Effect of large particle content on strength and failure mode of binary granular mixture in shear under plane strain condition

¹ Yamaguchi University, Graduate school of science and technology for innovation, 2-16-1, Tokiwadai, Ube, Yamaguchi, 755-0097 Japan
² University of Yamanashi, Graduate Faculty of Interdisciplinary Research, 4-4-37, Takeda, Kofu, Yamanashi, 400-8511 Japan

^* Corresponding author: mtaue2022@gmail.com

Abstract

The strength and failure modes of binary granular mixture composed of two different sized particles, such as gravel and sand, vary depending on the content of gravel (large particle content). The binary granular mixture structures are classified into small particle skeleton structure, intermediate skeleton structure, and large particle skeleton structure, depending on the large particle content. The authors propose a microscopic model to evaluate the range of large particle content in the intermediate skeleton structure, and confirm its applicability in Angle of reposed experiment. Parameters obtained from the experiment, such as “ peak principal stress difference” and “ principal stress difference at large axial strain” as strength, “ shear band slip angle” and “shear band width “ as failure mode, were discussed for large particle content. The results showed that the large-particle content of the intermediate skeleton ranged from 8.7% ~ 52.7% for the peak principal stress difference, 3.2% ~ 44.1% for the principal stress difference at large axial strain, 12.0% ~ 77.3% for the shear band slip angle, and 4.1% ~ 81.2% for the shear band width. The microscopic model calculated range for the intermediate skeleton structure was 2.3%~66.4%, which is generally wider than the experimental results under confining pressure. The microscopic model gives the range of the initial (sedimentary) state of the intermediate skeleton structure. It is inferred that the range of the intermediate skeleton structure narrows with increasing confining pressure. Therefore, the microscopic model should take into account the effect of confining pressure.