Analytical study on dissipation of excess pore water pressure around tunnels with semi-permeable boundary conditions

A consolidation-rheology coupling model for soils is established by introducing semi-permeable boundary condition based on the Terzaghi-Rendulic consolidation theory and the Burgers viscoelastic model. The dissipation expression of excess pore water pressure is derived, which is around the tunnel with partially sealed shell lining in viscoelastic media by means of the complex function method. Moreover, comprehensive analysis is carried out on the effect of various permeable conditions on the dissipation and distribution of the excess pore water pressure around the tunnel, with Shanghai Metro Line 2 as the engineering background. The results show that the dissipation rate outside the tunnel lining becomes faster as the relative permeability coefficient of lining to surrounding soils rises. The initial excess pore water pressure and its dissipation rate decrease as the distance from surrounding soils to the lining turns farther.