عنوان مقاله [English]
Nowadays statistic approaches are widely used for rock slope stability, because they are simple and quick. The most famous of these methods for stability analysis of fractured rock masses is the key-block method (KBM). An extension to KBM, called key-group method (KGM) considers not only individual key-blocks but also groups of collapsible blocks into an iterative and progressive analysis. In iterations some of the groups can be extended and included a great part on the rock slope.
One of the most important problems in this approach is to define the critical surface (critical key-group) .In this paper we present an approach for finding the critical group which can be called directional key-group method ,Because grouping of blocks progresses in the direction of slide surfaces of groups. This was carried out using the Mathematica high-level programming language. Finally it was shown that the proposed method yields more realistic results than the basic key-block method and a comparison with results obtained using a distinct element method (UDEC), demonstrated the ability of this method.