Application of transient electromagnetic method in tunnel exploration

Along with the economic development, large tunnels need to be constructed in many high mountains or complex structure regions, and the design and construction of detailed tunnel exploration become particularly important. Transient electromagnetic method （TEM） uses a non-grounded loop or an electrode to send a prima-ry electromagnetic pulse into the ground, and observes spatial and temporal distribution of secondary electro-magnetic field, which is widely applied in mineral resource exploration, engineering geology, etc. The applica-tion of TEM in the tunnel construction of Kaiyuan Temple is researched in this study. The smoke loop inversion is adopted for inverting the transient electromagnetic data. The drilling data and high density resistivity method data are combined for comparison. The obtained inversion result greatly coincides with the actual conditions. Therefore, the geophysical prospecting basis can be provided for the division of stratum, delineation of geologi-cal structure, and design and construction of tunnel pavement. By virtue of TEM, drilling data and high density resistivity method, the tunnel construction of Kaiyuan Temple has obtained satisfactory results.