Study The Geologic Analytical Method On Karst Advanced Forecasting Of Tunnel Engineering On Yiwan Railway

With the rapid engineering development on the traffic and resources exploitation in our country, more and more deeply-buried tunnels are constructed, which are long or across the mountains, and the followed construction calamities receive the extensive concerns, especially in the southwest area, it seems particularly outstanding that various kinds of problems related to karst calamity during the course of tunnel construction. In addition, the karst calamities influence the project progress and increase the fabrication cost of the project as well as threaten the security of constructors seriously. So the karst calamities receive much concerns of the railway construction unit, In order to avoid or reduce this kind of problems, the advanced forecasting technology arises to make the project constructed safely and speedily.There are some basic means about advanced geologic forecasting of the tunnel including geological analytical method, geophysical prospecting method, level geological drilling method. Combining the actual conditions of three key tunnels,qiyueshan tunnel and baziling tunnel and yesanguan tunnel, on the line of the Yiwan railway, this paper has systemically study the geological analytical method of the advanced forecasting, and investigated the characteristics of surface karst development and deeper karst development disclosed in the construction, analysed the karst development disciplinarian and calamity mechanism, thus researched the key geological factors of karst development. Through analyzing and researching the stratum lithology, geologic structure, the change of physiognomy and landform, surface drainage, the supply and runoff and drainage of groundwater in the range of groundwater drainage areas, we can sum up and bring forward the geological analytical index system of karst advanced forecasting, and set up the technical route of geological analytical method on karst advanced forecasting, thus nail down the formation of geological analytical method, then forecast danger zones of the three long tunnels by using geological analytical method. According to the geological analytical index system, we can develop the expert system of advanced geologic forecasting by the development of software.