DEFORMATION MECHANISM OF SLOPE COVERED WITH CLINOSOL AT TUNNEL ENTRANCE AND ASSOCIATED EXCAVATION TECHNOLOGY IN NORTH HUBEI PROVINCE

The slope with colluvial soil near the entrance of tunnels has poor self-stability after excavation and is influenced by tunnel excavation. Therefore landslides can occur frequently, which can bring economic losses and endanger the safety of construction workers. This paper is based on Xiangshan tunnel and conduct three-dimensional finite element numerical simulation model on the basis of tunnel site topography and geology. It analyzes the changing processes of displacement and stress of slope near tunnel entrance and the influence of tunnel excavation to slope. Then, it optimizes the excavation scheme of tunneling. The research result shows that the abrupt change of gradient between excavation slope and original slope induces stress concentration and forms potential slip surface. Then, the tunnel excavation can impact greatly on deformation, stress and strain of front slope. Excavating slope in layers can effectively improve the stress-strain state of the slope. An appropriate shape of slope has a significant influence on stability of slope near tunnel entrance.