Importance of Dilatancy on the Evolution of Failure Mechanism of a Strip Footing Resting on Horizontal Ground

Abstract

This paper reports about a finite element based numerical analysis of the failure mechanism developed beneath a strip footing resting on horizontal ground. The observed failure mechanism is manifested in terms of incremental deviatoric strain patterns. In order to address the effect of dilatancy, both associated and non-associated flow rule had been considered. A series of simulation on foundation models were carried out to examine the influence of mesh refinement schemes and soil shear strength properties on the failure mechanism. The numerical outcomes have been verified against experimental investigations available in literature. It has been observed that angle of dilatancy ( $$\psi$$ ) plays a significant role in influencing the evolution of the failure mechanism. Consideration of non-associated flow rule ( $$\psi$$ ≠ φ, φ is the angle of internal friction) leads to the development of asymmetric failure mechanisms, marked by one-directional soil movement beneath the footing, exhibiting mode-switching phenomenon at- or near-failure conditions. Considering associated flow rule ( $$\psi$$ = φ) results in the evolution of a symmetric failure mechanism at the failure condition of the footing. The present study reveals that beyond $$\psi$$ = 3φ/4, a transition from the asymmetric to symmetric failure mechanism occurs. The study shows that, based on the appreciable agreements of the resulting pressure-settlement curves and the ratio of rightward-to-leftward displacement of the footing, FE simulations conducted with different angles of dilatancy can be effectively used to identify the angle of dilatancy prevalent in an experimental investigation.