Rock slope instabilities are discussed in the context of decision making for risk assessment and management. Hence, the state of the slope and possible failure mechanism need to be defined first. This is done with geometrical and mechanical models for which recent developments are presented. This leads with appropriate consideration of uncertainties to risk determination and to the description of tools for risk management through active and passive countermeasures, including warning systems. The need for sensitivity analysis is then demonstrated, and final comments address updating through information collection.
This paper addresses rock slopes, specifically rock slope instabilities. In this context, the mechanics underlying instabilities and corresponding models are very briefly reviewed to provide a basis for the major topic of this paper: Decision making as applied to risk management of rock slopes. Before further outlining the structure and context of this paper, it is necessary to define the rock slope instabilities that will be considered. There are several differing definitions, e.g. Goodman and Kieffer (2000); Cruden and Varnes (1996); Varnes (1958), and what will be used here are the two categories, "rock slides" and "rock falls". Possible subcategories for rock slides are planar wedge-, rotational slides; toppling will also be considered in this category. For rockfalls,movement of single blocks in formof falling, jumping and rolling will be included as well as rock avalanches consisting of multiple rock blocks interacting in a flow-like mechanism. Simply looking at these instability processes will quickly lead to the conclusion that it is often not possible to clearly separate them, e.g. a rotational slide may end up as an avalanche. The eventual goal of this paper and, most importantly, of most practical applications is to assess and manage risk associated with rock slope instabilities by making appropriate decisions.