Optical-radar combined directional imaging method and device for rock mass structure around borehole

Abstract

The application discloses a borehole surrounding rock mass structure optical-radar combined directional imaging method and equipment, comprising the following steps: S1, optical detection of a borehole inner wall is carried out by using a borehole television optical probe, and a borehole wall two-dimensional imaging profile is acquired; S2, rock mass structure surface morphological parameters are identified and extracted according to the borehole wall two-dimensional imaging profile; S3, borehole surrounding structure detection is carried out by using a borehole radar probe; S4, radar signal profile signal processing and migration imaging are carried out, and an imaging profile of a borehole surrounding rock mass structure surface is acquired; and S5, three-dimensional modeling of the rock mass structure surface is carried out. The borehole optical-radar combined observation provides more optical geological prior information, helps directional imaging rock mass structure identification, realizes multi-element data fusion in the rock mass structure surface inversion process, and completes fine identification of the rock mass structure surface.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of borehole radar and optical detection of rock mass structure, and in particular to a borehole optical-radar combined directional imaging method and device for rock mass structure around a borehole. BACKGROUND

[0002] Borehole camera optical detection is a logging method that can obtain intuitive images of the borehole wall rock mass structure. The principle is to use a special optical reflection prism coupling device to continuously display the borehole wall images in a full range of directions. The image completely records the borehole wall rock mass structure information, including bedding, fractures, pores and their depth and orientation information. However, borehole optical testing can only observe the borehole wall and cannot identify the concealed rock mass structure outside the borehole. Since the deep engineering rock mass structure is more intensive and complex, the concealed rock mass structure is often the key to engineering investigation, disaster risk assessment and support design and construction of deep tunnels. The inherent defects of borehole optical observation are severely magnified in deep tunnel rock mass engineering.

[0003] Borehole radar reflection method identifies rock mass structure features through the travel time, amplitude and phase of electromagnetic waves. Although borehole optical imaging has made important research achievements in automatic identification of borehole wall rock mass structure, single optical imaging can only identify the rock mass structure exposed by the borehole, and cannot identify the concealed structure inside the surrounding rock. However, a large number of randomly distributed and combined concealed rock mass structure is the main cause of most disasters in engineering. Borehole radar reflection detection is a potential method to reveal the concealed rock mass structure, but the initial model of electromagnetic wave inversion is difficult to estimate, resulting in unstable inversion and unclear identification of the target body orientation. There is an urgent need for a single-hole borehole radar reflection directional migration imaging method and device based on borehole optical prior information. SUMMARY

[0004] To solve the above problems, the present application provides a borehole optical-radar combined directional imaging method and device for rock mass structure around a borehole, which provides more optical geological prior information for borehole optical-radar combined observation, helps directional imaging rock mass structure identification, realizes multi-data fusion in rock mass structure inversion, and completes fine identification of rock mass structure. The technical solution is as follows:

[0005] The first aspect of the present application provides a radar reflection directional migration imaging method of borehole optical prior information, comprising the following steps:

[0006] S1, optical detection of the inner wall of the borehole is performed using a borehole television optical probe to obtain a borehole wall two-dimensional imaging profile;

[0007] S2, rock mass structure surface morphological parameters are identified and extracted according to the borehole wall two-dimensional imaging profile;

[0008] S3 uses borehole radar probe to detect the structure around the borehole;

[0009] S4 radar signal profile signal processing and migration imaging to obtain imaging profiles of rock mass structural surfaces around the borehole;

[0010] Three-dimensional modeling of S5 rock mass structural surface.

[0011] For example, in the optical-radar combined directional imaging method of the rock structure around the borehole provided in one embodiment, the optical detection of the inner wall of the borehole using a borehole television optical probe in S1 includes the following steps: lowering the borehole television optical probe into the borehole, and controlling the optical probe to move at a uniform speed to perform panoramic photography of the inner wall of the borehole, and after panoramic transformation and borehole wall reconstruction, finally expanding the photography results into a continuous two-dimensional imaging section in the north direction of the borehole wall eye.

[0012] For example, in the optical-radar combined directional imaging method for the rock mass structure around the borehole provided in one embodiment, the rock mass structural surface morphological parameters in S2 include inclination, dip angle, and gap width. According to the morphological fitting curve of the two-dimensional imaging profile curve of the borehole wall, the inclination α of the structural surface satisfies the following calculation formula:

[0013]

[0014] Among them, x min is the horizontal coordinate value of the pixel point where the minimum value point in the fitting curve is located; d is the diameter of the drilling hole, and Δw is the horizontal pixel width of the drilling hole image;

[0015] The inclination angle β of the structural surface satisfies the following calculation formula:

[0016]

[0017] Among them, y max y is the vertical coordinate value of the pixel point where the highest value point in the fitting curve is located; min is the vertical coordinate value of the pixel point where the lowest value point in the fitting curve is located; Δh is the vertical pixel width of the image;

[0018] The gap width D of the structural surface satisfies the following calculation formula:

[0019]

[0020] Where C is the total number of binary image columns of the drilling image; Δy i is the difference in the vertical coordinates of the edge points in the i-th column of the binary image.

[0021] For example, in the optical-radar combined directional imaging method of the rock structure around the borehole provided in one embodiment, the use of a borehole radar probe to detect the structure around the borehole in S3 includes the following steps: lowering the borehole radar probe into the borehole, and the radar antenna transmits and receives electromagnetic wave signals at a preset signal collection point distance during movement.

[0022] For example, in the optical-radar joint directional imaging method of the rock structure around the borehole provided in one embodiment, the radar signal profile signal processing and migration imaging in S4 include the following steps: performing median filtering and band-pass filtering on the obtained signal profile, filtering out the direct wave signal with strong energy in the profile by median filtering, and filtering out the additional noise in the signal by band-pass filtering; estimating the relative dielectric constant of the rock medium based on the lithology around the borehole, calculating the propagation velocity of the electromagnetic wave signal, and using this as the velocity field of the medium around the borehole; processing the radar signal profile by the Kirchhoff migration imaging algorithm, and returning the reflected wave energy in the time domain to its real interface in the spatial domain, thereby obtaining an imaging profile of the rock structure surface around the borehole.

[0023] For example, in the optical-radar combined directional imaging method for rock mass structures around a borehole provided in one embodiment, the radar signal migration imaging algorithm in S4 includes the following steps: performing numerical simulation of borehole radar detection, generating signal records by numerically solving the three-dimensional electromagnetic wave equation, and ultimately forming a time domain profile consisting of several signals, and filtering out high-energy direct wave signals in the profile by median filtering, where the median filter satisfies the following formula:

[0024] y(x)=MEDIUM(s(xd),…,s(x),…,s(x+d)) Formula (4);

[0025] Among them, MEDIUM() means taking the median of the sequence, d represents the filter width, s(x) is the original signal, and y(x) is the filtered signal;

[0026] The direct wave component is eliminated according to the following formula, leaving only the reflected wave for the subsequent migration imaging process:

[0027] s * (x) = s(x) - y(x) Formula (5);

[0028] The reflected waves generated by the structural surface are subjected to migration imaging processing, and the imaging method satisfies the following formula:

[0029]

[0030] Where u(x, z, t = 0) represents the wave field value of any point in the imaging range at imaging condition time t = 0, z(t) is the time depth, which is calculated by t·V / 2, and V is the velocity field of the medium around the borehole; u(x r ,z=0,τ) means The wave field value received in the borehole at the moment, r is the distance from the imaging point to the detection point, and θ is the incident angle of the electromagnetic wave;

[0031] The imaging results are transformed into the fk domain according to the following formula:

[0032] M(ω,k)=∫∫u(t,x)e -iωt e -ikx dtdx formula (7);

[0033] Where u(t,x) is the imaging section in the time-distance domain (tx), and M(ω,k) is the data in the frequency-wavenumber domain (ω-k);

[0034] In the frequency-wavenumber domain, fk filtering is applied to separate the cross-borehole structural surface on both sides of the borehole. The fk filtering process satisfies the following calculation formula:

[0035] M s (ω,k)=M(ω,k)·H(ω,k) Equation (8);

[0036]

[0037] Among them, H(ω,k) is the fk filter, M s (ω,k) is the imaging section after filtering;

[0038] The wave number (k) of the structural surface tilted to the right in the imaging section is positive, and vice versa. Based on this difference, the different parts of the structural surface on both sides of the borehole are separated, and the complete shape of the structural surface is restored in two-dimensional or three-dimensional space based on the dip and inclination extracted from the optical imaging results.

[0039] For example, in the optical-radar combined directional imaging method of the rock structure around the borehole provided in one embodiment, the three-dimensional modeling of the rock structure surface in S5 includes the following steps: extracting the energy part with cross-hole structural surface characteristics in the radar imaging section, corresponding it to the two-dimensional imaging section of the borehole wall and calculating the extension length of the structural surface outside the borehole; based on the structural surface morphological parameters extracted from the two-dimensional imaging section of the borehole wall, restoring the rock structure surface along its dip and inclination in three-dimensional space to both sides of the borehole, thereby forming a three-dimensional modeling of the rock structure surface.

[0040] A second aspect of the present application provides a radar reflection wave directional migration imaging device for borehole optical prior information, comprising a host, a wire rack, a data transmission network cable, a borehole television optical probe, and a borehole radar probe. The data transmission network cable is wound around the wire rack, one end of the data transmission network cable is connected to the host, and the other end is connected to the borehole television optical probe or the borehole radar probe. The data transmission network cable connected to the borehole television optical probe or the borehole radar probe is placed into the borehole through the wire rack, and the wire rack can automatically calibrate the placement depth.

[0041] A third aspect of the present application provides an electronic device, characterized in that it includes: a memory and a processor, wherein the processor is used to implement the above-mentioned optical-radar combined directional imaging method of the rock structure around the borehole when executing the computer management program stored in the memory.

[0042] The fourth aspect of the present application provides a computer-readable storage medium on which a computer management program is stored, characterized in that when the computer management program is executed by a processor, the above-mentioned optical-radar combined directional imaging method of the rock structure around the borehole is implemented.

[0043] The beneficial effects of a combined optical-radar directional imaging method and device for rock mass structure around a borehole provided in some embodiments of the present application are as follows: based on the optical prior information of the borehole, the present application can perform borehole radar directional offset imaging of the rock mass structure surface passing through the borehole. Compared with the traditional borehole optical detection, the morphology of the rock mass structure surface within a certain range around the borehole can be detected. The detection range is extended from the parameter identification of the rock mass structure surface of the borehole wall to the three-dimensional reconstruction of the rock mass structure within a radius of 10 meters around the borehole, breaking through the problem of "one-hole view" of the traditional borehole optical detection and eliminating the multi-solution of borehole optical detection. Compared with the non-directional detection of the traditional borehole radar dipole antenna, the present application can directionally detect the azimuth, dip, inclination, strike and other parameters of the rock mass structure within a certain range around the borehole, through optical and The combined analysis of radar and borehole radar realizes the directional detection of ordinary borehole radar; compared with borehole acoustic wave or radar full waveform inversion or tomographic imaging inversion, the method adopted in this application is mainly offset imaging, which does not involve complex parameter setting and inversion iteration, has obvious advantages in computational cost and stability, and can realize the automation of borehole radar data; compared with the traditional two-dimensional offset imaging method, the Kirchhof migration based on borehole optical extraction of azimuth information can realize three-dimensional reconstruction of borehole radar data; the present application can realize the refined directional identification of hidden structural surfaces inside the rock mass around the borehole, including the identification of the inclination, dip, gap width and extension length of the rock structural surface, which helps to improve the accuracy of underground engineering surveys and provide reliable geological data for engineering disaster risk assessment and support design and construction. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the embodiments of this specification or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0045] Figure 1 This is a schematic structural diagram of the radar reflection wave directional migration imaging device for borehole optical prior information of this application;

[0046] Figure 2 This is a schematic diagram of the working mode of the borehole radar probe of this application;

[0047] Figure 3 This is a model diagram of the drilling and cross-hole rock structure surface in one embodiment of the present application;

[0048] Figure 4 This is a simulated borehole television optical imaging diagram;

[0049] Figure 5 This is the numerical simulation of the borehole radar wave profile;

[0050] Figure 6 This is the result of borehole radar wave profile migration imaging;

[0051] Figure 7 This is the result of the borehole radar migration imaging after filtering and reconstruction;

[0052] Figure 8 Schematic diagram of the three-dimensional restoration of the rock structure surface. DETAILED DESCRIPTION

[0053] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0054] Unless otherwise defined, the technical or scientific terms used in this disclosure should have the usual meanings understood by persons of ordinary skill in the field to which this disclosure belongs. The words "first", "second" and similar terms used in this disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. Words such as "include" or "comprise" mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as "connect" or "connected" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0055] The first aspect of the present application provides a radar reflection wave directional migration imaging device for borehole optical prior information, such as Figure 1 As shown, it includes a host 1, a wire rack 2, a data transmission network cable 3, a drilling TV optical probe 4 and a drilling radar probe 5. The data transmission network cable 3 is wound on the wire rack 2, one end of the data transmission network cable 3 is connected to the host 1, and the other end is connected to the drilling TV optical probe 4 or the drilling radar probe 5. The data transmission network cable 3 connected to the drilling TV optical probe 4 or the drilling radar probe 5 is placed into the borehole through the wire rack 2, and the wire rack 2 can automatically calibrate the placement depth.

[0056] Among them, the data collected by the borehole TV optical probe 4 or the borehole radar probe 5 is transmitted to the on-site host 1 for storage through the data transmission network cable 3 and can be viewed and analyzed in real time through the built-in software. In actual work, the cable connected to the borehole TV optical probe 4 or the borehole radar probe 5 is placed into the borehole through the wire rack 2 placed on the ground. The wire rack 2 can automatically calibrate the insertion depth, and the depth of entry into the borehole can also be manually read through the scale marked on the cable. The borehole TV optical probe 4 can perform optical imaging of the inner wall of the borehole in real time through panoramic high-definition photography. The imaging results are displayed in the host 1 as a two-dimensional profile or a three-dimensional bar graph. The imaging results can be used to measure the occurrence (inclination, dip, etc.) of the cross-borehole rock structure surface. The borehole radar probe 5 transmits electromagnetic waves to the entire space around the borehole through its built-in dipole antenna and receives reflected waves to detect the discontinuity surface of the rock mass around the borehole, such as Figure 2As shown, the detection method involves transmitting and receiving radar signals at fixed intervals as the radar moves at a constant speed toward the borehole depth. The radar transmitting antenna operates at a center frequency between 30 and 200 MHz, and the distance between the transmitting and receiving antennas is approximately 30 cm. Because the radar antenna transmits and receives reflected signals in a 360-degree angle around the borehole, its detection results can only determine the shape of the reflector or its distance from the borehole, but not its azimuth. Therefore, a comprehensive interpretation combined with optical imaging results is required to achieve directional, high-precision imaging of cross-hole rock mass structural surfaces.

[0057] A second aspect of the present application provides a method for directional migration imaging of radar reflection waves based on borehole optical prior information, which uses the above-mentioned directional migration imaging device for radar reflection waves based on borehole optical prior information to perform directional migration imaging of radar reflection waves based on borehole optical prior information, including the following steps:

[0058] S1 uses a borehole television optical probe to perform optical detection on the inner wall of the borehole to obtain a two-dimensional imaging profile of the borehole wall;

[0059] Specifically, the process includes the following steps: connecting the borehole television optical probe 4 to the data transmission network cable 3, and connecting the other end of the data transmission network cable 3 to the host 1; lowering the borehole television optical probe 4 into the borehole through the operating wire rack 2, and controlling the optical probe to move at a uniform speed to perform panoramic photography (or record video) of the inner wall of the borehole; the host 1 enters the borehole depth based on the recorded probe, undergoes panoramic transformation, and reconstructs the borehole wall; and finally, expands the photography results into a continuous two-dimensional imaging profile in the north direction of the borehole wall.

[0060] S2 extracts the morphological parameters of the rock mass structural surface based on the two-dimensional imaging profile of the hole wall;

[0061] Specifically, the cross-hole structural surface of the rock mass is identified and extracted based on the two-dimensional imaging profile of the hole wall, and the structural surface morphological parameters, including dip, inclination, gap width, etc., are automatically calculated;

[0062] S3 uses borehole radar probe to detect the structure around the borehole;

[0063] Specifically, the borehole radar probe 5 is connected to the data transmission network cable 3, and the other end of the data transmission network cable is connected to the host 1. The borehole radar probe 5 is lowered into the borehole by operating the wire rack 2. During the movement, the radar antenna transmits and receives electromagnetic wave signals at a preset signal collection point spacing. A smaller point spacing can generally ensure the continuity of the signal profile. According to the detection accuracy requirements, the center frequency of the radar transmitting antenna can generally be set to 100-200MHz. The detection result is a time-depth radar signal profile that is approximately self-excited and self-received.

[0064] S4 radar signal profile signal processing and migration imaging to obtain imaging profiles of rock mass structural surfaces around the borehole;

[0065] Specifically, the following steps are included: performing median filtering and bandpass filtering on the obtained signal profile, filtering out the high-energy direct wave signal in the profile by median filtering, and filtering out the additional noise in the signal by bandpass filtering; estimating the relative dielectric constant of the rock medium based on the lithology around the borehole, calculating the propagation speed of the electromagnetic wave signal, and using this as the velocity field of the medium around the borehole; processing the radar signal profile using the Kirchhoff migration imaging algorithm built into the host 1 software program, and returning the reflected wave energy in the time domain to its real interface in the spatial domain, thereby obtaining an imaging profile of the rock structure surface around the borehole.

[0066] Three-dimensional modeling of S5 rock mass structural surface.

[0067] Specifically, the following steps are included: extracting the energy part with cross-hole structural surface characteristics in the radar imaging section, corresponding it to the two-dimensional imaging section of the hole wall and calculating the extension length of the structural surface outside the borehole; based on the structural surface morphological parameters extracted from the two-dimensional imaging section of the hole wall, restoring the rock structural surface along its dip and inclination in three-dimensional space to both sides of the borehole to form a three-dimensional model of the rock structural surface.

[0068] The method for extracting parameters of the structural surface of the borehole television optical probe imaging section and the borehole radar migration imaging algorithm in S2 and S4 are as follows:

[0069] by Figure 3 The numerical model of the borehole and its surrounding rock mass structure surface is used as an example to illustrate. Figure 3 The cylinder at the center represents a borehole with a radius of 10 cm. The borehole is surrounded by a homogeneous rock medium with a relative dielectric constant of 6. The rock mass contains two cross-borehole structural planes with dips and inclinations of 90°E and 45° (with the positive x-axis as due north). The gaps in both planes are 4 cm wide and are completely filled with air with a relative dielectric constant of 1. Numerical modeling is used to simulate the process of borehole television probes and borehole radar probes detecting downward from z = 0 along the borehole.

[0070] Figure 4 The expanded cross-section of the borehole optical imaging plane at a depth of 3.5-6.5m is shown, in which the curved part represents the cross-hole structural surface, and its curve shape is approximately similar to the sine function image. By fitting the curve, the structural surface occurrence (i.e., morphological parameters) can be calculated.

[0071] The inclination α of the structural surface satisfies the following calculation formula:

[0072]

[0073] Among them, x min is the horizontal coordinate value of the pixel point where the minimum value point in the fitting curve is located; d is the diameter of the drilling hole, and Δw is the horizontal pixel width of the drilling hole image;

[0074] The inclination angle β of the structural plane satisfies the following calculation formula:

[0075]

[0076] Wherein, y max is the vertical coordinate value of the pixel point where the highest value point in the fitting curve is located; y min is the vertical coordinate value of the pixel point where the lowest value point in the fitting curve is located; Δh is the vertical pixel width of the image;

[0077] The gap width D of the structural plane satisfies the following calculation formula:

[0078]

[0079] Wherein, C is the total column number of the binary image of the borehole image; Δy i is the difference of the vertical coordinates of the edge points of the i-th column of the binary image.

[0080] The radar signal migration imaging algorithm in S4 includes the following steps: the source wavelet used for numerical simulation of borehole radar detection is a Ricker wavelet with a main frequency of 200 MHz, and 50 ns of signal records are generated by numerically solving a three-dimensional electromagnetic wave equation. Since the borehole radar probe moves sequentially from top to bottom by 9 m, and signals are excited and received every 0.1 m interval, a time domain profile composed of 91 signals is finally formed, as shown in Figure 5 (a), it can be seen that there is a direct wave signal with a large energy ratio on the profile, which covers the effective reflected wave signal. Since its phase axis is a horizontal line, the signal component can be effectively removed by applying median filtering along the depth direction.

[0081] The median filter satisfies the following formula:

[0082] y(x) = MEDIUM(s(x-d),...,s(x),...,s(x+d)) Formula (4);

[0083] Wherein, MEDIUM() represents taking the median value of the sequence, d represents the filter width, s(x) is the original signal, and y(x) is the filtered signal;

[0084] The direct wave component is removed according to the following formula to retain only the reflected wave for subsequent migration imaging process:

[0085] s * (x) = s(x)-y(x) Formula (5);

[0086] The reflection wave phase axis generated by the structural plane has the form of an inclined straight line in the time domain profile, but still cannot correctly reflect the structural plane form and extension length, so the reflection wave generated by the structural plane is subjected to migration imaging processing, and the imaging method satisfies the following formula:

[0087]

[0088] Where u(x, z, t = 0) represents the wave field value of any point in the imaging range at imaging condition time t = 0, z(t) is the time depth, which is calculated by t·V / 2, and V is the velocity field of the medium around the borehole; u(x r ,z=0,τ) means The wave field value received in the borehole at the moment, r is the distance from the imaging point to the detection point, θ is the incident angle of the electromagnetic wave, and the imaging result is as follows Figure 6 As shown;

[0089] The imaging results are transformed into the fk domain according to the following formula:

[0090] M(ω,k)=∫∫u(t,x)e -iωt e -ikx dtdx formula (7);

[0091] Where u(t,x) is the imaging section in the time-distance domain (tx), and M(ω,k) is the data in the frequency-wavenumber domain (ω-k);

[0092] In the frequency-wavenumber domain, fk filtering is applied to separate the cross-borehole structural surface on both sides of the borehole. The fk filtering process satisfies the following calculation formula:

[0093] M s (ω,k)=M(ω,k)·H(ω,k) Equation (8);

[0094]

[0095] Among them, H(ω,k) is the fk filter, M s (ω,k) is the imaging section after filtering;

[0096] The wave number (k) of the structural surface tilted to the right in the imaging section is positive, and vice versa. Based on this difference, the different parts of the structural surface on both sides of the borehole are separated, such as Figure 7 (a) and 7(b), and the complete morphology of the structural surface is plotted in two dimensions (e.g. Figure 7 (c)) or three-dimensional space (as shown Figure 8 shown) restored.

[0097] Based on the borehole optical prior information, this application can perform borehole radar directional offset imaging on the rock structure surface through the borehole. Compared with the traditional borehole optical detection, it can detect the shape of the rock structure surface within a certain range around the borehole. The detection range is extended from the parameter identification of the rock structure surface of the borehole wall to the three-dimensional reconstruction of the rock structure within a radius of 10 meters around the borehole, breaking through the problem of "one-hole view" of traditional borehole optical detection and eliminating the multi-solution of borehole optical detection. Compared with the non-directional detection of the traditional borehole radar dipole antenna, this application can directionally detect the rock within a certain range around the borehole. The azimuth, dip, inclination, strike and other parameters of the body structure are analyzed jointly by optics and radar to realize the directional detection of ordinary borehole radar; compared with borehole acoustic wave or radar full waveform inversion or tomographic imaging inversion, the method adopted in this application is mainly offset imaging, which does not involve complex parameter settings and inversion iterations, has obvious advantages in computing cost and stability, and can realize the automation of borehole radar data; compared with the traditional two-dimensional offset imaging method, the Kirchhof migration based on borehole optical extraction of azimuth information can realize three-dimensional reconstruction of borehole radar data.

[0098] A third aspect of the present application provides an electronic device, characterized in that it includes: a memory and a processor, wherein the processor is used to implement the above-mentioned optical-radar combined directional imaging method of the rock structure around the borehole when executing the computer management program stored in the memory.

[0099] The fourth aspect of the present application provides a computer-readable storage medium on which a computer management program is stored, characterized in that when the computer management program is executed by a processor, the above-mentioned optical-radar combined directional imaging method of the rock structure around the borehole is implemented.

[0100] Although the implementation scheme of the present application has been disclosed as above, it is not limited to the applications listed in the description and implementation mode. It can be fully applied to various fields suitable for the present application. For those familiar with this field, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present application is not limited to the specific details and illustrations shown and described herein.

Claims

1. A method for combined optical-radar directional imaging of rock mass structure around a borehole, characterized in that: The following steps are involved: S1 uses a borehole television optical probe to perform optical detection on the inner wall of the borehole to obtain a two-dimensional imaging profile of the borehole wall; S2 extracts the morphological parameters of the rock mass structural surface based on the two-dimensional imaging profile of the hole wall; S3 uses borehole radar probe to detect the structure around the borehole; S4 radar signal profile signal processing and migration imaging, to obtain an imaging profile of the rock structure surface around the borehole; the S4 radar signal profile signal processing and migration imaging includes the following steps: median filtering and bandpass filtering are performed on the obtained signal profile, the direct wave signal with strong energy in the profile is filtered out by median filtering, and the additional noise in the signal is filtered out by bandpass filtering; the relative dielectric constant of the rock medium is estimated based on the lithology around the borehole, and the propagation speed of the electromagnetic wave signal is calculated, which is used as the velocity field of the medium around the borehole; the radar signal profile is processed by the Kirchhoff migration imaging algorithm, and the reflected wave energy in the time domain is attributed to its real interface in the spatial domain, thereby obtaining an imaging profile of the rock structure surface around the borehole S5 rock mass structural surface 3D modeling; The Kirchhoff migration imaging algorithm in S4 includes the following steps: numerical simulation of borehole radar detection, numerical solution of the three-dimensional electromagnetic wave equation, generation of signal records, and ultimately formation of a time domain profile consisting of several signals. The median filter is used to filter out the high-energy direct wave signal in the profile. The median filter satisfies the following equation: y(x)=MEDIUM(s(xd),…,s(x),…,s(x+d)) Formula (1); Among them, MEDIUM() means taking the median of the sequence, d represents the filter width, s(x) is the original signal, and y(x) is the filtered signal; The direct wave component is eliminated according to the following formula, leaving only the reflected wave for the subsequent migration imaging process: s * (x) = s(x) - y(x) Formula (2); The reflected waves generated by the structural surface are subjected to migration imaging processing, and the imaging method satisfies the following formula: Where u(x, z, t = 0) represents the wave field value of any point in the imaging range at imaging condition time t = 0, z(t) is the time depth, which is calculated by t·V / 2, and V is the velocity field of the medium around the borehole; u(x r ,z=0,τ) means The wave field value received in the borehole at the moment, r is the distance from the imaging point to the detection point, and θ is the incident angle of the electromagnetic wave; The imaging results are transformed into the fk domain according to the following formula: M(ω,k) = ∫∫u(t,x)e -iωt e -ikx dtdx Equation (4); Where u(t,x) is the imaging section in the time-distance domain (tx), and M(ω,k) is the data in the frequency-wavenumber domain (ω-k); In the frequency-wavenumber domain, fk filtering is applied to separate the cross-borehole structural surface on both sides of the borehole. The fk filtering process satisfies the following calculation formula: M s (ω,k)=M(ω,k)·H(ω,k) Equation (5); Among them, H(ω,k) is the fk filter, M s (ω,k) is the imaging section after filtering; The wave number (k) of the structural surface tilted to the right in the imaging section is positive, and vice versa. Based on this difference, the different parts of the structural surface on both sides of the borehole are separated, and the complete shape of the structural surface is restored in two-dimensional or three-dimensional space based on the dip and inclination extracted from the optical imaging results.

2. The optical-radar combined directional imaging method for rock mass structure around a borehole according to claim 1, characterized in that: The optical detection of the inner wall of the borehole using the borehole television optical probe in S1 includes the following steps: placing the borehole television optical probe into the borehole, controlling the optical probe to move at a uniform speed, taking a panoramic shot of the inner wall of the borehole, performing a panoramic transformation and a borehole wall reconstruction, and finally unfolding the shooting results into a continuous two-dimensional imaging section in the north direction of the borehole wall eye.

3. The optical-radar combined directional imaging method for rock mass structure around a borehole according to claim 2, characterized in that: The morphological parameters of the rock mass structural surface in S2 include inclination, dip angle, and gap width. According to the morphological fitting curve of the two-dimensional imaging profile curve of the hole wall, the inclination α of the structural surface satisfies the following calculation formula: Among them, x min is the horizontal coordinate value of the pixel point where the minimum value point in the fitting curve is located; d is the diameter of the drilling hole, and Δw is the horizontal pixel width of the drilling hole image; The inclination angle β of the structural surface satisfies the following calculation formula: Among them, y max y is the vertical coordinate value of the pixel point where the highest value point in the fitting curve is located; min is the vertical coordinate value of the pixel point where the lowest value point in the fitting curve is located; Δh is the vertical pixel width of the image; The gap width D of the structural surface satisfies the following calculation formula: Where C is the total number of binary image columns of the drilling image; Δy i is the difference in the vertical coordinates of the edge points in the i-th column of the binary image.

4. The optical-radar combined directional imaging method for rock mass structure around a borehole according to claim 1, characterized in that: In S3, a borehole radar probe is used to detect the structure around the borehole. The method comprises the following steps: placing a borehole radar probe into a borehole, and transmitting and receiving electromagnetic wave signals at a preset signal collection point distance during the movement of the radar antenna.

5. The optical-radar combined directional imaging method for rock mass structure around a borehole according to claim 1, characterized in that: The three-dimensional modeling of the rock mass structural surface in S5 includes the following steps: extracting the energy portion with cross-hole structural surface characteristics in the radar imaging section, corresponding it to the two-dimensional imaging section of the hole wall and calculating the extension length of the structural surface outside the borehole; based on the structural surface morphological parameters extracted from the two-dimensional imaging section of the hole wall, restoring the rock mass structural surface along its inclination and dip angle in three-dimensional space to both sides of the borehole to form a three-dimensional model of the rock mass structural surface.

6. The device for the optical-radar combined directional imaging method of rock mass structure around a borehole according to any one of claims 1 to 5, characterized in that: It includes a host, a wire rack, a data transmission network cable, a drilling television optical probe and a drilling radar probe. The data transmission network cable is wound on the wire rack, one end of the data transmission network cable is connected to the host, and the other end is connected to the drilling television optical probe or the drilling radar probe. The data transmission network cable connected to the drilling television optical probe or the drilling radar probe is placed into the borehole through the wire rack, and the wire rack can automatically calibrate the placement depth.

7. An electronic device, characterized in that: include: A memory and a processor, wherein the processor is configured to implement the optical-radar combined directional imaging method for rock mass structure around a borehole as described in any one of claims 1 to 5 when executing a computer management program stored in the memory.

8. A computer-readable storage medium storing a computer management program, characterized in that: When the computer management program is executed by the processor, the optical-radar combined directional imaging method of the rock structure around the borehole as claimed in any one of claims 1 to 5 is implemented.

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