Conductivity characteristics of the Xiaojiang fault in highway tunnel of wakeamo

The terrain conditions and geological structure of the mountainous areas in western China are complex. To meet the design requirements for the expressway, the route adopts the design of deep-buried super-long tunnels in hilly areas. If the highway tunnel passes through faulty structures, such as improper selection of structure and foundation form, it can cause collapse and structural instability during construction. Therefore, basic characteristics of faults and information that is more accurate should be provided during the survey process to avoid subsequent problems. The frequency and magnitude of earthquakes in this study area are high and available data show that the Xiaojiang fault was still active during the Quaternary Holocene period, which is a high-risk area for earthquakes. Therefore, a set of comprehensive technologies, such as geophysical prospecting, geological survey, and drilling, and was used to identify faults and their characteristics and to visually display underground information within a certain depth range. Here, the magnetotelluric method was used to analyze the electrical characteristics and structure of the highway tunnel. In addition, the electrical characteristics and structure of the Xiaojiang fault were discussed. Geological surveys and drilling agree well with the analysis and interpretation of the research results and further proposed a processing and interpretation method for correcting the dip angle of the fault using the statistical results from the long axis dip angle of the tensor polarization map for the wave impedance. Thus, a large amount of information in the tunnel site can be effectively obtained for predicting and evaluating the Xiaojiang fault. Furthermore, our results provide strong technical support for designing and operating highway tunnels, with meaningful experience and reference for future geophysical processing and interpretation.