Progressive failure in elastic-viscoplastic media: from theory to practice

In the risk assessment of soil movement, the comprehension of unexpected collapses involving creeping landslides is crucial. The transition from creeping to fast landslides is very hard to justify theoretically and simulate numerically. In this paper, the authors intend to demonstrate that even the integration of a basic elastic strain softening constitutive relationship under simple shear conditions is sufficient to capture such a transition. With this aim, an infinite slope, a homogeneous cemented/bonded soil and an oscillating water table level are considered. The onset of instability is shown to be anticipated by a local increase in strain rate within the shear band, behaving like a precursory signal. The size of the shear band, evolving with time and not depending only on the material grain size distribution, is governed by both the amplitude of the imposed perturbation and the material constitutive parameters.