Karst Development Characteristics and Water Inrush Risk Assessment of Railway Tunnel in a Difficult and Dangerous Mountain Area

A railway tunnel in a difficult and dangerous mountain area is an important control project. The regional tectonic movement is active, and the engineering geological environment is extremely complex. In order to prepare to evaluate the risk of water inrush in the tun–nel, the hydrogeological characteristics of the Tunnel were investigated and analyzed in depth by means of geological mapping, deep hole drilling, etc. The groundwater runoff system in the site area is roughly divided into local surface runoff system, shallow runoff system and regional deep run off system, and following the multiple and multilevel analysis and evaluation ideas, different evaluation indicators are selected to construct tunnel surges in the insoluble rock section and the soluble rock section. According to the evaluation system of water inrush risk, it is concluded that the water inrush problem in the Tunnel is mainly of low risk, and the high and extremely high risk sections only account for about 4% and 1% of the total length of the tunnel, which is mainly controlled by limestone (T₃b) and Eaideng fault zone.