New Perspectives on Soil Creep

Abstract

Soil exhibit viscous creep behavior, and the creep strain rate is known to change greatly with time. Various possible reasons for the changing creep rate are considered. The writers propose a mechanism for interparticle sliding that is both viscous and frictional. The mechanism is based upon rate process theory and leads to an expression for the sliding velocity of two contacting particles in terms of the ratio between the tangential and normal contact force components. This interparticle sliding mechanism was incorporated into a numerical discrete element model of a large assembly of circular particles. Numerical simulations with the assembly displayed creep behavior that is very similar to soils. The creep rate increased with greater applied stress, decreased rapidly with time, and exhibited creep rupture at large stress levels. Changes in the creep rate are shown to result from the changes in contact forces that accompanied deformation of the entire assembly. Such deformation‐dependent changes are thought to be the primary reason for the changing creep rate of soils with time.