Tunnel water body advance detection system and method based on blasting induced seismic response

Abstract

The present application belongs to the field of geophysical prospecting technology, and provides a tunnel water-bearing body advanced detection system and method based on blasting induced seismic-electric response, which takes the blasting initiation moment of the initiation control unit as a unified starting point, collects the seismic wave field signal output by the detector and the seismic-electric field signal output by the electrode array, and performs advanced detection on the front water-bearing body structure according to the seismic wave field signal and the seismic-electric field signal. The present application can fully utilize the natural excitation source in the construction process, realize rapid and simple layout in a limited space, and has the ability to resist strong interference and stably collect weak signals, thereby ensuring timely and reliable identification of the front water-bearing body structure of the working face during the construction process, and providing strong guarantee for the safe construction of the tunnel.

Description

Technical Field

[0001] This invention belongs to the field of geophysical exploration technology. Specifically, it relates to an advanced detection system and method for tunnel water-bearing bodies based on blast-induced seismic-electric response. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] During tunnel construction, water inrush and mudslides are among the main risks affecting project safety. Especially in areas with complex geological conditions, the location and scale of aquifers ahead of the tunnel face are uncertain, easily leading to construction accidents. How to achieve advanced detection of aquifers ahead of the tunnel face during construction is a key issue in tunnel engineering safety control.

[0004] Currently used advanced detection methods include ground-penetrating radar, transient electromagnetic methods, seismic methods, electrical methods, and acoustic methods. These methods acquire physical field signals by deploying sensors, coils, electrodes, or detectors in tunnels or on the surface, and then process the data to infer the geological conditions ahead. Under general geological conditions, these methods can provide certain underground information.

[0005] However, the following prominent problems still exist in the complex construction environment of tunnels: First, the surrounding rock conditions of tunnels are complex, and conventional electromagnetic and electrical methods attenuate rapidly in conductive water-bearing media, while radar penetration distance is limited, making it difficult to predict the structure of water-bearing bodies at greater distances; Second, during the tunneling process, there are multiple strong interference sources such as blasting, mechanical vibration, and power systems, which can easily submerge conventional observation signals, making it difficult to extract effective information; Third, most existing methods rely on independent excitation sources or large-scale sensor deployment, while the narrow space and humid environment of tunnels make equipment installation and maintenance very difficult. Summary of the Invention

[0006] To address the aforementioned problems, this invention proposes a tunnel aquifer detection system and method based on blast-induced seismic-electric response. This system can fully utilize natural excitation sources during construction, enabling rapid and convenient deployment within a limited space. It also possesses the ability to resist strong interference and stably acquire weak signals, thereby ensuring timely and reliable identification of aquifer structures ahead of the tunnel face during construction and providing strong support for safe tunnel construction.

[0007] According to some embodiments, the present invention adopts the following technical solution:

[0008] A tunnel aquifer detection system based on blast-induced seismic-electric response includes:

[0009] The tracked vehicle-mounted main unit, signal acquisition and wireless transmission unit, blasting synchronization triggering device, electrode array for installation in boreholes in the sidewalls of the tunnel, and detectors for installation on the sidewalls of the tunnel. The blasting synchronization triggering device includes a detonation control unit for controlling the generation of seismic waves by detonation.

[0010] The signal acquisition and wireless transmission unit is used to acquire the seismic wave field signal output by the detector and the seismoelectric field signal output by the electrode array, using the detonation time of the detonation control unit as the unified start time point, and send them to the tracked vehicle-mounted host. The tracked vehicle-mounted host is used to perform advanced detection of the water-bearing structure ahead based on the seismic wave field signal and the seismoelectric field signal.

[0011] As an alternative implementation, the tracked vehicle-mounted host includes: a system control module, a time reference module, a signal transmission and data processing module, and an inversion processing module. The system control module is communicatively connected to the time reference module, and the time reference module is communicatively connected to the detonation control unit and the signal transmission and data processing module, respectively.

[0012] The signal acquisition and wireless transmission unit acquires the seismic wave field signal output by the detector and the seismoelectric field signal output by the electrode array and sends them to the signal transmission and data processing module. The signal transmission and data processing module processes the data and sends it to the inversion processing module. The inversion processing module is used to perform advanced detection of the water-bearing structure ahead based on the pre-processed seismic wave field signal and the seismoelectric field signal.

[0013] As an alternative implementation, the signal acquisition and wireless transmission unit includes a control acquisition module, the electrode array adopts a dual parallel line array structure, adjacent electrodes form an electric dipole sensor, and each electrode of the electrode array is connected to the control acquisition module via a cable.

[0014] Each electrode surface of the electrode array is provided with a polarization-sensitive coating formed by a composite of carbon-based conductive material and porous ceramic. The porous structure of the polarization-sensitive coating is used to retain moisture or conductive medium.

[0015] Furthermore, the detector is used to be arranged on the left and right sides of the electrode array and connected to the control acquisition module through a cable. The detector is a broadband anti-saturation detector, including: detector housing, composite coil, suspension support, magnetic core, bottom spring and damping block;

[0016] The suspension support inside the detector housing is used to flexibly suspend the magnetic core. The composite coil is wound on the low-noise magnetic core. One end of the bottom spring is connected to the detector housing, and the other end of the bottom spring is connected to the damping block.

[0017] Furthermore, the signal acquisition and wireless transmission unit also includes a signal amplification and filtering module, a positioning module, a power supply module, a wireless transmission module, and an antenna. The power supply module is used to supply power to the signal amplification and filtering module, the positioning module, the wireless transmission module, and the control acquisition module.

[0018] The control acquisition module is connected to the signal amplification and filtering module, the positioning module, and the wireless transmission module, respectively. The wireless transmission module is connected to the antenna.

[0019] The control and acquisition module is used to simultaneously sample the seismoelectric field signal output by the electrode array and the seismic wave field signal output by the detector under the constraint of a unified start-up time. The acquired seismoelectric field signal and seismic wave field signal are processed by the signal amplification and filtering module and then transmitted to the tracked vehicle-mounted host through the wireless transmission module and antenna.

[0020] Furthermore, the signal amplification and filtering module includes a signal amplifier and a filter. The signal amplifier is a transient adaptive low-noise amplifier used to amplify weak seismoelectric field signals under blasting excitation. The filter is a narrowband tunable filter bank resistant to power frequency interference, used to highlight and retain characteristic frequency band signals of seismoelectric effect in strong blasting background, and to perform bandwidth constraint on the seismic wave field signal output by the broadband anti-saturation detector.

[0021] Furthermore, the control acquisition module retains only valid segments within a set time window after the blast, and performs time delay and weighting processing on the multi-channel signals in combination with the geometric arrangement of the electrode array. The signals on both sides of the sidewall are superimposed to suppress lateral interference, and the signals along the tunnel direction are synthesized into forward-pointing observations.

[0022] As an alternative implementation method, the blasting source at the tunnel face is located on the central axis in front of the tunnel face. A charging hole is pre-drilled in the surrounding rock at the location of the blasting source at the tunnel face, and explosives and detonators are loaded.

[0023] The detonation control unit is wirelessly connected to the tracked vehicle-mounted host to receive blasting trigger commands and control the detonation of explosives in the charging hole to generate seismic waves and produce seismoelectric effects in the surrounding rock.

[0024] A method for advanced detection of water-bearing bodies in tunnels based on blast-induced seismic-electric response, utilizing the aforementioned advanced detection system for water-bearing bodies in tunnels based on blast-induced seismic-electric response, includes the following processes:

[0025] Holes are drilled in the sidewalls on both sides of the tunnel face, and electrodes are arranged in a double parallel line array in the holes, keeping the spacing consistent to form an electrode array. Detectors are placed at preset positions on both sides of the electrode array.

[0026] Install signal acquisition and wireless transmission units within the location range of each electrode array and connect them to the cables of the corresponding electrode array and detector;

[0027] A charging hole is reserved on the central axis of the tunnel face, detonators and explosives are filled in, an initiation control unit is set up, and remote communication pairing between the initiation control unit and the tracked vehicle-mounted host is completed.

[0028] Move the tracked vehicle-mounted main unit to the safe area behind the working face and establish communication with each signal acquisition and wireless transmission unit and the detonation control unit;

[0029] The tracked vehicle-mounted host sends an initiation command to the detonation control unit to initiate the blasting. At the moment of initiation, each electrode array and detector begins to synchronously collect the seismic electric field signal and the seismic wave field signal.

[0030] After the seismic electric field signal and seismic wave field signal are acquired, they are sent to the tracked vehicle-mounted host through the corresponding signal acquisition and wireless transmission unit. The inversion processing module in the tracked vehicle-mounted host performs advanced detection of the water-bearing structure ahead based on the seismic wave field signal and the seismic electric field signal.

[0031] As an alternative implementation method, advance detection of aquifer structures ahead is performed based on seismic wavefield signals and seismoelectric field signals, including:

[0032] By combining the collected seismic electric field signals, geological survey data, seismic wave field signals, spatial positioning information of blasting sources and time synchronization information, a three-dimensional unstructured mesh finite element model covering the tunnel area is constructed.

[0033] In the modeling process of the mesh finite element model, the seismic wave field signal is first used to establish the medium velocity model and to calibrate the blasting excitation time and wave field propagation characteristics, providing geometric and temporal constraints for the calculation of the seismoelectric field. The seismoelectric field signal, as the main data source for the inversion of electrical parameters, is used to characterize the distribution characteristics of the water-bearing body. The seismic wave field signal and the seismoelectric field signal are jointly incorporated into the inversion objective function: the seismic wave residual term is used to constrain the velocity model and the source time, and the seismoelectric signal residual term is used to constrain the electrical distribution.

[0034] The propagation process of the seismic electric field under blasting excitation was simulated by forward modeling using a mesh finite element model. After the forward modeling was completed, the simulation results were compared with the measured seismic electric field signal and seismic wave field signal. An inversion objective function containing the two types of observations was constructed. After the inversion was completed, a three-dimensional image of the water-bearing body in front of the tunnel face was generated.

[0035] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0036] This invention utilizes blasting during tunnel construction as a natural excitation source, while simultaneously collecting seismic electric field and seismic wave field signals. This method avoids the deployment of additional strong source equipment, reduces on-site construction risks and layout complexity, and improves economy and applicability.

[0037] This invention addresses the challenges of narrow tunnel spaces, humid environments, and limited electrode placement. It proposes an embedded dual parallel line electrode array in the sidewall boreholes. This arrangement enhances the stable contact between the electrodes and the surrounding rock, reduces contact resistance, and forms a differential observation channel. This effectively suppresses interference and improves the signal-to-noise ratio within a limited space, ensuring sensitive detection and accurate positioning of water-bearing structures ahead of the tunnel face.

[0038] This invention incorporates a transient adaptive amplifier and a narrowband adjustable filter in the signal processing stage, combined with a nanosecond-level time base and a high-speed sampling unit, to achieve stable capture of the weak amplitude, wide bandwidth, and rapidly decaying seismoelectric field signal under blast excitation. Simultaneously, a time window acquisition method is employed, recording only the effective signal within a short period after the blast. Furthermore, the geometric characteristics of the electrode array are used for delay and weighted superposition to suppress irrelevant interference and highlight the in-phase response ahead. This ensures both the integrity and authenticity of the transient signal while significantly improving the signal-to-noise ratio, detection sensitivity, and result reliability.

[0039] The inversion processing module of this invention employs joint inversion of seismoelectric field signals and seismic wave field signals. The seismic wave field signals provide velocity models and source time constraints to correct the location of seismoelectric imaging. The seismoelectric field signals are highly sensitive to water-bearing bodies and can correct the physical property distribution of seismic inversion. The two types of data are updated synchronously and complement each other in the same three-dimensional model, effectively avoiding the multi-solution problem caused by a single data source, thereby significantly improving the accuracy, stability and identification ability of water-bearing body structure imaging.

[0040] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0041] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0042] Figure 1 This is a schematic diagram of the water-bearing body detection system provided in Embodiment 1 of the present invention;

[0043] Figure 2 A schematic diagram of a broadband anti-saturation detector structure is provided for Embodiment 1 of the present invention;

[0044] Figure 3 This invention provides a schematic diagram of the signal acquisition and wireless transmission unit structure according to Embodiment 1 of the present invention;

[0045] Figure 4 This is a schematic diagram of the structural principle of the water-bearing body detection system provided in Embodiment 1 of the present invention;

[0046] Figure 5 This is a flowchart of the water-bearing body detection method provided in Embodiment 2 of the present invention;

[0047] The components include: 1. Tracked vehicle-mounted main unit; 2. Signal acquisition and wireless transmission unit; 3. Water-bearing structure; 4. Electrode array; 5. Working face blasting source; 6. Tunnel cavity; 7. Surrounding rock; 8. Broadband anti-saturation detector; 9. Cable; 10. Detonation control unit; 11. Charging hole; 12. Seismic wave; 13. Electric field line; 14. Detector housing; 15. Composite coil; 16. Suspension support; 17. Low-noise magnetic core; 18. Bottom spring; 19. Damping block; 20. Acquisition and transmission housing; 21. Positioning module; 22. Signal amplification and filtering module; 23. Antenna; 24. Wireless transmission module; 25. Control and acquisition module; 26. Power supply module. Detailed Implementation

[0048] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0049] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0050] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0051] Where there is no conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0052] Example 1

[0053] This embodiment proposes an advanced detection system for tunnel aquifers based on blast-induced seismoelectric response. Utilizing seismic waves generated during tunnel construction as a natural excitation source, a dual-parallel-line array electrode is deployed within boreholes in the tunnel sidewalls. Combined with a broadband anti-saturation detector and a high-precision signal acquisition unit, the system acquires transient seismoelectric field signals and seismic wave field signals after blasting. Differential observation, filtering and noise reduction, and time window truncation effectively improve the signal-to-noise ratio. Furthermore, by combining seismoelectric-seismic wave joint inversion, the location and extent of the aquifer structure ahead are obtained, thus providing a safe and reliable advanced detection method for tunnel construction.

[0054] Specifically, the advanced detection system in this embodiment, such as Figure 1 , Figure 2 and Figure 3 As shown, the system includes: a tracked vehicle-mounted main unit 1, a signal acquisition and wireless transmission unit 2, a water-bearing structure 3 (surrounded by electric field lines 13), an electrode array 4, a face blasting source 5, a tunnel cavity 6, surrounding rock 7, a broadband anti-saturation detector 8, a cable 9, a detonation control unit 10, a charging hole 11 (the explosion generates seismic waves 12, which in turn generate seismoelectric effect excitation), a detector housing 14, a composite coil 15, a suspension support 16, a low-noise magnetic core 17, a bottom spring 18, a damping block 19, an acquisition and transmission housing 20, a positioning module 21, a signal amplification and filtering module 22, an antenna 23, a wireless transmission module 24, a control and acquisition module 25, and a power supply module 26, etc.

[0055] The tracked vehicle-mounted host 1 is located in the safe zone behind the tunnel face. It employs a tracked chassis structure, enabling flexible movement within the tunnel environment. The tracked vehicle-mounted host 1 internally houses a system control module, a time reference module, a signal transmission and data processing module, and an inversion processing module. The system control module coordinates and controls the entire system; the time reference module distributes a unified clock signal to each acquisition unit; the signal transmission and data processing module receives and processes data from each acquisition unit; and the inversion processing module performs calculations on the received data and generates the distribution results of the aquifer structure 3.

[0056] The time reference module includes a GNSS receiver unit and a local high-stability oscillator. The GNSS receiver unit receives satellite signals and outputs a reference pulse, while also providing an absolute time stamp. The local oscillator is preferably a temperature-controlled crystal oscillator (OCXO) or a rubidium atomic clock, used to maintain a highly stable clock when satellite signals are limited inside the tunnel. The drift rate is preferably less than 10. -9 / day.

[0057] In this embodiment, preferably, the electrode array 4 is arranged in the boreholes of the sidewalls on both sides of the tunnel cavity 6, and adopts a double parallel line array structure. The electrode spacing in the same array is consistent, and two adjacent electrodes form an electric dipole sensor. All electrodes are connected to the signal acquisition and wireless transmission unit 2 through the cable 9.

[0058] Furthermore, the electrode surface is coated with a polarization-sensitive coating formed by a composite of carbon-based conductive material and porous ceramic. The coating has a porous structure, and water or conductive gel can be retained in the pores, thereby forming a larger effective contact area between the electrode and the rock wall, so that the electrode always maintains a low contact resistance. At the same time, the electrolyte in the pores increases the charge storage capacity of the interface, making it easier to capture the weak charge changes generated by the blasting transient, thereby enhancing the induction capability of seismic electric field signals from the source.

[0059] In this embodiment, preferably, as follows: Figure 3 As shown, the signal acquisition and wireless transmission unit 2 is an integrated sealed structure, and the acquisition and transmission housing 20 has dustproof, waterproof, and shockproof performance. Internally, it sequentially integrates a power supply module 26, a control acquisition module 25, a signal amplification and filtering module 22, a positioning module 21, and a wireless transmission module 24. The power supply module 26 is located at the bottom of the acquisition and transmission housing 20, uses a replaceable lithium battery pack, and has low power consumption and power monitoring functions. The signal amplification and filtering module 22 is located on the front circuit board of the acquisition and transmission housing 20 and is connected to the electrode array 4 and the broadband anti-saturation detector 8. The control acquisition module 25 is responsible for the logic control and module coordination of the acquisition process. The positioning module 21 records the unit's installation position. The wireless transmission module 24 is connected to the antenna 23 and transmits the acquired data to the tracked vehicle-mounted host 1.

[0060] The blasting source 5 at the tunnel face is located on the central axis in front of the tunnel face. A charging hole 11 is pre-drilled in the surrounding rock 7 at this location and filled with explosives and detonators. The detonation control unit 10 in the blasting synchronization triggering device is wirelessly connected to the tracked vehicle-mounted host 1 to receive the blasting triggering command and control the explosives in the charging hole 11 to detonate, thereby generating seismic waves 12 in the surrounding rock 7 and generating seismic-electric effect excitation.

[0061] A broadband anti-saturation detector 8 is positioned outside the electrode array 4 to synchronously acquire seismic wavefield signals, such as... Figure 2 As shown, the broadband anti-saturation detector 8 adopts a structure in which the composite coil 15 and the damping block 19 work together: the suspension support 16 inside the detector housing 14 is used to elastically suspend the low-noise magnetic core 17, the composite coil 15 is wound on the low-noise magnetic core 17, one end of the bottom spring 18 is connected to the detector housing 14, and the other end of the bottom spring 18 is connected to the damping block 19.

[0062] The composite coil 15 includes a main coil and an auxiliary coil. The main coil receives signals across the entire frequency band, while the auxiliary coil generates a reverse induced current under strong vibration conditions to counteract excessive amplitude and prevent output saturation. The damping block 19 constrains the moving parts, limiting their excessive displacement in the near-field of the blast. The suspension support 16 provides elastic suspension and precise positioning for the low-noise magnetic core 17, ensuring a stable working position for the core during vibration. Simultaneously, the damping block 19 adjusts the system's inherent frequency and damping characteristics to avoid resonance distortion, thereby expanding the overall operating frequency band. The low-noise magnetic core 17 ensures the detector's sensitivity across the entire frequency band, and the bottom spring 18 further distributes the impact load, enhancing the detector's stability under strong blasting conditions. Through this structural design, the detector's frequency response range covers 1 Hz to 5 kHz, with a dynamic range exceeding 120 dB, enabling it to output stable amplitude and complete frequency band seismic wave field signals even under strong blasting conditions in the near-field.

[0063] In this embodiment, preferably, the signal amplification and filtering module 22 (including a signal amplifier and a filter) performs differential acquisition of the signals from adjacent electrodes of the electrode array 4, that is, directly measures the potential difference between adjacent electrodes. This cancels out the common parts of environmental noise and power frequency interference, while retaining the electric field differences related to the water-bearing structure 3 ahead. This improves the prominence of the effective signal during the acquisition stage. The differential signal then enters a multi-stage filter, which is equipped with power frequency notch filtering, low-frequency cutoff, and high-frequency suppression channels. This effectively removes power frequency interference and low-frequency blasting noise, retaining only the main frequency band where the seismoelectric effect is excited. The front-end limiting protection circuit prevents distortion caused by excessive voltage at the moment of blasting, thereby ensuring stable acquisition of the seismoelectric field signal. At the same time, the filter can also perform bandwidth constraint on the seismic wave field signal output by the broadband anti-saturation detector 8 to weaken irrelevant frequency band interference and ensure complete waveform recording of the seismic wave field signal.

[0064] In this embodiment, preferably, as follows: Figure 4 As shown, the system control module sends a synchronization command to the time reference module. The time reference module provides a nanosecond-level unified time scale and sends the detonation trigger signal to the detonation control unit, enabling the blasting source at the working face to complete activation under a unified timing sequence. Simultaneously, the time reference module distributes the synchronized acquisition signal to each signal acquisition and wireless transmission unit through the signal transmission and data processing module to ensure that each acquisition channel operates under the same time reference. Taking the blasting initiation moment as the unified start time point, the control acquisition module, under the constraint of a unified time scale, simultaneously samples the seismic electric field signal output by the electrode array and the seismic wave field signal output by the broadband anti-saturation detector at a sampling rate of not less than 1MHz. The two types of signals acquired are processed by the signal amplification and filtering module and then transmitted to the tracked vehicle-mounted host through the wireless transmission module and antenna. The signal transmission and data processing module and the inversion processing module complete the reception and interpretation, realizing the reliable identification of the location and boundary of the water-bearing structure ahead.

[0065] To reduce irrelevant interference from the seismoelectric field signal, the control acquisition module 25 records the signal according to a preset short acquisition window after the blasting excitation, retaining the effective time period containing the transient response of the seismoelectric effect, and setting reference intervals before and after the window for baseline correction. In the signal transmission and data processing module, channel alignment is performed based on the unified time stamp embedded during sampling, and time delay and weighted synthesis are implemented in combination with the geometric arrangement of the electrode array 4: the signals of the left and right rows of electrodes are differentially superimposed to cancel lateral noise, and the multi-channel signals along the tunnel direction are delayed and summed to form a forward-pointing observation, thereby significantly enhancing the in-phase signal generated by the water-bearing structure 3 and effectively suppressing random noise and lateral scattering signals.

[0066] Example 2

[0067] In this embodiment, a method for advanced detection of tunnel aquifers based on blast-induced seismic-electric response is proposed. The method utilizes the tunnel aquifer advanced detection system based on blast-induced seismic-electric response proposed in Embodiment 1, such as... Figure 5 As shown, geological surveys of the target area are first conducted, followed by drilling holes in the tunnel sidewalls and arranging dual parallel line array electrodes. Seismic waves are then generated through blasting at the tunnel face, producing seismoelectric field signals and seismic wave field signals due to the seismoelectric effect. These signals are then collected and wirelessly transmitted to the tracked vehicle-mounted main control unit. The seismoelectric field and seismic wave field signals are then preprocessed to establish a three-dimensional unstructured finite element inversion model. A joint inversion calculation of the seismoelectric field and seismic wave field is then performed to locate and image the water-bearing structure ahead of the tunnel face. This model is then compared with the advance drilling information. If they do not match, the process returns to the "establishment of the three-dimensional unstructured finite element inversion model" step and is repeated. If they match, the exploration is complete, providing a basis for construction.

[0068] More specifically, it includes the following steps:

[0069] Step 1: Drill holes at the designed locations on both sides of the tunnel face, and embed the electrode array 4 in the holes in a double parallel line array, ensuring consistent spacing between electrodes within the same array. Adjacent electrodes form an electric dipole sensor to receive the seismic electric field signal generated by the blast. Broadband anti-saturation detectors 8 are pre-installed on both sides of the electrode array 4 to acquire seismic wave field signals. All electrodes and broadband anti-saturation detectors 8 are connected to the signal acquisition and wireless transmission unit 2 via cables 9.

[0070] Preferably, in this embodiment, the drilling depth, hole spacing, and electrode spacing are determined according to specific detection requirements to ensure effective sensing of electromagnetic signals.

[0071] Step 2: Fix the signal acquisition and wireless transmission unit 2 near each group of electrode arrays 4, introduce the cable 9 from the bottom interface of the acquisition and transmission housing 20, connect it to the internal signal amplification and filtering module 22 and control acquisition module 25, and have the positioning module 21 record the installation position coordinate information for subsequent inversion processing positioning.

[0072] Step 3: Reserve a charging hole 11 on the central axis of the tunnel face, fill it with explosives and detonators, and install the detonation control unit 10. The detonation control unit 10 in the blasting synchronization triggering device is wirelessly paired with the tracked vehicle-mounted host 1 to ensure that it can remotely receive detonation commands.

[0073] In the specific implementation process, when the seismic wave 12 reaches the solid-liquid interface of the water-bearing structure 3, it generates a seismoelectric effect and excites a transient electromagnetic field signal.

[0074] Step 4: Move the tracked vehicle-mounted host 1 to the safe area behind the working face, turn on the system power, and the tracked vehicle-mounted host 1 synchronizes with each signal acquisition and wireless transmission unit 2 at the nanosecond level through the time reference module to ensure that the blasting triggering and data acquisition operate under a unified time reference.

[0075] Step 5: The tracked vehicle-mounted host 1 sends a blasting command to the detonation control unit 10, triggering the blasting device to initiate blasting, generating seismic waves 12, which in turn generate seismoelectric effects in the surrounding rock 7. At the moment of detonation, each electrode array 4 and the broadband anti-saturation detector 8 start acquiring data under the control of a synchronization signal, recording the seismoelectric field signal and the seismic wave field signal respectively.

[0076] In the specific implementation process, the electric dipole sensor and the broadband anti-saturation detector 8 in the electrode array 4 sense the signal in real time, and the acquisition system acquires data at an ultra-high sampling rate (preferably, the sampling rate is greater than or equal to 1 MHz);

[0077] Step 6: After signal acquisition is completed, each signal acquisition and wireless transmission unit 2 sends data to the signal transmission and data processing module of the tracked vehicle-mounted host 1 via the wireless transmission module 24. After preprocessing the acquired data, the inversion processing module uses Maxwell's equations as the basis for forward modeling, constructs a three-dimensional unstructured mesh model, and uses the finite element method to perform data inversion, generating the distribution results of the aquifer structure 3 ahead, interpreting the geological conditions ahead of the tunnel face, and comparing the inversion results with the information obtained from advance drilling to verify the accuracy of the identification of the aquifer structure 3.

[0078] In this embodiment, the specific processing procedure of step 6 includes:

[0079] The collected seismic electric field signals are combined with geological survey data, seismic wave field signals, spatial positioning information of blasting sources and time synchronization information to construct a three-dimensional unstructured mesh finite element model covering the tunnel area. The mesh finite element model adopts irregular tetrahedral element division and local mesh refinement is carried out in the tunnel face and key areas in front of it to meet the high-precision simulation requirements of seismic electric field under complex geological conditions.

[0080] In the modeling process of the mesh finite element model, the seismic wavefield signal is first used to establish the medium velocity model and calibrate the blasting excitation time and wavefield propagation characteristics, thus providing geometric and temporal constraints for the seismoelectric field calculation. The seismoelectric field signal serves as the main data source for the inversion of electrical parameters, used to characterize the distribution characteristics of the water-bearing body. The seismic wavefield signal and the seismoelectric field signal are jointly incorporated into the inversion objective function: the seismic wave residual term is used to constrain the velocity model and the source time, while the seismoelectric signal residual term is used to constrain the electrical distribution.

[0081] The model is based on Maxwell's equations in the time domain and is used for forward modeling to simulate the propagation process of the seismic electric field under blasting excitation, and to solve for the electric field intensity distribution:

[0082] (1);

[0083] (2);

[0084] in, Let be the electric field intensity vector, representing the intensity and direction of the electric field; This is the magnetic field strength vector, representing the strength and direction of the magnetic field; Permeability; It is electrical conductivity; Where is the dielectric constant. For current density, This refers to curl in vector analysis.

[0085] After the forward modeling is completed, the simulation results are compared with the measured seismoelectric field signals and seismic wave field signals to construct an inversion objective function that includes both types of observations. :

[0086] (3);

[0087] in, and These are the observation data and forward modeling operator for the seismoelectric field signal, respectively. and These are the observation data and forward modeling operators for the seismic wavefield signal, respectively. The first term... Fitting constrained seismoelectric data, second term Fitting the constrained seismic wavefield signal, third term Regularization constraints are used to maintain the rationality and stability of the model. represents norm operation, m represents model parameters, and C represents regularization operator.

[0088] Based on the objective function of Equation (3), the Gauss-Newton iterative method is used to update the parameters. The gradient is calculated by the adjoint field method, and the velocity model and the electrical model are synchronously corrected in each iteration. In this way, the seismoelectric field signal and the seismic wave field signal complement each other, which can effectively suppress multiple solutions and improve the stability and accuracy of the inversion results.

[0089] After the inversion is completed, a three-dimensional image of the aquifer in front of the tunnel face is generated. The imaging results are compared with the results of the advance drilling. If they are consistent, they are directly applied to the identification of the aquifer structure. If there are differences, the acquisition parameters or the inversion grid density can be adjusted or recalculated to improve the accuracy.

[0090] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made by those skilled in the art without creative effort within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A tunnel aquifer detection system based on blast-induced seismic-electric response, characterized in that, include: The tracked vehicle-mounted main unit, signal acquisition and wireless transmission unit, blasting synchronization triggering device, electrode array for installation in boreholes in the sidewalls of the tunnel, and detectors for installation on the sidewalls of the tunnel. The blasting synchronization triggering device includes a detonation control unit for controlling the generation of seismic waves by detonation. The signal acquisition and wireless transmission unit is used to acquire the seismic wave field signal output by the detector and the seismoelectric field signal output by the electrode array, taking the detonation time of the detonation control unit as the unified start time point, and send them to the tracked vehicle-mounted host. The tracked vehicle-mounted host is used to perform advanced detection of the water-bearing structure ahead based on the seismic wave field signal and the seismoelectric field signal. The signal acquisition and wireless transmission unit includes a control acquisition module. The electrode array adopts a dual parallel line array structure, with adjacent electrodes forming an electric dipole sensor. Each electrode of the electrode array is connected to the control acquisition module via a cable. Each electrode surface of the electrode array is provided with a polarization-sensitive coating formed by carbon-based conductive material and porous ceramic composite, which uses the porous structure of the polarization-sensitive coating to retain moisture or conductive medium. The signal acquisition and wireless transmission unit also includes a signal amplification and filtering module, which includes a signal amplifier and a filter. The signal amplifier is used to amplify the weak seismoelectric field signal under blasting excitation; the filter is used to highlight and retain the characteristic frequency band signal of the seismoelectric effect in the background of strong blasting, and to constrain the bandwidth of the seismic wave field signal output by the broadband anti-saturation detector. The control acquisition module retains only valid segments within a set time window after the blast. Combined with the geometric arrangement of the electrode array, it performs time delay and weighting processing on the multi-channel signals. After superimposing the signals from both sides of the sidewall, the signals along the tunnel direction are combined into a forward-pointing observation.

2. The tunnel aquifer detection system based on blast-induced seismic-electric response as described in claim 1, characterized in that, The tracked vehicle-mounted host includes: a system control module, a time reference module, a signal transmission and data processing module, and an inversion processing module. The system control module is communicatively connected to the time reference module, and the time reference module is communicatively connected to the detonation control unit and the signal transmission and data processing module, respectively. The signal acquisition and wireless transmission unit acquires the seismic wave field signal output by the detector and the seismoelectric field signal output by the electrode array and sends them to the signal transmission and data processing module. The signal transmission and data processing module processes the data and sends it to the inversion processing module. The inversion processing module is used to perform advanced detection of the water-bearing structure ahead based on the pre-processed seismic wave field signal and the seismoelectric field signal.

3. The tunnel aquifer detection system based on blast-induced seismic-electric response as described in claim 1, characterized in that, The detector is used to be arranged on the left and right sides of the electrode array and connected to the control acquisition module through a cable. The detector is a broadband anti-saturation detector, which includes: detector housing, composite coil, suspension support, magnetic core, bottom spring and damping block; The suspension support inside the detector housing is used to flexibly suspend the low-noise magnetic core. The composite coil is wound on the magnetic core. One end of the bottom spring is connected to the detector housing, and the other end of the bottom spring is connected to the damping block.

4. The tunnel aquifer detection system based on blast-induced seismic-electric response as described in claim 1, characterized in that, The signal acquisition and wireless transmission unit also includes a positioning module, a power supply module, a wireless transmission module, and an antenna. The power supply module provides power to the signal amplification and filtering module, the positioning module, the wireless transmission module, and the control acquisition module. The control acquisition module is connected to the signal amplification and filtering module, the positioning module, and the wireless transmission module, respectively. The wireless transmission module is connected to the antenna. The control and acquisition module is used to simultaneously sample the seismoelectric field signal output by the electrode array and the seismic wave field signal output by the detector under the constraint of a unified start-up time. The acquired seismoelectric field signal and seismic wave field signal are processed by the signal amplification and filtering module and then transmitted to the tracked vehicle-mounted host through the wireless transmission module and antenna.

5. The tunnel aquifer detection system based on blast-induced seismic-electric response as described in any one of claims 1-4, characterized in that, The blasting source at the tunnel face is located on the central axis in front of the tunnel face. Charge holes are pre-drilled in the surrounding rock at the location of the blasting source at the tunnel face, and explosives and detonators are filled in. The detonation control unit is wirelessly connected to the tracked vehicle-mounted host to receive blasting trigger commands and control the detonation of explosives in the charging hole to generate seismic waves and produce seismoelectric effects in the surrounding rock.

6. A method for advanced detection of water-bearing bodies in tunnels based on blast-induced seismic-electric response, characterized in that, Using the tunnel aquifer advanced detection system based on blast-induced seismic-electric response as described in any one of claims 1-4, Includes the following processes: Holes are drilled in the sidewalls on both sides of the tunnel face, and electrodes are arranged in a double parallel line array in the holes, keeping the spacing consistent to form an electrode array. Detectors are placed at preset positions on both sides of the electrode array. Install signal acquisition and wireless transmission units within the location range of each electrode array and connect them to the cables of the corresponding electrode array and detector; A charging hole is reserved on the central axis of the tunnel face, detonators and explosives are filled in, an initiation control unit is set up, and remote communication pairing between the initiation control unit and the tracked vehicle-mounted host is completed. Move the tracked vehicle-mounted main unit to the safe area behind the working face and establish communication with each signal acquisition and wireless transmission unit and the detonation control unit; The tracked vehicle-mounted host sends an initiation command to the detonation control unit to initiate the blasting. At the moment of initiation, each electrode array and detector begins to synchronously collect the seismic electric field signal and the seismic wave field signal. After the seismic electric field signal and seismic wave field signal are acquired, they are sent to the tracked vehicle-mounted host through the corresponding signal acquisition and wireless transmission unit. The inversion processing module in the tracked vehicle-mounted host performs advanced detection of the water-bearing structure ahead based on the seismic wave field signal and the seismic electric field signal.

7. The method for advanced detection of tunnel aquifers based on blast-induced seismic-electric response as described in claim 6, characterized in that, Advanced detection of aquifer structures ahead based on seismic wavefield signals and seismoelectric field signals, including: By combining the collected seismic electric field signals, geological survey data, seismic wave field signals, spatial positioning information of blasting sources and time synchronization information, a three-dimensional unstructured mesh finite element model covering the tunnel area is constructed. In the process of modeling the mesh finite element model, the seismic wave field signal is first used to establish the medium velocity model and to calibrate the blasting excitation time and wave field propagation characteristics, providing geometric and temporal constraints for the calculation of the seismic electric field; Seismoelectric field signals serve as the primary data source for electrical parameter inversion, used to characterize the distribution features of water-bearing bodies. Seismic wave field signals and seismoelectric field signals are jointly incorporated into the inversion objective function: the seismic wave residual term is used to constrain the velocity model and source time, while the seismoelectric signal residual term is used to constrain the electrical distribution. The propagation process of the seismic electric field under blasting excitation was simulated by forward modeling using a mesh finite element model. After the forward modeling was completed, the simulation results were compared with the measured seismic electric field signal and seismic wave field signal. An inversion objective function containing two types of observations was constructed for inversion. After the inversion was completed, a three-dimensional image of the water-bearing body in front of the tunnel face was generated.

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