The Application Of Transient Electromagnetic Methods (TEM) In The Tunnel Advanced Forecast And Its Effect Research

During the tunneling we faced varieties of harmful geological objects frequently, such as rock fracture zones, karst caves, water outburst quick mud, then Transient Electromagnetic Method (TEM) is a method of advanced geological forecast of tunnel to solve the problems. In this paper, the basic theory of TEM and its method of working are studied, on the basis of gathering the previous materials and analyzing achievements of TEM, We sum up interpretation methods and the general rules of interpreting maps, and explore a suit of elucidative standard preliminary. TEM is applied in advanced geological forecast in Mingyuexia tunnel Projects, and on the basis of integrating engineering geological data and comparative analyzing the result of TEM with TSP and actual situation, we evaluate the applicability and the effect of TEM. And get these conclusions from study as follows:1.Based on integrating the data of engineering geology, TEM is applied in advanced geological forecast of Mingyuexia tunnel. Comparative analyzing the result of TEM with TSP and actual situation indicate that the effect of water forecast of TEM is better than the other forecasting methods, and TEM also has obvious advantages, such as more accurate and low cost, taking shorter working hours in the tunnel, and having wider application prospect. But the forecasting of TEM is influenced by some interferential factors in the tunnel, such as the self inductance and mutual inductance in coils, mechanical equipment in tunnel, excess surface water etc. And to a certain extent, it will affect the accuracy of forecasting results.2.The elucidative methods are summarized and a suit of elucidative standard is explored through combining the general rules with application fruit of TEM in the tunnels.3.The applied experiences of the TEM is summed up. The problems of working in the tunnels, processing the data and the data interpretation are put forward, such as the records of data acquisition site, setting instrument parameters, identification of data quality and interpretation combining with previous data etc. Simultaneously,the necessary improvement and the problems which need to be solved of TEM applied in tunnel geological forecast are pointed out. The assumption about the future further work is put forward.