Abstract: High earth-core rockfill dams are often designed with a contact layer inserted between the earth core and concrete cushion to reduce the otherwise too large deformation gradient at the interface while retaining strong impermeability. Large shear deformation induced by high water pressure puts this contact layer under a complex strain-stress and seepage state, and much attention is drawn to whether it is more susceptible to seepage damage. Previous experimental studies have shown its permeability is lowered under large shear displacement between the earth core and structure, but the mechanism is not clear yet. This study conducts multi-field simulations using a multi-body model to shed light on the mechanism of interface seepage. Based on Biot’s consolidation theory, we develop a mathematical model to simulate the seepage across the interface under large shear deformation, adopting joint elements to describe the contact relations between different layers at the interface. The simulation results reveal the evolution process of stress-strain and void ratio in the soil specimen as well as the seepage mechanism of the interface under shear.

Key words: contact clay, soil-structure interface, seepage mechanism, high earth-rockfill dam