Method and system for orienting and imaging sound wave detection data in tunnel hole

Abstract

The invention provides an orientation and imaging method and system for sound wave detection data in a tunnel hole, and the method comprises the steps: obtaining sound wave data in different directions responding to the same excitation sound wave, rotating the sound wave data until an orthogonal component disappears, and determining the direction of a reflector according to a rotation angle; carrying out weighted summation on the sound wave data acquired by the receiving array to obtain scalar output, calculating an optimal weight to receive a target signal from a reflector orientation to the greatest extent, and carrying out weighted processing according to the optimal weight to obtain a superposed signal; and solving a three-dimensional elastic wave wave equation based on the processed superposed signal to obtain a forward wave field and a reverse wave field, and performing migration imaging by using a cross-correlation imaging condition to obtain a three-dimensional migration imaging result. The method can enhance the signal-to-noise ratio of the weak reflection signal, and achieves the quick and accurate judgment of the orientation of the target body in front of the tunnel face.

Description

Technical Field

[0001] The invention belongs to the technical field of tunnel advance prediction, and in particular relates to a method and system for orienting and imaging acoustic wave detection data in a tunnel hole. 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] With the increase in the scale and difficulty of tunnel construction, the current mainstream geophysical methods are unable to accurately perceive the effective information in front of the tunnel face due to the influence of narrow space and electromagnetic interference. The research on tunnel fine advance detection methods is not in-depth, and it is urgent to explore a usable fine advance detection method suitable for the complex environment of the tunnel.

[0004] A series of achievements in the research foundation of acoustic wave remote detection theory and measurement methods provide a basis for the processing and interpretation of hole perimeter structure and reflection wave data. At present, the imaging methods that are widely used in reflection acoustic wave measurement are diffraction scanning superposition method, generalized Radon transform migration method, Kirchhoff integral migration method, equivalent offset migration method, etc. Since the reflected wave in the measured data of acoustic wave remote detection is a weak signal relative to the direct wave, the signal-to-noise ratio is low, and the formation velocity changes greatly along the well axis, further work needs to be done on the calculation speed and effect of the migration. At the same time, in the study of directional methods, the direction of the reflector is often identified by comparing the strength of the reflected energy in different directions. This method can quantitatively determine the direction of the target body, but due to the low signal-to-noise ratio of the reflected wave and the interference of false reflected waves, the result is often large in error. Therefore, in order to make up for this defect and further improve the reliability of the interpretation of borehole acoustic wave data, it is necessary to improve the signal-to-noise ratio of the reflected wave and combine the directional method with the imaging method.

[0005] In summary, the current borehole acoustic wave migration imaging method mainly uses the ray method, which still has the following problems: 1) The elastic wave is simplified into ray propagation, which has a large error with the actual situation and limits the imaging accuracy of the method. 2) Imaging and orientation are calculated separately, which does not fully utilize the advantages of the dipole sound source. 3) The full-wave signal recorded by the borehole acoustic wave receiver contains mode waves, reflection waves and other types, which interfere with suppression, making the effective signal unclear and the signal-to-noise ratio poor. Summary of the invention

[0006] In order to solve the above problems, the present invention proposes a method and system for directional and imaging acoustic wave detection data in a tunnel hole. The present invention can enhance the signal-to-noise ratio of weak reflection signals while taking advantage of the dipole directionality.

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

[0008] A method for directing and imaging acoustic wave detection data in a tunnel hole, comprising the following steps:

[0009] Acquire sound wave data of different orientations in response to the same excitation sound wave, rotate the sound wave data until the orthogonal component disappears, and determine the orientation of the reflector according to the rotation angle;

[0010] The sound wave data acquired by the receiving array is weighted and summed to obtain a scalar output, and the optimal weight is calculated to maximize the reception of target signals from the direction of the reflector. Weighted processing is performed according to the optimal weight to obtain a superimposed signal;

[0011] Based on the processed superposition signal, the three-dimensional elastic wave equation is solved to obtain the forward wave field and the reverse wave field. The migration imaging is performed using the cross-correlation imaging condition to obtain the three-dimensional migration imaging result.

[0012] As an optional implementation, the excitation sound wave includes an excitation sound wave of a monopole sound source and an excitation sound wave of an orthogonal dipole sound source.

[0013] As an optional implementation, a single dipole sound source sequentially excites sound waves, and four receiving sensors spaced 90° apart in the circumferential direction record four different component waveforms in different directions.

[0014] As an optional implementation, the received four-component waveform is rotated using the Alford rotation method. When it is rotated to be parallel or perpendicular to the direction of the reflector, the rotated orthogonal components disappear, and the orientation of the reflector can be determined based on the rotation angle.

[0015] As an optional implementation, according to the determined reflector orientation and the amplitude of the reflected wave received when the monopole is excited, the interface orientation is determined by comparing the intensity of the signals on both sides, and the maximum angle of the SH wave reflected energy is the angle of the reflection interface.

[0016] As an optional implementation, a weighted sum is performed on the acquired acoustic wave data to obtain a scalar output, and the process of calculating the optimal weight includes: calculating the error between the actual output signal of the receiving array and the expected output signal, constructing a cost function and continuously iterating to minimize the mean square value of the estimated error, and differentiating the weight vector therein to obtain the optimal weight solution.

[0017] As an optional implementation method, based on the processed superposition signal, the three-dimensional elastic wave equation is solved to obtain the forward wave field and the reverse wave field. The process includes: under the condition of point source excitation, constructing the elastic wave equation in the three-dimensional isotropic medium, using the high-order difference method to perform differential discretization on the elastic wave equation, and calculating the forward wave field extension according to the exciting sound source wavelet, taking the processed superposition signal as the exciting sound source, transmitting it back, and calculating the reverse wave field extension.

[0018] A tunnel bore acoustic wave detection data orientation and imaging system, comprising:

[0019] An orientation determination module is used to obtain sound wave data of different orientations in response to the same excitation sound wave, rotate the sound wave data until the orthogonal component disappears, and determine the orientation of the reflector according to the rotation angle;

[0020] The adaptive beamforming module is configured to perform weighted summation on the acoustic wave data acquired by the receiving array to obtain a scalar output, calculate an optimal weight value to maximize the reception of target signals from the direction of the reflector, perform weighted processing according to the optimal weight value, and obtain a superposition signal;

[0021] The migration imaging module is configured to solve the three-dimensional elastic wave equation based on the processed superposition signal to obtain the forward wave field and the reverse wave field, perform migration imaging using the cross-correlation imaging condition, and obtain the three-dimensional migration imaging result.

[0022] A computer-readable storage medium is used to store computer instructions, and when the computer instructions are executed by a processor, the steps in the above method are completed.

[0023] An electronic device comprises a memory and a processor, and computer instructions stored in the memory and executed on the processor. When the computer instructions are executed by the processor, the steps in the above method are completed.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. The present invention adopts a directional observation method of sound waves in tunnel holes, including a monopole sound source and a dipole sound source. When the instrument is working, the monopole sound source excites sound waves in turn, and four receiving sensors separated by 90° in the circumferential direction record four different component waveforms in different directions. The four-component data is used to realize the directional transmission and directional reception of sound waves, and the azimuth of the target body in front of the tunnel face is quickly and accurately determined.

[0026] 2. The present invention adopts an adaptive beamforming technology based on Gaussian cumulant characteristics to enhance the detection of sound waves from a specific direction while suppressing noise from other directions; improves the signal-to-noise ratio of sound wave data and makes it easier to identify relevant sound sources in a noisy tunnel environment.

[0027] 3. The present invention combines directional acoustic wave detection with three-dimensional imaging technology, inputs processed acoustic wave data, solves the three-dimensional elastic wave equation through the finite difference method, obtains the extended wave field of the sound source and receiving transducer, and then uses the cross-correlation imaging condition to perform offset imaging to obtain three-dimensional offset imaging results, which helps to identify potential dangers such as cavities or unstable rock formations.

[0028] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] 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.

[0030] Figure 1 A schematic diagram of a sound source directional observation mode provided by an embodiment;

[0031] Figure 2 A schematic diagram of beamforming provided in accordance with an embodiment. DETAILED DESCRIPTION

[0032] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0033] 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.

[0034] 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.

[0035] In the absence of conflict, the embodiments in this application and the features in the embodiments may be combined with each other.

[0036] Embodiment 1

[0037] A method for directing and imaging acoustic wave detection data in a tunnel hole based on beamforming, such as Figure 2 As shown, the following steps are included:

[0038] Step 1: Design a directional observation method for sound waves in the hole, including a monopole sound source and an orthogonal dipole sound source. When the instrument is working, the monopole sound source excites the sound waves in turn, such as Figure 1 As shown, four receiving sensors separated by 90° in the circumferential direction record four different component waveforms in different directions. The four-component data is used to realize the directional transmission and directional reception of sound waves and determine the direction of the abnormal body.

[0039] The implementation scheme is:

[0040] (1) When a monopole sound source is excited, the four components are recorded as mx1, mx2, my1, and my2. When a cross-dipole sound source is excited, the four components are recorded as xx, xy, yx, and yy, where xx = xx1-xx2, xy = xy1-xy2, yx = yx1-yx2, and yy = yy1-yy2.

[0041] (2) Assuming that the angle between the sound source direction X and the direction of the reflector interface is α, the sound source vector is decomposed into two components, one parallel and the other perpendicular to the direction of the reflector interface. Then SHcosα and SVsina are generated. Projecting them to the receiver direction respectively can obtain the xx signal in the same direction as the sound source direction and the xy signal orthogonal to the sound source direction:

[0042] xx=SHcos 2 α+SVsin 2 α

[0043] xy=-SHcosαsinα+SVsinαcosα

[0044] Similarly, if the sound source points to y, we can get the yy signal in the same direction as the sound source and the yx signal orthogonal to the sound source:

[0045] yy=SVcos 2 α+SHsin 2 α

[0046] yx=-SHcosαsinα+SVsinαcosα

[0047] (3) From the above formula, when α = 90° and 0°, the orthogonal components xy and yx are both zero, so the orientation can be determined based on the minimum value of the orthogonal components. The Alford rotation method is used to rotate the received four-component waveform. When it is rotated to be parallel or perpendicular to the direction of the reflector, the rotated orthogonal components disappear, and the orientation of the reflector can be determined based on the rotation angle.

[0048] Assume the rotation angle is θ, then define the rotation matrix as:

[0049]

[0050] The rotated four-component signal is:

[0051]

[0052] The new orthogonal components are:

[0053] XY=-xxsinθcosθ-yxsin2θ+cos20xy+yysinθcosθ

[0054] YX=-xxsinθcosθ-xysin2θ+coS2θxy+yysinθcosθ

[0055] (4) The wave field slices of SH and SV waves in different directions can be obtained by using the obtained four-component data:

[0056]

[0057] The maximum angle of SH reflected energy is the angle of the reflection interface, that is, when the polarization direction of the dipole source is parallel to the reflection interface, the SH wave reflection amplitude is the largest. Due to the radiation characteristics of the dipole source, the direction determined by the above method has an uncertainty of 180°.

[0058] (5) When the distance from the reflector to the borehole is much greater than the aperture, the reflected wave can be regarded as a plane wave incident on the borehole. Therefore, the waveform amplitude of the receiving sensor close to the incident wave is the strongest. The orientation calculated by the above formula is combined with the amplitude of the received reflected wave when the monopole is excited. The interface orientation can be quickly determined by comparing the signal strengths on both sides.

[0059] Step 2: Adopt an adaptive beamforming technology based on Gaussian cumulant characteristics to perform weighted summation on the collected array receiving data to obtain a scalar output, calculate the optimal weight, maximize the reception of target signals from the direction of the dipole pointing, and suppress interference signals at the same time, so that the array beam can adaptively point to the direction of the incoming wave, thereby improving the system's output signal-to-noise ratio and making it easier to identify related sound sources in noisy tunnel environments.

[0060] The implementation scheme is:

[0061] (1) The core concept of beamforming is to calculate the optimal weights. The output of the receiving array is the product of the received signal vector of each array element and the weight of each array element. Let the weight vector be W, then the array output can be expressed as:

[0062]

[0063] Among them, w i (θ) is the weight vector of the i-th received signal, x i (t) is the signal received by each array element.

[0064] (2) By constructing a cost function and iterating continuously, the mean square value of the estimation error is minimized. Assuming that the array acoustic wave receiving signal is x(t), the array actual output signal is y(t), and the expected output signal is d(t), the error between the array output signal and the expected signal is:

[0065] e(t)=y(t)-d(t)=w H (θ)x(t)-d(t)

[0066] Construct the cost function:

[0067] J(w)=d H (t)∧d(t)-2w H (θ)x(t)∧d(t)+w H (θ)x(t)∧x(t)w

[0068] Where ∧=diag[λ N-1 , ..., λ, 1];

[0069] (3) Taking the derivative of the above formula with respect to w, we can get the optimal weight solution:

[0070] w opt =[x(t)∧x(t)] -1 x(t)∧d(t)

[0071] (4) After weighting, the superimposed signal is output to obtain high signal-to-noise ratio sound wave data.

[0072] Step 3: Input the processed acoustic wave data, solve the three-dimensional elastic wave equation through the finite difference method, obtain the extended wave field of the sound source and receiving transducer, and then use the cross-correlation imaging condition to perform offset imaging to obtain the three-dimensional offset imaging result, which helps to identify potential hazards such as cavities or unstable rock formations.

[0073] The implementation scheme is:

[0074] (1) Under the condition of point source excitation, the elastic wave equation in a three-dimensional isotropic medium can be written as:

[0075]

[0076] Where τ ii is the normal stress component in the x, y, and z directions, τ ij is the shear stress direction in the corresponding direction, v x 、v x 、v z are the velocity components in the x, y, and z directions, ρ is the density of the medium, α and β are the longitudinal and transverse wave velocities in the medium, respectively, and t is time.

[0077] (2) The above elastic wave equation is differentially discretized using the high-order difference method. The forward wave field extension can be calculated by inputting the excitation sound source wavelet S(t). The processed sound wave data U(t) is used as the excitation sound source and transmitted back to calculate the inverse wave field extension

[0078] (3) By cross-correlating the forward wave field and the reverse wave field, the imaging value under three-dimensional conditions can be obtained:

[0079]

[0080] Embodiment 2

[0081] A tunnel bore acoustic wave detection data orientation and imaging system, comprising:

[0082] An orientation determination module is used to obtain sound wave data of different orientations in response to the same excitation sound wave, rotate the sound wave data until the orthogonal component disappears, and determine the orientation of the reflector according to the rotation angle;

[0083] The adaptive beamforming module is configured to perform weighted summation on the acoustic wave data acquired by the receiving array to obtain a scalar output, calculate an optimal weight value to maximize the reception of target signals from the direction of the reflector, perform weighted processing according to the optimal weight value, and obtain a superposition signal;

[0084] The migration imaging module is configured to solve the three-dimensional elastic wave equation based on the processed superposition signal to obtain the forward wave field and the reverse wave field, perform migration imaging using the cross-correlation imaging condition, and obtain the three-dimensional migration imaging result.

[0085] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0086] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0087] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0088] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process in the computer or other programmable device. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0089] 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 by those skilled in the art within the spirit and principle of the present invention without creative labor shall be included in the protection scope of the present invention.

Claims

1. A method for directing and imaging acoustic wave detection data in a tunnel hole, characterized in that: The following steps are involved: Acquire sound wave data of different orientations in response to the same excitation sound wave, rotate the sound wave data until the orthogonal component disappears, and determine the orientation of the reflector according to the rotation angle; The sound wave data acquired by the receiving array is weighted and summed to obtain a scalar output, and the optimal weight is calculated to maximize the reception of target signals from the direction of the reflector. Weighted processing is performed according to the optimal weight to obtain a superimposed signal; Based on the processed superposition signal, the three-dimensional elastic wave equation is solved to obtain the forward wave field and the reverse wave field. The migration imaging is performed using the cross-correlation imaging condition to obtain the three-dimensional migration imaging result.

2. A method for directing and imaging acoustic wave detection data in a tunnel hole as claimed in claim 1, characterized in that: The excitation sound waves include excitation sound waves of a monopole sound source and excitation sound waves of an orthogonal dipole sound source.

3. A method for directing and imaging acoustic wave detection data in a tunnel hole as claimed in claim 1, characterized in that: The single dipole sound source excites sound waves in turn, and four receiving sensors spaced 90° apart in the circumferential direction record four different component waveforms in different directions.

4. A method for directing and imaging acoustic wave detection data in a tunnel hole as claimed in claim 1, characterized in that: The received four-component waveform is rotated using the Alford rotation method. When it is rotated to be parallel or perpendicular to the direction of the reflector, the rotated orthogonal components disappear, and the orientation of the reflector can be determined based on the rotation angle.

5. A method for directing and imaging acoustic wave detection data in a tunnel hole as claimed in claim 1, characterized in that: According to the determined orientation of the reflector and the amplitude of the reflected wave received during monopole excitation, the orientation of the interface is determined by comparing the intensity of the signals on both sides. The maximum angle of the SH wave reflected energy is the angle of the reflection interface.

6. A method for directing and imaging acoustic wave detection data in a tunnel hole as claimed in claim 1, characterized in that: The acquired acoustic wave data is weighted and summed to obtain a scalar output. The process of calculating the optimal weight includes: calculating the error between the actual output signal of the receiving array and the expected output signal, constructing a cost function and iterating continuously to minimize the mean square value of the estimated error, and differentiating the weight vector therein to obtain the optimal weight solution.

7. A method for directing and imaging acoustic wave detection data in a tunnel hole as claimed in claim 1, characterized in that: Based on the processed superposition signal, the three-dimensional elastic wave equation is solved to obtain the forward wave field and the reverse wave field. The process includes: under the condition of point source excitation, the elastic wave equation in the three-dimensional isotropic medium is constructed, the elastic wave equation is differentially discretized by the high-order difference method, the forward wave field extension is calculated according to the exciting sound source wavelet, the processed superposition signal is used as the exciting sound source, and it is transmitted back to calculate the reverse wave field extension.

8. A tunnel bore acoustic wave detection data orientation and imaging system, characterized in that: include: An orientation determination module is used to obtain sound wave data of different orientations in response to the same excitation sound wave, rotate the sound wave data until the orthogonal component disappears, and determine the orientation of the reflector according to the rotation angle; The adaptive beamforming module is configured to perform weighted summation on the acoustic wave data acquired by the receiving array to obtain a scalar output, calculate an optimal weight value to maximize the reception of target signals from the direction of the reflector, perform weighted processing according to the optimal weight value, and obtain a superposition signal; The migration imaging module is configured to solve the three-dimensional elastic wave equation based on the processed superposition signal to obtain the forward wave field and the reverse wave field, perform migration imaging using the cross-correlation imaging condition, and obtain the three-dimensional migration imaging result.

9. A computer-readable storage medium, characterized in that: Used to store computer instructions, which, when executed by a processor, complete the steps of the method according to any one of claims 1 to 7.

10. An electronic device, characterized in that: The method comprises a memory and a processor, and computer instructions stored in the memory and executed on the processor, wherein when the computer instructions are executed by the processor, the steps in the method according to any one of claims 1 to 7 are completed.

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