Seepage force in a drained circular tunnel: An analytical approach

This study deals with the investigation of analytical solutions for the seepage forces acting on the lining in a drained circular tunnel under the steady-state groundwater flow condition. Two different boundary conditions (one for zero water pressure and the other for a constant total head) along the tunnel circumference are mentioned. Simple closed-form analytical solutions for seepage force along the tunnel circumference are derived in a theoretically consistent way for two different boundary conditions by using the conformal mapping technique. The seepage force predictions are compared to investigate the differences among the solutions. It is shown that the seepage forces acting on the lining should be considered for a drained tunnel and that the seepage forces greatly increase for a very deep tunnel.