TBM airborne array seismic-electromagnetic combined detection method and system

Abstract

The invention relates to a TBM airborne array earthquake-electromagnetic combined detection method and system, and the method comprises the steps: carrying out the miniaturization and modularization of an earthquake wave device and an electromagnetic wave device collection device based on two geophysical prospecting methods, namely an array type earthquake wave reflection method and an array type electromagnetic wave reflection method, in TBM construction tunnel geology advanced detection, and carrying the earthquake wave device and the electromagnetic wave device collection device on a TBM body; a full-space array type pole distribution scheme is adopted, a seismic-electric integrated receiving device is developed, seismic signals and electromagnetic signals are synchronously received, seismic wave reflection and scattering combined imaging and electromagnetic incident wave and reflected wave coherent imaging are realized based on an ellipsoid focusing algorithm, terminal control is performed through upper computer fusion software, and the imaging precision is improved. And integration of parameter setting, data acquisition and processing and result display is realized. According to reflection energy spectrum information of a seismic wave method and coherent energy information of an electromagnetic wave method, achievement joint interpretation is carried out, the precision of a detection result is improved, meanwhile, geophysical prospecting multiplicity of solutions is reduced, and comprehensive detection of lithology, construction, underground water and the like of unfavorable geology within the range of 100 m in front of a TBM cutterhead is achieved.

Description

Technical Field

[0001] This invention belongs to the fields of tunnel engineering and engineering geophysical exploration technology, and particularly relates to a TBM airborne array seismic-electromagnetic joint detection method and system. Background Technology

[0002] In TBM tunnel construction, accurate advance geological forecasting of geological conditions and potential geological hazards in front of the cutterhead plays a crucial role in ensuring normal TBM tunneling and preventing machine jamming risks. Existing detection methods that can be mounted on the TBM body are mainly seismic wave reflection methods, including mounted HSP and SAP methods. These technologies, based on physical properties such as density and wave velocity, have achieved certain results in detecting structural and tectonic features. For groundwater advance detection, the TBM-borne induced polarization method is the main approach, including TIP and TEAM methods. These technologies, based on surrounding rock resistivity parameters, have achieved some success in groundwater detection; however, due to limitations in method principles and tunnel environment, the detection distance is too short (≤30m), making it difficult to meet the needs of rapid TBM tunneling. Furthermore, on-site testing is time-consuming and labor-intensive.

[0003] This invention aims to combine passive source seismic wave detection technology, artificial source electromagnetic wave detection technology, and TBM high-mechanization construction scenarios, proposing a TBM airborne array seismic-electromagnetic joint detection method and system. By using a working mode of passive source seismic wave excitation, active source electromagnetic wave excitation, and seismo-electromagnetic integrated full-space array reception, it acquires seismic reflection energy spectrum and electromagnetic reflection energy information. While improving the accuracy of detection results, it reduces the ambiguity of geophysical exploration and achieves the goal of comprehensive detection of lithology, structure, groundwater, and other information of adverse geological conditions within 100m in front of the TBM cutterhead. Summary of the Invention

[0004] The purpose of this invention is to provide a TBM airborne array seismic-electromagnetic joint detection method and system, which uses a working mode of passive source seismic wave excitation, active source electromagnetic wave excitation, and seismo-electromagnetic integrated full-space array reception to obtain seismic reflection energy spectrum and electromagnetic reflection energy information. This improves the accuracy of detection results while reducing the ambiguity of geophysical exploration, and achieves the goal of comprehensive detection of lithology, structure, groundwater and other information of adverse geological conditions within 100m in front of the TBM cutterhead.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A TBM-based airborne array seismic-electromagnetic joint detection method includes the following steps: S1: Deploy a full-space array seismic-electromagnetic observation system: Install electromagnetic signal transmitters and seismic-electromagnetic receivers at designated locations, and simultaneously acquire seismic and electromagnetic signals through a dedicated seismic-electromagnetic integrated signal acquisition device inside the borehole; S2: Deploy the TBM airborne equipment system: fuse the array seismic wave reflection method and array electromagnetic wave reflection method acquisition modules and eliminate the separate display terminals, and mount the fusion module on the TBM body; S3: Distributed acquisition of seismic and electrical data: Data acquisition using seismic wave reflection method and electromagnetic reflection method was carried out during TBM tunneling and downtime. S4: Processing and Imaging Seismoelectric Data: Perform specified preprocessing on seismic wave data and electromagnetic wave data respectively, and realize joint imaging of seismic wave reflection and scattering, and coherent imaging of electromagnetic incident wave and reflected wave based on ellipsoid focusing algorithm; S5: Integrated Water-Rock Interpretation: The results are jointly interpreted based on the reflection energy spectrum information of the seismic wave method and the coherent energy information of the electromagnetic wave method. The integrity of the surrounding rock is characterized by the seismic reflection energy spectrum, and the water content of the surrounding rock is characterized by the electromagnetic reflection energy.

[0006] Preferably, in step S1, eight holes are drilled symmetrically at equal intervals in the excavated section of the TBM. The two holes furthest from the cutterhead are used for the installation of the electromagnetic signal transmitting device, and the six holes closest to the cutterhead are used for the installation of the seismic-electromagnetic receiving device. Seismic and electromagnetic signals are simultaneously acquired through a dedicated seismic-electromagnetic integrated signal acquisition device inside the holes.

[0007] Preferably, the specific process of step S1 is as follows: S11: Measurement point selection: Based on the TBM body structure and the size of the working space, two symmetrical measurement lines are laid out on the walls of the excavated tunnel. The measurement lines are laid out on the left and right sidewalls, the left and right upper arches, and the left and right lower arches of the tunnel. Each measurement line needs to be laid out with 4 measurement points at equal intervals, with the distance between measurement points ranging from 2.0m to 4.0m. The distance from the front measurement point to the cutterhead should not exceed 20.0m. S12: Drilling Operation at Measurement Points: In open-type TBM scenarios, drilling operations are carried out on the exposed surrounding rock of the tunnel wall. When anchor mesh support is used, drilling operations are carried out at the gaps in the steel mesh. The borehole diameter is 40mm, the drilling depth is not less than 1.0m, and the borehole opening is tilted upwards at 5-10°. In shield-type TBM scenarios, drilling operations are carried out according to the grouting holes of the tunnel segments or the gravel holes. After passing through the tunnel segments or gravel layers, the drilling depth into the rock is not less than 1.0m. S13: Equipment Installation: Install integrated seismic and electromagnetic signal acquisition devices in 6 boreholes near the cutter head end and electromagnetic signal transmitting devices in 2 boreholes far from the cutter head end. Salt water coupling is used between the bottom of the borehole and the device, and plaster and anchoring agent are used to couple the borehole opening and the device to fix the acquisition device.

[0008] Preferably, the in-hole dedicated seismic-electromagnetic integrated signal acquisition device includes a seismic acquisition module and an electromagnetic acquisition module. The seismic acquisition module includes a cable slot 1, an internal signal transmission cable 2, an extension sleeve 3, a seismic module protective shell 4, and a moving coil seismic sensor 5. The electromagnetic acquisition module includes a cable slot 1, an internal signal transmission cable 2, an electromagnetic module connector 6, a rear partition of the electrode chamber 7, a ceramic electrode chamber 8, a copper rod electrode 9, a saturated copper sulfate solution 10, a front partition of the electrode chamber 11, and a top protective layer 12. The integrated seismic-electromagnetic signal acquisition device transmits signals to the outside through three cable slots 1. The cable slots 1 are connected to the moving-coil seismic sensor 5 through the internal signal transmission cable 2 to receive seismic signals. The moving-coil seismic sensor 5 is fixed to the front end of the extension sleeve 3 through the seismic module protective shell 4. The electromagnetic acquisition module is connected to the seismic acquisition module through the electromagnetic module connector 6. The entire electromagnetic acquisition module can be directly replaced through the electromagnetic module connector 6. The ceramic electrode chamber 8 of the electromagnetic acquisition module is fixed to the front electrode chamber 11 through the rear electrode chamber partition 7. The ceramic electrode chamber 8 is filled with saturated copper sulfate solution 10. The copper rod electrode 9 is fixed inside the ceramic electrode chamber 8. The electrical signals in the surrounding rock are transmitted to the copper rod electrode 9 through the saturated copper sulfate solution 10, penetrating the ions in the surrounding rock through the ceramic electrode chamber 8, thereby realizing the acquisition of electrical signals in the surrounding rock.

[0009] Preferably, in step S3, the same observation system is used when collecting seismic and electrical data in stages. Data is collected using both seismic wave reflection and electromagnetic reflection methods during TBM tunneling and downtime. The seismic wave reflection method uses the rock-breaking vibration of the cutter head during TBM tunneling as the seismic source, and receives the seismic reflection signal in the surrounding rock through the integrated seismic-electrical acquisition device. The electromagnetic reflection method uses a transmitter to emit high-frequency pulse electromagnetic waves to the surrounding rock during TBM downtime, and receives the electromagnetic reflection signal in the surrounding rock through the integrated seismic-electrical acquisition device.

[0010] Preferably, the specific process of distributing and collecting seismic and electrical data in step S3 is as follows: S31: High-frequency pulsed electromagnetic signal transmission: During TBM downtime, positive and negative high-frequency pulsed current signals are supplied to T1 and T2 respectively to generate high-frequency incident electromagnetic waves on the surrounding rock. The electromagnetic wave frequency is 1.5 × 10⁻⁶. 6 Hz, and measure in real time the voltage signal of the electromagnetic incident wave in the transmitting electrode decaying over time; S32: Array electromagnetic wave reflection data acquisition: While transmitting high-frequency pulse electromagnetic waves to the surrounding rock, array electromagnetic wave reflection data acquisition is started simultaneously. The voltage signal of electromagnetic reflected waves in the surrounding rock decaying over time is measured in real time through the R1~R6 integrated seismoelectric receiving device. S33: Array seismic wave reflection data acquisition: After completing the array electromagnetic wave reflection data acquisition, during the tunneling operation of the TBM, based on the TBM tunneling noise as the vibration source, and relying on the R1~R6 seismoelectric integrated receiving device, a full-space array seismic wave reflection data acquisition group is carried out.

[0011] Preferably, the specific implementation process of seismic-electromagnetic data ellipsoidal focusing imaging in step S4 is as follows: S41: Seismic wave data preprocessing: The original seismic signal is filtered to remove interference from environmental vibration and TBM self-vibration to obtain the reflected wave signal. Based on the spatial location information of R1 to R6, the cross-correlation calculation and data superposition calculation of multiple sets of reflected wave signals are performed to obtain the common shot gather data of the seismoelectric integrated receiving device R1 to R6. S42: Electromagnetic wave data preprocessing: Perform spectrum analysis on the transmission voltage data of transmitting devices T1 to T2 and the measurement voltage data of R1 to R6 respectively, and perform spectrum normalization calculation based on the transmission voltage to obtain the normalized electromagnetic detection data of the integrated seismoelectric receiving device R1 to R6. S43: Ellipsoid focusing imaging: Using any two points from R1 to R6 as the foci of the ellipsoid, based on the ellipsoid focusing principle, energy projection is performed on the preprocessed seismic data and electromagnetic data respectively. Energy focusing imaging is performed on the multichannel combined data formed by any pairwise combination of R1 to R6 to obtain the reflection energy spectrum information of the seismic wave method and the coherent energy information of the electromagnetic wave method within 100 meters in front of the tunnel face.

[0012] Preferably, the specific process of the integrated water-rock interpretation in step S5 is as follows: the integrity of the surrounding rock is characterized by the seismic reflection energy spectrum information, and the larger the value of the seismic reflection energy spectrum, the worse the relative integrity of the surrounding rock; the water content of the surrounding rock is characterized by the electromagnetic wave coherent energy information, and the larger the value of the electromagnetic reflection energy, the greater the relative water content of the surrounding rock.

[0013] The beneficial effects of this invention include: (1) By deploying a full-space array seismic-electromagnetic observation system, seismic waves and electromagnetic signals are collected simultaneously. Combining the advantages of the two methods, seismic waves are sensitive to the integrity of the surrounding rock and electromagnetic waves are sensitive to water content, so as to realize the coordinated detection of the integrity and water content of the surrounding rock in front of the tunnel face, overcome the limitations of a single method under complex geological conditions, and improve the identification accuracy of geological anomalies.

[0014] (2) Based on the characteristics of the TBM body structure and working space, the drilling layout and equipment installation method were optimized. The drilling was carried out using the grouting holes of the tunnel segments and the gaps in the anchor mesh, and the system was fixed by coupling with brine and gypsum, so that the observation system could adapt to different TBM scenarios such as open-type and shield-type. At the same time, the rock-breaking vibration of the cutter head during TBM tunneling was used as the seismic source to collect electromagnetic data during the downtime. No additional seismic source was required, and the normal tunneling of the TBM was not interfered with, which significantly improved the detection efficiency.

[0015] (3) A dedicated seismic-electromagnetic signal acquisition device is used to achieve synchronous and stable acquisition of seismic and electromagnetic signals, and the adaptability of the equipment is improved through modular design. In data processing, an ellipsoidal focusing algorithm is introduced to perform energy focusing imaging based on the combination of multiple receiver points, which effectively suppresses interference and improves the resolution of the reflected energy spectrum and coherent energy information within 100 meters in front of the tunnel face, providing high-quality data support for subsequent interpretation.

[0016] (4) The TBM-borne detection system improves the applicability of the method and the convenience of on-site testing, significantly reducing the time and personnel required for equipment transport and system connection. Through the integrated seismo-electromagnetic detection device design, both seismic wave and electromagnetic wave detection are achieved using the same observation system. Compared with existing technologies, this significantly reduces the time spent on TBM construction during on-site testing, alleviating the conflict between geological forecasting and excavation procedures. The multi-method combined detection approach improves the accuracy of detection results while reducing geophysical ambiguity, enabling comprehensive detection of lithology, structure, and groundwater information within 100m of unfavorable geological conditions in front of the TBM cutterhead. This meets the technical requirements of rapid TBM tunneling for extended detection distance and accuracy. Attached Figure Description

[0017] Figure 1 This is a schematic flowchart of the TBM airborne array seismic-electromagnetic joint detection method of the present invention.

[0018] Figure 2 This is a diagram of the full-space array observation system of the present invention.

[0019] Figure 3 This is a structural diagram of the integrated seismic-electric signal acquisition device of the present invention. Detailed Implementation

[0020] The following is in conjunction with the appendix Figures 1-3 The present invention will be further described in detail below: Example 1 See appendix Figure 1 As shown, a TBM airborne array seismic-electromagnetic joint detection method includes the following steps: S1: Deploy a full-space array seismic-electromagnetic observation system: Install electromagnetic signal transmitters and seismic-electromagnetic receivers at designated locations, and simultaneously acquire seismic and electromagnetic signals through a dedicated seismic-electromagnetic integrated signal acquisition device inside the borehole; S2: Deploy the TBM airborne equipment system: fuse the array seismic wave reflection method and array electromagnetic wave reflection method acquisition modules and eliminate the separate display terminals, and mount the fusion module on the TBM body; S3: Distributed acquisition of seismic and electrical data: Data acquisition using seismic wave reflection method and electromagnetic reflection method was carried out during TBM tunneling and downtime. S4: Processing and Imaging Seismoelectric Data: Perform specified preprocessing on seismic wave data and electromagnetic wave data respectively, and realize joint imaging of seismic wave reflection and scattering, and coherent imaging of electromagnetic incident wave and reflected wave based on ellipsoid focusing algorithm; S5: Integrated Water-Rock Interpretation: The results are jointly interpreted based on the reflection energy spectrum information of the seismic wave method and the coherent energy information of the electromagnetic wave method. The integrity of the surrounding rock is characterized by the seismic reflection energy spectrum, and the water content of the surrounding rock is characterized by the electromagnetic reflection energy.

[0021] In this embodiment, step S1 involves drilling eight holes at equal intervals and symmetrically in the excavated section of the TBM. The two holes furthest from the cutterhead are used for the installation of electromagnetic signal transmitting devices, while the six holes closest to the cutterhead are used for the installation of seismic-electromagnetic receiving devices. Seismic and electromagnetic signals are simultaneously acquired through a dedicated seismic-electromagnetic integrated signal acquisition device inside the holes, thereby realizing the deployment of a full-space array-type observation system.

[0022] The specific process of step S1 is as follows: S11: Measurement point selection: See [link] Figure 2 Based on the TBM's structure and the size of the working space, two symmetrical survey lines are laid out on the walls of the excavated tunnel. The survey lines are laid out on the left and right sidewalls, the left and right upper arches, and the left and right lower arches of the tunnel. Each survey line needs to be laid out with four measuring points at equal intervals, with the spacing between measuring points ranging from 2.0m to 4.0m. The distance from the front measuring point to the cutterhead does not exceed 20.0m. S12: Drilling Operations at Measurement Points: In open-type TBM scenarios, drilling operations are carried out on the exposed surrounding rock of the tunnel wall. When anchor mesh support is used, drilling operations are carried out at the gaps in the steel mesh. The borehole diameter is approximately 40mm, the drilling depth is not less than 1.0m, and the borehole opening is tilted upwards at 5-10°. In shield-type TBM scenarios, drilling operations are carried out based on the grouting holes of the tunnel segments or the gravel holes. It is necessary to ensure that the drilling depth into the rock after penetrating the tunnel segments or gravel layers is not less than 1.0m. S13: Equipment Installation: Install integrated seismic and electromagnetic signal acquisition devices in 6 boreholes near the cutter head end and electromagnetic signal transmitting devices in 2 boreholes far from the cutter head end. Salt water coupling is used between the bottom of the borehole and the device to reduce grounding resistance. Plaster and anchoring agent are used to couple the borehole opening and the device to fix the acquisition device.

[0023] Example 2 Based on Example 1, see Figure 3 The in-hole dedicated seismic-electromagnetic integrated signal acquisition device includes a seismic acquisition module and an electromagnetic acquisition module. The seismic acquisition module includes a cable slot 1, an internal signal transmission cable 2, an extension sleeve 3, a seismic module protective shell 4, and a moving coil seismic sensor 5. The electromagnetic acquisition module includes a cable slot 1, an internal signal transmission cable 2, an electromagnetic module connector 6, a rear partition of the electrode chamber 7, a ceramic electrode chamber 8, a copper rod electrode 9, a saturated copper sulfate solution 10, a front partition of the electrode chamber 11, and a top protective layer 12. The integrated seismic-electromagnetic signal acquisition device transmits signals to the outside through three cable slots 1. The cable slots 1 are connected to the moving-coil seismic sensor 5 through the internal signal transmission cable 2 to receive seismic signals. The moving-coil seismic sensor 5 is fixed to the front end of the extension sleeve 3 through the seismic module protective shell 4 to ensure the overall rigidity of the seismic acquisition module. The electromagnetic acquisition module is connected to the seismic acquisition module through the electromagnetic module connector 6. Since the electromagnetic acquisition module is a vulnerable device, the entire electromagnetic acquisition module can be directly replaced through the electromagnetic module connector 6. The ceramic electrode chamber 8 of the electromagnetic acquisition module is fixed to the front electrode chamber 11 through the rear electrode chamber partition 7. The ceramic electrode chamber 8 is filled with saturated copper sulfate solution 10. The copper rod electrode 9 is fixed inside the ceramic electrode chamber 8. The electrical signal in the surrounding rock is transmitted to the copper rod electrode 9 through the saturated copper sulfate solution 10, penetrating the ions in the surrounding rock through the ceramic electrode chamber 8, thereby realizing the acquisition of electrical signals in the surrounding rock.

[0024] In step S3, the same observation system is used to collect seismic and electrical data in stages. Data is collected using both seismic wave reflection and electromagnetic reflection methods during TBM tunneling and downtime. The seismic wave reflection method uses the rock-breaking vibration of the cutter head during TBM tunneling as the seismic source and receives the seismic reflection signal in the surrounding rock through the integrated seismic-electrical acquisition device. The electromagnetic reflection method uses a transmitter to emit high-frequency pulse electromagnetic waves to the surrounding rock during TBM downtime and receives the electromagnetic reflection signal in the surrounding rock through the integrated seismic-electrical acquisition device.

[0025] The specific process of distributing and collecting seismic and electrical data in step S3 is as follows: S31: High-frequency pulsed electromagnetic signal transmission: After the full-space array observation system is deployed, during the TBM shutdown interval, positive and negative high-frequency pulsed current signals are supplied to T1 and T2 respectively to generate high-frequency incident electromagnetic waves on the surrounding rock. The electromagnetic wave frequency is 1.5 × 10⁻⁶. 6 Hz, and measure in real time the voltage signal of the electromagnetic incident wave in the transmitting electrode decaying over time; S32: Array electromagnetic wave reflection data acquisition: While transmitting high-frequency pulse electromagnetic waves to the surrounding rock, array electromagnetic wave reflection data acquisition is started simultaneously. The voltage signal of the electromagnetic reflected wave in the surrounding rock attenuates over time through the R1 to R6 integrated seismoelectric receiving device. To ensure that the detection depth is not less than 100 meters, the recording time of a single electromagnetic measurement is not less than 80 μs, and no less than 10 sets of valid data are collected at the same mileage. S33: Array seismic wave reflection data acquisition: After completing the array electromagnetic wave reflection data acquisition, during the tunneling operation of the TBM, based on the TBM tunneling noise as the vibration source, and relying on the R1~R6 seismoelectric integrated receiving device, the full-space array seismic wave reflection method data acquisition is carried out. To ensure that the detection depth is not less than 100 meters, the recording time of a single seismic measurement is not less than 512ms, each data set is acquired 50 times, and no less than 4 sets of valid data are acquired at the same mileage.

[0026] Example 3 Based on Example 1 or Example 2, the specific implementation process of seismic-electromagnetic data ellipsoidal focusing imaging in step S4 is as follows: S41: Seismic wave data preprocessing: The original seismic signal is filtered to remove interference such as environmental vibration and TBM self-vibration to obtain the reflected wave signal. Based on the spatial location information of R1 to R6, the cross-correlation calculation and data superposition calculation of multiple sets of reflected wave signals are performed to obtain the common shot gather data of the seismoelectric integrated receiving device R1 to R6. S42: Electromagnetic wave data preprocessing: Perform spectrum analysis on the transmission voltage data of transmitting devices T1 to T2 and the measurement voltage data of R1 to R6 respectively, and perform spectrum normalization calculation based on the transmission voltage to obtain the normalized electromagnetic detection data of the integrated seismoelectric receiving device R1 to R6. S43: Ellipsoid focusing imaging: Using any two points from R1 to R6 as the foci of the ellipsoid, based on the ellipsoid focusing principle, energy projection is performed on the preprocessed seismic data and electromagnetic data respectively. Energy focusing imaging is performed on the multichannel combined data formed by any pairwise combination of R1 to R6, thereby obtaining the reflection energy spectrum information of the seismic wave method and the coherent energy information of the electromagnetic wave method within 100 meters in front of the tunnel face.

[0027] The specific process of the integrated water-rock interpretation in step S5 is as follows: the integrity of the surrounding rock is characterized by the seismic reflection energy spectrum information. The larger the value of the seismic reflection energy spectrum, the worse the relative integrity of the surrounding rock. The water content of the surrounding rock is characterized by the electromagnetic wave coherence energy information. The larger the value of the electromagnetic reflection energy, the greater the relative water content of the surrounding rock.

[0028] Example 4 In this embodiment, a specific example of the above-mentioned TBM airborne array seismic-electromagnetic joint detection method is illustrated using a high-speed railway tunnel engineering scenario. For instance, a high-speed railway tunnel is 12.6 km long and is being excavated using an open-face TBM with a diameter of 6.3 m. The tunnel traverses strata primarily composed of sandstone and limestone, with local fault fracture zones and water-rich sections. Accurate identification of the integrity and water content of the surrounding rock within 100 m in front of the tunnel face is necessary through advanced geological prediction to provide a basis for adjusting TBM excavation parameters and controlling risks. The implementation process is as follows: Deploy a full-space array seismic-electromagnetic observation system: Measurement point selection: Based on the TBM body structure and tunnel cross-section (width × height = 6.8m × 7.2m), two symmetrical measurement lines were laid out on the excavated tunnel wall. Left side measurement line: upper left wall, upper left arch, lower left arch, left side wall (4 measurement points). Right side measurement line: upper right wall, upper right arch, lower right arch, right side wall (4 measurement points). The spacing between measurement points is 3.0m, and the distance from the first measurement point at the front end to the cutterhead is 15.0m (meeting the ≤20.0m requirement).

[0029] Drilling operation: Since an open TBM is used and the tunnel wall is supported by anchor mesh, drilling is carried out at the gaps in the steel mesh: the hole diameter is 40mm, the depth is 1.2m (≥1.0m), and the hole opening is tilted upwards at 8° (within the range of 5 to 10°).

[0030] Equipment Installation: Dedicated in-hole vibration-electric signal acquisition devices are installed in the six boreholes (R1-R6) closest to the cutterhead. 500mL of saline solution is injected into the bottom of each borehole for coupling. The borehole openings are secured with a combination of quick-setting plaster and anchoring agent to ensure tight contact between the sensors and the surrounding rock. Electromagnetic signal transmitters are installed in the two boreholes furthest from the cutterhead (T1 and T2), using the same installation method to ensure good conductivity between the electrodes and the surrounding rock.

[0031] The TBM onboard equipment system is deployed by integrating the array seismic wave acquisition module, the array electromagnetic wave acquisition module, and the data fusion processing unit, eliminating the need for a separate display terminal. It is mounted on a custom bracket below the control room on the left side of the TBM body, avoiding the tunneling vibration source. The fusion module receives the seismic and electromagnetic signals from R1 to R6 in real time, synchronously stores them, and transmits them to the display screen in the TBM main control room, enabling real-time data monitoring.

[0032] Seismoelectric data acquisition in stages: High-frequency pulsed electromagnetic signal transmission and acquisition: During the TBM tool change interval (approximately 1 hour), electromagnetic detection is initiated: Positive and negative high-frequency pulsed currents are applied to T1 and T2 respectively, with a transmission frequency of 1.5 × 10⁻⁶. 6 The electromagnetic wave emitted at Hz was used to measure the voltage decay curve of the transmitting electrode in real time. Electromagnetic reflected wave signals were synchronously acquired by R1 to R6 for 20 minutes to obtain voltage data of 6 electromagnetic reflected waves decaying over time.

[0033] Seismic wave reflection data acquisition: After the TBM resumed tunneling, the rock-breaking vibration of the cutter head (about 50-200Hz) was used as the natural source. Seismic reflection signals were continuously acquired by R1 to R6. A set of common blast gather data was generated every 5 minutes. The total acquisition time was 3 hours, and the tunneling depth was about 15m.

[0034] Seismic data processing and imaging: Seismic wave data preprocessing: The original seismic signal was bandpass filtered at 20-150Hz to remove TBM body vibration (5-10Hz) and environmental noise (>200Hz); Based on the spatial coordinates of R1-R6, with a spacing of 3m and symmetrical distribution, the cross-correlation of multiple sets of reflected wave signals was calculated to improve the signal-to-noise ratio and superimposed to obtain 6 common shot gather data.

[0035] Electromagnetic wave data preprocessing: Perform spectrum analysis on the transmitted voltage data from T1 to T2 and the received voltage data from R1 to R6, and extract 1.5×10⁻⁶... 6 Hz main frequency component; spectrum normalization is performed based on the transmission voltage to eliminate the influence of transmission intensity differences and obtain normalized electromagnetic detection data.

[0036] Ellipsoidal focusing imaging: Using any two points from R1 to R6 (e.g., R1 and R2, R1 and R3, etc.) as ellipsoidal foci, energy projection is performed on the preprocessed data based on the ellipsoidal focusing algorithm. Seismic wave imaging: By focusing multi-channel combined data, the seismic reflection energy spectrum distribution (unit: dB) within a 100m range ahead of the tunnel face is obtained. Electromagnetic wave imaging: Through coherence analysis of incident and reflected waves, the electromagnetic coherence energy distribution (unit: mV²) within a 100m range ahead of the tunnel face is obtained.

[0037] Integrated water-rock interpretation: Rock integrity assessment: Seismic reflection energy spectrum data shows a high energy value zone (25-30 dB) in the 50-70 m range ahead of the tunnel face, significantly higher than normal surrounding rock (10-15 dB), indicating poor rock integrity in this area, possibly a fractured zone. Rock water content assessment: Electromagnetic coherence energy data shows a synchronous high energy value zone (80-100 mV²) in the aforementioned 50-70 m range, much higher than normal surrounding rock (30-50 mV²), indicating strong water content in this area. Overall conclusion: Combined interpretation determines that the 50-70 m range ahead of the tunnel face is a fractured, water-rich zone. It is recommended that the TBM speed be reduced to 30% of its rated speed, and that pre-grouting and water-stopping measures be prepared in advance.

[0038] The TBM airborne array seismic-electromagnetic joint detection method and system of the present invention, through the deployment of a full-space array seismic-electromagnetic observation system in TBM construction scenarios, TBM airborne equipment systems, step-by-step acquisition of seismic and electromagnetic data, seismic and electromagnetic data processing and imaging, and integrated water-rock interpretation, is applicable to the lithology, structure, and groundwater of adverse geological conditions ahead of TBMs. It should be noted that although specific embodiments of the present invention have been described, this is not a limitation on the scope of protection of the present invention. All modifications that can be made without creative effort based on the technical solution of the present invention are still within the scope of protection of the present invention.

Claims

1. A TBM airborne array seismic-electromagnetic joint detection method, characterized in that, Includes the following steps: S1: Deploy a full-space array seismic-electromagnetic observation system: Install electromagnetic signal transmitters and seismic-electromagnetic receivers at designated locations, and simultaneously acquire seismic and electromagnetic signals through a dedicated seismic-electromagnetic integrated signal acquisition device inside the borehole; S2: Deploy the TBM airborne equipment system: fuse the array seismic wave reflection method and array electromagnetic wave reflection method acquisition modules and eliminate the separate display terminals, and mount the fusion module on the TBM body; S3: Distributed acquisition of seismic and electrical data: Data acquisition using seismic wave reflection method and electromagnetic reflection method was carried out during TBM tunneling and downtime. S4: Processing and Imaging Seismoelectric Data: Perform specified preprocessing on seismic wave data and electromagnetic wave data respectively, and realize joint imaging of seismic wave reflection and scattering, and coherent imaging of electromagnetic incident wave and reflected wave based on ellipsoid focusing algorithm; S5: Integrated Water-Rock Interpretation: The results are jointly interpreted based on the reflection energy spectrum information of the seismic wave method and the coherent energy information of the electromagnetic wave method. The integrity of the surrounding rock is characterized by the seismic reflection energy spectrum, and the water content of the surrounding rock is characterized by the electromagnetic reflection energy.

2. The TBM airborne array seismic-electromagnetic joint detection method according to claim 1, characterized in that, In step S1, eight boreholes are drilled symmetrically at equal intervals in the excavated section of the TBM. The two boreholes furthest from the cutterhead are used for the installation of electromagnetic signal transmitting devices, and the six boreholes closest to the cutterhead are used for the installation of seismic-electromagnetic receiving devices. Seismic and electromagnetic signals are simultaneously acquired through a dedicated seismic-electromagnetic integrated signal acquisition device inside the borehole.

3. The TBM airborne array seismic-electromagnetic joint detection method according to claim 2, characterized in that, The specific process of step S1 is as follows: S11: Measurement point selection: Based on the TBM body structure and the size of the working space, two symmetrical measurement lines are laid out on the walls of the excavated tunnel. The measurement lines are laid out on the left and right sidewalls, the left and right upper arches, and the left and right lower arches of the tunnel. Each measurement line needs to be laid out with 4 measurement points at equal intervals, with the distance between measurement points ranging from 2.0m to 4.0m. The distance from the front measurement point to the cutterhead should not exceed 20.0m. S12: Drilling Operation at Measurement Points: In open-type TBM scenarios, drilling operations are carried out on the exposed surrounding rock of the tunnel wall. When anchor mesh support is used, drilling operations are carried out at the gaps in the steel mesh. The borehole diameter is 40mm, the drilling depth is not less than 1.0m, and the borehole opening is tilted upwards at 5-10°. In shield-type TBM scenarios, drilling operations are carried out according to the grouting holes of the tunnel segments or the gravel holes. After passing through the tunnel segments or gravel layers, the drilling depth into the rock is not less than 1.0m. S13: Equipment Installation: Install integrated seismic and electromagnetic signal acquisition devices in 6 boreholes near the cutter head end and electromagnetic signal transmitting devices in 2 boreholes far from the cutter head end. Salt water coupling is used between the bottom of the borehole and the device, and plaster and anchoring agent are used to couple the borehole opening and the device to fix the acquisition device.

4. The TBM airborne array seismic-electromagnetic joint detection method according to claim 2, characterized in that, The in-hole dedicated seismic-electromagnetic integrated signal acquisition device includes a seismic acquisition module and an electromagnetic acquisition module. The seismic acquisition module includes a cable slot (1), an internal signal transmission cable (2), an extension sleeve (3), a seismic module protective shell (4), and a moving coil seismic sensor (5). The electromagnetic acquisition module includes a cable slot (1), an internal signal transmission cable (2), an electromagnetic module connector (6), a rear partition of the electrode chamber (7), a ceramic electrode chamber (8), a copper rod electrode (9), a saturated copper sulfate solution (10), a front partition of the electrode chamber (11), and a top protective layer (12). The integrated seismic-electric signal acquisition device transmits signals to the outside through three cable slots (1). The cable slots (1) are connected to the moving coil seismic sensor (5) through the internal signal transmission cable (2) to receive seismic signals. The moving coil seismic sensor (5) is fixed to the front end of the extension sleeve (3) through the seismic module protective shell (4). The electromagnetic acquisition module and the seismic acquisition module are connected through the electromagnetic module connector (6). The entire electromagnetic acquisition module can be replaced directly through the electromagnetic module connector (6). The ceramic electrode chamber (8) of the electromagnetic acquisition module is fixed to the front partition (11) of the electrode chamber through the rear partition (7) of the electrode chamber. The ceramic electrode chamber (8) is filled with saturated copper sulfate solution (10). The copper rod electrode (9) is fixed in the ceramic electrode chamber (8). The electrical signal in the surrounding rock is transmitted to the copper rod electrode (9) through the saturated copper sulfate solution (10) through the ceramic electrode chamber (8) and penetrates into the surrounding rock. The electrical ions are then transmitted to the copper rod electrode (9) to realize the acquisition of electrical signals in the surrounding rock.

5. The TBM airborne array seismic-electromagnetic joint detection method according to claim 1, characterized in that, In step S3, the same observation system is used to collect seismic and electrical data in stages. Data is collected using both seismic wave reflection and electromagnetic reflection methods during TBM tunneling and downtime. The seismic wave reflection method uses the rock-breaking vibration of the cutter head during TBM tunneling as the seismic source and receives the seismic reflection signal in the surrounding rock through the integrated seismic-electrical acquisition device. The electromagnetic reflection method uses a transmitter to emit high-frequency pulse electromagnetic waves to the surrounding rock during TBM downtime and receives the electromagnetic reflection signal in the surrounding rock through the integrated seismic-electrical acquisition device.

6. The TBM airborne array seismic-electromagnetic joint detection method according to claim 5, characterized in that, The specific process of distributing and collecting seismic and electrical data in step S3 is as follows: S31: High-frequency pulsed electromagnetic signal transmission: During TBM downtime, positive and negative high-frequency pulsed current signals are supplied to T1 and T2 respectively to generate high-frequency incident electromagnetic waves on the surrounding rock. The electromagnetic wave frequency is 1.5 × 10⁻⁶. 6 Hz, and measure in real time the voltage signal of the electromagnetic incident wave in the transmitting electrode decaying over time; S32: Array electromagnetic wave reflection data acquisition: While transmitting high-frequency pulse electromagnetic waves to the surrounding rock, array electromagnetic wave reflection data acquisition is started simultaneously. The voltage signal of electromagnetic reflected waves in the surrounding rock decaying over time is measured in real time through the R1~R6 integrated seismoelectric receiving device. S33: Array seismic wave reflection data acquisition: After completing the array electromagnetic wave reflection data acquisition, during the tunneling operation of the TBM, based on the TBM tunneling noise as the vibration source, and relying on the R1~R6 seismoelectric integrated receiving device, a full-space array seismic wave reflection data acquisition group is carried out.

7. The TBM airborne array seismic-electromagnetic joint detection method according to claim 1, characterized in that, The specific implementation process of seismic-electromagnetic data ellipsoidal focusing imaging in step S4 is as follows: S41: Seismic wave data preprocessing: The original seismic signal is filtered to remove interference from environmental vibration and TBM self-vibration to obtain the reflected wave signal. Based on the spatial location information of R1 to R6, the cross-correlation calculation and data superposition calculation of multiple sets of reflected wave signals are performed to obtain the common shot gather data of the seismoelectric integrated receiving device R1 to R6. S42: Electromagnetic wave data preprocessing: Perform spectrum analysis on the transmission voltage data of transmitting devices T1 to T2 and the measurement voltage data of R1 to R6 respectively, and perform spectrum normalization calculation based on the transmission voltage to obtain the normalized electromagnetic detection data of the integrated seismoelectric receiving device R1 to R6. S43: Ellipsoid focusing imaging: Using any two points from R1 to R6 as the foci of the ellipsoid, based on the ellipsoid focusing principle, energy projection is performed on the preprocessed seismic data and electromagnetic data respectively. Energy focusing imaging is performed on the multichannel combined data formed by any pairwise combination of R1 to R6 to obtain the reflection energy spectrum information of the seismic wave method and the coherent energy information of the electromagnetic wave method within 100 meters in front of the tunnel face.

8. The TBM airborne array seismic-electromagnetic joint detection method according to claim 1, characterized in that, The specific process of the integrated water-rock interpretation in step S5 is as follows: the integrity of the surrounding rock is characterized by the seismic reflection energy spectrum information. The larger the value of the seismic reflection energy spectrum, the worse the relative integrity of the surrounding rock. The water content of the surrounding rock is characterized by the electromagnetic wave coherence energy information. The larger the value of the electromagnetic reflection energy, the greater the relative water content of the surrounding rock.

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