| Karst is extensively existed in China. With the development of railway, more and more tunnels will be constructed in area of karst. Karst is a kind of poor geology condition. It affects seriously the safety of construction and operation of tunnels.This thesis expounds the mechanism of the deeply embedded tunnel under water load in the area of high groundwater level. Mechanical behaviors of lining structure under high hydraulic pressure are analyzed with plane finite element model. Numerical analysis concerning the influence of karst caves is carried out by using the ANSYS program. The contents of the thesis are as follows:Firstly, the Shenghongqing tunnel design and karst water outburst situation are introduced. Karst development distribution and causes of inrush water of the Shenghongqing tunnel are presented with the electromagnetic geophysical prospecting results. Based on the abundant hydrogeology material and field study of investigation and design of Shenghongqing tunnel, the water inflow volume is calculated by the rainfall infiltration method.Secondly, by collecting the material related to the water load, the author exhaustively expounds the mechanism of water load in the area of high groundwater level. Mechanical behaviors of lining structure under high hydraulic pressure are analyzed with plane finite element model. Through checking calculation and comparing schemes, discharge tunnel design is put forward.Finally, two-dimensional numerical analysis of tunnel construction is performed by considering the influence of karst caves. For karst caves with different sizes at different locations, the displacement field, strain field and plastic zone are obtained.The research result presented in this thesis is helpful for understanding the mechanical behavior of the tunnel lining when the influence of karst caves is considered. It provides reasonable suggestions for the safe, reliable and economic design and treatment of the tunnel in karst areas. |
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