Numerical analysis of granular soil-structure interface behavior at large shearing displacement: evolution and characterization

This paper presents the interface behavior between cohesionless granular soil and moving boimding structure using finite element method and a micro-polar elasto-plastic continuum model. The focus of investigation is on the consideration of rough, medium rough and relatively smooth interfaces. In this regard, plane monotonic shearing of an infmitc extended narrow granular soil layer between two parallel rigid boundaries of varying surface roughness is simulated under the conditions of constant vertical pressureand free dilatancy. To describe the essential mechanical properties of granular soil, an elasto-plastic singlehardening soil model enhanced by polar quantities i.e., Cosserat rotations, curvatures, and couple stresses is employed. Furthennore, the mean grain diameter as the material characteristic length is implemented in the model to properly predict the thickness of shear band formed along the interface as well as to consider the scale effect in the simulations. Particular attention is paid to the influence of boundary condition on theshear behavior of granular soil layer. In this regard, the additional micro-polar kinematical boundary conditions along the boundaries allow more detailed description of the surface roughness of adjoining structure. It is shown that the assumed boundary conditions have strong influences on the granular soil behavior in terms shear band thickness and mobilized interface hiction angle. For large shearing, the shear deformations and polar quantities are localized within a narrow zone, called shear band, parallel to the direction of shearing and the state quantities tend towards a stationary state. It is also revealed that the location of shear bands is different in an infinite or finite shear layer.

Keywords:

Micro-polar continuum , elasto-plasticity , interface shearing , granular soil , finite element