The paper deals with the slope failure analysis along road cut slope of Luhri area, Himachal Pradesh. The area experiences local as well as regional slides every year. Extensive field study has been carried out to collect the geological information as well as to collect the representative rock samples for the determination of geotechnical properties of rock. These properties have been used after converting rock sample strength into rockmass strength as input parameters for the numerical simulation of slope using FLAC 3D. The computed deformations and the stress distribution, along the failure surface, have been compared with the field observations and found to be in good agreement. Finite difference method (FDM) has been applied on the slope stability analysis of the area under the investigation. The overall factor of safety indicates slope is critically stable and need proper attention to stabilize it.
Slope failure is a frequent phenomenon especially in Himalayan regions due to its active geo-dynamic nature. These failures are due to accumulation and release of stress within the slope mass which brings rapid mass movement on slope forming materials. This may resulted into loss of life and property every year. These problems are further aggravated when water bodies flowing through the slope mass. These failures can not be completely eradicated but its proper analyses will help us to find out better method to stabilize it under varying stress condition. The road section under investigation lies on the left bank of the river Satluj, which is connected by Hindustan Tibet Road (NH- 22).The major rock types exposed in the study area are Quartz Mica Schist, Quartzite, Slate and Limestone which belongs to the Shimla group of Proterozoic age. On August 14, 2007 a huge landslide due to cloudburst has been occurred in Dharla village near Rampur and 62 people have been died and huge loss of property. Therefore, there is a need to study the geological and physico-mechanical properties of the rock and develop an appropriate and suitable scientific models or methodology which will help to minimize or control the landslide in that area. The results of slope stability analysis using finite element method (FEM) based on shear strength reduction technique have been dealt by Duncan  and provided a number of valuable information concerning the advantage and disadvantage of FEM for practical slope engineering problem. DEM and discontinuous deformation analysis (DDA) can be used to simulate large block movements in peculiar geological media consisting of large number of blocks which can break on presumed fracture planes during the calculation process without any external intervention [2,3]. However, precise block geometry and more experience are required for a reasonable simulation. Singh et.al  demonstrated the capability of three dimensional, FDM to study the hill slope stability of Rudraprayag area. A number of study have been carried out using Finite element method as well as finite difference method to determine the factor of safety of slopes [5, 6, 7, 8].