Aiming at the weak interlayer, potential structural plane or abnormal area that may have some risks in geotechnical engineering, a method of monitoring abnormal structure and evaluating potential geological hazards in geotechnical engineering based on phased array ultrasonic scanning imaging technique was proposed. The real-time ultrasonic video images of the internal structure of rock and soil mass at various positions and different angles in the target area, and the ultrasonic imaging profile of the processed internal abnormal structure can be obtained. The binarization features of abnormal structures in the images were statistically analyzed. The total number of non-zero pixels, non-zero discontinuous light spots and stripe bands is obtained. The ratio of the boundary length of all light spots and stripe bands to the number of pixels occupied by all light spots and stripe bands was obtained. Based on this, the criterion of the degree of potential geological hazards is established, and the visual monitoring of the internal abnormal structure of rock and soil mass and the accurate evaluation of potential geological hazards are realized. Based on the refined diagnosis and analysis of local abnormal areas, this method solves the problems that the existing techniques cannot realize the visual monitoring of the internal fine structure of rock and soil mass and carry out the refined analysis and evaluation of the potential geological hazards. This paper provides a new approach for the stability and safety analysis of geotechnical engineering or slope engineering.
Research Article
The visual detection of inner abnormal structures and potential geological hazards assessment method for buried rock and soil mass
https://doi.org/10.21203/rs.3.rs-1955955/v1
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ultrasonic scanning imaging
abnormal structures
structural plane
visual monitoring
geological disasters
China is one of the countries with the most serious natural disasters in the world, with many kinds of disasters, wide distribution, high frequency of occurrence and heavy losses. Moreover, China's overall capacity for disaster prevention and control is still relatively weak. The improvement of the capacity for disaster prevention and control is very important for the safety of people's lives and property and national security. Due to the large mountainous area, complex topographic and geological conditions, abundant rainfall, strong human engineering activities and frequent geological disasters in China, it is of great significance to study the means of geological disaster prevention and mitigation for national economic construction and public safety.
The occurrence of geological disasters usually starts from the erosion damage and stress imbalance of local rock and soil structure, especially the weak structure or soil-rock interface area under the action of water (Ko, et al., 2020, Lemieux, 2011, Schimmel, et al., 2019). Therefore, geological investigation and visual diagnosis of abnormal structures in rock and soil are important means of disaster prevention and mitigation. At present, traditional geological radar or acoustic sounding instrument can only realize the geological exploration of a larger scope (Golpasand, et al., 2019, Li, et al., 2017, Ward, et al., 2020). Aiming at specific areas of weak intercalations in geotechnical engineering or potential structural surface, there may be some risks for these abnormal areas (Liggins, et al., 2010, Mazarovich, 2012, Valensise and Pantosti, 2001). However, the traditional method is difficult to achieve fine analysis in precision, and unable to realize the visual monitoring inside the abnormal structure and the evaluation of the potential geological hazards. All of these may affect the stability and safety of a large range of geotechnical engineering or slope engineering (McGuire, 2010, Rahman, et al., 2015, Royse, 2011). Therefore, a new detection method is urgently needed to visually monitor the abnormal structure inside the rock and soil mass with possible risks and accurately evaluate the potential geological hazards (Brideau, et al., 2009, Delsanto and Hirsekorn, 2004, Wang and Li, 2018).
Due to the increasing renewal and rapid development of science and technology, multidisciplinary cross-application and leap-forward development have become a consensus. Modern medical ultrasound diagnostic technology has been improved and extended applications (Choudhary, et al., 2019, Mandrone, 2016, Poelma, 2017). The new ultrasound scanning imager with good real-time performance, strong penetration and high resolution has been well applied in hydrogeology and engineering investigation (Crapper, et al., 2000, Xiao, et al., 2015, Zou, et al., 2018), which has preliminarily solved the imaging measurement and diagnostic analysis of the suspended sediment concentration (Zou, et al., 2016), underwater topography (Zou, et al., 2015) and flow field in the river engineering physical model (Ma, et al., 2018) by ultrasonic scanning techniques (Zou, et al., 2014). Therefore, it is of practical urgency and theoretical necessity to use the advanced medical diagnosis technology for reference and apply it to the visual monitoring and analysis of the weak structure area.
In order to solve the problem of visual monitoring of abnormal internal structure of rock and soil mass, this paper provides a visual monitoring method of abnormal internal structures and potential geological hazard assessment method for buried rock and soil mass based on ultrasonic phased array scanning imaging techniques. We adopt the test, theory, and practice mutual verification way. In order to realize the visual monitoring of the internal structure of quickly and effectively, this paper directly uses a mature medical or veterinary B-mode ultrasound imager, namely an ultrasound scanning imager to carry out the test.
Ultrasound scanning imager is an ultrasonic scanning imaging device by using ultrasonic phased array technology, which can realize the penetrating imaging of the internal structure of human body and objects (Sanderson and Yeung, 2002, Verwer, et al., 2010, Wang, et al., 2019). In this paper, projection scanning imaging and focusing imaging of the internal structure of rock and soil mass can be realized by using this equipment under the action of water or special coupling agent. The ultrasonic imaging probe used by the ultrasound scanning imager has two kinds of type, that is convex array probe and linear array probe. The ultrasonic frequency of the probe is usually set as 2 MHz and 5 MHz. In general, the convex array probe is used to obtain a wider range, while the linear array probe is used to obtain more precise and accurate targets but the detecting range is smaller (Saroglou and Kallimogiannis, 2017). After adjusting the relevant configuration of the ultrasound scanning imager, the ultrasonic wave emitted by the ultrasonic imaging probe can easily penetrate the internal structure of the rock and soil mass in general test conditions (Cui and Qin, 2019, Gheibi and Hedayat, 2018, Raef, et al., 2015), and relatively clear ultrasonic scanning image can be obtained. This image clearly records the reflection attenuation of the internal structure of the rock and soil mass within a range of about 1 meter in front of the probe, as shown in Fig. 1. namely the abnormal structures preliminarily detected inside the rock and soil mass.
In order to fix and move the ultrasonic imaging probe conveniently, sliders, clamps and other devices are used to fix the ultrasonic imaging probe and move it under the drive of sliders or push rods. For both indoor and outdoor tests, this method can be used to conduct ultrasonic imaging detection tests on the shallow surface and internal structure of rock and soil mass in some certain area. One of the fixation methods of the ultrasonic imaging probe is shown in Fig. 2.
Figure 2 is a model test device in an indoor water tank. In the model test, the geological survey of the underwater target area, the ultrasonic imaging survey of the shallow surface and the internal structure of the rock and soil mass can be realized by moving the probe. In addition, for the internal structure of the rock and soil mass inside the borehole, the probe of the ultrasound scanning imager can be fixed on the bracket and put into the target area inside the borehole. The probe can move up and down, left, and right, and rotate 360 degrees freely with the help of the drilling platform or special equipment and auxiliary devices, such as push rod or slider and clamp, etc. One of the fixed modes is shown in Fig. 3.
For the convenience of description, the abnormal structure in this paper refers to the ultrasonic imaging structure composed of abnormal spots, stripes and other imaging features of the structural plane, broken zone, hole, and weak interlayer in addition to the normal rock and soil mass in the ultrasonic scanning image. The ultrasonic image mentioned in this paper refers to the ultrasonic scanning image of the internal structure of rock and soil mass obtained directly by the ultrasound scanning imager, which is the original ultrasonic imaging image obtained directly. The ultrasonic imaging profile of the internal structure of rock and soil mass mentioned in this paper refers to the processed ultrasonic image that can reflect the internal structure characteristics of rock and soil mass and its variation range, which is the ultrasonic profile that can reflect the specific structural characteristics of the internal structure of rock and soil mass (Sharma and Singh, 2018, Talukdar, et al., 2018, Vila and Malla, 2016).
3.1 The potential geological hazards assessment method
In this paper, a visual monitoring and potential geological hazard assessment method based on phased array ultrasound scanning imager is proposed for abnormal surface and internal structures of rock and soil mass. In this method, the ultrasonic imaging probe is fixed on the bracket and placed in the target area, and the ultrasonic video image of the target area is obtained, and the abnormal structure in the video image is automatically recognized and counted, and the visual monitoring is realized. Then, the ultrasonic imaging probe is rotated or shifted, and the sectional images from multiple angles are combined and stitched together as necessary to statistically analyze the binarization features of abnormal internal structures and establish corresponding relations. Finally, the degree of potential geological hazards in the target area is evaluated qualitatively and quantitatively according to the binarization characteristics. This method mainly takes the following steps, as shown in Fig. 4.
3.2 Description of main steps
Step (1) Fix the ultrasonic imaging probe and obtain the ultrasonic video image of the target area.
The ultrasonic imaging probe is based on the principle of phased array ultrasonic scanning imaging techniques. It can realize the ultrasonic scanning imaging inside the hole wall of rock and soil mass when there is water or water has been injected inside the borehole, or with the help of a specific coupling agent. Among them, the ultrasonic image of the borehole wall profile of rock and soil mass is shown in Fig. 1. During the process of fixing the ultrasonic imaging probe, the frequency and relevant configuration of the ultrasonic wave should be adjusted according to the fact that ultrasonic wave can penetrate about 1 meter into the internal structure of rock and soil mass, and the ultrasonic video image can be obtained relatively clear.
Step (2) Intelligently recognize the abnormal structures in video images and realize the visual monitoring.
Aimed at the real-time obtained ultrasonic video images by using ultrasound scanning imager, the abnormal structures in ultrasonic scanning images were identified automatically by image processing method and analyzed qualitatively and quantitatively. The specific implementation method is as follows. Firstly, the ultrasound imaging video (*.cin file) is directly obtained by using the ultrasound scanning imager. Then, Gaussian filtering method and open-close operation method are used to remove the high-frequency and low-frequency noise signals in the ultrasonic scanning image, filter out the noise, retain the ultrasonic images of abnormal structures, such as structural planes and broken zones in the internal structure of rock and soil mass, and obtain the binarization images of abnormal structures. After that, the number of ultrasonic spots, the number of boundary stripes and their total area in the binary image were analyzed statistically. Finally, the visual monitoring of the abnormal structure inside the rock and soil mass can be realized by monitoring the changes of these light spots and boundary stripes.
Step (3) Rotate or translate the probe and assemble video images from multiple angles
The process is to obtain multiple ultrasonic video images of the internal structure of rock and soil mass from multiple angles by rotating or translating the ultrasonic imaging probe and repeating steps 2~3, to realize the visual monitoring of the internal structure of rock and soil mass in a wider range. In order to continuously and multifaceted visual monitoring of the abnormal structures in rock and soil mass, a push rod was designed to facilitate the rotation and movement of ultrasonic imaging probe.
The push rod has the following characteristics: (1) each push rod is hollow fine stainless steel pipe, outer diameter of 15 mm, inner diameter of 10 mm, the internal channeling can take away the cable; (2) each push rod is 2 meters, and from the front end to the rear end is marked on the depth scale, and the rear end is marked on the 360 degrees of azimuth; (3) the rear end of each push rod can be connected with the front end of the next push rod through a nut; (4) The front end of the first push rod shall be connected with the ultrasonic imaging probe, and the ultrasonic imaging probe can be fixed by the rotary nut to realize the in-situ rotation of the probe, translation, sliding and lateral tilt of the probe. Through the push rod, the ultrasonic imaging probe can realize the translation and tilt scanning imaging of the hole wall inside the borehole and the rotation scanning imaging of the bottom of the borehole. The three kinds of ultrasonic scanning imaging schematics are shown in Fig. 5.
By reading the number of the push rod and the scale on the last push rod to calculate the total length of the push rod, the accurate position of the ultrasonic imaging probe in the borehole can be known. And read the rotation angle of the last push rod to know the direction of the ultrasonic imaging probe in the borehole. The position and direction of the ultrasonic imaging probe in the borehole can be calculated. The real-time information of the position and direction of the probe is used to calculate the ultrasonic scanning image obtained in each position direction corresponding to the internal structure information of the rock and soil mass inside the inner wall of the borehole.
The specific implementation method is as follows: according to the total length and rotation angle of the push rod, the ultrasonic scanning image of the current rotation angle at the current position in the hole is obtained, and then the ultrasonic video image of the internal structure of the rock and soil mass at the angle of the position is obtained. After a period, the rotation angle or move to the next position, and according to the ultrasonic video image of the rotation angle at the position, the ultrasonic video image of the internal structure of the rock and soil mass at the next position angle can be obtained. Thus, the ultrasonic video images of the internal structure of the rock and soil mass at each position and angle are successively obtained. Finally, the ultrasonic video images of multiple angles and positions are obtained. After analyzing several groups of ultrasonic video images, the ultrasonic scanning imaging profiles of the internal structure of the rock and soil mass and the corresponding schematic diagram of the ultrasonic scanning imaging are shown in Fig. 6.
As can be seen from Fig. 5 and Fig. 6, necessary combination, mosaic, and fusion of profile images from multiple angles can more completely realize the ultrasonic imaging monitoring of the internal structure of the whole target area. Therefore, according to the ultrasonic video images of the internal structure of the rock and soil mass at each position and each angle and the corresponding depth position and rotation angle information, the sorting and combination of ultrasonic imaging profiles at multiple positions and angles were carried out in order from deep to shallow and from large to small. Among them, some overlapped areas are necessary for image mosaic and information fusion. Finally, the more detailed internal structure information and multidimensional profile structure information of rock and soil mass in a wider range are obtained.
Step (4) Statistically analyze the binarization characteristics of abnormal structures and establish the corresponding relation quantity.
According to the ultrasonic imaging profile of multiple angle positions, the binary image features of the ultrasonic imaging profile of the internal structure at each angle position are statistically analyzed, and these binarization characteristics are classified as the abnormal structures inside the rock and soil mass, and the qualitative and quantitative analysis is carried out after that.
According to the binarization characteristics in the ultrasonic imaging profile of the internal structure, firstly, the total number of pixels in the non-zero region is counted, that is, the total area of the abnormal structure, S, which is equivalent to the internal profile of the rock and soil mass. Then, the total number of non-zero discontinuous light spot blocks and stripe bands N was counted, and the ratio of the boundary length of each light spot block and stripe band to the number of pixels in each light spot block and stripe band was counted, and then the ratio sum of all light spot blocks and stripe bands, referred to as the proportion to length ratio L, was obtained. Finally, the change of these light spots and stripes in the binary image is monitored, and the corresponding relationships between the light spots and stripes and the actual geotechnical engineering structure were established.
The number of light spots and stripe bands can be identified by identifying the number of non-zero region blocks. In addition, in the binarization image, if the pixel value is non-zero, the statistic number can be increased by 1. Since each pixel occupies a certain area and the image area is composed of several pixel points, the number of pixel points within a certain range also represents the pixel area S, which is different from the total number of optical patches and stripe bands N.
Step (5) Assess the degree of potential geological hazards qualitatively and quantitatively according to the binarization characteristics.
According to the statistical binarization characteristics in the ultrasonic imaging profile of the internal structure of rock and soil mass, we can get these conclusions after a lot of experimental demonstration. That is, the corresponding relationships between the abnormal structures and the binarization statistical characteristics in the rock and soil mass. (1) If the total area S of the abnormal structure is large, it indicates that there may be many areas of impurity fragments (fracture zone) in the rock and soil mass; (2) If the total number of light spots and stripes in the statistics is more than N, it indicates that there may be more impurity fragments in the rock and soil mass; (3) If the total ratio L of light patch and stripe in statistics is large, it reflects that there may be many fracture structural planes or relatively regular broken areas in rock and soil mass.
Therefore, a potential geological hazard possibility parameter K can be established qualitatively and quantitatively according to these correspondence relations, which can be used to evaluate the possible existence of potential geological hazards in the internal structure of rock and soil mass. Under certain conditions, this parameter K can reflect the degree of potential geological hazards that may exist in the internal structure of rock and soil mass in the detected area.
3.3 Criteria for judging the degree of potential geological hazards
It is assumed that the total area covered by the ultrasonic imaging probe is A, that is, corresponding to the total number of pixels in the ultrasonic scanning image, and the correction coefficient T is defined as the ratio of the binarization threshold of the ultrasonic scanning image to the ultrasonic frequency power. Thus, the possibility parameter K of potential geological disasters can be defined as:
Then, the following rules should be observed to determine the possibility parameter K of potential geological disasters: (1) The correction coefficient value T should be determined according to the image processing results of the internal structure of the intact rock and soil mass under ideal conditions in the ultrasonic scanning image, and the K value of the internal structure can be set as 1 under ideal conditions; This process is the calibration process of standard parameters before the experimental test, and this process should be carried out before the formal ultrasonic scanning monitoring experiments. (2) When the total number of statistical spot blocks and stripe bands N is less than 3, the relation of potential geological disaster possibility parameter K is not valid. At this time, the image processing method can only be changed by adjusting the equipment.
Under the above rules and relevant definitions, there is a direct proportional relationship between the possibility of the existence of potential geological disasters in the abnormal structure inside the rock and soil mass and K, that is, the greater the value of K, the greater the possibility of the existence of potential geological disasters. Therefore, the assessment method for the degree of potential geological hazards of abnormal structures in rock and soil mass is as follows:
(1) When K is less than or equal to 1, it is judged that the possibility of geological disasters exists in this region is small, and the internal structure of rock and soil mass is relatively stable.
(2) When K is greater than 1 and less than 10, it is determined that there are certain potential geological disasters in this region, and the internal structure of rock and soil mass is relatively broken. If L value is large and S/N is small, there is a risk of geological landslide in this region. Currently, if L value is small and S/N is large, there is a risk of geological collapse in this area. The whole area has certain potential geological hazard risk.
(3) When K is greater than 10 and less than 100, it is judged that there is a large risk of potential geological disasters in this region, and the internal structure of rock and soil mass is relatively unstable. When K is greater than 100, it is determined that there is an error in the calculation process of K value, that there is a large error in the correction coefficient T, or that the relevant prerequisites have not been effectively observed.
The Apogee 1100 full digital color Doppler ultrasound diagnostic system is used as the ultrasound scanning imager, and the convex array probe of 2 MHz is used as the best ultrasonic frequency and the ultrasonic imaging probe. After the ultrasound scanning imager and the probe of this system are configured, the probe is fixed on the push rod and placed under the drilling hole with a depth of 11.5 meters. At this time, the hole is filled with muddy water with a high suspended sediment concentration, which can make the ultrasonic imaging probe better contact with the borehole wall, and if necessary, special mud powder is put into the ultrasonic probe as a coupling agent with the rock and soil mass in the borehole wall. In this case, the previous experiments have ensured that the determination rule of the possibility parameter K of potential geological disasters conforms to the current measured experiment conditions. This time, the correction coefficient T value in the formulas (1) is about 8.27 after calibration experiments.
Taking the internal structure of the rock and soil mass of the borehole wall as an example, the main steps of the process are as follows:
Step 1. Set up the ultrasonic scanning imaging testing system for the borehole wall of rock and soil mass and its related accessories. For example, the power supply, cable, bracket, push rod and other accessories for field testing. The preparation work before the formal ultrasound scanning imaging test should be finished. For example, adjust the optimal setting of the ultrasound scanning imager before the test, so that the ultrasound scanning imager can work in the best working state immediately, as shown in Fig. 7.
Step 2. Fix the ultrasonic imaging probe on the first push rod, thread the inner tube and connect the five push rods successively, and fix the position of the fifth push rod. The reading and rotation angle of the fifth putter are 1.5 meters and 45 degrees respectively. Currently, the position of the ultrasonic imaging probe in the borehole is 9.5 m and the position direction is 45 degrees north by east.
Step 3. Connect the power supply and turn on the ultrasound scanning imager. At this time, the transmission imaging of the internal structure of the borehole wall by the ultrasonic wave sent out by the ultrasonic imaging probe in the borehole can be seen on the screen of the ultrasound scanning imager. For example, we can see the ultrasonic imaging spots formed by the debris damaged area inside the borehole and the banded stripes formed by the internal structural planes of the rock and soil mass. After the ultrasonic scanning imaging system is adjusted, the ultrasonic video image at the angle position can be saved and the *.cin file of the ultrasonic video image can be transmitted in real time through the data line, if the ultrasonic scanning image at the current angle position is clearly visible.
Step 4. For the transmitted ultrasonic scanning video image (*.cin file), the video image processing technology is used to parse a sequence of single images. According to each frame of ultrasonic scanning image, the imaging characteristics, and corresponding relations of the internal structure of the borehole wall in the image were analyzed.
Step 5. In order to monitor the abnormal structure inside the rock and soil mass in the borehole wall from many aspects and angles, the position of the push rod that moves slowly in order or rotates the push rod. The translation and tilt scanning imaging of the ultrasonic imaging probe in the borehole wall and the rotation scanning imaging at the bottom of the borehole were realized, and then the ultrasonic scanning images of the internal structure of multiple borehole walls at different positions and angles were obtained. Multiple ultrasonic video images (*.cin files) and visual monitoring results at different positions and angles were successively saved. According to the order from deep to shallow and from large to small, the ultrasonic imaging profile of the internal structure of rock and soil mass at multiple positions and angles was sorted and combined. Additionally, necessary image mosaic and information fusion were carried out in some overlapping areas. Finally, a wide range of internal structure information and multi-dimensional profile structure information of the rock and soil mass were obtained, and the image data were saved successively until the end of the whole experimental testing process.
Step 6. After all the measurement points in the target area are completed, pull out the ultrasonic imaging probe of the push rod and its fixed part, and clean up the equipment and instruments. Pack all the video and image data, as well as the depth position and rotation angle of the recording file information.
According to the ultrasonic video image data and recorded files packed in the field, the binarization characteristics of the internal structures in the ultrasonic imaging profile at each angle position were analyzed and statistically by using the video image processing method. These binarization characteristics can be generalized to the abnormal structural characteristics inside the rock and soil mass. The corresponding relationship between the characteristics of each binarization image and the internal structure of the corresponding rock and soil mass in the original video was observed.
Firstly, Gaussian filtering method and open-close operation method are used to remove high-frequency and low-frequency noise signals in ultrasonic scanning images, that is, filtering noise. The ultrasonic images of abnormal structures, such as structural plane and fracture zone in the internal structure of rock and soil mass, were retained to obtain the binary images of abnormal structures. Then, the number of ultrasonic spots, the number of boundary stripes and their total area in the binary image were analyzed statistically. Finally, the visual monitoring of the abnormal structure inside the rock and soil mass can be realized by monitoring the changes of these light spots and boundary stripes.
By using methods such as ultrasonic image mosaic and data fusion, the reconstruction of the abnormal area inside the rock and soil mass can be finally realized during the process of ultrasonic image analysis. The reconstruction effect diagram is shown in Fig. 8。
According to the above steps and the organized data file, the total number of pixel points S1~Sn in the non-zero area of each frame in ultrasonic video image was counted successively with the angle position in each hole as the unit. The total number of nonzero discontinuous light spots and stripe bands is N1~Nn. The proportion of each spot block and stripe band is L1~Ln. The average value of S1~Sn is 2568.31. The average value of N1~Nn is 16.42; The average value of L1~Ln is 738.29.
According to the formula (1) of potential geological disaster possibility parameter K, the standard value of ultrasonic scanning image A = 768*576, and T = 8.27, the calculation result of K can be obtained as 2568.31 ÷ (768 × 576) × 738.29 ÷ 16.42 × 8.27 ≈ 2.16. According to the potential geological hazard assessment method, the value of S is 2568.31 ÷ 16.42 = 156.41, and the value of L is 738.29. It can be determined that the internal structure of the rock and soil mass in the area on the hole wall is relatively broken, and there may be a risk of landslide and a certain risk of potential geological disaster in the area.
In this paper, for the visual diagnosis and fine analysis of local abnormal areas in rock and soil mass, a phased array ultrasonic scanning imaging method is adopted to monitor the internal abnormal structure of rock and soil mass and evaluate the potential geological hazards. This method solves the problem that the existing technology can not realize the visual monitoring of the internal structure of rock and soil mass and carry out fine analysis and evaluation of the potential geological hazards. The following conclusions can be obtained after our experimental tests:
(1) This method can solve the problems of visualization observation and real-time ultrasonic imaging detection of the internal structure of rock and soil mass after mud filling or muddy washing hole. Compared with traditional resistivity measurement hole, this method is more convenient and simpler with intuitive and real-time advantages, which can solve the problem that traditional borehole camera system must wash the borehole repeatedly before the optical imaging measurement of borehole wall.
(2) Traditional borehole camera equipment and methods can only observe the structure surface of rock and soil mass on the borehole wall. This paper uses the principle of ultrasonic transmission scanning imaging to realize the transmission imaging and visual observation of the internal structure of rock and soil mass in the borehole wall. The problem of transmission imaging and visual diagnosis of internal structure of rock and soil mass can be saved, so as the fine analysis and measurement of abnormal structure after them.
(3) The method can be equipped with a specific push rod. The ultrasonic imaging probe can be moved up and down and left and right and rotate 360 degrees freely. It is convenient for the ultrasonic imaging detection analysis of the internal structure in the narrow space with multiple directions and angles and the later engineering applications.
(4) Visual diagnosis and real-time monitoring analysis of borehole wall or hole internal structure can be realized by using the transmission and real-time performance of the phased array ultrasound scanning imager.
(5) In this paper, the corresponding relationship between the ultrasonic binarization characteristic image after specific processing and the abnormal structure inside the rock and soil mass is directly established. A set of criteria for evaluating the degree of potential geological hazards is constructed, which can facilitate the mass image data processing and a wide range of engineering application.
Data Availability Statement
All data generated or analyzed during this study are included in this article.
Acknowledgments
All of images and data are from our actual drilling engineering and permitted by the owners. Another, this work was supported by the National Natural Science Foundation of China (42007266) and the Natural Science Foundation of Hubei Province (2019CFB345). We are compliance with Ethical Standards and all authors declare that this paper has no conflict of interest. Finally, we are grateful for the many helpful and constructive comments from many anonymous reviewers.
Compliance with Ethical Standards
Declaration of Interest Statement
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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