Study On The Risk Assessment Methods Of The Geological Disaster During The Tunnel Construction In Karst Areas On Yiwan Railway

Since the disaster caused by Karst area inrush during the tunnel construction in Karst area, will result in dramatic damage to vast area, people are increasingly focusing on it in resent time.This paper will focus on the geological disasters caused by Karst area inrush during the present tunnel construction in Karst area, based on the tunnel project at typical Karst area along side of the YiWan railway, by investigating the local hydrogeological conditions and engineering geological conditions and analyzing Karst geological data, gushing water monitoring data, meteorological data of the tunnel project area.On these bases, this paper will analyze the main causing factors and the forming principles of the geological disasters caused by Karst area inrush. The main study will be as following:(1) To study and analyze the concerned data about the study on geological disasters caused by Karst area inrush in typical tunnel project, and then absorb the basic features and forming principles and influential factors of them.The tunnel inrush in Karst area is dynamic and changing, which is not only related with the construction conditions and tunnel features but also restricted by the hydrogeological conditions. And the letter is also infected by the geological conditions such as terrain conditions, lithology and geological structure.(2) To analyze the key indicators such as the monitoring data of inflow, the pressure and the rainfall, then study the monitoring methods of the key indicators of the geological disasters by Karst area inrush during the tunnel construction.(3) By analyzing the geological background and the monitored data of the Karst area in typical project, to study six influential factors as risk assessment of the geological disasters by Karst area inrush, including lithology, geological structure, surface water system, groundwater system, elevation karst and tunnel design. Then, this paper will make sure the index weights through AHP, and build the risk evaluation index system of geological disasters by Karst area inrush, as well as the risk grading classification of it in tunnel construction.(4) To compare and analyze the basic theory and method of the geological disaster risk evaluation, and build evaluation model by choosing comprehensive index based on AHP according to the features of geological disasters by Karst area inrush in tunnel construction, and to go on the risk evaluation of it. (5) By choosing the typical part of the QiYue mountain tunnel project, and making use of previous studying method to do the risk evaluation, to reach the conclusion that the risk evaluation method presented in this paper is capable of appropriately evaluating the geological disasters by Karst area inrush.