DISASTER-INDUCED MECHANISM AND ITS TREATMENT IN SHALLOW-BURIED KARST TUNNEL
KANG Yong1，YANG Chunhe1，ZHANG Peng2
(1. State Key Laboratory of Geomechanics and Geotechnical Engineering，Institute of Rock and Soil Mechanics， Chinese Academy of Sciences，Wuhan，Hubei 430071，China；2. Chongqing Monorail Transit Engineering Co.， Ltd.，Chongqing 400081，China)
Abstract：Aiming at disasters that happen in shallow-buried Yunwushan karst tunnel，the disaster-induced mechanism is theoretically analyzed；and also the stability of surrounding rock and its support system are evaluated through numerical simulation and in-situ monitoring. It shows that，the five key disaster-induced factors in shallow-buried Yunwushan karst tunnel are shallow-buried depth，soft cover，karst development and scale，groundwater supply，and engineering factors. The inrush of surface water into the collapsing area is a dominant factor for collapse expanding. From simulating and monitoring results of stresses and displacements，the surrounding rock and support system are proven to be stable after the implement of support enhancement；and the conclusions would be helpful for the further research related to shallow-buried karst tunnels and similar engineering practices in China or other regions with karst geological problems. It would be highly essential to take quick and appropriate measurements in the excavation of karst tunnel. What is more，the measurements must be subjected to the existing geological conditions，therefore，the frequency of karst disasters can be possibly reduced to avoid the increase of engineering costs，and to accelerate construction progress.
