Stability Assessment of Rock Slopes Using Modified SMR Technique and Kinematic Analysis along SH - 53 between Dunda and Uttarkashi, Uttaranchal

The stability of rock slopes along the highways is a major concern to the road maintenance agency as well as for the safety of those plying on these roads. Any kind of slope failure may lead to disruption in traffic, socio-economic activities, loss of property, injuries or sometimes even deaths of humans and/or livestock, and environmental degradation. Therefore, an assessment ofthe stability conditions along these highways is quite important. Though several techniques of slope stability analysis viz. boundary element method, finite element method, finite difference method, discriminant analysis etc. are available, yet the slope mass rating (SMR) technique has been found to be quite useful due to the ease with which it can be practiced, and its effectiveness in interpreting stability and recommending control measures. The technique is based on the well established rock mass rating (RMR) technique. The rock mass rating technique has been used earlier in many mining and engineering projects related to tunnels and underground structures.

SMR technique is a field based study which involves collection of data on rock types, their strength, quality, condition of discontinuities, spacing of discontinuities, orientation of discontinuities, ground water conditions and method of slope excavation etc Eight sites, selected on the basis of good exposures of the rock outcrops and the slopes that have been blasted or mechanically disturbed during road construction or at some later stage, were studied and analysed for their potential degree of stability using SMR approach. However, the type of probable failure and the direction of movement have been assessed on the basis of kinematic analysis. The kinematic method also helped in identifying the potentially unfavorable planes that could be involved in the movement. The results indicate that the technique can be usefully exploited for assessing the stability of rock slopes in the Himalayan terrain.