, A4, A5 and A6 at different locations of the under-excavation electrical resistivity detection system to obtain pure abnormal response data of power supply electrodes A1, A2, A3, A4, A5 and A6 at different locations. Step 5: Using the pure anomalous apparent resistivity data corresponding to the power supply electrodes A1, A2 and A3 at different positions obtained in Step 4, predict the distance of the anomalous body in front of the tunneling face. Step 6: Using the pure anomalous apparent resistivity data corresponding to the power supply electrodes A1, A4, A5, and A6 at different positions obtained in Step 4, predict the left-right and up-down positions of the anomalous body in front of the tunneling working face.

4. The under-excavation electrical resistivity tomography (EDT) method as described in claim 3, characterized in that, Step 1 is performed as follows: The under-excavation electrical resistivity tomography (EDT) advanced detection system is deployed at a distance from the tunneling face. R At position 0, 4m≤ R 0≤10m; The entire electrical resistivity tomography (EDT) advance detection system moves forward with the tunnel excavation, with a moving step distance of [missing information]. R 1, 10m≤ R 1≤20m; Step distance R 1 represents the distance between adjacent measuring electrodes. Dp Integer multiples of; During the movement, the distance between A1 and the tunneling face should always be maintained at [distance]. R 0 remains unchanged; The positions of the under-excavation electrical resistivity tomography (EDT) system are numbered according to their distance from the starting position of the tunneling operation, with larger numbers for greater distances. The current position of the EDT system is recorded as follows: i ; With the starting position of the tunneling as the origin and the direction of tunneling as the coordinate system, the coordinate system is as follows: x In the axial direction, record the coordinate positions of the power supply electrode and the measuring electrode; record the position information of the tunneling electrical method advance detection system in tabular form, including the position number of the tunneling electrical method advance detection system, the distance from the tunneling electrical method advance detection system to the tunneling start position, the distance from the tunneling electrical method advance detection system to the tunneling working face, the power supply electrode number and corresponding coordinate position, and the measuring electrode number and corresponding coordinate position.

5. The under-excavation electrical resistivity tomography (EDT) method as described in claim 4, characterized in that, Step 2 is performed as follows: During the acquisition of electrical resistivity tomography (EDT) data, the power supply electrodes are switched in turn according to their numerical order; when the first electrode is in the sequence of its number, the power supply electrodes are switched sequentially. i s When each power supply electrode transmits a signal, all measuring electrodes acquire voltage signals; after all power supply electrodes have completed one round of signal transmission, a complete set of observation data is obtained. A complete set of observation data includes Ns × Nr Each data record contains, in sequence, the location number of the tunneling electrical resistivity tomography (TMT) advanced detection system, the power supply electrode number and its corresponding coordinate position, the measurement electrode number and its corresponding coordinate position, the transmitting current, and the receiving voltage; the data records are arranged in ascending order of the power supply electrode number and the measurement electrode number. The under-tunnel electrical resistivity tomography (EDT) system continuously collects data at each location, with a total of [number] cycles. n c ≥5 times.

6. The under-drilling electrical resistivity tomography (EDT) method as described in claim 5, characterized in that, In step 3, for multiple sets of observation data collected cyclically at the same location by the under-excavation electrical resistivity tomography (EDT) system, the received voltage in each data record is first divided by the transmitted current to normalize the received voltage; then, the normalized received voltages with the same power supply electrode number and measurement electrode number in the multiple sets of observation data are superimposed to calculate the average voltage; finally, the calculated average voltage is converted into apparent resistivity data. Will be in position i No. c The voltage data obtained from the second cycle is recorded as follows: U ic Current data is recorded as I ic ; U ic and I ic All are one-dimensional arrays with a length of . Ns × Nr Normalized received voltage ; Underground electrical resistivity tomography (EDT) advanced detection system at location i go through n c The average voltage value obtained from the second cycle U i The calculation formula is as follows: Corresponding apparent resistivity value ρ i The calculation formula is as follows: In the formula, K This is the device coefficient.

7. The under-drilling electrical resistivity tomography (EDT) method as described in claim 6, characterized in that, Step 5 is performed as follows: The under-excavation electrical resistivity tomography (EDT) advanced detection system will be used at the location i The pure anomalous apparent resistivity data corresponding to the power supply electrodes A1, A2, and A3 are recorded as follows: , , Plot the corresponding apparent resistivity curves and observe whether the three apparent resistivity curves overlap. like , , The three corresponding apparent resistivity curves basically overlap, indicating that the anomaly ahead of the tunneling face is far away and outside the effective detection range of the electrical resistivity tomography (EDT) advance detection system. At this point, we continue to analyze the pure anomaly apparent resistivity data corresponding to the power supply electrodes A1, A2, and A3 at the next location. , , The corresponding apparent resistivity curves are obtained until the three apparent resistivity curves separate from each other. like , , The three corresponding apparent resistivity curves are separated from each other, indicating the presence of an anomaly ahead of the tunneling face, within the effective detection range of the electrical resistivity tomography (EDT) advance detection system; assuming the coordinates of the anomaly are... x Take at least two sets of spatially consecutive detection data, with the spatial locations numbered as follows: i , i +1, at this time, the coordinate positions of the power supply electrodes A1, A2, and A3 along the survey line are arranged in ascending order, as follows: , , , , , The coordinates of the extreme points of the corresponding apparent resistivity curve along the survey line are as follows: , , , , , ; Calculate each power supply electrode to The distance is in the following form: X =[0， ， ， ， ， ]； Calculate the distance between each power supply electrode and its corresponding extreme point on the apparent resistivity curve, in the following form: D =[ ， ， ， ， ， ]； by X The horizontal axis is... D Using the vertical axis as the ordinate, we perform curve fitting using the following formula: In the above formula, A is the slope obtained by fitting, and B is the intercept obtained by fitting. when D When =0, , This represents the abnormal body to The distance; The formula for predicting the coordinate position of the anomaly in front of the tunneling face at the current tunneling location is as follows: ； The formula for predicting the distance from the anomaly to the tunneling face is as follows: 。 8. The under-drilling electrical resistivity tomography (EDT) method as described in claim 7, characterized in that, Step 6 is performed as follows: (1) Prediction of left and right directions Using the pure anomalous apparent resistivity data corresponding to the power supply electrodes A1, A4, and A5 at different locations obtained in step 4, the left and right orientations of the anomalous body in front of the tunneling face are predicted, as follows: The under-excavation electrical resistivity tomography (EDT) advanced detection system will be used at the location i The pure anomalous apparent resistivity data corresponding to the power supply electrodes A1, A4, and A5 are recorded as follows: , , Plot the corresponding apparent resistivity curves and observe whether the three apparent resistivity curves overlap. like , , The three corresponding apparent resistivity curves basically overlap, indicating that the anomaly ahead of the tunneling face is far away and outside the effective detection range of the electrical resistivity tomography (EDT) advance detection system. At this point, we continue to analyze the next location. , , The corresponding apparent resistivity curves are used until the apparent resistivity curve corresponding to power supply electrode A1 separates from the apparent resistivity curves corresponding to power supply electrodes A4 and A5. like The corresponding apparent resistivity curve and and The corresponding apparent resistivity curves are separated, indicating the presence of an anomaly ahead of the tunneling face, within the effective detection range of the electrical resistivity tomography (EDT) advance detection system; further, it is determined that... and Do the two corresponding apparent resistivity curves overlap? like and If the two corresponding apparent resistivity curves basically overlap, it indicates that the anomaly is located directly in front of the tunneling face. like and The two corresponding apparent resistivity curves are separated from each other. Further, the magnitude of the abnormal amplitude of the two sets of apparent resistivity data is determined. if The abnormal amplitude is greater than The abnormal amplitude indicates that the abnormal body is closer to the power supply electrode A4, which is located to the left front of the tunneling face; if The abnormal amplitude is greater than The abnormal amplitude indicates that the abnormal body is closer to the power supply electrode A5, which is located in the right front of the tunneling face. (2) Prediction of vertical and horizontal orientation Using the pure anomalous apparent resistivity data of A1, A2, and A6 at different locations obtained by the under-excavation electrical resistivity prediction system in step 4, the vertical position of the anomalous body in front of the tunnel face is predicted. When A1 and A2 are located on the tunnel floor and A6 is located on the tunnel roof, the specific details are as follows: The under-excavation electrical resistivity tomography (EDT) advanced detection system will be used at the location i The pure anomalous apparent resistivity data corresponding to times A1, A2, and A6 are recorded as follows: , , Plot the corresponding apparent resistivity curves and observe whether the three apparent resistivity curves overlap. like , , The three corresponding apparent resistivity curves basically overlap, indicating that the anomaly ahead of the tunneling face is far away and outside the effective detection range of the electrical resistivity tomography (EDT) advance detection system. At this point, we continue to analyze the next location. , , The corresponding apparent resistivity curves are used until the apparent resistivity curve corresponding to power supply electrode A2 separates from the apparent resistivity curves corresponding to power supply electrodes A1 and A6. like The corresponding apparent resistivity curve and and The corresponding apparent resistivity curves are separated, indicating the presence of an anomaly ahead of the tunneling face, within the effective detection range of the electrical resistivity tomography (EDT) advance detection system; further, it is determined that... and Do the two corresponding apparent resistivity curves overlap? like and If the two corresponding apparent resistivity curves basically overlap, it indicates that the anomaly is located directly in front of the tunneling face. like and The two corresponding apparent resistivity curves are separated from each other. Further, the magnitude of the abnormal amplitude of the two sets of apparent resistivity data is determined. if The abnormal amplitude is greater than The abnormal amplitude indicates that the abnormal body is closer to the power supply electrode A1, and it is located slightly below and in front of the tunneling face; if The abnormal amplitude is greater than The abnormal amplitude indicates that the abnormal body is closer to the power supply electrode A6, and it is located slightly above and in front of the tunneling face.

9. The under-excavation electrical resistivity tomography (EDT) method as described in claim 3, characterized in that, It also includes step 7, constrained inversion imaging of anomalies in front of the tunneling face; the specific operation is as follows: Multiple sets of continuous advance detection data from the electrical method during tunneling are taken in spatial location to perform inversion imaging of anomalies in front of the tunneling face; at the same time, the anomaly prediction information obtained in steps 5 and 6 is used as prior information to constrain the inversion process.

10. The under-drilling electrical resistivity tomography (EDT) method as described in claim 3, characterized in that, It also includes step 8, risk warning, the specific operation of which is as follows: based on the constrained inversion imaging results of the anomaly in front of the tunneling working face, water hazard risk warning is carried out by analyzing the changing characteristics of the low-resistivity anomaly area in front of the tunneling working face during the tunneling process; When the area of ​​low-resistivity anomaly becomes more focused and the magnitude of the low-resistivity anomaly becomes larger, it is inferred that there is a potential water hazard ahead of the tunnel face, and drilling is required to verify and take relevant measures.

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