Application of audio magnetotelluric method in detecting buried faults in water diversion tunnels

Abstract Diversion tunnels play a critical role in water conservancy and hydropower projects. However, due to complex geological conditions, especially the influence of buried fault structures that are difficult to observe below the surface directly, construction processes often face significant challenges such as rock mass instability, seepage, and abrupt geological changes. Audio magnetotelluric (AMT) technology, as a high-resolution electromagnetic exploration method, demonstrates remarkable advantages in detecting buried fault structures due to its sensitivity to deep subsurface features and wide applicability. This study focuses on a specific diversion tunnel project, conducting a detailed analysis of the distribution characteristics of buried faults along the tunnel alignment. These include the orientation, scale, depth, and relationship of the faults with surrounding geological structures. By comparing and validating the detection results, the study further establishes the applicability and reliability of the AMT method under complex geological conditions.