Advanced geological detection method and system for dangerous rock in front of hammering tunnel face

Abstract

The invention provides an advanced geological detection method and system for dangerous rock in front of a hammering tunnel face, and belongs to the technical field of advanced geological predication.A handheld rock drill serves as a seismic source excitation device, then seismic wave signals are collected and transmitted to a processing module through a seismic collector to be processed, no extra equipment needs to be added, and the method and system are simple and convenient to operate. The method has the advantages that the construction progress is not influenced, engineering construction does not need to be paused, engineering construction and detection can be carried out at the same time, the operation efficiency is greatly improved, the working time of constructors in dangerous areas is shortened, and the safety risk is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of geological prediction, and relates to advanced geological prediction technology for tunnels, and specifically to an advanced geological detection method and system for dangerous rocks ahead of a hammer heading face. Background Art

[0002] During the construction of tunnels and underground projects, the detection of surrounding rock in front of the face is crucial to construction safety and project quality, and mechanization and automation have become the direction of change for tunnels and underground projects in complex environments. In the early practice of tunnel exploration and construction, the technical means of advance prediction detection were mainly geological radar detection, artificial or blasting sources to stimulate seismic waves. See the patent document CN201710371184.6, which discloses a multi-source seismic interference method for tunnel advance geological prediction, including first setting up multiple sources on the face of the tunnel at one end of the excavated tunnel, and laying out a seismic detector group on the face and side wall at the other end; then detonating all the sources at the same time to stimulate seismic waves; collecting transmitted seismic waves through the laid seismic detector group to form seismic records; finally, these seismic records are subjected to seismic interference processing to obtain the characteristic spectrum of the unexcavated area of ​​the tunnel, and the tunnel is advanced geologically predicted by analyzing the characteristic spectrum. The advanced geological prediction technology recorded in the patent document requires that detonation holes be opened on the face before detonation detection during construction. This not only occupies a large space in the tunnel, but also takes a long time from preparation to implementation, usually at least 2 hours, resulting in stagnation of construction progress and reduced project efficiency. Summary of the invention

[0003] In view of the existing advanced geological prediction technology described in the above background technology, its implementation process is time-consuming and there are technical problems that affect engineering efficiency. To address this technical problem, the present invention proposes a method and system for advanced geological detection of dangerous rocks in front of a hammer face.

[0004] The present invention uses a handheld rock drill as a seismic source excitation device, then collects seismic wave signals, and transmits the seismic wave signals to a processing module for processing via a seismic acquisition instrument. No additional equipment is required, and no drilling and detonation are required. The impact on the construction progress is small, which greatly improves the work efficiency, reduces the working time of construction personnel in dangerous areas, and reduces safety risks.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] The present invention provides a method for advanced geological detection of dangerous rocks in front of a hammer face, comprising the following steps:

[0007] S1: A detector group is installed at the bottom of the anchor rod in the tunnel body or at a position perpendicular to the tunnel wall, and a pilot detector is installed on the handheld rock drill. The pilot detector and the detector group are both connected to the seismic acquisition instrument in communication, and the seismic acquisition instrument is connected to the processing module in communication via a wireless ad hoc network;

[0008] S2: Use a handheld rock drill to strike the tunnel body to generate an array of seismic wave signals;

[0009] S3: The detector group and the pilot detector cooperate with the seismic acquisition instrument to collect seismic wave signals of each source excitation point, wherein the seismic wave signals include the detector signals collected by the detector group, the detector signals collected by the pilot detector and the source signals collected by the seismic acquisition instrument, and the position information of each source excitation point is recorded, and the seismic wave signals of each source excitation point are transmitted to the processing module;

[0010] S4: The processing module forms a forward seismic beam based on the position information of each source excitation point, the detector signal collected by the detector group and the detector signal collected by the pilot detector;

[0011] The processing module pre-processes the detector signals collected by the detector group of each seismic source excitation point and the seismic source signals collected by the seismic acquisition instrument to form a denoised seismic wave signal of each seismic source excitation point, and calculates the seismic wave velocity according to the position information of each seismic source excitation point and the denoised seismic wave signal;

[0012] S5: Determine the seismic shear wave velocity distribution and the seismic longitudinal wave velocity distribution based on the seismic wave velocity to form a velocity distribution result;

[0013] S6: Based on the forward seismic beam and velocity distribution results, an interpolation algorithm is used to form a forward image, and the forward image is used to observe the results of advance detection of dangerous rocks in front of the tunnel face.

[0014] It is further defined that in step S2, the array seismic wave signal refers to a seismic wave signal with multi-point distribution formed by striking at different positions of the tunnel body.

[0015] It is further defined that in step S4, the process of forming the forward seismic beam is:

[0016] Performing noise reduction processing on the detector signals collected by the leading detector and the detector signals collected by the detector group at each earthquake source excitation point, and calculating the time difference of the observation system through the detector signals of the leading detector and the detector signals of the detector group after the noise reduction processing;

[0017] The seismic wave velocity is determined based on the location information of each source excitation point and the time difference of the observation system to adjust the phase of the seismic wave at different times and form a forward seismic beam with good focusing and directionality.

[0018] It is further defined that in step S4, the processing module pre-processes the detector signals collected by the detector group of each seismic source excitation point and the seismic source signal collected by the seismic acquisition instrument, specifically including: cross-correlating the detector signals collected by the detector group of each seismic source excitation point and the seismic source signal collected by the seismic acquisition instrument through a cross-correlation algorithm, constructing a virtual seismic trace, and forming a plurality of virtual seismic trace signals, performing noise suppression and signal enhancement through the plurality of virtual seismic trace signals to form an enhanced seismic wave signal of each seismic source excitation point, and performing noise reduction processing on the enhanced seismic wave signal to form a denoised seismic wave signal;

[0019] The calculation model for cross-correlating the detector signals collected by the detector group at each source excitation point and the source signals collected by the seismic acquisition instrument through the cross-correlation algorithm is:

[0020]

[0021] D ij (τ max )=D i (t+τ max )

[0022] Where D i is the detector signal collected by the i-th detector in the detector group; τ is the time delay; t is the acquisition time; S(t) is the source signal collected by the seismic acquisition instrument; CCF ij (τ) is the cross-correlation function; τ max The maximum time delay; j is the number of the source excitation point.

[0023] It is further defined that the noise reduction processing adopts any one of energy balance, bandpass filtering, automatic gain control, reflected wave extraction or longitudinal and shear wave separation.

[0024] It is further defined that the forming of the forward image by using the interpolation algorithm in step S6 specifically includes: determining the seismic wave propagation velocity corresponding to the spatial grid point by using the forward seismic beam and the velocity distribution result, and then determining the seismic wave propagation velocity at each spatial point by using the interpolation algorithm based on the seismic wave propagation velocity corresponding to the spatial grid point;

[0025] Among them, the calculation formula for determining the seismic wave propagation velocity at each spatial point using an interpolation algorithm based on the seismic wave propagation velocity corresponding to the spatial grid point is:

[0026]

[0027] Where v(x, y, z) is the seismic wave propagation velocity at each spatial point, unit: m / s; b is the sequence number of the spatial grid point, unit: piece; N is the total number of spatial grid points, unit: piece; ω bis the interpolation weight of the b-th spatial grid point, dimensionless; v(x b ,y b ,z b ) is the seismic wave propagation velocity at the bth spatial grid point.

[0028] It is further defined that the interpolation weight of the b-th spatial grid point is determined based on an inverse distance weighted method, a bilinear interpolation method or a spline interpolation method.

[0029] The present invention discloses an advance geological detection system for dangerous rocks in front of a hammer face, which is applied to the above-mentioned advance geological detection method for dangerous rocks in front of a hammer face, and comprises a handheld rock drill, a detector group, a pilot detector, a seismic acquisition instrument, a processing module and an observation module, wherein the detector group and the pilot detector are both communicatively connected to the seismic acquisition instrument, the seismic acquisition instrument is communicatively connected to the processing module via a wireless ad hoc network, the seismic acquisition instrument sends a seismic wave signal of each source excitation point to the processing module, the processing module is connected to the observation module, the seismic wave signal comprises a detector signal collected by the detector group, a detector signal collected by the pilot detector and a source signal collected by the seismic acquisition instrument; the pilot detector is installed on the handheld rock drill, and the detector group is installed at the bottom of the anchor rod in the tunnel body or at a position perpendicular to the tunnel wall;

[0030] The handheld rock drill is used to strike the tunnel body to form an array of seismic wave signals;

[0031] The processing module is used to form a forward seismic beam based on the position information of each seismic source excitation point, the detector signal collected by the detector group and the detector signal collected by the lead detector; pre-process the detector signal collected by the detector group of each seismic source excitation point and the seismic source signal collected by the seismic acquisition instrument to form a denoised seismic wave signal of each seismic source excitation point, and calculate the seismic wave velocity according to the position information of each seismic source excitation point and the denoised seismic wave signal; determine the seismic shear wave velocity distribution and the seismic longitudinal wave velocity distribution based on the seismic wave velocity to form a velocity distribution result, and send the forward seismic beam and the velocity distribution result to the observation module;

[0032] The observation module is used to receive the forward seismic beam and velocity distribution results, and use the interpolation algorithm to form a forward image based on the forward seismic beam and velocity distribution results, and observe the advance detection results of dangerous rocks in front of the tunnel face through the forward image.

[0033] It is further defined that the said geophone group and the seismic acquisition instrument constitute an observation system;

[0034] The detector group includes multiple groups of detectors, each group of detectors includes multiple detectors, and the multiple detectors in each group are connected to the seismic acquisition instrument;

[0035] The distance between two adjacent detectors in each group of detectors is 1.5m-2m.

[0036] It is further defined that the array seismic wave signal is formed by using a handheld rock drill to perform multi-point tapping along a straight line on the tunnel body, wherein the first seismic source excitation point is no more than 3 meters away from the heading face, and the distance between two adjacent seismic source excitation points is no more than 2 meters.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] 1. The present invention provides a method for advanced geological detection of dangerous rocks in front of a hammer face. The method uses a handheld rock drill as a source excitation device, then collects seismic wave signals, and transmits the seismic wave signals to a processing module for processing via a seismic acquisition instrument. No additional equipment is required, and no drilling and detonation are required. The impact on the construction progress is relatively small. There is no need to suspend the project construction. The project construction can be carried out while the detection is carried out, which greatly improves the working efficiency, reduces the working time of the construction personnel in the dangerous area, and reduces the safety risks.

[0039] 2. The present invention utilizes a handheld rock drill as a seismic source excitation device, which can quickly and conveniently generate a large number of high-quality seismic source signals, and the striking position, intensity and time can be precisely controlled.

[0040] 3. In the present invention, the seismic acquisition instrument is connected to the processing module through a wireless ad hoc network, and the wireless transmission method of the ad hoc network is adopted, which effectively avoids the complexity of wiring in the traditional prediction method and simplifies the installation and maintenance process.

[0041] 4. The observation system of the present invention is designed for long-term deployment in the tunnel body, does not affect construction, does not require frequent assembly and disassembly, and improves the stability and reliability of observation.

[0042] 5. The present invention utilizes a cross-correlation algorithm to perform cross-correlation processing on the detector signals collected by the detector group of each earthquake source excitation point and the earthquake source signals collected by the seismic acquisition instrument, constructs a plurality of virtual seismic trace signals, and utilizes these virtual signals to perform noise suppression and signal enhancement, and forms a plurality of virtual seismic trace signals, and performs noise suppression and signal enhancement through a plurality of virtual seismic trace signals to form an enhanced seismic wave signal of each earthquake source excitation point, thereby improving the signal-to-noise ratio of the seismic wave signal.

[0043] 6. In the present invention, any one of energy balance, bandpass filtering, automatic gain control, reflection wave extraction or longitudinal and transverse wave separation is used to enhance the seismic wave signal for noise reduction processing, thereby achieving effective removal of noise in the seismic wave signal of each source excitation point. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1A schematic diagram of the source excitation point of the present invention;

[0045] Figure 2 It is a schematic diagram of the method for advanced geological detection of dangerous rocks in front of the face of the hammer according to the present invention;

[0046] In the figure, 1-source excitation point, 2-detector, 3-handheld rock drill. DETAILED DESCRIPTION

[0047] The technical solution of the present invention is further explained below in conjunction with the accompanying drawings and embodiments, but the present invention is not limited to the implementation methods of the following description.

[0048] See also Figure 2 The present invention proposes a method for advanced geological detection of dangerous rocks in front of a hammer face, comprising the following steps:

[0049] S1: A detector group is installed at the bottom of the anchor rod in the tunnel body or at a position perpendicular to the tunnel wall, and a pilot detector is installed on the handheld rock drill 3. The pilot detector and the detector group are both connected to the seismic acquisition instrument in communication, and the seismic acquisition instrument is connected to the processing module in communication via a wireless ad hoc network.

[0050] S2: Use the handheld rock drill 3 to strike the tunnel body to form an array seismic wave signal; specifically, the array seismic wave signal refers to using the handheld rock drill 3 to strike different positions of the tunnel body to form a multi-point distributed seismic wave signal.

[0051] S3: The detector group and the pilot detector cooperate with the seismic acquisition instrument to collect the seismic wave signal of each source excitation point 1, wherein the seismic wave signal includes the detector 2 signal collected by the detector group, the detector 2 signal collected by the pilot detector and the source signal collected by the seismic acquisition instrument, and records the position information of each source excitation point 1, and transmits the seismic wave signal of each source excitation point 1 to the processing module.

[0052] S4: The processing module forms a forward seismic beam based on the position information of each source excitation point 1, the detector 2 signal collected by the detector group and the detector 2 signal collected by the pilot detector;

[0053] The processing module preprocesses the detector 2 signal collected by the detector group of each seismic source excitation point 1 and the seismic source signal collected by the seismic acquisition instrument to form a denoised seismic wave signal of each seismic source excitation point 1, and calculates the seismic wave velocity based on the position information of each seismic source excitation point 1 and the denoised seismic wave signal.

[0054] S5: Determine the seismic shear wave velocity distribution and the seismic longitudinal wave velocity distribution based on the seismic wave velocity to form a velocity distribution result.

[0055] S6: Based on the forward seismic beam and velocity distribution results, an interpolation algorithm is used to form a forward image, and the forward image is used to observe the results of advance detection of dangerous rocks in front of the tunnel face.

[0056] According to the construction cycle, the detector group can be moved regularly (one week or two weeks) along the excavation direction of the tunnel, and steps S1-S6 can be repeated to perform full-process detection along with the entire tunnel excavation process.

[0057] Preferably, the handheld rock drill 3 in the present invention is a handheld pneumatic rock drill.

[0058] In the present invention, the process of forming the forward seismic beam in step S4 is as follows: performing noise reduction processing on the detector 2 signal collected by the leading detector of each seismic source excitation point 1 and the detector 2 signal collected by the detector group, and calculating the time difference of the observation system through the detector 2 signal of the leading detector and the detector 2 signal of the detector group after the noise reduction processing; determining the seismic wave velocity according to the position information of each seismic source excitation point 1 and the time difference of the observation system, so as to adjust the phase of the seismic wave at different times, and form a forward seismic beam with good focusing and directionality.

[0059] In the present invention, in step S4, the processing module pre-processes the detector 2 signal collected by the detector group of each seismic source excitation point 1 and the seismic source signal collected by the seismic acquisition instrument, specifically including: cross-correlation processing is performed on the detector 2 signal collected by the detector group of each seismic source excitation point 1 and the seismic source signal collected by the seismic acquisition instrument through a cross-correlation algorithm, a virtual seismic trace is constructed, and a plurality of virtual seismic trace signals are formed, noise suppression and signal enhancement are performed through the plurality of virtual seismic trace signals to form an enhanced seismic wave signal of each seismic source excitation point 1, and the enhanced seismic wave signal is subjected to noise reduction processing to form a denoised seismic wave signal; the detector signal and the seismic source signal are processed through a cross-correlation algorithm to filter out irrelevant noise, improve the signal-to-noise ratio of the signal, and thus improve the recording quality of the seismic wave signal.

[0060] The calculation model for cross-correlating the detector 2 signal collected by the detector group of each source excitation point 1 and the source signal collected by the seismic acquisition instrument through the cross-correlation algorithm is:

[0061]

[0062] D ij (τ max )=D i (t+τ max )

[0063] Where D i is the signal of detector 2 collected by the i-th detector 2 in the detector group; τ is the time delay; t is the acquisition time; S(t) is the source signal collected by the seismic acquisition instrument; CCFij (τ) is the cross-correlation function; τ max The maximum time delay; j is the number of the source excitation point.

[0064] In the present invention, in step S2, the use of a handheld rock drill 3 to tap the tunnel body to form an array seismic wave signal is specifically as follows: the handheld rock drill 3 is used to perform multi-point tapping along a straight line on the tunnel body to form an array seismic wave signal, wherein the first source excitation point is no more than 3 meters away from the heading, and the distance between two adjacent source excitation points 1 is no more than 2 meters.

[0065] In the present invention, the noise reduction process adopts any one of energy balance, bandpass filtering, automatic gain control, reflection wave extraction or longitudinal wave and shear wave separation.

[0066] Energy balance is the abbreviation of the inter-channel / intra-channel energy balance method. It is to perform energy normalization processing on different virtual seismic channel signals of the same source excitation point, that is, channel equalization processing. The purpose of channel equalization is to weaken the energy deviation caused by differences in signal path, detector sensitivity or geological conditions, and ensure that the signal strength of all channels is at a relatively consistent level. Channel equalization averages the energy of each channel of the detector signal to make the energy distribution of the seismic record more uniform, thereby providing a unified and balanced input condition for subsequent data denoising. This can effectively avoid the situation where some channels cause noise amplification or filtering failure due to excessive energy, and prevent channels with too little energy from being ignored or mistaken for noise components during the denoising process. Channel equalization can not only improve the accuracy and robustness of the denoising algorithm, but also improve the stability and reliability of subsequent signal analysis, ensuring the integrity and identifiability of effective seismic wave signals.

[0067] The calculation formula for energy balance processing is:

[0068]

[0069] Where D(t) is the denoised seismic wave signal, D norm (t) is the normalized seismic wave signal, [t0, t1] is the signal analysis time window; t is the acquisition time.

[0070] The bandpass filtering method removes the noise of irrelevant frequency bands, extracts the target frequency band signal, and analyzes the spectrum X(f) of the source signal S(t) through Fourier transform to determine the main frequency band range of the source [f min ,f max ], according to the main frequency band range, high-pass filter and low-pass filter are involved to remove irrelevant noise. Among them, the transfer function of the low-pass filter is: Filter out the noise that is higher than the effective frequency band of the source signal; the transfer function of the high-pass filter is: f is the current frequency of the filter response, filtering out noise below the effective frequency band of the source signal. By designing the high-pass filter and the low-pass filter, the main frequency band range of the source signal [f min ,f max ], remove noise and enhance signal quality.

[0071] Automatic gain control adjusts the dynamic range of the target signal and enhances the weaker signal by setting the time window width T win To dynamically adjust the signal amplitude, the specific formula is:

[0072]

[0073] Where D AGC (t) is the signal after automatic gain control, t is the acquisition time, T win is the time window width, t′ is the independent variable in the integration, representing any moment within the time window, and D(t) is the denoised seismic wave signal.

[0074] Reflection wave extraction is based on the analysis of waveform characteristics selected in the time window, including: using the arrival time T of the first arrival wave a , define the reflection wave extraction time window [T s ,T e ], where T s =T a +Δt1,T e =T a +Δt2, Δt1, Δt2 are preset delay times respectively. The reflected wave and the direct wave are separated by wavelet transform, and the reflected wave signal is enhanced by using the time-frequency domain characteristics.

[0075] The longitudinal and transverse wave separation analyzes the characteristics of the reflected waves and obtains the geological information corresponding to the seismic longitudinal waves and seismic transverse waves. Based on the difference in seismic information of different components of the manual rock drill 3 seismic signal received by the detector, different directional filters are designed to separate the seismic longitudinal waves and seismic transverse waves. A directional filter is designed to separate the seismic longitudinal waves and seismic transverse waves by controlling the propagation direction of the signal. Since the propagation directions of seismic longitudinal waves and seismic transverse waves are different, the filter can be designed by setting appropriate directional parameters. The directionality of the filter is determined by analyzing the propagation direction of the seismic wave and the arrangement of the detector group. The transfer function H(θ) of the directional filter depends on the angle θ (propagation direction) and the characteristics of the target wave. The directional filter function can be expressed as:

[0076]

[0077] In the formula, θ represents the propagation direction of seismic waves, θ min and θ max is the specified effective direction range, f is the seismic wave frequency, Hdir (f,θ) is the transfer function of the directional filter, which is used to describe the response of the filter at different frequencies f and directional angles θ.

[0078] In the present invention, forming a forward image by using an interpolation algorithm in step S6 specifically includes: determining the seismic wave propagation velocity corresponding to the spatial grid point by using the forward seismic beam and the velocity distribution result, and then determining the seismic wave propagation velocity at each spatial point by using an interpolation algorithm based on the seismic wave propagation velocity corresponding to the spatial grid point;

[0079] Among them, the calculation formula for determining the seismic wave propagation velocity at each spatial point using an interpolation algorithm based on the seismic wave propagation velocity corresponding to the spatial grid point is:

[0080]

[0081] Where v(x, y, z) is the seismic wave propagation velocity at each spatial point, unit: m / s; b is the sequence number of the spatial grid point, unit: piece; N is the total number of spatial grid points, unit: piece; ω b is the interpolation weight of the b-th spatial grid point, dimensionless; v(x b ,y b ,z b ) is the seismic wave propagation velocity of the b-th spatial grid point, in m / s. The interpolation weight of the b-th spatial grid point is determined based on the inverse distance weighted method, the bilinear interpolation method or the spline interpolation method.

[0082] The forward modeling simulates the seismic wave propagation process, specifically: construct a geological model based on the forward seismic beam and velocity distribution results; define the source position and excitation time based on the source signal generated by the handheld rock drill; perform time step calculation based on the wave equation in combination with numerical methods (such as finite difference method, finite element method) to simulate the propagation of the seismic wave field in the medium; collect simulated seismic wave field data (detector signal) at the detector group position to generate theoretical seismic records (virtual seismic traces); process and visualize the simulation results to obtain a forward image, and mark the abnormal reflection wave area in the forward image to identify the distribution of dangerous rocks in front of the face.

[0083] The present invention discloses an advance geological detection system for dangerous rocks in front of a hammer face, which is applied to the above-mentioned advance geological detection method for dangerous rocks in front of a hammer face, and comprises a handheld rock drill 3, a detector group, a pilot detector, a seismic acquisition instrument, a processing module and an observation module. The detector group and the pilot detector are both connected to the seismic acquisition instrument in communication, and the seismic acquisition instrument is connected to the processing module in communication via a wireless ad hoc network. The seismic acquisition instrument sends the seismic wave signal of each source excitation point 1 to the processing module, and the processing module is connected to the observation module. The seismic wave signal comprises a detector 2 signal collected by the detector group, a detector 2 signal collected by the pilot detector, and a source signal collected by the seismic acquisition instrument. The pilot detector is installed on the handheld rock drill 3, and the detector group is installed at the bottom of the anchor rod in the tunnel body or at a position perpendicular to the tunnel wall.

[0084] Handheld rock drill 3: used to strike the tunnel body to form array seismic wave signals;

[0085] Processing module: used to form a forward seismic beam based on the position information of each seismic source excitation point 1, the signal of the detector 2 collected by the detector group and the signal of the detector 2 collected by the lead detector; pre-process the signal of the detector 2 collected by the detector group of each seismic source excitation point 1 and the source signal collected by the seismic acquisition instrument to form a denoised seismic wave signal of each seismic source excitation point 1, and calculate the seismic wave velocity according to the position information of each seismic source excitation point 1 and the denoised seismic wave signal; determine the seismic shear wave velocity distribution and the seismic longitudinal wave velocity distribution based on the seismic wave velocity, form a velocity distribution result, and send the forward seismic beam and the velocity distribution result to the observation module;

[0086] The observation module is used to receive the forward seismic beam and velocity distribution results, and use the interpolation algorithm to form a forward image based on the forward seismic beam and velocity distribution results, and observe the advance detection results of dangerous rocks in front of the tunnel face through the forward image.

[0087] The system for advanced geological detection of dangerous rocks in front of a hammering face in the present invention is completely corresponding to a method for advanced geological detection of dangerous rocks in front of a hammering face. For the contents of the processing module and the contents of the observation module that are not fully described in the part about the system for advanced geological detection of dangerous rocks in front of a hammering face, please refer to the description of the method for advanced geological detection of dangerous rocks in front of a hammering face mentioned above.

[0088] In the present invention, the detector group and the seismic acquisition instrument constitute an observation system; see Figure 1The detector group includes multiple groups of detectors, each group of detectors includes multiple detectors 2, and the multiple detectors 2 in each group are connected to the seismic acquisition instrument; preferably, the detector group includes 6-8 groups of detectors, and each group of detectors includes 4 detectors 2. The distance between two adjacent detectors 2 in each group of detectors is 1.5m-2m, specifically 1.5m, 1.6m, 1.7m, 1.8m, 1.9m or 2.0m. The deployed detectors 2 are connected to the seismic acquisition instrument to form a 6-8 ring stereoscopic observation system. The multiple detectors in the detector group are distributed in different spatial positions, and can receive seismic wave information at different distances and angles, ensure resolution, conduct all-round monitoring of geological conditions, and reduce blind spots.

[0089] In the present invention, each group of geophones is distributed around the circumference of the tunnel.

[0090] In the present invention, the detector 3 is installed at the bottom of the anchor rod in the tunnel body or at a position perpendicular to the tunnel wall. When the detector is installed at a position perpendicular to the tunnel wall, a hole with a depth of 1.5m-2m needs to be drilled in the tunnel wall, the detector is installed in the hole, and coupled and fixed with a coupling agent.

[0091] In the present invention, the array seismic wave signal is formed by using a handheld rock drill 3 to perform multi-point tapping along a straight line on the tunnel body, wherein the first source excitation point 1 is no more than 3 meters away from the heading face, and the distance between two adjacent source excitation points 1 is no more than 2 meters.

[0092] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit the present application. Although the present application has been described in detail with reference to the aforementioned embodiments, a person of ordinary skill in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some or all of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the present application.

Claims

1. A method for advanced geological detection of dangerous rocks in front of a hammer face, characterized in that: The following steps are involved: S1: A detector group is installed at the bottom of the anchor rod in the tunnel body or at a position perpendicular to the tunnel wall, and a pilot detector is installed on the handheld rock drill. The pilot detector and the detector group are both connected to the seismic acquisition instrument in communication, and the seismic acquisition instrument is connected to the processing module in communication via a wireless ad hoc network; S2: Use a handheld rock drill to strike the tunnel body to generate an array of seismic wave signals; S3: The detector group and the pilot detector cooperate with the seismic acquisition instrument to collect seismic wave signals of each source excitation point, wherein the seismic wave signals include the detector signals collected by the detector group, the detector signals collected by the pilot detector and the source signals collected by the seismic acquisition instrument, and the position information of each source excitation point is recorded, and the seismic wave signals of each source excitation point are transmitted to the processing module; S4: The processing module forms a forward seismic beam based on the position information of each source excitation point, the detector signal collected by the detector group and the detector signal collected by the pilot detector; The processing module pre-processes the detector signals collected by the detector group of each seismic source excitation point and the seismic source signals collected by the seismic acquisition instrument to form a denoised seismic wave signal of each seismic source excitation point, and calculates the seismic wave velocity according to the position information of each seismic source excitation point and the denoised seismic wave signal; S5: Determine the seismic shear wave velocity distribution and the seismic longitudinal wave velocity distribution based on the seismic wave velocity to form a velocity distribution result; S6: Based on the forward seismic beam and velocity distribution results, an interpolation algorithm is used to form a forward image, and the forward image is used to observe the results of advance detection of dangerous rocks in front of the tunnel face.

2. The method for advanced geological detection of dangerous rocks in front of the hammer face according to claim 1 is characterized in that: In step S2, the array seismic wave signal refers to a seismic wave signal with multi-point distribution formed by striking at different positions of the tunnel body.

3. The method for advanced geological detection of dangerous rocks in front of the hammer face according to claim 1 is characterized in that: In step S4, the process of forming the forward seismic beam is as follows: Performing noise reduction processing on the detector signals collected by the leading detector and the detector signals collected by the detector group at each earthquake source excitation point, and calculating the time difference of the observation system through the detector signals of the leading detector and the detector signals of the detector group after the noise reduction processing; The seismic wave velocity is determined based on the location information of each source excitation point and the time difference of the observation system to adjust the phase of the seismic wave at different times and form a forward seismic beam with good focusing and directionality.

4. The method for advanced geological detection of dangerous rocks in front of the hammer face according to claim 3 is characterized in that: In the step S4, the processing module pre-processes the detector signals collected by the detector group of each seismic source excitation point and the seismic source signal collected by the seismic acquisition instrument, specifically including: cross-correlation processing is performed on the detector signals collected by the detector group of each seismic source excitation point and the seismic source signal collected by the seismic acquisition instrument through a cross-correlation algorithm, a virtual seismic trace is constructed, and a plurality of virtual seismic trace signals are formed, noise suppression and signal enhancement are performed through the plurality of virtual seismic trace signals to form an enhanced seismic wave signal of each seismic source excitation point, and noise reduction processing is performed on the enhanced seismic wave signal to form a denoised seismic wave signal; The calculation model for cross-correlating the detector signals collected by the detector group at each source excitation point and the source signals collected by the seismic acquisition instrument through the cross-correlation algorithm is: D ij (t max )=D i (t+τ max ) Where D i is the detector signal collected by the i-th detector in the detector group; τ is the time delay; t is the acquisition time; S(t) is the source signal collected by the seismic acquisition instrument; CCF ij (τ) is the cross-correlation function; τ max The maximum time delay; j is the number of the source excitation point.

5. The method for advanced geological detection of dangerous rocks in front of the hammer face according to claim 4 is characterized in that: The noise reduction process adopts any one of energy balance, bandpass filtering, automatic gain control, reflection wave extraction or longitudinal wave and shear wave separation.

6. The method for advanced geological detection of dangerous rocks in front of the hammer face according to claim 1 is characterized in that: The step S6 of forming a forward image by using an interpolation algorithm specifically includes: determining the seismic wave propagation velocity corresponding to the spatial grid point through the forward seismic beam and the velocity distribution result, and then determining the seismic wave propagation velocity at each spatial point by using an interpolation algorithm based on the seismic wave propagation velocity corresponding to the spatial grid point; Among them, the calculation formula for determining the seismic wave propagation velocity at each spatial point using an interpolation algorithm based on the seismic wave propagation velocity corresponding to the spatial grid point is: Where v(x, y, z) is the seismic wave propagation velocity at each spatial point, unit: m / s; b is the sequence number of the spatial grid point, unit: piece; N is the total number of spatial grid points, unit: piece; ω b is the interpolation weight of the b-th spatial grid point, dimensionless; v(x b ,y b ,z b ) is the seismic wave propagation velocity at the bth spatial grid point.

7. The method for advanced geological detection of dangerous rocks in front of the hammer face according to claim 6 is characterized in that: The interpolation weight of the b-th spatial grid point is determined based on an inverse distance weighted method, a bilinear interpolation method or a spline interpolation method.

8. A system for advanced geological detection of dangerous rocks in front of a hammer face, applied to the method for advanced geological detection of dangerous rocks in front of a hammer face as claimed in claim 1, characterized in that: It includes a handheld rock drill, a detector group, a pilot detector, a seismic acquisition instrument, a processing module and an observation module. The detector group and the pilot detector are both connected to the seismic acquisition instrument in communication. The seismic acquisition instrument is connected to the processing module in communication through a wireless ad hoc network. The seismic acquisition instrument sends the seismic wave signal of each source excitation point to the processing module. The processing module is connected to the observation module. The seismic wave signal includes the detector signal collected by the detector group, the detector signal collected by the pilot detector and the source signal collected by the seismic acquisition instrument. The pilot detector is installed on the handheld rock drill, and the detector group is installed at the bottom of the anchor rod in the tunnel body or at a position perpendicular to the tunnel wall. The handheld rock drill is used to strike the tunnel body to form an array of seismic wave signals; The processing module is used to form a forward seismic beam based on the position information of each seismic source excitation point, the detector signal collected by the detector group and the detector signal collected by the pilot detector; Preprocessing the detector signals collected by the detector group of each seismic source excitation point and the seismic source signals collected by the seismic acquisition instrument to form a denoised seismic wave signal of each seismic source excitation point, and calculating the seismic wave velocity according to the position information of each seismic source excitation point and the denoised seismic wave signal; determining the seismic shear wave velocity distribution and the seismic longitudinal wave velocity distribution based on the seismic wave velocity to form a velocity distribution result, and sending the forward seismic beam and the velocity distribution result to the observation module; The observation module is used to receive the forward seismic beam and velocity distribution results, and use the interpolation algorithm to form a forward image based on the forward seismic beam and velocity distribution results, and observe the advance detection results of dangerous rocks in front of the tunnel face through the forward image.

9. The system for advanced geological detection of dangerous rocks in front of the hammer face according to claim 8 is characterized in that: The geophone group and the seismic acquisition instrument constitute an observation system; The detector group includes multiple groups of detectors, each group of detectors includes multiple detectors, and the multiple detectors in each group are connected to the seismic acquisition instrument; The distance between two adjacent detectors in each group of detectors is 1.5m-2m.

10. The system for advanced geological detection of dangerous rocks in front of the hammer face according to claim 8, characterized in that: The array seismic wave signal is formed by using a handheld rock drill to perform multi-point tapping along a straight line in the tunnel body. The first seismic source excitation point is no more than 3 meters away from the heading face, and the distance between the two adjacent seismic source excitation points is no more than 2 meters.

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