title: Use of elastic stability analysis to explain the stress-dependent nature of soil strength.
abstract: The peak and critical state strengths of sands are linearly related to the stress level, just as the frictional resistance to sliding along an interface is related to the normal force. The analogy with frictional sliding has led to the use of a 'friction angle' to describe the relationship between strength and stress for soils. The term 'friction angle' implies that the underlying mechanism is frictional resistance at the particle contacts. However, experiments and discrete element simulations indicate that the material friction angle is not simply related to the friction angle at the particle contacts. Experiments and particle-scale simulations of model sands have also revealed the presence of strong force chains, aligned with the major principal stress. Buckling of these strong force chains has been proposed as an alternative to the frictional-sliding failure mechanism. Here, using an idealized abstraction of a strong force chain, the resistance is shown to be linearly proportional to the magnitude of the lateral forces supporting the force chain. Considering a triaxial stress state, and drawing an analogy between the lateral forces and the confining pressure in a triaxial test, a linear relationship between stress level and strength is seen to emerge from the failure-by-buckling hypothesis.
authors.affiliation: Department of Civil and Environmental Engineering , Imperial College London , London SW7 2AZ, UK.
authors.forename: Kevin J
authors.initials: KJ
authors.lastname: Hanley
authors.affiliation: Department of Civil and Environmental Engineering , Imperial College London , London SW7 2AZ, UK.
authors.forename: Catherine
authors.initials: C
authors.lastname: O'Sullivan
authors.affiliation: Department of Civil and Environmental Engineering , Imperial College London , London SW7 2AZ, UK.
authors.forename: M Ahmer
authors.initials: MA
authors.lastname: Wadee
authors.affiliation: Department of Civil and Environmental Engineering , Imperial College London , London SW7 2AZ, UK ; Department of Civil and Environmental Engineering , The University of Hong Kong , Pokfulam Road, Hong Kong, People's Republic of China.
authors.forename: Xin
authors.initials: X
authors.lastname: Huang
keywords: buckling; failure; soil mechanics