Sensitivity of G₀ and stress-strain relation of geomaterials to grain shape and surface roughness

¹ Public Works Research Institute, 1-6 Minamihara, Ibaraki 305-8516, Tsukuba, Japan
² The University of Tokyo, Institute of Industrial Science, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan

^* Corresponding author: ootsubo-m573cm@pwri.go.jp

Abstract

It is empirically known that the packing property and mechanical responses of cohesionless granular materials are influenced by grain shape. For example, the attainable range of void ratio depends on grain shape; angular materials tend to exhibit greater friction angles. Besides, shear wave velocity (V_s ) and small-strain shear modulus (G₀ ) of sphere assemblies are affected by surface roughness. However, consensus has yet to be reached on the combined effect of grain shape and surface roughness on G₀ and stress-strain relation. This contribution aims to evaluate the shape-roughness combined effect on the strain-dependent mechanical responses of granular materials. Three groups of glass beads having different grain shapes and a silica sand were used, and their grain surfaces were roughened through a systematic procedure using a milling machine. In total, eight materials were subjected to triaxial compression after measurement of V_s. The experimental results reveal that the stress-strain relation of angular particles is remarkably affected by the surface roughness, whereas the roughness effect on the stress-dependent variation in G₀ is limited for angular particles.