The behaviour of an assembly of rotund, rigid, cohesionless particles. Ill

Abstract

In the two previous parts a formal proof has been given of the stress-dilatancy equation of Rowe for an assembly of rigid, cohesionless particles. It has been shown that states of anisotropy arising in the triaxial test may be derived by considering the relative motions of the particles, there being a limiting state of anisotropy which can be approached after large deformations have occurred. It is now shown that the accompanying dilation ultimately destroys the high state of anisotropy, the degree of anisotropy decreasing with increasing volume. When ultimately the assembly is deforming at constant volume, the angle of shearing resistance Φ c. v. has a value which may be calculated from the angle of particle friction Φ μ , and the calculation is performed for a range of values of Φ μ . The formation of slip bands in the triaxial test is then discussed, and it is shown that, under uniform stress, slip lines are not to be expected until well after the attainment of the peak stress, except at low values of Φ μ . The fall-off in stress in the triaxial test is shown to arise, not from the formation of slip lines, but from the destruction of anisotropy due to dilation.