Study Of Hydrogeological Conceptual Model For Underwater Tunnel

As the specific characteristics of engineering environmental and the severity of potential groundwater inflow disaster, underwater tunnels have become to be high-risk underground projects. Therefore, predicting the possible disasters in the tunnel area before excavation becomes important to the security of tunnel construction and normal operation. So far, the general method for prediction of tunnel inflow is to simulate the dynamic groundwater flow field within the tunnel area. And the precondition to realize this step is to set up a scientific, reasonable and accurate hydrogeological conceptual model of the study area.This thesis took the Shiziyang Underwater Tunnel for example. By collecting the geological and hydrological data from the tunnel area, this thesis conceptualized the hydrogeological conditions of the tunnel and analyzed the parameters like boundary conditions, sources and sinks, permeability of the aquifers. The thesis has such research results:(1) An evaluation index system was established by inferring the factors that could impact the division of hydrogeological units, including the strata lithology, geological structure, geographic and geomorphic conditions, permeability, water table and the embedded depths of tunnel.(2) By using the AHP-fuzzy comprehensive method, we set up a discriminative model for the division of hydrogeological units.(3) Then the Shiziyang Tunnel was divided into 6 sections by this model and the hydrogeological conceptual model was set up for each tunnel division. These 6 divisions were DIK33+660～DIK34+710, DIK34+710～DIK38+520, DIK38+520～950, DIK38+950～DIK39+940, DIK39+940～DIK42+260 and DIK42+260 DIK43+000.This thesis proposed a way of establishing scientific and accurate hydrogeological conceptual model for Shiziyang Underwater Tunnel, and also has provided a theoretical reference and the guiding sense for other underwater tunnels.