Low and high strain macrobehavior of grain masses - the effect of particle eccentricity

High, medium, and low strain tests were conducted on green peas, white navy beans, and rice. These grains were selected to assess the effect of particle eccentricity on the mechanical behavior at different strain levels. Tests included interfacial ring shear, axisymmetric and true triaxials, simple shear, and wave propagation measurements. Index properties, microfabric analysis, and mechanical parameters are documented. Differences were found between the behavior of rice and the other two grains, which were explained as the result of the mechanical and geometrical characteristics of grains. Low-strain measurements reflected contact properties and fabric; both low and high strain properties were affected by stress history; major fabric changes occurred when shear strains exceed 3 to 10%; and extensive particle alignment took place after high shear deformation in elongated particles such as rice. The shear behavior at the interface with a rough surface was very similar for the three grains.