Application of 3D electrical resistivity tomography to a tunnel in a karst area

During the rainfall season the leakage of water in Nanshibi highway tunnel seriously influences the traffic of the tunnel, resulting in security risk. In order to find out the paths of leakage and sources of the water, this work used different devices of the high-resolution electrical resistivity to carry out in-situ measurements. Combining this survey with local geological conditions and other survey data available, the leakage situation of the tunnel was analyzed in detail. The results show that the high-density electrical method can work well by using different measurement devices and different running ways. In the Nanshibi tunnel, there are numerous karst cracks. The karst water mainly comes from the leakage of Meiling reservoir and supplement of rainfalls. Several major paths of the leakage have been clarified by the survey. This case study shows that the 3D imaging of electrical resistivity of the highresolution electrical method can reveal underground geological structure, which is of significance for detection and treatment of karst hazards.