Abstract: The common geological hazards in construction of tunnels in karst terrain are: karst rock cavern, underground river, groundwater gush and sudden mud flow etc. These hazards often induce significant difficulties and prolonged construction schedule. This paper presents a case history of mitigation measures used in a very large karst rock cavern in Chengkou to Wanyuan Expressway project. The tunnel liner consider the impact loading of from rock falls.

Key words: Large Karst Rock Cavern, Secondary Lining, Impact Loads, Analytical Model