Research On The Distribution Law Of Seepage Field And The Water Pressure Characteristics Of Lining Structure In Subject To Underwater Tunnel Of Weak Surrounding

Considering the first subsea tunnel by drilling and blasting method in China mainland——subsea tunnel on Xiamen Xiang’an as the engineering background. Using numerical simulation and model test research methods, this thesis has made research on Seepage Field and tunnel grouting circle lining behind the distribution of the water load, the main results are as follows:(1) Using the numerical calculation to analysis the impact of the thickness and the permeability of the primary lining、the scope and the permeability of the grouting and the different excavation methods on the seepage field of the underwater tunnel. Concluded the distribution law of water pressure upon lining and outer surface of grouted ring.(2) Using the model test system researched by Tunnel&Underground Engineering Test Research Center to do the model test research on the distribution law of the seepage field of the underwater tunnel. The distribution law of the water pressure at the outer surface of the grouted ring and the lining back in the process of the entire plugging, limited drainage and increasing the water load are researched. In the same condition of displacement, the water pressure of the invert of the tunnel and outfall of the both sides are smaller than the pressure of the side wall and the vault.The water pressure of measuring points out of the grouting circle decrease with the increase of the displacement. The water pressure and flow meet a linear relationship.(3) From the surface of the soil above the tunnel to the vault, water pressure is substantially hydrostatic pressure distribution. In the grouting circle, water pressure decreases rapidly, this showed that reduction effect on the water pressure of grouting circle is obvious; From the outside of grouting circle to the bottom of the tunnel, the water pressure increases linearly. Outside the grouting circle, water pressure basically showing hydrostatic pressure distribution. Within the circle, as the depth increases, the water pressure increases faster.(4) In order to study the impact of different grouting parameters on the seepage field, we change the thickness and the permeability coefficient of the grouting circle. With the increase of the thickness, the displacement decrease. As the same displacement, the pressure increase with the decrease of the permeability coefficient of grouting circle. Especially in the case of the limited drainage, as different permeability circumstances, the water pressure of the same point behind the lining and grouting different from the point behind the grouting circle. With the permeability of routing circle,the free displacement is reduced accordingly.