Karst Water Development Characteristics And Risk Assessment In A Tunnel Area Of Xi’an-Chengdu Passenger Railway

Tunnel excavation in karst area or tectonic belt, could drain a part of karst groundwater, causing a series of secondary environment problems. Combining the field geological survey and analysis of the collected data, focusing on the tunnel and the spatial distribution of aquifer lithology combination characteristics, the paper found out the karst water dynamic conditions of the tunnel. Using the existing tunnel gushing water risk evaluation system, the paper forecasts where the gushing water may occur in the process of tunnel excavation and the degree of danger, to guide the tunnel construction. The paper also preliminarily evaluates tunnel gushing water’s influence on the environment.First of all, according to the characters of exposing groundwater, lithology, structure, landform and water enrichment k, the area is divided into five karst systems. Then analyzation was programmed on flood water inrush in tunnel sections. Development characteristics of karst water was summarized based on the seasons change, and dangerous sections differentiated to evaluate possibility of water inrush in the tunnel.On this basis above,according to the tunnel gushing water risk evaluation index,2 tunnel in the study area were divided into danger zone, high danger zone and middile danger zone. Simutaneously, tunnel gushing water quantity wass forecasted by methods of rainfall infiltration and groundwater dynamics. Finally the secondary environment disasters that may be led by water gushing is evaluated.