Mode Classification and Disaster-Causing Mechanism of Water Inrush in Karst Tunnels

Handong Chu, Guangli Xu, Zhang Yu, Pola Liu, Jifeng Wang
Based on the specific investigation and analysis of dozens of typical water inrush accidents in 18 karst tunnels lying on several highway and railway lines in China, a novel mode classification of water inrush is presented: one is called unrevealed-mode water inrush which occurs before the karst water-bearing structures are revealed, and the other one is called revealed-mode water inrush which happens after revealing the water-bearing structures accordingly. The disaster-causing mechanisms of
more » ... ing mechanisms of unrevealed-mode and revealed-mode water inrush are all due to the failure of against-inrush layer which is able to resist karst water, but different because of the type of against-inrush layer. The against-inrush layer of unrevealed-mode water inrush is rock mass, and its failure form consists of tensile-shear failure, hydraulic fracture failure and key block instability based on crack distribution in against-inrush rock mass. The disaster process from crack extension to formation of water inrush channel in against-inrush rock mass is accurately and visually displayed through numerical simulation technology. The against-inrush layer of revealed-mode water inrush is filling, the failure form of which consists of shear failure and seepage failure. Piping, soil flow and scour constitute Vol. 21 [2016], Bund 23 7170 seepage failure. This mode classification provides a fresh and distinct research approach for mechanism of water inrush, and then a scientific basis for putting forward targeted control technology of water inrush can be given.