PROBABILISTIC APPROACH TO STABILITY ANALYSIS OF ABUTMENTS OF JAMRANI DAM

Abstract

A 130m high dam has been proposed across the Gaula River at Jamrani (29016'N: 79°36'E)in Nainital District of Uttar Pradesh. The site is located in a narrow reach of the river having a cord-height ratio of 3.3 . The lower Siwalik exposed at the dam site comprises thick bedded sandstone interbedded with subordinate claystone and siltstone. The right abutment slope controlled by south dipping joints is steeper (50°-70°) than left bank slope (400-50°). Factors which influence the stability of a slope usually vary in some range in construction sites. In a deterministic analysis, all the parameters are assumed to be "determined". However, because of the random nature of the parameters, the actual factor of safety of the slope can be higher or lower than that produced by a deterministic analysis. In order to consider the uncertainty of these factors in the analysis and design of a rock slope, probabilistic methods should be applied. Study of rock slopes has been carried out for both the deterministic and probabilistic method. of analysis and comparisons have been made between them. Based on the results, the capacity of the cable anchors for increasing the probability of success of all the slopes, has been worked out.