As a discontinuous media element,contact surface element is commonly used to simulate discontinuous deformation between different medium and the tangential stiffness coefficient will have great effect on results of numerical computation.Taking concrete impermeable wall as research object, Duncan Chang nonlinear elastic soil model and Goodman contact model are introduced. Through different values of tangential stiffness coefficient,finite element method is used to study distribution laws of deformation and stress of impermeable wall.Research results show that compressive and tensile stress will be lowered when tangential stiffness coefficient is reduced, thus stress state of impermeable wall will be improved and abrupt change of stress between overlay and rock layer will be minished, which is propitious to unleash performance and safety of impermeable wall.
