ELECTROMAGNETIC EXPLORATION ON GEOLOGICAL STRUCTURE OF EXPRESSWAY TUNNEL IN KARST AREA

During the construction of expressway tunnel in Karst area,the geological structure near the tunnel line should be known,especially whether Karst and fractured zone develop or not,which have important influence on the safety of tunnel construction. In the geophysical exploration work on bad geologic body of deep-long tunnel,Controlled Source Audio Frequency Magnetotellurics Method(CSAMT) is fairly effective one. In this paper,we compared the original sounding curve near the borehole with the electrical resistivity of the borehole samples,to check the reliability of the data. Combination with geological interpretation and verification,the results show that CSAMT method has a good effect in exploring the geological structure of tunnel in Karst area,and has a certain guiding significance for tunnel construction.