Research on the Application of Geophysical Exploration in Tunnel Survey

The accuracy of geological survey plays an important role in the cost and safety of tunnel construction. In recent years, with the development of expressway from plain to mountain, the geological conditions of highway tunnels are becoming more and more complex. The interpretation results of geophysical exploration can well present the geological conditions of the tunnel in the form of surface. The geophysical exploration technology used varies with the burial depth of the tunnel. High density resistivity method has high resolution in shallow layer, which can accurately and quickly detect karst caves, faults and other geological structures in the shallow buried section of tunnel portal. The results will play a guiding role in the prevention and treatment of geological disasters such as tunnel portal landslide, collapse and roof fall. The magnetotelluric method is used to measure the depth of tens to 3000 m, which can be used to detect the fault, water content and other geological conditions in the deep buried section of the tunnel. The comprehensive geophysical exploration method combining high-density resistivity method and magnetotelluric method is adopted for highway tunnels in mountainous areas, which can provide relatively accurate geological survey reports, effectively reduce geological diseases during construction and operation, reduce project cost, and ensure the safety of traffic after operation. This method is worth using for reference.