ABSTRACT
The interface between a granular medium and an element of structure is a surface of discontinuity which plays a determining role in the design of works of civil engineering, such as deep foundations or works in reinforced earth. This interface phenomenon, which is classically studied at a macroscopic scale, calls for grain-level, microscopic observations.
The ring simple shear apparatus allows direct observations of interface layers for sand as well as for Schneebeli rolls. In particular, we track the tangential displacements and the rotations of particles.
Although both materials exhibit similar qualitative behaviors, grain motion tends to be significantly more chaotic for sand than for Schneebeli rolls. Results are found in good qualitative agreement with other experiments and with numerical simulations.
