Variation in Angle of Internal Friction with Confining Pressure

摘要

The report summarizes published results of triaxial compression tests on cohesionless materials at high confining pressures. The data presented herein indicate a curved strength envelope, resulting in a decrease in angle of internal friction with increase in normal stress. An analysis of the data is made and a functional relation is presented for the phi sub o angle (angle of maximum stress obliquity) in terms of normal stress on the failure plane. The significance of a curved strength envelope is investigated for the stability of infinite, simple finite, and crater slopes composed of dry cohesionless material. Preliminary analyses for the case of a partially submerged crater slope are also presented. The analyses indicate that a deep failure surface may be more critical than a shallow surface when the phenomenon of a curved strength envelope is considered. Empirical stable slope data abstracted from a letter concerning canal excavation by nuclear cratering are presented in Appendix A. (Author)