The Application Of TEM In Tunnel Fore Geological Forecast And Its Interpretation Methods

There are many mountains and hills in the west of our country. The tunnels always are adopted to cross the mountains when building the superhighway. Bad geological conditions, especially all kinds of geological disasters always become the hardest problems to be solved in the tunnels construction. If there are lots of karst in the tunnel region, there will be the probability of water and mud effusing badly. So it is very pivotal to adopt the fast and effective earth physics reconnoiter methods for forecasting the karst water.TEM (Transient Electromagnetic Methods) is one of earth physics methods which is hypersensitive to lower fresistance objects. So there will must be very good developmental foreground to use it to forecast the bad geological conditions including water. But there are also localizations to use the TEM for the tunnel fore geological forecast. Among them, the actual elucidative standard which is not immovable and uniform is the most influence factor to the forecasting results and it debases the precision of the results greatly. So researching the applicability of the tunnel fore geological forecast by the TEM and exploring its uniform elucidative standard have very important meaning to advance the forecasting precision and accelerate its development.This text is based on collecting the research information of the forthgoers and analysing the domestic and international research fruits of the TEM. And the TEM was used to be a method of fore geological forecast in the Tongluoshan tunnel, Mingyueshan tunnel, Zipingpu tunnel and Huayinshan tunnel. And the TEM got a very good appliance effect by comparing the forecasting result with the geological analysis, fore drilling and the construction result. We hope to summarize elucidative methods, find the rules of the elucidative charts and explore a suit of elucidative standard by the experiences, application fruit in the tunnels and the numerical value simulation analysis to the different kinds of styles of the bad geological disasters and got these conclusions from study as follows:1. The engineering geological conditions of the Tongluoshan tunnel, Mingyueshan tunnel and the other tunnels were analyzed amply. And the tunnel mileages which may have karst water were concluded. The TEM were used to forecast the karst water. And the forecasting results were compared with the geological expert analysis, fore drilling and the construction results. The TEM shows the great advantage in forecasting karst water and the forecasting results are exact mostly. The cost is low and the woking time is short. But the veracity of the forecasting results was influenced by some interferential factors in the tunnels.2. Firstly, the numerical value simulation results are contrasted with the successful forecasting examples and the appropriate models and parameters will be chosen. Then the numerical value simulation analysis will be carried on to get the influence electromotive force attenuation curves of each point according to the kinds of the karst. Lastly, the charts of the relative resistance rate isoline will be contrasted with each other and the rules of the elucidative charts have been found.3. The elucidative methods will be summarized and a suit of elucidative standard will be explored through the expert experiences, application fruit in the tunnels and the numerical value simulation analysis for the different kinds of styles of the bad geological disasters.4. The applied experiences of the TEM will be summed up. The problems of the procedure of woking in the tunnels, the methods of calculateing the datas and the elucidation was be brought forward. And the contents which need to be ameliorated and the problems which need to be solved as early as possible of the TEM tunnel fore geological forecast will be put forward.