Spring-block models are a useful tool for modeling avalanche-like dynamics for catastrophic landslides. This paper examines the statistical behavior of the failure of a rock (or soil) slope taking into account the effect of roughness, through the use of the real contact area of sliding surface. It also examines the role of rainfall and assesses its effect on slope stability, as well as on the problem of natural hazard prediction. To this end, the article addresses also the emergence of possible precursor phenomena within the aforementioned context through the enrichment of a two-dimensional spring-block model with evolving displacement gradients and stochasticity. Cellular automaton simulations were used to verify the model predictions, which can be useful to geotechnical engineers and to engineering geologists, since an early prediction of the initiation of a rapid landslide can minimize its catastrophic results through proper safety and precautionary measures.
The investigation of the formation mechanisms of sliding surfaces in different types of landslides is an open problem of scientific research. Especially for the catastrophic landslides that have a major impact on human activities, the effect of heavy rain is very important in studying the stability of slopes prone to these huge movements of geological materials. A general rule is that the intensity of catastrophic landslides usually increases after heavy rain. Consequently, the reduction in slope's stability resulting from water pressure applied within the rock mass defects (joints etc.) is the most important effect in rain-induced landslides (Okura et al. 2002, Lourenco et al. 2006, Wyllie & Mah 2008, Peruccacci et al. 2012). The main failure mechanism during landslides is that shear takes place along either a discrete sliding surface, or within a zone, underneath the surface. If the shear force (driving force) is greater than the shear strength of the interface (resisting force) then the slope will be unstable. Instability could take the form of displacement that may or may not be tolerable, resulting in the collapse of the slope either suddenly or progressively (Rahn 1996). Zaiser & Aifantis (2001, 2003), and Zaiser and coworkers (Zaiser et al. 2004, Zaiser et al. 2009) have introduced the evolution of deformation/slip avalanches when material softening and stochasticity is stabilized by higher-order gradients of the constitutive variables. The higher-order gradients are necessary for the convergence of numerical solutions of either continuum or discrete models (Aifantis 1984, 1987, 2012).