## 3 Integrated Geophysical Exploration Techniques for Earth and Rock Dams  
### Principles of Integrated Geophysical Exploration Techniques System  
Earth and rock dams are affected by many factors in the process of hidden danger detection, mainly human and natural factors, with the impact of natural factors being more prominent. The geology in some areas is complex, and it is difficult to achieve the expected detection results using one technology alone. Therefore, the use of two or more detection techniques can help perform detections quickly, and the error can be minimized in a reasonable range. The integrated geophysical exploration techniques can be used in earth and rock dam projects with complex geology to ensure the accuracy of the detection results.  
The integrated geophysical exploration techniques system should follow the detection principle of overall first, then local, and rough first and then fine. Multiple geophysical exploration techniques should be used in combination to validate and complement each other [94]. For leakage path detection of earth and rock dams, particularly for large- and medium-sized earth and rock dams, a combination of various geophysical exploration techniques should be used in accordance with certain principles to comprehensively and accurately detect hidden dangers in earth and rock dams. The principles are as follows.  
1. Start with an overall probe. Geophysical exploration techniques with a lower resolution and higher efficiency can be used for the overall detection of possible leakage paths in earth and rock dams.
2. This is followed by localized precision detection. Geophysical exploration technology with a higher accuracy and resolution can be used for the fine detection of key areas where the leakage path may exist, for a more accurate identification and positioning of the leakage path in earth and rock dams.
3. The use of a single geophysical survey technique can only obtain a single physical parameter of earth and rock dams. When performing hidden danger detection, a combination of physical parameters should be chosen. The different methods should complement each other, should be mutually verifiable, and constrain each other to ensure the diversity of the detection parameters present detection results from multiple perspectives, and improve the detection accuracy [95].  
Integrated geophysical exploration techniques [96] are a means of combining two or more geophysical exploration techniques for the multiangle detection of a target project. Following the principles of the above system, methods with a shallow detection depth and high accuracy are selected and combined with detection methods with a large detection depth and relatively low accuracy to obtain richer and more complete detection information, providing guidance for the design and construction of projects [97]. [PERSON] et al. [98] used the electrical resistivity tomography method and the transient surface wave method to measure the distribution and density of potential leakage in tailings dams, and the two methods complement each other to obtain good results. [PERSON] et al. [51] used the integrated geophysical exploration method of the TEM and controlled source audio frequency magnetometer (CSAMT) to investigate the hidden danger state in detail. The results were mutually confirmed to be good. Figure 10 shows the process of integrated geophysical exploration techniques.