Babak Ebrahimian - Faculty of Civil, Water and Environmental Engineering, Shahid Beheshti University, Tehran, Iran
Ali Noorzad - Faculty of Civil, Water and Environmental Engineering, Shahid Beheshti University, Tehran, Iran
Ahmadreza Mahboubi Ardakani - Faculty of Civil, Water and Environmental Engineering, Shahid Beheshti University, Tehran, Iran

The interface between cohesionless granular body and structure is analyzed using finite element (FE) method and a micro -polar elasto-plastic constitutive model. Plane quasi-static shearing of an infinitely long and narrow granular strip bounded by parallel rigid walls of varying surface roughness is investigated under the conditions of free dilatancy and constant vertical pressure. The employed constitutive relations can realistically reproduce the essential properties of granular bodies in a wide range of pressures and densities during monotonous deformation paths. The influences of polar variables including micro-rotation, micro-curvature, couple stress, void ratio and mean particle size are taken into account as well. The well formulated equations of coupled micro-polar kinematic boundary conditions are innovatively developed to describe different interface roughness conditions, considering a ratio between particle slip and rotation along the boundaries, wall roughness and particle diameter. Emphasis is given to the wall roughness effect on the thickness of localized shear zone and the evolution of mobilized wall friction angle. FE results show that the surface roughness has an evident effect on the shear resistance mobilized along the interface. It is demonstrated that the rotation resistance of particles adjacent to the boundaries with different surface roughness can be modeled in a physically natural manner using the proposed polar boundary conditions.

Soil-structure interface, Wall roughness, Micro-polar continuum, Granular materials, Finite element method.