## 3 Detection Technology of Adverse Geological Bodies  
### Borehole Multi-Source Heterogeneous Detection Technology  
Due to the ever-changing geological conditions in karst development areas and the multiplicity of interpretation tasks, the combination of multiple detection methods is often needed to solve practical problems in practical projects. The so-called dynamic detection technology is a kind of detection technology that adjusts the layout and detection scheme of the survey points in real time. It works according to the established operation process, the detection task and the geological conditions of the site, so as to know whether there are any adverse geological bodies that may cause safety hazards to the project in the area of concern, thus achieving high efficiency and economy. It first conducts a comprehensive detection and on-site real-time analysis of a single hole, then judges whether there are adverse geological phenomena and whether it can meet the engineering safety requirements. This guides it whether or not to add new boreholes until it meets the requirements of the detection task, so as to realize the dynamic adjustment of the detection scheme.  
Because the antenna of the borehole radar can receive a scattered echo from the abnormal body around the borehole in all directions, and the three-dimensional information is stored in the form of a two-dimensional time series during data acquisition, the size and depth of the abnormal body from the borehole axis can only be analyzed from the radar data of a single hole. Consequently, the azimuth information of the abnormal body cannot be determined. The data of borehole camera and borehole acoustic scanning can only identify the geological conditions of the borehole wall and its surroundings, including the trend and inclination of the fracture joint surface, and the distribution of the cavity area and karst area around the borehole wall. In order to quantitatively describe the distribution of abnormal geological bodies around the borehole, joint analysis of porous data is required. In order to determine whether the site is karst, with cavities and other adverse geological bodies in a certain area, dynamic detection technology is an economical and efficient method.  
As shown in Figure 7, first select a place near the area of interest to make the first borehole A, and carry out optical imaging, borehole radar and borehole directional acoustic scanning according to the operation process of dynamic detection technology to predict whether there is any adverse geological body that may cause safety hazards to the project in the site. If not, there is no need to increase the borehole work. If it is found that there may be adverse geological bodies in the site, but the location is unknown, It is necessary to increase the borehole and survey work. The hole detected in borehole A may be either in the site area of concern (e.g., E) or outside the site area (e.g., F), so it is necessary to add a borehole B. If the detected hole is far beyond the scope of the site area from borehole B, it means that the borehole measured in borehole A is not in the site area, and the test work of the next borehole does not need to be added; otherwise, another borehole C needs to be added. At this time, the size and location of the abnormal body in the borehole can be estimated through the optical imaging of the borehole, borehole radar and the borehole directional acoustic scanning data of all three boreholes, and its impact on the project can be evaluated, so as to carry out the reinforcement measures for the subsequent works.