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Estimation of probability of failure for stepped path sliding with three joint sets

1999-08-28
Korgan, H
Ozgenoglu, O
In jointed rock masses, sliding along a stepped path surface formed by two or more joint sets and sometimes shearing through the intact rock portion between the joints, is much likely to occur than sliding along single continuous surface. Although it has been focused on the two-joint set (i.e. one major and one cross joint set) stepped path sliding problem, there is little work on the analysis of stepped path sliding with three joint sets. In this paper, a simulation model developed for the analysis of stepped path sliding incorporating three joint sets is introduced firstly, and a parametric study is carried out to determine the three-joint set probability of failure using the de;eloped model and "step-by-step" approach secondly. Results indicate that both methods of analysis estimate close probability of failure values when stepped paths are not formed completely continuous (i.e. with an amount of intact rock portion on the path). An increase in the amount of intact rock portion along the path cause the probability of failure to decrease. Furthermore, the mean length of major joints, the mean dip angle of major and cross joints, and mean spacing of cross joints are effective on the three-joint set probability of failure for stepped path sliding.