Description of soils based on geomechanical criteria for improved landslide classification

This paper presents a proposal, developed as part of the EC-sponsored SafeLand project, to supplement existing landslide classifications with a more detailed description of the geomechanical characteristics of the materials to include the effects of “structure” and stress history, as determined by depositional and post-depositional processes. This provides a valuable insight into and a rational basis for the modelling of the physical mechanisms that govern the triggering and subsequent development of landslides. The classification, behaviour and minimum requirements for the constitutive modelling of saturated clays and sands are summarized here. The use of advanced constitutive models which include, where necessary, progressive damage to the microstructure of the material helps to predict the conditions and the style of triggering and of subsequent movement of landslides, depending on the type of material, even in first time landslides. Numerical examples are presented, illustrating the different response to rapid perturbation of sensitive clays versus mechanically overconsolidated clays and of “loose” sands versus “dense” sands.