DYNAMIC ESTIMATING THE KARST TUNNEL WATER INRUSH BASED ON MONITORING DATA DURING EXCAVATION

The tunnel water gushing has long been a difficult hydrogeological problem, especially in karst areas. It affects the entire process of tunnel construction, operation and maintenance. In view of the complex disaster-causing mechanism and difficult quantitative predictions of water inrush, several theoretical methods are adopted to realize dynamic assessment of water inrush in the progressive process of tunnel construction. According to a survey conducted in the Zoumaling tunnel near Chongqing, China, 62% of its total length, e.g., 1525 m is associated with karst (including a fault fracture zone). On the basis of collecting real-time monitoring data about water inrush in the excavated section of the Zoumaling tunnel, a fuzzy data analysis method has been used to analyze the content of seven common ions in the inflow water, which makes it possible to classify the groundwater types and to establish the hydrogeological model of the tunnel site. In order to forecast the possibility and quantity of water inrush, it is essential to accurately model the groundwater system spatially. The preliminary forecasting result about untapped section reveals a small possibility of a sudden water inflow disaster and 35,000 m(3)/d water inflow, which is close to the ultimately measured quantity of water. This study provides a theoretical reference for the prediction of water inrush during tunnel construction, and the main characteristic of this study is reflected in the real-time prediction of tunnel water inrush according to actual tunnel inflow of excavated sections. This approach can be applied in similar situations for the prediction of tunnel water inrush in other karst regions.