Cross-hole sound wave reflection imaging method

Abstract

The invention discloses a cross-hole sound wave reflection imaging method, and relates to the field of geotechnical engineering reconnaissance, and the method comprises the steps: employing a coding sound wave emission assembly to generate a group of coding sound wave signals with different frequencies, and transmitting the coding sound wave signals to the surrounding stratum of an emission drill hole; a coding sound wave receiving assembly is adopted to receive direct transmission wave signals of all coding sound waves transmitted to a receiving drill hole through a stratum and all coding reflection wave signals reflected by geologic bodies in the stratum, corresponding coding electric signals are generated through induction, and the coding electric signals are converted into coding sound wave digital signals through a coding sound wave transmitting assembly; the transmission sound wave signal and the reflection sound wave signal are analyzed through data analysis processing software; and if the total number of times of coded sound wave detection reaches the preset number of times, determining a three-dimensional formation wave impedance imaging graph of the formation outside the connecting line between the transmitting drill hole and the receiving drill hole according to the time and the amplitude in the reflected sound wave signal corresponding to any frequency. According to the invention, large-span and high-resolution reflection imaging can be realized.

Description

Technical Field

[0001] The present application relates to the field of geotechnical engineering investigation, and in particular to a cross-hole acoustic wave reflection imaging method. Background Art

[0002] Cross-hole acoustic transmission tomography is a technology that reconstructs geological features through acoustic wave data between two boreholes. It has a good effect on various engineering detection abnormal bodies such as karst, collapse columns, fissures, cracks, fractured zones, weak interlayers, underground cavities and unknown buried objects. The principle of cross-hole acoustic transmission tomography is based on the matrix inversion method of ray tracing. It belongs to the category of ray theory tomography methods and is of great significance in rock mechanics research and non-destructive quality testing of concrete components. Specifically, the use of acoustic transmission tomography technology to detect the distribution of physical properties inside concrete components can quantitatively determine the quality or defects of the components, which plays an important role in concrete quality testing of various projects.

[0003] Although cross-hole acoustic transmission tomography has achieved very good results, it can only use the acoustic characteristic data of the strata between the two boreholes to reconstruct geological feature imaging, and cannot use the acoustic characteristic data of the strata outside the two-hole connection line to reconstruct geological feature imaging, especially the strata area outside the two-hole connection line is much larger than the strata area between the two-hole connection line. If cross-hole acoustic transmission tomography is used to achieve large-area fine detection imaging, it will require many more geological boreholes, a lot of drilling costs, and a long drilling time. Summary of the invention

[0004] The purpose of this application is to provide a cross-hole acoustic wave reflection imaging method, which can achieve large-span, high-resolution reflection imaging.

[0005] To achieve the above objectives, this application provides the following solutions:

[0006] The present application provides a cross-hole acoustic wave reflection imaging method, comprising:

[0007] Sending an imaging instruction to the coded acoustic wave transmitting component through the data analysis and processing software; wherein the coded acoustic wave transmitting component is currently at a first position;

[0008] Based on the imaging instructions, the coded acoustic wave transmitting component is used to generate a set of coded acoustic wave signals of different frequencies according to a preset modulation coding strategy and propagate them to the surrounding strata of the transmitting borehole;

[0009] A coded acoustic wave receiving assembly is used to receive all direct transmission wave signals of coded acoustic waves propagated through the stratum to the receiving borehole and all coded reflection wave signals reflected by geological bodies in the stratum, and to induce and generate corresponding coded electrical signals;

[0010] Convert all the coded electrical signals into coded sound wave digital signals through the coded sound wave transmitting component;

[0011] All the coded acoustic wave digital signals are interpreted by the data analysis and processing software based on the preset modulation and coding strategy to analyze the transmitted acoustic wave signal and the reflected acoustic wave signal, and the time and amplitude of the reflected acoustic wave signal are extracted, and a coded acoustic wave detection is marked as completed;

[0012] If the total number of coded acoustic wave detections does not reach a preset number, the first position is updated to a next position, and then the step of using the coded acoustic wave transmitting component to generate a set of coded acoustic wave signals of different frequencies according to a preset modulation coding strategy and propagating them to the surrounding strata of the transmitting borehole is returned;

[0013] If the total number of coded acoustic wave detections reaches a preset number, a three-dimensional formation wave impedance imaging diagram of the strata outside the line between the transmitting borehole and the receiving borehole is determined based on the time and amplitude of the reflected acoustic wave signal corresponding to any frequency.

[0014] According to the specific embodiments provided in this application, this application has the following technical effects: This application provides a cross-hole acoustic wave reflection imaging method, which detects and images the strata between and outside the two borehole lines, and can achieve large-scale geological detection through two holes, thereby improving the ability of various engineering projects to detect abnormal bodies. In addition, the reflected acoustic wave signal is identified, and the geological body in the stratum is identified and analyzed through the reflected acoustic wave signal to achieve high-resolution reflection imaging, which can further assist in the construction of geological feature imaging of the strata outside and between the two borehole lines. This application scheme can greatly reduce the number of geological drilling holes, drilling costs and detection time, and has great social value and economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. 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 creative work.

[0016] Figure 1 A schematic diagram of a flow chart of a cross-hole acoustic wave reflection imaging method provided in one embodiment of the present application;

[0017] Figure 2 A schematic plan view of a device for executing a method provided in an embodiment of the present application;

[0018] Figure 3 A three-dimensional schematic diagram of a device for executing a method provided in an embodiment of the present application;

[0019] Figure 4 Schematic diagram of three-dimensional slice of cross-hole acoustic wave reflection impedance imaging effect.

[0020] Figure numerals: 1-acoustic receiver, 2-acoustic transmitter, 3-computer and processing and analysis software, 4-acoustic receiving sensor string, 5-acoustic transmitting probe, 6-acoustic receiving cable, 7-acoustic transmitting cable, 8-receiving borehole, 9-transmitting borehole, 10-water, 11-cable bracket, 12-transmitted acoustic wave signal, 13-reflected acoustic wave signal, 14-stratum, 15-geological body. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0022] In order to make the purpose, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0023] In an exemplary embodiment, Figure 1 As shown, a cross-hole acoustic wave reflection imaging method is provided. Figure 2 and Figure 3 In the embodiment of the present application, the cross-hole acoustic wave reflection imaging method includes:

[0024] Step 100, sending an imaging instruction to a coded acoustic wave emitting component through data analysis and processing software; wherein the coded acoustic wave emitting component is currently at a first position.

[0025] Specifically, the coded acoustic wave transmitting assembly includes an acoustic wave receiver 1, an acoustic wave transmitter 2, an acoustic wave transmitting probe 5, and an acoustic wave transmitting cable 7; the coded acoustic wave receiving assembly includes an acoustic wave receiving sensor 4. The acoustic wave receiving cable 6 is connected to the acoustic wave receiving sensor string 4, and the acoustic wave receiving sensor string 4 is placed and hung at the bottom of the receiving borehole 8 to ensure that the sensor on the acoustic wave receiving sensor string 4 is in a suspended state, and the acoustic wave receiving cable 6 is connected to the acoustic wave receiver 1 through a cable bracket 11. The acoustic wave transmitting cable 7 is connected to the acoustic wave transmitting probe 5 and placed at the bottom of the transmitting borehole 9, and the acoustic wave transmitting cable 7 is connected to the acoustic wave transmitter 2 through a cable bracket 11. The acoustic wave receiver 1 and the acoustic wave transmitter 2 are connected for communication control via a cable or wireless network, and are respectively arranged near the receiving borehole 8 and the transmitting borehole 9. The data analysis and processing software uses a computer and processing and analysis software 3, which is used to control the work of the sound wave receiver 1, and sends it to the sound wave receiver 1 through a wired or wireless network, and then the sound wave receiver 1 transmits it to the sound wave transmitter 2 through a wireless or wired network. This process is not limited by distance. The receiving borehole 8 and the transmitting borehole 9 are filled with liquid sound wave propagation medium (such as water 10), and the elevation of the bottom of the receiving borehole 8 and the bottom of the transmitting borehole 9 is as high as possible. The corresponding first position can be the height of the lowest sound wave receiving sensor in the sound wave receiving sensor string 4, corresponding to the position in the transmitting borehole 9.

[0026] In addition, the acoustic wave transmitting probe 5 is a piezoelectric ceramic material probe or a giant magnetostrictive material probe or an electric spark probe or an explosive source. The sensor of the acoustic wave receiving sensor string 4 is made of a piezoelectric ceramic tube, and receives all the information of the transmitted acoustic wave signal 12 and the reflected acoustic wave signal 13 around the borehole by receiving the water 10 in the borehole 8.

[0027] Step 200, based on the imaging instruction, using the coded acoustic wave transmitting component, according to a preset modulation coding strategy, generates a set of coded acoustic wave signals of different frequencies and propagates them to the surrounding strata of the transmitting borehole; wherein the coded acoustic wave signal generated by the coded acoustic wave transmitting component is a spherical point source acoustic wave, which propagates in all directions to the surrounding strata through the liquid acoustic wave propagation medium contained in the transmitting borehole.

[0028] Specifically, the acoustic wave receiver 1 starts working according to the imaging instruction and generates an acoustic wave emission control instruction; the acoustic wave transmitter 2 generates a driving signal according to the acoustic wave emission control instruction; the acoustic wave transmitting probe 5 generates an acoustic wave signal according to the driving signal and transmits it to the strata around the borehole through the water 10 in the transmitting borehole 9; when there is a geological body 15 with different wave impedance in the stratum 14 outside the line between the receiving borehole 8 and the transmitting borehole 9, a reflected acoustic wave signal 13 will be generated when the transmitted acoustic wave signal 12 propagates to the geological body 15, and the reflected acoustic wave signal 13 will propagate to the receiving borehole 8.

[0029] Step 300, a coded acoustic wave receiving assembly is used to receive all the direct transmission wave signals of the coded acoustic waves propagated through the stratum to the receiving borehole and all the coded reflected wave signals reflected by the geological body in the stratum, and to induce and generate corresponding coded electrical signals. Specifically, the transmitted acoustic wave signal 12 and the reflected acoustic wave signal 13 are transmitted to the water 10 in the receiving borehole 8 and are sensed by the acoustic wave receiving sensor string 4, and a corresponding coded electrical signal is generated.

[0030] Step 400: convert all the coded electrical signals into coded acoustic digital signals by the coded acoustic transmitting component, specifically, convert all the coded electrical signals into coded acoustic digital signals by the acoustic receiver 1.

[0031] Step 500, all the coded acoustic wave digital signals are interpreted by the data analysis and processing software based on the preset modulation and coding strategy to identify the transmitted acoustic wave signal and the reflected acoustic wave signal, and the time and amplitude of the reflected acoustic wave signal are extracted, and a coded acoustic wave detection is marked as completed.

[0032] In an application example, all the coded sound wave digital signals are interpreted by the data analysis and processing software based on the preset modulation and coding strategy to analyze the transmitted sound wave signal and the reflected sound wave signal, including: all the coded sound wave digital signals are interpreted by the data analysis and processing software based on the preset modulation and coding strategy to obtain the transmitted sound wave signals corresponding to different frequencies; the first wave time in the transmitted sound wave signal is extracted; the wave signal received after the first wave time is taken as the starting moment and the preset time interval is marked as the reflected sound wave signal.

[0033] Step 600, if the total number of coded acoustic wave detections does not reach the preset number, the first position is updated to the next position, and then the step of using the coded acoustic wave transmitting component to generate a set of coded acoustic wave signals of different frequencies according to a preset modulation coding strategy and propagating them to the surrounding strata of the transmitting borehole is returned.

[0034] In an application example, the coded sound wave receiving component includes multiple coded sound wave receiving sensors; all the coded sound wave receiving sensors are arranged at equal intervals on a straight line; the coded sound wave transmitting component includes a sound wave transmitting probe 5; the step of updating the first position to the next position includes: lifting the sound wave transmitting probe 5 upward by a displacement value to reach the next position; the displacement value is equal to the value of the distance between two adjacent coded sound wave receiving sensors, that is, when the position is updated, the sound wave transmitting probe 5 is lifted by a transmitting point distance.

[0035] Step 700, if the total number of coded acoustic wave detections reaches a preset number, a three-dimensional formation wave impedance imaging diagram of the strata outside the line between the transmitting borehole and the receiving borehole is determined based on the time and amplitude of the reflected acoustic wave signal corresponding to any frequency. Corresponding to the above application example, when the total number of coded acoustic wave detections reaches a preset number, the acoustic wave transmitting probe 5 is lifted to the height of the uppermost acoustic wave receiving sensor of the acoustic wave receiving sensor string 4.

[0036] In an application example, the cross-hole acoustic wave reflection imaging method further includes: analyzing the three-dimensional formation wave impedance imaging map through the data analysis and processing software to determine the state of the geological body in the formation; the state of the geological body is the presence of the geological body or the absence of the geological body. That is, the computer and the processing and analysis software 3 analyze the time and amplitude of the reflected acoustic wave signal 3, analyze whether there is a geological body 15 in the formation 14 outside the line between the transmitting borehole 9 and the receiving borehole 8, and finally generate a three-dimensional imaging map of the formation 14 outside the line between the two boreholes. The geological information of the geological body 15 can be analyzed through three-dimensional slices, such as Figure 4 When there is a geological body 15 with a wave impedance change in the stratum 14, a reflected sound wave signal 13 will be generated. The analysis method is to perform calculation analysis based on the principle of sound wave reflection, that is, to analyze the three-dimensional stratum wave impedance imaging map through the data analysis and processing software, which is implemented by the following formula:

[0037] A R =A0R.

[0038]

[0039] z1=ρ1v1;z2=ρ2v2。

[0040] Among them, A R is the amplitude of the reflected sound wave generated by the geological body, A0 is the amplitude of the sound wave when the coded sound wave signal emitted by the coded sound wave transmitting component propagates to the surface of the geological body, R is the reflection wave coefficient of the geological body; z1 is the wave impedance of the formation; Z2 is the wave impedance of the geological body; v1 is the sound wave velocity of the formation, v2 is the sound wave velocity of the geological body, ρ1 is the rock density of the formation, and ρ2 is the rock density of the geological body.

[0041] In another application example, the cross-hole acoustic wave reflection imaging method further includes: displaying the three-dimensional formation wave impedance imaging map by the data analysis and processing software.

[0042] In another application example, the present application also reads the first wave time and amplitude of the transmitted acoustic wave signal through a computer and processing and analysis software, calculates the two-dimensional acoustic wave velocity profile image and the two-dimensional acoustic wave amplitude attenuation profile image of the stratum 14 between the transmitting borehole 9 and the receiving borehole 8, and analyzes the changes in the stratum from the two parameters of the acoustic wave velocity and amplitude attenuation of the stratum, which can more accurately analyze the information of the stratum. And through the cross-hole acoustic wave detection of two boreholes, the acoustic wave reflection stratum detection outside the connecting line between the two boreholes and the acoustic wave transmission stratum tomography detection between the two boreholes can be completed simultaneously.

[0043] In summary, the present invention has the ability to detect and image the strata between and outside the two boreholes, thereby increasing the detection range of the two holes and improving the ability of various engineering projects to detect abnormal bodies (such as karst, sinkholes, fissures, cracks, fractured zones, weak interlayers, underground cavities and unidentified buried objects), greatly reducing the number of geological drill holes, drilling costs and detection time, and has great social value and economic benefits.

[0044] The technical features of the above embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0045] This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core ideas of this application. At the same time, for those skilled in the art, according to the ideas of this application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A cross-hole acoustic wave reflection imaging method, characterized in that: The cross-hole acoustic wave reflection imaging method comprises: Sending an imaging instruction to the coded acoustic wave transmitting component through the data analysis and processing software; wherein the coded acoustic wave transmitting component is currently at a first position; Based on the imaging instructions, the coded acoustic wave transmitting component is used to generate a set of coded acoustic wave signals of different frequencies according to a preset modulation coding strategy and propagate them to the surrounding strata of the transmitting borehole; A coded acoustic wave receiving assembly is used to receive all the direct transmission wave signals of the coded acoustic waves propagated through the stratum to the receiving borehole and all the coded reflection wave signals reflected by the geological body in the stratum, and to induce and generate corresponding coded electrical signals; Convert all the coded electrical signals into coded sound wave digital signals through the coded sound wave transmitting component; All the coded acoustic wave digital signals are interpreted by the data analysis and processing software based on the preset modulation and coding strategy to analyze the transmitted acoustic wave signal and the reflected acoustic wave signal, and the time and amplitude of the reflected acoustic wave signal are extracted, and a coded acoustic wave detection is marked as completed; If the total number of coded acoustic wave detections does not reach a preset number, the first position is updated to a next position, and then the step of using the coded acoustic wave transmitting component to generate a set of coded acoustic wave signals of different frequencies according to a preset modulation coding strategy and propagating them to the surrounding strata of the transmitting borehole is returned; If the total number of coded acoustic wave detections reaches a preset number, a three-dimensional formation wave impedance imaging diagram of the strata outside the line between the transmitting borehole and the receiving borehole is determined based on the time and amplitude of the reflected acoustic wave signal corresponding to any frequency.

2. The cross-hole acoustic wave reflection imaging method according to claim 1, characterized in that: The data analysis and processing software is used to interpret all the coded sound wave digital signals based on the preset modulation and coding strategy to analyze the transmitted sound wave signals and the reflected sound wave signals, including: Decoding all the coded sound wave digital signals based on the preset modulation coding strategy by the data analysis and processing software to obtain the transmitted sound wave signals corresponding to different frequencies; Extracting the first wave time in the transmitted sound wave signal; Taking the first wave time as the starting moment, the wave signal received after a preset time interval is marked as a reflected sound wave signal.

3. The cross-hole acoustic wave reflection imaging method according to claim 1, characterized in that: The cross-hole acoustic wave reflection imaging method further comprises: The three-dimensional stratum wave impedance imaging diagram is analyzed by the data analysis and processing software to determine the state of the geological body in the stratum; the state of the geological body is the presence of the geological body or the absence of the geological body.

4. The cross-hole acoustic wave reflection imaging method according to claim 3, characterized in that: The step of analyzing the three-dimensional formation wave impedance imaging diagram by the data analysis and processing software is implemented by the following formula: A R =A0R; z1=ρ1v1;z2=ρ2v2; Among them, A R is the amplitude of the reflected sound wave generated by the geological body, A0 is the amplitude of the sound wave when the coded sound wave signal emitted by the coded sound wave transmitting component propagates to the surface of the geological body, R is the reflection wave coefficient of the geological body; z1 is the wave impedance of the formation; z2 is the wave impedance of the geological body; v1 is the sound wave velocity of the formation, v2 is the sound wave velocity of the geological body, ρ1 is the rock density of the formation, and ρ2 is the rock density of the geological body.

5. The cross-hole acoustic wave reflection imaging method according to claim 1, characterized in that: The cross-hole acoustic wave reflection imaging method further comprises: displaying the three-dimensional formation wave impedance imaging diagram by means of the data analysis and processing software.

6. The cross-hole acoustic wave reflection imaging method according to claim 1, characterized in that: The coded acoustic wave signal generated by the coded acoustic wave transmitting component is a spherical point source acoustic wave, which is transmitted in all directions to the surrounding strata through the liquid acoustic wave propagation medium contained in the transmitting borehole.

7. The cross-hole acoustic wave reflection imaging method according to claim 1, characterized in that: The coded sound wave receiving component includes a plurality of coded sound wave receiving sensors; all the coded sound wave receiving sensors are arranged in a straight line at equal intervals; the coded sound wave transmitting component includes a sound wave transmitting probe; The step of updating the first position to the next position includes: lifting the acoustic wave transmitting probe upward by a displacement value to reach the next position; the displacement value is equal to the value of the distance between two adjacent coded acoustic wave receiving sensors.

Images