Shield tunnel electromagnetic three-field synchronous monitoring method along with excavation vibration

Abstract

The invention discloses a shield tunnel while-digging earthquake electromagnetic three-field synchronous monitoring method. The method comprises the steps that a while-digging earthquake observation system, a while-digging electric field observation system and a while-digging electromagnetic field observation system are arranged in a shield construction tunnel; a seismic-electromagnetic integrated monitoring system is built, and the system comprises a while-digging seismic data processing system, a while-digging electric field data processing system and a while-digging electromagnetic field data processing system; and the abnormal structure and the water yield property in front of the tunnel are evaluated, so that the electromagnetic multi-field synchronous monitoring in front of the shield tunnel along with the digging vibration is realized. According to the invention, three geophysical field signals of earthquakes, electric fields and electromagnetic waves can be monitored at the same time, excavation and exploration can be realized at the same time, and the tunneling efficiency is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of shield tunnel excavation technology, and specifically refers to a method for synchronous monitoring of seismic, electromagnetic, and electric fields during shield tunnel excavation. Background Art

[0002] Complex geological environments pose great challenges to the rapid excavation of shield tunnels. Transparency of the geological conditions ahead during excavation contributes to the safe construction of shield tunnels. To improve the excavation efficiency and ensure excavation safety, shield tunnels need to establish a real-time advanced detection system with high intelligent equipment, high processing timeliness, and high credibility of geological models for simultaneous excavation and exploration, which poses new requirements for advanced detection technologies. Tunnel advanced geological geophysical exploration technology is an effective means to understand the geological conditions ahead of the tunnel face during tunnel construction, reduce or eliminate geological disasters during construction, and ensure construction safety. Existing advanced geophysical exploration methods must suspend tunnel excavation operations during detection to avoid the impact of the construction environment on data collection, and there are problems such as heterogeneous equipment, scattered construction, sparse data, and impact on excavation. Therefore, how to achieve "simultaneous excavation and exploration" is an urgent problem to be solved in the current advanced detection of shield tunnels.

[0003] Tunnel advanced geological geophysical exploration technology is an effective means to understand the geological conditions ahead of the tunnel face during tunnel construction, reduce or eliminate geological disasters during construction, and ensure production safety. Commonly used advanced geophysical exploration technologies include direct current method, transient electromagnetic method, and reflection seismic method, etc. However, in existing excavation geophysical exploration, usually only the signals of a single geophysical field are observed, and currently, during the detection of traditional advanced geophysical exploration methods, excavation operations need to be suspended to avoid the impact of the construction operation environment on the detection data, reducing the tunnel excavation efficiency and unable to achieve simultaneous excavation and exploration. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for synchronous monitoring of seismic, electromagnetic, and electric fields during shield tunnel excavation, which can simultaneously monitor the signals of three geophysical fields of earthquake, electric field, and electromagnetic wave, and can achieve simultaneous excavation and exploration, improving the tunnel excavation efficiency.

[0005] To achieve the above purpose, a method for synchronous monitoring of seismic, electromagnetic, and electric fields during shield tunnel excavation according to the present invention includes the following steps: Step 1: Arrange a simultaneous excavation seismic observation system, a simultaneous excavation electric field observation system, and a simultaneous excavation electromagnetic field observation system in the shield construction tunnel respectively; Step 2: Build an integrated seismic, electromagnetic, and electric field monitoring system, which includes a simultaneous excavation seismic data processing system, a simultaneous excavation electric field data processing system, and a simultaneous excavation electromagnetic field data processing system; Step 3: The simultaneous excavation seismic data processing system uses the constructed seismic delayed source advanced imaging method to convert and image the data; Step 4: The in - tunneling electric field data processing system adopts the electrical method for advanced detection; Step 5: The in - tunneling electromagnetic field data processing system processes the electromagnetic data by using the time - frequency analysis method; Step 6: Evaluate the abnormal structures and water - richness in front of the tunnel according to the processing results of Steps 3 to 5, so as to realize the synchronous monitoring of in - tunneling seismic, electromagnetic and multiple fields in front of the shield tunnel.

[0006] As a further solution of the present invention: In Step 1, the in - tunneling seismic observation system includes a plurality of geophones, which are respectively arranged in the linear area and the circular area. In the linear area, they are arranged along the segment on one side of the tunnel alignment. Starting from the connection between the front shield and the middle shield of the shield machine, a number of vertical geophones are arranged at equal intervals in the same height along the tunnel alignment towards the excavation rear. The Z - direction of the geophone is perpendicular to the tunnel segment wall; the circular area is arranged at the starting point of the linear area, and a number of geophones are evenly arranged along the tunnel in a circular shape.

[0007] As a further solution of the present invention: The in - tunneling electric field observation system includes a plurality of wall - attached electrodes, which are respectively arranged in the linear area and the circular area. In the linear area, a number of wall - attached electrodes with equal spacing are arranged at the same height along the tunnel alignment towards the excavation rear, and a number of wall - attached electrodes are evenly spaced in the circular area.

[0008] As a further solution of the present invention: The in - tunneling electromagnetic field observation system is to arrange a three - component electromagnetic coil at the connection between the front shield and the middle shield of the shield machine. The three - component electromagnetic coil includes the X - direction, Y - direction, and Z - direction. Among them, the X - direction is consistent with the tunnel alignment, the Y is perpendicular to the X in the horizontal direction of the tunnel, and the Z is the vertical direction of the tunnel.

[0009] As a further solution of the present invention: In Step 2, the seismic - electromagnetic integrated monitoring system further includes arranging a seismic - electromagnetic integrated monitoring base station in the central control room of the shield machine. The upper end of the seismic - electromagnetic integrated monitoring base station is connected to the ground switch and the server through the existing network of the shield machine. The lower end of the seismic - electromagnetic integrated monitoring base station accesses the cables of the in - tunneling seismic, electric, and magnetic fields to control the signal acquisition of the in - tunneling seismic observation system, in - tunneling electric field observation system, and in - tunneling electromagnetic field observation system. The ground server accesses the Internet to remotely transmit the in - tunneling seismic, electric, and magnetic field data to the data processing center in real - time. The data processing center includes a multi - field processing system workstation and a monitoring platform.

[0010] As a further solution of the present invention: In Step 3, the seismic delay source advanced imaging method includes the following steps: Perform pulse cross - correlation processing on the data, and thus a high - resolution quasi - active source single - shot record can be obtained ; and then use the full-scattering migration method to achieve imaging of the anomalies in front of the tunnel; the pulse cross-correlation processing method is as follows: S1: Calculate the autocorrelation of the single-channel seismic record where , represents the time delay; S2: Construct the Toeplitz autocorrelation matrix , , where represent the rows and columns of the matrix respectively; S3: Apply the Levinson recursion algorithm to solve the Yule-Walker equation: , where is the prediction coefficient vector, is the autocorrelation vector, and the deconvolution factor can be obtained through recursion; S4: Pulse the signal ; S5: Further calculate the autocorrelation of the pulsed signal , from which the seismic single-channel record of the pseudo-active source can be obtained: S6: Based on S1 to S5, process the signals of the remaining seismic channels in sequence, and thus the high-resolution seismic single-shot record of the pseudo-active source can be obtained; The full-scattering migration method includes the following steps: S1: Establish the advanced detection model (X, Y), where X is the tunnel driving direction, i.e., the horizontal direction, Y is the tunnel vertical direction, the origin is the face position, and the travel time of the scattered wave propagation of a certain grid is calculated with the center position of the grid point : ; In the formula t s is the travel time of the scattered wave from the source to the grid, t r is the travel time of the scattered wave from the grid to the geophone, x s and x r are the horizontal coordinates of the source and the geophone respectively, V is the stacking velocity; S2: Calculate the scattered wave energy value in each grid, specifically by calculating the sum of squares of the values within a certain time window at the travel time t of each grid under different source-receiver pairs; S3: Based on S1 to S2 in the full-scattering migration method, the advanced imaging result can be obtained, where the position corresponding to the grid with a large scattered wave energy value is the anomaly position.

[0011] As a further solution of the present invention: In step four, the electrical method for advanced detection includes the following steps: First, divide the area in front of the detection into grids and perform grid meshing. Extract the measured apparent resistivity data and eliminate anomalies according to the limiting conditions of AM and MN. Then, perform weighted processing on the apparent resistivity measured under different MN at the same power supply point. Next, assign values to each unit grid. Finally, calculate the apparent resistivity of the unit grid, and thus obtain the resistivity distribution map in front of the tunnel excavation. Here, A is the power supply electrode, M and N are the measurement electrodes, and AM and MN respectively represent the potential differences between the two electrodes.

[0012] As a further solution of the present invention: In step five, the time-frequency analysis method includes the following steps: First, select the signals in the stable section during tunneling and calculate its multiple intrinsic mode functions, which are recorded as IMF1~IMFn from high frequency to low frequency in sequence; then extract the main frequency and amplitude in the IMF respectively, denoted as the main frequency f IMF1 , f IMF2 ……, f IMFn and amplitude A IMF1 , A IMF2 ……, A IMFn energy. Thus, the characteristic frequency and energy distribution of the electromagnetic signals during tunneling can be obtained. Then, take the average of the multiple amplitude values corresponding to the main frequency of each IMF of the signals in different stable sections during tunneling, and denote them as A1, A2, ……, A n and use this as the threshold; when the amplitude of the characteristic frequency of the actually monitored signal exceeds 1.5 times the corresponding threshold, it indicates that the signal is abnormal at this characteristic frequency; when the number of abnormal characteristic frequencies reaches 1 / 2 of the total characteristic frequencies, it is considered that the electromagnetic field during tunneling is abnormal at this time and an alarm is given, thereby realizing the monitoring of the electromagnetic field during tunneling.

[0013] Compared with the prior art, the present invention uses the seismic observation system during tunneling, the electric field observation system during tunneling, and the electromagnetic field observation system during tunneling to collect seismic, electric field, and electromagnetic signal data during the tunneling process, and synchronously monitors the seismic, electric field, and electromagnetic three-field signals in real time through the integrated seismic, electromagnetic, and electric field monitoring system; by designing a reasonable integrated seismic, electromagnetic, and electric field monitoring system in the limited space of the construction tunnel, continuous dynamic monitoring of the geophysical field during tunneling can be achieved, providing a large amount of data for the detection of geological anomalies and water hazards in front of the shield tunnel, and improving the tunneling efficiency of the tunnel. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is a schematic flow chart of the method for synchronous monitoring of seismic, electromagnetic, and electric fields during tunneling of the shield tunnel of the present invention.

[0015] Figure 2It is a structural schematic diagram of the arrangement position of the true electromagnetic three-field sensor of the shield tunnel in the present invention.

[0016] Figure 3 It is a structural framework diagram of the integrated seismic electromagnetic monitoring system in the present invention.

[0017] Figure 4 (a) is the original record of the seismic monitoring during tunneling in the present invention, Figure 4 (b) is the single-shot record of the pseudo-active source after pulse cross-correlation processing.

[0018] Figure 5 It is the result of the seismic imaging ahead during tunneling in the present invention.

[0019] Figure 6 It is the resistivity distribution map in front of the tunnel excavation in the present invention.

[0020] Figure 7 It is the processing result diagram of the electromagnetic signal during tunneling in the present invention, where Figure 7 (a) is the frequency diagram of the original electromagnetic signal, Figure 7 (b) is the spectrum diagram of the original battery signal, Figure 7 (c) is the frequency diagram of IMF1 with a main frequency of 147 Hz / peak value of 0.09 mV, Figure 7 (d) is the spectrum diagram of IMF2 with a main frequency of 633 Hz / peak value of 0.06 mV, Figure 7 (e) is the frequency diagram of IMF3 with a main frequency of 244 Hz / peak value of 0.04 mV, Figure 7 (f) is the spectrum diagram of IMF4 with a main frequency of 197 Hz / peak value of 0.02 mV.

[0021] In the figure: 1. Cutter head, 2. Front shield, 3. Wall-mounted electrode, 4. Three-component electromagnetic coil, 5. Middle shield, 6. Rear shield, 7. Linear region, 8. Seismic geophone, 9. Annular region. Specific implementation mode

[0022] The present invention will be further described below with reference to the accompanying drawings.

[0023] As Figure 1 shown, a method for synchronous monitoring of the seismic electromagnetic three fields during shield tunnel excavation includes the following steps: Step 1: Arrange a seismic monitoring system during tunneling, an electric field monitoring system during tunneling, and an electromagnetic field monitoring system during tunneling in the shield construction tunnel respectively; Step 2: Build an integrated seismic electromagnetic monitoring system, which includes a seismic data processing system during tunneling, an electric field data processing system during tunneling, and an electromagnetic field data processing system during tunneling; Step 3: The seismic data processing system during tunneling uses the constructed seismic delay source imaging method to convert and image the data; Step 4: The data processing system for the advancing electric field adopts the electric method for advanced detection; Step 5: The data processing system for the advancing electromagnetic field adopts the time-frequency analysis method to process the electromagnetic data; Step 6: Evaluate the abnormal structures (such as karst and faults) and water abundance in front of the tunnel according to the processing results of Steps 3 to 5, and realize the synchronous monitoring of the advancing seismic electromagnetic multi-fields in front of the shield tunnel.

[0024] As Figure 2 shown, the shield machine successively includes a cutter head 1, a front shield 2, a middle shield 5, and a rear shield 6 from front to back. In Step 1, the advancing seismic observation system includes a plurality of geophones 8, and the geophones 8 are respectively arranged in a linear region 7 and an annular region 9. The linear region 7 is arranged along the segment on one side of the tunnel alignment. Starting from the connection between the front shield 2 and the middle shield 5 of the shield machine, 24 vertical geophones 8 with a spacing of 1 m are successively arranged at the same height along the tunnel alignment towards the tunneling rear. The Z direction of the geophone 8 is perpendicular to the tunnel segment wall; the annular region 9 is arranged at the starting point of the linear region 7, and eight geophones 8 are evenly spaced along the tunnel ring and are respectively located in eight directions of the upper, lower, left, right, upper left, lower left, upper right, and lower right of the tunnel annular region 9.

[0025] The advancing electric field observation system includes a plurality of wall-mounted electrodes 3, and the wall-mounted electrodes 3 are respectively arranged in the linear region 7 and the annular region 9. The arrangement in the linear region 7 is the same as that of the geophone in the linear region. Starting from the connection between the front shield 2 and the middle shield 5 of the shield machine, 24 wall-mounted electrodes 3 with a spacing of 5 m are successively arranged at the same height along the tunnel alignment towards the tunneling rear; the annular region 9 is that eight wall-mounted electrodes are evenly spaced along the tunnel ring at the starting point of the linear region 7 and are also respectively located in eight directions of the upper, lower, left, right, upper left, lower left, upper right, and lower right of the tunnel annular region 9.

[0026] The advancing electromagnetic field observation system is specifically to arrange a three-component electromagnetic coil 4 at the connection between the front shield 2 and the middle shield 5 of the shield machine. The three-component electromagnetic coil 4 includes an X direction, a Y direction, and a Z direction, where the X direction is the same as the tunnel alignment, Y is perpendicular to X in the horizontal direction of the tunnel, and Z is the vertical direction of the tunnel.

[0027] In Step 2, as Figure 3As shown in the figure, the specific composition of the integrated vibration, electricity and magnetism monitoring system is to arrange an integrated vibration, electricity and magnetism monitoring base station in the central operation room of the shield machine. The upper end of the integrated vibration, electricity and magnetism monitoring base station is connected to the ground switch and server through the existing network of the shield machine. The lower end of the integrated vibration, electricity and magnetism monitoring base station is connected to the cables for the vibration, electricity and magnetism fields during tunneling to control the signal acquisition of the seismic observation system during tunneling, the electric field observation system during tunneling, and the electromagnetic field observation system during tunneling. The ground server is connected to the Internet to transmit the data of the vibration, electricity and magnetism fields during tunneling to the data processing center in real time and remotely. The data processing center includes a multi-field processing system workstation and a monitoring platform, which have functions such as data processing, result interpretation, and risk identification.

[0028] In step three, the seismic delayed source advanced imaging method includes the following steps: performing pulse cross-correlation processing on the data, from which a high-resolution pseudo-active source single-shot record can be obtained , as Figure 4 shown; then using the full-scattering migration method to realize the imaging of anomalies in front of the tunnel, as Figure 5 shown; where the pulse cross-correlation processing method is: S1: Calculate the autocorrelation of the single-channel seismic record s ( t ), , representing the time delay; S2: Construct the Toeplitz autocorrelation matrix , , where represent the rows and columns of the matrix respectively; For example, the form of a third-order Toeplitz matrix is ; S3: Apply the Levinson recursion algorithm to solve the Yule-Walker equation: , where is the prediction coefficient vector, is the autocorrelation vector, and the deconvolution factor can be obtained through recursion; S4: Pulse the signal ; S5: Further calculate the autocorrelation of the pulsed signal , from which the seismic single-channel record of the pseudo-active source can be obtained: S6: Based on the above steps S1 to S5, process the signals of the remaining seismic channels in sequence, and thus a high-resolution seismic single-shot record of the pseudo-active source can be obtained.

[0029] The full-scattering migration method includes the following steps: S1: Establish an advanced detection model (X, Y), where X is the tunnel driving direction, i.e., the horizontal direction, Y is the tunnel vertical direction, the origin is the face position, and the center position of the grid point (x m ，y n ) Calculate the travel time of the scattered wave propagating in a certain grid: ; In the formula t s is the travel time of the scattered wave from the source to the grid, t r is the travel time of the scattered wave from the grid to the geophone, x s and x r are the horizontal coordinates of the source and the geophone respectively, V is the stacking velocity; S2: Calculate the scattered wave energy value in each grid, specifically by calculating the sum of squares of the values within a certain time window at the travel time of each grid under different source-receiver pairs; t ; S3: Based on the above S1 to S2, the advanced imaging result can be obtained, where the position corresponding to the grid with a large scattered wave energy value is the abnormal position.

[0030] In step four, the electrical method for advanced detection includes the following steps: First, divide the area in front of the detection and perform grid meshing, extract the measured apparent resistivity data and eliminate the anomalies according to the limiting conditions of AM and MN, then perform weighted processing (vertical stacking) on the apparent resistivity measured under different MNs at the same power supply point, then assign values to each unit grid (spatial offset processing), and finally calculate the apparent resistivity of the unit grid, thus obtaining the resistivity distribution map in front of the tunnel excavation, as Figure 6 shown. Where A is the power supply electrode, M and N are the measurement electrodes, and AM and MN respectively represent the potential differences between the two electrodes.

[0031] In step five, the time-frequency analysis method includes the following steps: First, select the signals in the stable section during tunneling and calculate their multiple intrinsic modes, which are recorded as IMF1~IMFn from high frequency to low frequency in sequence; then extract the dominant frequency and amplitude in the IMF respectively, denoted as the dominant frequency f IMF1 , f IMF2 , ……, f IMFn and the amplitude A IMF1 , A IMF2 , ……, A IMFn energy. Thus, the characteristic frequency and energy distribution of the electromagnetic signal during tunneling can be obtained. Then, take the average of the multiple amplitude values corresponding to the dominant frequency of each IMF in the signals within different stable sections during tunneling, and denote them as A1, A2, ……, A nAnd use this as the threshold; when the amplitude of the characteristic frequency of the actually monitored signal exceeds 1.5 times the corresponding threshold, it indicates that the signal is abnormal at this characteristic frequency; when the number of abnormal characteristic frequencies reaches 1 / 2 of the total characteristic frequencies, it is considered that the electromagnetic field during tunneling is abnormal at this time and a warning is issued, thus realizing the monitoring of the electromagnetic field during tunneling.

[0032] Method for obtaining intrinsic mode: Perform mode decomposition on the electromagnetic signals in the X, Y, and Z directions respectively E x ( t ), E y ( t ), and E z ( t ), which specifically includes the following steps: S1: Calculate the local maximum and minimum values of the signal, and generate the upper and lower envelopes through cubic spline interpolation e max ( t ), and e min ( t ); S2: Calculate the average envelope ; S3: Update the signal and extract the candidate IMF: ; S4: Repeat steps S1~S3 until the standard deviation threshold of the IMF is satisfied; S5: Separate the current IMF, denoted as , and at this time the residual term ; S6: Repeat the above steps for the residual term until the residual is negligible, and thus the subsequent IMFs can be obtained, denoted as IMF2~IMFn.

[0033] As Figure 7 shown, Figure 7 Figure (a) is the frequency diagram of the original electromagnetic signal, Figure 7 Figure (b) is the spectrogram of the original battery signal, Figure 7 Figure (c) is the frequency diagram of IMF1 with the main frequency of 147 Hz and the peak value of 0.09 mV, Figure 7 Figure (d) is the spectrogram of IMF2 with the main frequency of 633 Hz and the peak value of 0.06 mV, Figure 7 Figure (e) is the frequency diagram of IMF3 with the main frequency of 244 Hz and the peak value of 0.04 mV, Figure 7 Figure (f) is the spectrogram of IMF4 with the main frequency of 197 Hz and the peak value of 0.02 mV.

[0034] The present invention can synchronously observe seismic, electromagnetic, and geomagnetic field signals. By designing a reasonable integrated seismic, electromagnetic, and geomagnetic monitoring system in the limited space of a construction tunnel, continuous dynamic monitoring of the in-situ geophysical field during tunneling can be achieved, providing a large amount of data for the detection of geological anomalies and water hazards ahead of the shield tunnel. The present invention forms a set of methods for synchronous multi-field observation of seismic, electromagnetic, and geomagnetic fields during shield tunneling, which includes multi-field observation layout, real-time signal acquisition, and transmission, and will help to break through the problem of advanced detection of shield tunnels.

Claims

1. A method for synchronously monitoring three fields of electromagnetic in shield tunneling during excavation, characterized in that: The following steps are involved: Step 1: Arrange the tunneling seismic observation system, tunneling electric field observation system and tunneling electromagnetic field observation system in the shield construction tunnel respectively; Step 2: Build an integrated seismic and electromagnetic monitoring system, which includes a seismic data processing system, an electric field data processing system, and an electromagnetic field data processing system. Step 3: The excavation seismic data processing system uses the constructed seismic time-delay source advance imaging method to convert and image the data; Step 4: The excavation electric field data processing system adopts the electrical advance detection method; Step 5: The excavation electromagnetic field data processing system uses the time-frequency analysis method to process the electromagnetic data; Step 6: Based on the processing results of steps 3 to 5, evaluate the abnormal structure and water-richness in front of the tunnel, and realize synchronous electromagnetic multi-field monitoring of the shield tunnel in front of the shield tunnel.

2. The method for synchronously monitoring three fields of electromagnetic in shield tunneling according to claim 1 is characterized in that: In step 1, the excavation seismic observation system comprises a plurality of seismic detectors (8), and the seismic detectors (8) are respectively arranged in a linear area (7) and an annular area (9), wherein the linear area (7) is arranged along the segment on one side of the tunnel direction, and a plurality of vertical seismic detectors (8) are arranged at intervals at the same height along the tunnel direction and toward the rear of the excavation, with the Z direction of the seismic detector (8) being perpendicular to the tunnel segment wall; and the annular area (9) is arranged at the starting point of the linear area (7), and a plurality of seismic detectors (8) are evenly arranged along the tunnel ring.

3. The method for synchronously monitoring three fields of electromagnetic in shield tunneling according to claim 1 is characterized in that: The excavation electric field observation system comprises a plurality of wall-attached electrodes (3), wherein the wall-attached electrodes (3) are respectively arranged in a linear region (7) and an annular region (9); in the linear region (7), at the same height along the tunnel direction, a plurality of wall-attached electrodes (3) are arranged at equal intervals toward the rear of the excavation; and in the annular region (9), a plurality of wall-attached electrodes (3) are evenly spaced.

4. The method for synchronously monitoring three fields of electromagnetic in shield tunneling according to claim 1 is characterized in that: The tunneling electromagnetic field observation system comprises a three-component electromagnetic coil (4) arranged at the connection between the front shield (2) and the middle shield (5) of the shield machine, wherein the three-component electromagnetic coil (4) includes an X direction, a Y direction, and a Z direction, wherein the X direction is consistent with the direction of the tunnel, the Y direction is perpendicular to the X direction in the horizontal direction of the tunnel, and the Z direction is the vertical direction of the tunnel.

5. The method for synchronously monitoring three fields of electromagnetic in shield tunneling according to claim 1 is characterized in that: In the step 2, the seismic and electromagnetic integrated monitoring system also includes arranging a seismic and electromagnetic integrated monitoring base station in the central operating room of the shield machine. The upper end of the seismic and electromagnetic integrated monitoring base station is connected to the ground switch and server through the existing network of the shield machine. The lower end of the seismic and electromagnetic integrated monitoring base station is connected to the cables of the seismic, electric and magnetic fields of the excavation to control the signal collection of the excavation seismic observation system, the electric field observation system and the electromagnetic field observation system. The ground server is connected to the Internet to transmit the seismic, electric and magnetic field data of the excavation to the data processing center in real time. The data processing center includes a multi-field processing system workstation and a monitoring platform.

6. The method for synchronous electromagnetic three-field monitoring of shield tunneling according to claim 1 is characterized in that: In step 3, the seismic time-lapse source advance imaging method includes the following steps: pulse cross-correlation processing is performed on the data, thereby obtaining a high-resolution pseudo-active source single shot record. ; Then the full scattering migration method is used to realize the imaging of the anomaly in front of the tunnel; the pulse cross-correlation processing method is: S1: Calculate single-channel seismic records Autocorrelation of , represents time delay; S2: Constructing the Toeplitz autocorrelation matrix , ,in Represent the rows and columns of the matrix respectively; S3: Apply the Levinson recursion algorithm to solve the Yule-Walker equation: ,in is the prediction coefficient vector, is the autocorrelation vector, and the deconvolution factor can be obtained by recursion ; S4: Pulsed signal ; S5: Further calculate the autocorrelation of the pulsed signal , thus the seismic single-channel record of the quasi-active source can be obtained; S6: Based on the above, the remaining seismic trace signals are processed in turn, thereby obtaining a high-resolution seismic single-shot record of a pseudo-active source; The total scatter migration method includes the following steps: S1: Establish an advanced detection model (X, Y), where X is the tunneling direction, i.e. the horizontal direction, Y is the vertical direction of the tunnel, the origin is the tunnel face position, and the center position of the grid point is the Compute the travel time of scattered wave propagation for a grid: ; In the formula t s is the travel time of the scattered wave from the source to the grid, t r is the travel time of the scattered wave from the grid to the detector, x s and x r are the horizontal coordinates of the source and the receiver, V is the superposition speed; S2: Calculate the scattered wave energy value in each grid, specifically by converting the propagation travel of each grid under different gun-detection pairs t The square sum of the values ​​within a certain time window is calculated at each moment; S3: Based on S1 to S2 in the total scattering migration method, the advanced imaging result can be obtained, in which the position corresponding to the grid with a large scattered wave energy value is the abnormal position.

7. The method for synchronous electromagnetic three-field monitoring of shield tunneling according to claim 1 is characterized in that: The electrical advance detection method in step 4 includes the following steps: first, the area and grid are divided into grids ahead of the detection, and the measured apparent resistivity data is extracted and anomalies are eliminated according to the restrictions of AM and MN. Then, the apparent resistivity measured under different MN at the same power supply point is weighted, and then each unit grid is assigned a value. Finally, the unit grid apparent resistivity is calculated, thereby obtaining a resistivity distribution map ahead of the tunnel excavation, wherein A is the power supply electrode, M and N are the measuring electrodes, and AM and MN represent the potential difference between the two electrodes respectively.

8. The method for synchronously monitoring three fields of electromagnetic in shield tunneling according to claim 1 is characterized in that: In step 5, the time-frequency analysis method includes the following steps: first, select the signal of the stable segment of the excavation and calculate its multiple eigenmodes, which are recorded as IMF1~IMFn from high frequency to low frequency; then extract the main frequency and amplitude in the IMF respectively, which are recorded as the main frequency f IMF1 , f IMF2 ,……, f IMFn and amplitude A IMF1 , A IMF2 ,……, A IMFn Energy, thus the characteristic frequency and energy distribution of the electromagnetic signal during tunneling can be obtained, and then the multiple amplitude values ​​corresponding to each IMF main frequency of the signal in different stable sections of tunneling are averaged and recorded as A1, A2, ..., A n And this is used as the threshold; when the characteristic frequency amplitude of the signal actually monitored exceeds 1.5 times the corresponding threshold, the signal is displayed as abnormal under this characteristic frequency; when the number of abnormal characteristic frequencies reaches 1 / 2 of the total characteristic frequencies, it is considered that there is an abnormality in the electromagnetic field while excavating and an early warning is issued, thereby realizing electromagnetic field while excavating.

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