Method and device for advanced geological detection by concentrated shear acoustic wave in tunnel boring machine construction

Abstract

The present invention belongs to the field of tunnel construction detection. In order to solve the problem that it is currently impossible to accurately detect small and medium-sized unfavorable geological bodies such as meter-level and sub-meter-level, a method and device for advanced geological detection of tunnel boring machine construction focused shear sound waves are provided. Among them, the tunnel boring machine construction focused shear sound wave advanced geological detection device includes a shear wave excitation module, a reflection wave acquisition module and a signal processing module; the shear wave excitation module uses the multi-point source signal delayed excitation focusing principle to excite and generate high-frequency focused sound waves, so that the high-frequency focused sound waves can achieve sound wave energy convergence and conversion into shear waves in front of the tunnel boring machine; the reflection wave acquisition module is used to collect the reflection waves generated when the shear waves encounter abnormal bodies; the signal processing module is used to receive the reflection waves collected by the reflection wave acquisition module, and use the time-frequency domain polarization weighted filtering method to extract the shear wave signal in the reflection wave, and then based on reverse time migration imaging, the meter-level and sub-meter-level abnormal body fine imaging is realized.

Description

Technical Field

[0001] The invention belongs to the field of tunnel construction detection, and in particular relates to a method and device for advanced geological detection by concentrated shear acoustic waves during tunnel boring machine construction. Background Art

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

[0003] Underground engineering construction under complex terrain conditions generally faces disaster sources such as isolated rocks, karst caves, and broken zones. The above-mentioned unfavorable geological conditions are more concealed, and the coexistence and mutual influence of multiple disasters can easily induce major disasters, easily causing landslides, machine jams, casualties and other disasters. Therefore, it is very necessary to accurately detect such hidden disaster sources to ensure the safety of tunnel boring machine construction.

[0004] The existing methods for advanced prediction of unfavorable geology during tunnel boring machine construction mainly include: seismic wave method and excitation plan method. Among them, the seismic wave method, such as the German ISP technology, installs a pneumatic impact source on the TBM support shoe to excite the pulse signal, installs six detectors in the anchor rods of the tunnel side wall to receive the signal, and uses the signal conversion relationship of Rayleigh surface wave-transverse wave-transverse wave-Rayleigh surface wave for imaging, thereby realizing the detection of abnormal geological bodies in front of the tunnel face; the seismic wave method can also use SAP technology, which uses a mechanical source to excite seismic wave signals, uses a highly sensitive three-component acceleration sensor to receive reflected echo signals, and realizes the detection of unfavorable geological bodies in front of the face through subsequent data processing and imaging. However, the main frequency of the seismic wave method is several hundred Hz, which is relatively low, and the detection resolution is difficult to meet the needs of fine detection of meter-level and sub-meter-level hidden disaster sources such as isolated rocks and caves. Excitation planning methods, such as the resistivity method, use the TBM downtime for detection. This method uses the difference in induced polarization effect between the detection object and the surrounding medium. By observing and studying the distribution law of the artificially established induced polarization field, it conducts advance detection of water-bearing structures. Due to the volume effect of this type of method, its resolution is usually not as good as the seismic wave method.

[0005] In summary, existing technologies are unable to accurately detect small and medium-sized adverse geological bodies such as meter-scale to sub-meter-scale. Summary of the invention

[0006] In order to solve the technical problems existing in the above-mentioned background technology, the present invention provides a method and device for advanced geological detection of tunnel boring machine construction by concentrated shear acoustic waves, which can obtain the distribution of geology and unfavorable geological bodies in front of the tunnel boring machine, and make a more accurate assessment of the occurrence of small and medium-sized unfavorable geological bodies such as meter-level to sub-meter-level unfavorable geological bodies in front of the tunnel boring machine. It can predict the rock quality in front of the tunnel boring machine and timely discover unfavorable geological bodies that may induce geological disasters. The construction plan of the tunnel boring machine can be optimized accordingly, and active disaster avoidance of unfavorable geological bodies can be achieved, providing a reference for ensuring the safety of tunnel boring machine construction.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] A first aspect of the present invention provides a device for advanced geological detection by concentrated shearing acoustic waves for construction of a tunnel boring machine.

[0009] A tunnel boring machine construction energy-gathering shearing acoustic wave advanced geological detection device, comprising:

[0010] Shear wave excitation module, reflection wave acquisition module and signal processing module;

[0011] The shear wave excitation module utilizes the multi-point source signal delayed excitation focusing principle to generate high-frequency focused sound waves, so that the high-frequency focused sound waves can achieve sound wave energy convergence and conversion into shear waves in front of the tunnel boring machine;

[0012] The reflected wave acquisition module is used to acquire reflected waves generated when the shear wave encounters an abnormal body;

[0013] The signal processing module is connected to the reflected wave acquisition module; the signal processing module is used to receive the reflected waves collected by the reflected wave acquisition module, and use the time-frequency domain polarization weighted filtering method to extract the shear wave signal in the reflected wave, and then based on reverse time migration imaging, to achieve meter-level to sub-meter-level fine imaging of anomalies.

[0014] As an implementation mode, in the signal processing module, a time-frequency domain polarization weighted filtering method is used to separate the longitudinal and transverse waves in the seismic record according to the difference in the polarization directions of the longitudinal and transverse waves at the reflection wave acquisition module, and the difference in the longitudinal and transverse wave polarization parameters is used. The process includes:

[0015] Calculate the azimuth angles between the polarization principal axis of the three-component acoustic wave data and the X-axis, Y-axis and Z-axis as polarization parameter characteristics;

[0016] According to the polarization parameter characteristics, the tunnel longitudinal and transverse wave separation filter is designed;

[0017] Based on the tunnel longitudinal and transverse wave separation filter, the longitudinal and transverse wave separation calculation is performed on the three-component sound wave time-frequency spectrum to extract the required effective transverse wave components.

[0018] As an implementation method, the tunnel longitudinal and transverse wave separation filter includes P wave, SH wave and SV wave filters, which are respectively:

[0019]

[0020]

[0021]

[0022] In the above formula, , and They are P wave, SH wave and SV wave filters respectively; and are the azimuth angles between the polarization principal axis and the X-axis, and the azimuth angles between the polarization principal axis and the Y-axis or the Z-axis respectively; , , , , , They respectively represent the azimuth of the projection of the polarization principal axis on the XOY plane and the X-axis, the azimuth of the projection of the polarization principal axis on the XOZ plane and the X-axis, the azimuth of the projection of the polarization principal axis on the XOZ plane and the Z-axis, the azimuth of the projection of the polarization principal axis on the YOZ plane and the Z-axis, the azimuth of the projection of the polarization principal axis on the XOY plane and the Y-axis, and the azimuth of the projection of the polarization principal axis on the YOZ plane and the Y-axis.

[0023] As an implementation method, the formula for extracting the required effective shear wave component is:

[0024]

[0025]

[0026]

[0027] in , and They represent the synchronous squeezed wavelet transform time-frequency spectrum corresponding to the three-component geophone seismic data; , and They represent the time-frequency spectra containing effective components of P wave, SH wave and SV wave after filtering.

[0028] As an implementation manner, in the signal processing module, the process of reverse time migration imaging includes:

[0029] The source wave field is determined by using the forward propagation of the source wave field. The calculation formula of the forward propagation of the source wave field is: ; is the seismic wave field forward propagation operator; is the source wave field; represents the earthquake source time function, i.e., the earthquake source wavelet; is the pulse function; is the spatial position vector; is the spatial position vector of the earthquake source; is the wave propagation time;

[0030] The detection point wave field is determined by using the detection point wave field back propagation; the calculation formula of the detection point wave field back propagation is: ; It is the adjoint operator for the extension of seismic wave field; is the wave field of the detection point; for earthquake records; is the spatial position vector of the detection point;

[0031] The cross-correlation imaging is performed using the source wave field and the receiver wave field, and its expression is:

[0032] ; is the migration imaging section; The duration of the earthquake record.

[0033] As an implementation manner, the shear wave excitation module includes a telescopic mechanism and a shear wave excitation head, and the telescopic mechanism is used to control the shear wave excitation head to perform a telescopic action.

[0034] As an embodiment, the telescopic mechanism includes a hydraulic telescopic controller and a hydraulic telescopic cylinder; the hydraulic telescopic cylinder is connected to the shear wave excitation head; the hydraulic telescopic controller is connected to the hydraulic telescopic cylinder, and is used to control the movement of the hydraulic telescopic cylinder to drive the shear wave excitation head to automatically extend and retract.

[0035] As an implementation mode, the outside of the shear wave excitation head is a sawtooth coupling device to achieve full contact between the shear wave excitation head and the surrounding rock; the inside of the shear wave excitation head is provided with a plurality of shear vibration submodules connected in series, and each shear vibration submodule vibrates under the action of electric current to excite a coded signal.

[0036] As an implementation mode, the shear wave excitation module is installed on the shield of the tunnel boring machine; the reflected wave acquisition module is installed on the cutter head of the tunnel boring machine; the reflected wave acquisition module is a three-component sensor array.

[0037] A second aspect of the present invention provides a method for advanced geological detection using concentrated shear acoustic waves during construction of a tunnel boring machine.

[0038] A method for advanced geological detection using concentrated shear acoustic waves for tunnel boring machine construction, comprising:

[0039] The principle of delayed excitation and focusing of multi-point source signals is used to generate high-frequency focused sound waves, so that the high-frequency focused sound waves can gather the sound wave energy in front of the tunnel boring machine and convert it into shear waves.

[0040] Obtain the reflected wave generated when the shear wave encounters an abnormal body;

[0041] The shear wave signal in the reflected wave is extracted using the time-frequency domain polarization weighted filtering method, and then reverse time migration imaging is used to achieve meter-level to sub-meter-level fine imaging of anomalies.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] (1) The present invention utilizes the delayed excitation focusing principle of multi-point source signals to generate high-frequency focused sound waves. The proposed multi-source point excitation method emits multi-frequency sound waves to propagate in a certain direction, controls their energy convergence in the detection target area and generates converted shear waves (i.e., shear waves). Through delayed focusing, the controllable high-energy excitation of sound-wave-induced shear waves is achieved. Compared with the traditional single-point excitation method of seismic waves, the detection distance and resolution are improved.

[0044] (2) The present invention utilizes high-frequency focused sound waves to converge the sound wave energy in front of the tunnel boring machine and convert it into shear waves to detect abnormal bodies. Compared with longitudinal waves, the detection resolution of abnormal bodies and other adverse geological conditions is higher.

[0045] (3) The present invention uses a time-frequency domain polarization weighted filtering method to extract the shear wave signal from the reflected wave and then performs reverse time migration imaging. The shear wave is extracted from two perspectives: original data (the longitudinal wave and the shear wave have different polarization directions) and wave field separation (arrival time and frequency difference characteristics). High-resolution shear wave signals can be obtained, effectively improving the imaging quality of poor geology.

[0046] (4) The present invention installs the shear wave excitation module on the shield of the tunnel boring machine, and controls the shear wave excitation head to perform telescopic action through the telescopic mechanism, thereby realizing the automatic excitation signal of the shear wave excitation module.

[0047] (5) The reflected wave acquisition module of the present invention adopts a three-component sensor array and is installed on the cutter head of the tunnel boring machine. It can automatically collect signals without relying on manual collection, effectively improving the efficiency of poor geological detection.

[0048] Advantages of additional aspects of the present invention will be given in part in the following description, and in part will become obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0050] Figure 1 It is an overall schematic diagram of a device for advanced geological detection of a tunnel boring machine for construction of concentrated shear acoustic waves according to an embodiment of the present invention;

[0051] Figure 2 Schematic diagram of a tunnel boring machine cutter head equipped with a focused energy shear acoustic wave instrument according to an embodiment of the present invention;

[0052] Figure 3 Schematic diagram of a shear acoustic wave excitation module mounted on a tunnel boring machine according to an embodiment of the present invention;

[0053] Figure 4 It is a flow chart of a method for advanced geological detection by concentrated shear acoustic waves during construction of a tunnel boring machine according to an embodiment of the present invention;

[0054] Figure 5 is the collected reflected wave;

[0055] Figure 6 yes Figure 5 The X-axis component of the reflected wave in;

[0056] Figure 7 yes Figure 5 The Y-axis component of the reflected wave in;

[0057] Figure 8 yes Figure 5 The Z-axis component of the reflected wave in;

[0058] Fig. 9 It is extracted using the FK filtering method Figure 5 The shear wave signal in the reflected wave is shown;

[0059] Fig.10 The polarization weighted filtering method in the time-frequency domain is used to extract Figure 5 The shear wave signal in the reflected wave is shown.

[0060] in:

[0061] 1. Tunnel side wall, 2. Tunnel boring machine construction environment, 3. Tunnel boring machine shield, 4. Shear wave excitation module, 5. Side cutter, 6. Center cutter, 7. Tunnel boring machine main beam, 8. Tunnel boring machine main control room and second-floor platform, 9. Reflection wave acquisition module, 10. Tunnel excavation face, 11. Tunnel boring machine cutter head, 12. Scraper, 13. Shear wave excitation source control cable, 14. Winding device, 15. Housing, 16. Shear wave excitation head, 17. Hydraulic telescopic controller, 18. Hydraulic telescopic cylinder, 19. Excitation head control line, 20. Shear vibration submodule, 21. Excitation source protection cover, 22. Serrated coupling device. DETAILED DESCRIPTION

[0062] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0063] It should be noted that the following detailed descriptions are all illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0064] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0065] The embodiment of the present invention provides a tunnel boring machine construction energy-gathering shear acoustic wave advance geological detection device, comprising: a shear wave excitation module, a reflection wave acquisition module and a signal processing module;

[0066] The shear wave excitation module utilizes the multi-point source signal delayed excitation focusing principle to generate high-frequency focused sound waves, so that the high-frequency focused sound waves can achieve sound wave energy convergence and conversion into shear waves in front of the tunnel boring machine;

[0067] The reflected wave acquisition module is used to acquire reflected waves generated when the shear wave encounters an abnormal body;

[0068] The signal processing module is connected to the reflected wave acquisition module; the signal processing module is used to receive the reflected waves collected by the reflected wave acquisition module, and use the time-frequency domain polarization weighted filtering method to extract the shear wave signal in the reflected wave, and then based on reverse time migration imaging, to achieve meter-level to sub-meter-level fine imaging of anomalies.

[0069] according to Figure 1 In the tunnel boring machine construction environment 2, the tunnel boring machine includes a tunnel boring machine main beam 7, a tunnel boring machine main control room and a second-floor platform 8, a tunnel boring machine shield 3 and a tunnel boring machine cutter head 11. The tunnel boring machine cutter head 11 is arranged at the tunnel excavation face 10. The shear wave excitation module 4 is installed on the tunnel boring machine shield 3. The number of shear wave excitation modules 4 is at least four, which are evenly installed on the tunnel boring machine shield 3 in a circumferential direction. The shear wave excitation module 4 can be fixed by welding or bolting, and the whole forms an angle of approximately 45° with the tunnel boring machine shield 3. The excitation surface of the shear wave excitation module 4 is parallel to the tunnel side wall 1. The reflection wave acquisition module 9 is installed on the tunnel boring machine cutter head 11 through the cutter head opening; the reflection wave acquisition module 9 is a three-component sensor array. The three-component sensor array is a three-component high-precision sensor that can achieve high-resolution acquisition of shear vibration signals.

[0070] like Figure 2As shown, the panel of the tunnel boring machine cutter head 11 is equipped with side cutters 5, center cutters 6 and scrapers 12 for cutting rock mass, and holes are opened on the panel to install reflected wave collection modules 9. The number of reflected wave collection modules 9 installed is not less than twelve and is evenly installed in both vertical and horizontal directions.

[0071] like Figure 3 As shown, the shear wave excitation module has an outer shell 15 made of steel to prevent damage caused by rocks and the like, and includes a telescopic mechanism and a shear wave excitation head 16 inside, wherein the telescopic mechanism is used to control the shear wave excitation head 16 to perform telescopic action.

[0072] Specifically, the telescopic mechanism includes a hydraulic telescopic controller 17 and a hydraulic telescopic cylinder 18; the hydraulic telescopic cylinder 18 is connected to the shear wave excitation head 16; the hydraulic telescopic controller 17 is connected to the hydraulic telescopic cylinder 18 and is used to control the movement of the hydraulic telescopic cylinder 18 to drive the shear wave excitation head 16 to automatically extend and retract. An excitation source protection cover 21 is designed outside the shear wave excitation head to protect the excitation head and prevent it from being worn.

[0073] The rear of the hydraulic telescopic controller 17 is connected to the shear wave excitation source control cable 13 through the take-up device 14. The shear wave excitation source control cable 13 is used to transmit a coded signal to the shear wave excitation head 16. The take-up device 14 converges and controls the shear wave excitation source control cable 13 during the extension and retraction of the cylinder to prevent the cable from being entangled. The hydraulic telescopic cylinder 18 is controlled by the hydraulic telescopic controller 17 to realize the automatic extension and retraction of the shear wave excitation head 16. The shear wave excitation head 16 is connected to the hydraulic telescopic controller 17 through the excitation head control line 19.

[0074] It should be noted here that, in other embodiments, the telescopic mechanism may also be implemented by other existing distinguishing methods, such as cylinder drive, etc., and those skilled in the art may make specific selections according to actual conditions.

[0075] In some embodiments, the outside of the shear wave excitation head 16 is a sawtooth coupling device 22 to achieve full contact between the shear wave excitation head and the surrounding rock.

[0076] A plurality of shear wave excitation submodules 20 connected in series are arranged inside the shear wave excitation head 16. Each shear wave excitation submodule 20 generates vibration under the action of electric current to excite a coded signal. The shear wave excitation submodule 20 is made of piezoelectric ceramic material.

[0077] The working principle of the tunnel boring machine construction energy-gathering shear acoustic wave advanced geological detection device of the embodiment of the present invention is:

[0078] A shear wave excitation module is installed on the shield of the tunnel boring machine. The shear wave excitation module uses the principle of delayed excitation focusing of multi-point excitation signals to excite high-frequency focused sound waves. The signal converges the sound wave energy in front of the tunnel boring machine and converts it into shear waves. When the shear wave encounters abnormal bodies such as boulders and caves, it will generate reflected waves.

[0079] At this time, the reflected wave acquisition module (such as a three-component sensor array) installed on the cutter head of the tunnel boring machine collects the reflected wave and transmits it to the signal processing module;

[0080] In the signal processing module, the received reflected wave signal is first preprocessed to suppress tunneling noise and electromagnetic noise. The longitudinal wave signal mixed in the reflected shear wave is suppressed by using the time-frequency domain polarization weighted filtering method, utilizing the difference in polarization directions of the longitudinal and shear wave signals. The shear wave signal is extracted and reverse time migration imaging is used to achieve fine imaging of the anomaly.

[0081] Specifically, Figure 4 As shown, the shear source installed on the shield of the tunnel boring machine is used to excite the high-energy shear source wave field, and the array acoustic wave sensor installed on the cutter head of the tunnel boring machine is used to receive the shear source wave field. The received data is first preprocessed, including bad track removal (i.e., eliminating abnormal data caused by instrument damage, noise interference, etc.) and bandpass filtering (i.e., filtering out useless frequency data in the received data). The polarization characteristics of the signal are analyzed, and the time-frequency domain polarization weighted filtering method is used to suppress the longitudinal wave signal to obtain the effective shear wave reflection signal. Finally, the reverse time migration imaging method is used to achieve fine imaging of meter- to sub-meter-scale abnormal bodies such as faults, broken zones, and boulders.

[0082] Among them, the collected reflected waves are as follows Figure 5 As shown, its X-axis component, Y-axis component and Z-axis component are respectively as follows Figure 6 , Figure 7 and Figure 8 shown.

[0083] In the signal processing module, a time-frequency domain polarization weighted filtering method is used to separate the longitudinal and transverse waves in the seismic record according to the difference in the polarization directions of the longitudinal and transverse waves at the reflection wave acquisition module and the difference in the polarization parameters of the longitudinal and transverse waves. The process includes:

[0084] Step a: Calculate the azimuth angles between the polarization principal axis of the three-component acoustic wave data and the X-axis, Y-axis and Z-axis as polarization parameter features.

[0085] Among them, the azimuth angle with respect to the x-axis needs to calculate the two angles corresponding to the projection of the polarization principal axis on the XOY plane and the XOZ plane:

[0086]

[0087]

[0088]

[0089] in, It represents the azimuth angle between the projection of the polarization axis on the XOY plane and the X axis. represents taking the real part of a complex number, is the eigenvector corresponding to the maximum eigenvalue, is a sign function; is the propagation time, is the frequency and R refers to the principal axis of polarization.

[0090] Step b: Design the tunnel longitudinal and transverse wave separation filter according to the polarization parameter characteristics. The calculation formula is:

[0091]

[0092]

[0093]

[0094] In the above formula, , and They are P wave, SH wave and SV wave filters respectively; and are the azimuth angles between the polarization principal axis and the X-axis, and the azimuth angles between the polarization principal axis and the Y-axis or the Z-axis respectively; , , , , , They respectively represent the azimuth of the projection of the polarization principal axis on the XOY plane and the X-axis, the azimuth of the projection of the polarization principal axis on the XOZ plane and the X-axis, the azimuth of the projection of the polarization principal axis on the XOZ plane and the Z-axis, the azimuth of the projection of the polarization principal axis on the YOZ plane and the Z-axis, the azimuth of the projection of the polarization principal axis on the XOY plane and the Y-axis, and the azimuth of the projection of the polarization principal axis on the YOZ plane and the Y-axis.

[0095] Step c: Based on the tunnel longitudinal and transverse wave separation filter, the longitudinal and transverse wave separation calculations are performed on the three-component sound wave time-frequency spectrum to extract the required effective transverse wave components.

[0096] The three filters can be used to extract the required active ingredients in a targeted manner, namely:

[0097]

[0098]

[0099]

[0100] in , and They represent the synchronous squeezed wavelet transform time-frequency spectrum corresponding to the three-component geophone seismic data; , and They represent the time-frequency spectra containing effective components of P wave, SH wave and SV wave after filtering.

[0101] In a specific implementation process, in the signal processing module, the process of reverse time migration imaging includes:

[0102] Use the forward propagation of the earthquake source wave field to determine the earthquake source wave field;

[0103] By using the detection point wave field back propagation, the detection point wave field is determined;

[0104] Cross-correlation imaging is performed using the source wavefield and the receiver wavefield.

[0105] The forward propagation calculation formula of the source wave field is:

[0106]

[0107] In the formula, is the seismic wave field forward propagation operator; is the source wave field; represents the earthquake source time function, i.e., the earthquake source wavelet; is the pulse function; is the spatial position vector; is the spatial position vector of the earthquake source; is the wave propagation time.

[0108]

[0109] In the formula, It is the adjoint operator for the extension of seismic wave field; is the wave field of the detection point; for earthquake records; is the spatial position vector of the detection point.

[0110]

[0111] In the formula, is the migration imaging section; The duration of the earthquake record.

[0112] The present invention extracts the required effective shear wave components, such as Fig.10 shown. Fig. 9 It is extracted using the FK filtering method Figure 5The shear wave signal in the reflected wave is shown in the figure. The FK filtering method transforms the waveform data from the time-space domain (TX) to the frequency-wavenumber domain (FK). Fig. 9 and Fig.10 It can be seen that the FK transformation in the FK filtering method introduces sidelobe interference, while the present invention adopts a time-frequency domain polarization weighted filtering method, which can more accurately separate the horizontal and vertical coordinates.

[0113] Based on the above-mentioned tunnel boring machine construction energy-gathering shearing acoustic wave advanced geological detection device, the tunnel boring machine construction energy-gathering shearing acoustic wave advanced geological detection method includes:

[0114] The principle of delayed excitation and focusing of multi-point source signals is used to generate high-frequency focused sound waves, so that the high-frequency focused sound waves can gather the sound wave energy in front of the tunnel boring machine and convert it into shear waves.

[0115] Obtain the reflected wave generated when the shear wave encounters an abnormal body;

[0116] The shear wave signal in the reflected wave is extracted using the time-frequency domain polarization weighted filtering method, and then reverse time migration imaging is used to achieve meter-level to sub-meter-level fine imaging of anomalies.

[0117] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A tunnel boring machine construction energy-gathering shear acoustic wave advanced geological detection device, characterized in that: include: Shear wave excitation module, reflection wave acquisition module and signal processing module; The shear wave excitation module utilizes the multi-point source signal delayed excitation focusing principle to generate high-frequency focused sound waves, so that the high-frequency focused sound waves can achieve sound wave energy convergence and conversion into shear waves in front of the tunnel boring machine; The reflected wave acquisition module is used to acquire reflected waves generated when the shear wave encounters an abnormal body; The signal processing module is connected to the reflected wave acquisition module; the signal processing module is used to receive the reflected waves collected by the reflected wave acquisition module, and use the time-frequency domain polarization weighted filtering method to extract the shear wave signal in the reflected wave, and then based on the reverse time migration imaging, to achieve meter-level to sub-meter-level fine imaging of the abnormal body; In the signal processing module, a time-frequency domain polarization weighted filtering method is used to separate the longitudinal and transverse waves in the seismic record according to the difference in the polarization directions of the longitudinal and transverse waves at the reflection wave acquisition module and the difference in the polarization parameters of the longitudinal and transverse waves. The process includes: Calculate the azimuth angles of the polarization principal axis of the three-component acoustic wave data to the X-axis, Y-axis, and Z-axis as polarization parameter features; among them, the azimuth angle to the x-axis requires calculating the two angles corresponding to the projection of the polarization principal axis on the XOY plane and the XOZ plane: in, It represents the azimuth angle between the projection of the polarization axis on the XOY plane and the X axis. represents taking the real part of a complex number, is the eigenvector corresponding to the maximum eigenvalue, is a sign function; is the propagation time, is the frequency, R refers to the principal axis of polarization; According to the polarization parameter characteristics, a tunnel longitudinal and transverse wave separation filter is designed; wherein the tunnel longitudinal and transverse wave separation filter includes P wave, SH wave and SV wave filters, which are respectively: In the above formula, , and They are P wave, SH wave and SV wave filters respectively; and are the azimuth angles between the polarization principal axis and the X-axis, and the azimuth angles between the polarization principal axis and the Y-axis or the Z-axis respectively; , , , , , They respectively represent the azimuth of the polarization principal axis projection on the XOY plane and the X-axis, the azimuth of the polarization principal axis projection on the XOZ plane and the X-axis, the azimuth of the polarization principal axis projection on the XOZ plane and the Z-axis, the azimuth of the polarization principal axis projection on the YOZ plane and the Z-axis, the azimuth of the polarization principal axis projection on the XOY plane and the Y-axis, and the azimuth of the polarization principal axis projection on the YOZ plane and the Y-axis; based on the tunnel longitudinal and transverse wave separation filter, the longitudinal and transverse wave separation calculations are performed on the three-component acoustic wave time-frequency spectrum to extract the required effective transverse wave components; The formula for extracting the required effective shear wave component is: in , and They represent the synchronous squeezed wavelet transform time-frequency spectrum corresponding to the three-component geophone seismic data; , and They represent the time-frequency spectra containing effective components of P waves, SH waves, and SV waves after filtering; In the signal processing module, the process of reverse time migration imaging includes: The source wave field is determined by using the forward propagation of the source wave field. The calculation formula of the forward propagation of the source wave field is: ; is the seismic wave field forward propagation operator; is the source wave field; represents the earthquake source time function, i.e., the earthquake source wavelet; is the pulse function; is the spatial position vector; is the spatial position vector of the earthquake source; is the wave propagation time; The detection point wave field is determined by using the detection point wave field back propagation; the calculation formula of the detection point wave field back propagation is: ; It is the adjoint operator for the extension of seismic wave field; is the detection point wave field; for earthquake records; is the spatial position vector of the detection point; The cross-correlation imaging is performed using the source wave field and the receiver wave field, and its expression is: ; is the migration imaging section; The duration of the earthquake record.

2. The device for advanced geological detection of tunnel boring machine construction energy-gathering shearing sound waves according to claim 1, characterized in that: The shear wave excitation module comprises a telescopic mechanism and a shear wave excitation head, and the telescopic mechanism is used to control the shear wave excitation head to perform a telescopic action.

3. The device for advanced geological detection by shear acoustic wave for tunnel boring machine construction as claimed in claim 2, characterized in that: The telescopic mechanism includes a hydraulic telescopic controller and a hydraulic telescopic cylinder; the hydraulic telescopic cylinder is connected to the shear wave excitation head; the hydraulic telescopic controller is connected to the hydraulic telescopic cylinder and is used to control the movement of the hydraulic telescopic cylinder to drive the shear wave excitation head to automatically telescope.

4. The device for advanced geological detection by shear acoustic wave for tunnel boring machine construction as claimed in claim 2, characterized in that: The outside of the shear wave excitation head is a sawtooth coupling device to achieve full contact between the shear wave excitation head and the surrounding rock; the inside of the shear wave excitation head is provided with a plurality of shear vibration submodules connected in series, each of which vibrates under the action of electric current to excite a coded signal.

5. The device for advanced geological detection by shear acoustic wave for tunnel boring machine construction as claimed in claim 1, characterized in that: The shear wave excitation module is installed on the shield of the tunnel boring machine; the reflected wave acquisition module is installed on the cutter head of the tunnel boring machine; the reflected wave acquisition module is a three-component sensor array.

6. A method for advanced geological detection using concentrated shear acoustic waves during tunnel boring machine construction, characterized in that: The tunnel boring machine construction energy-gathering shear acoustic wave advanced geological detection device according to any one of claims 1 to 5 comprises: The principle of delayed excitation and focusing of multi-point source signals is used to generate high-frequency focused sound waves, so that the high-frequency focused sound waves can gather the sound wave energy in front of the tunnel boring machine and convert it into shear waves. Obtain the reflected wave generated when the shear wave encounters an abnormal body; The shear wave signal in the reflected wave is extracted using the time-frequency domain polarization weighted filtering method, and then reverse time migration imaging is used to achieve meter-level to sub-meter-level fine imaging of anomalies.

Images