Numerical Simulation And Approximate Analytical Solution For Groundwater Flow In Vicinity Of The Face Of Shield Tunnel Excavations

With the great development of infrastructure construction in China, more and more underwater tunnels are planned to be into construction, some of them are shield tunnels in conditions of high water pressure and complicated stratum. In this paper, according to the characteristics of underwater shield tunnel construction, considering the conditions of high water pressure and complicated stratum, studying numerical simulation and approximate analytical solution for groundwater flow in vicinity of the face of shield tunnel excavations, the main topics of this thesis are as follows:(1) Numerical simulation for groundwater flow in vicinity of the face of homogeneous underwater sand gravel soil layer, homogeneous underwater clay soil layer and homogeneous water-rich sand gravel aquifer shield tunnel excavations is done respectively; considering different excavation face drainage boundary conditions, this thesis analyzes the distribution of pore water pressure, compares numerical results with the approximate analytical expression which is proposed by Perazzelli for limit equilibrium model and analyzes relative error at the same time.(2) Numerical simulation for groundwater flow in vicinity of the face of sand gravel-clay soil layer, complicated underwater stratum and complicated water-rich aquifer shield tunnel excavations is done respectively; considering different excavation face drainage boundary conditions, this thesis analyzes the distribution of pore water pressure and gets the approximate analytical expression of fitting hydraulic head used in limit equilibrium model. adopting the least squares method.(3) Numerical simulation for groundwater flow in vicinity of the face of a selected EPB shield tunnel excavation is done; this thesis analyzes the distribution of pore water pressure and gets the approximate analytical expression of fitting hydraulic head in limit equilibrium model on the drainage boundary condition that the pore water pressure of tunnel excavation face is fixed at 0,adopting the least squares method.