This paper presents a comparative study used for the analysis of the stability of slopes of the Amiya area, near Kathgodam Nainital, Uttaranchal, based on assumptions that the rock mass follows the Mohr–Coulomb failure criterion. An extensive field study has been carried out. Laboratory experiments have been conducted to calculate the various mechanical properties of the rock mass. These properties have been used as input parameters for the numerical simulation. The computed finite element deformations and the stress distribution, along the failure surface, have been compared with the field measurements and are found to be in good agreement. The study shows that the slope is perilously unstable.
The stability of large rock slopes which are vulnerable to rock mass (rotational) failures can be analyzed by traditional limit equilibrium methods such as Bishop¡¯s method (Bishop 1955), Janbu¡¯s simplified method (Janbu 1954) or the later improved sophisticated method (Janbu 1957, Spencer 1967) based on assumptions regarding the inclination and location of the interslice forces. For many cases, the limit equilibrium methods established have given relatively reliable results despite their limitations. However, they tend to give conservative values of factor of safety, since the full shear strength is assumed to be mobilized simultaneously along the failure surface. Duncan (1996) and Griffiths & Lane (1999) summarized the results of a survey on slope stability analysis using FEM based on the shear strength reduction technique and provided a number of valuable lessons concerning the advantage and disadvantage of FEM for use in practical slope engineering problems. DEM (Cundall & Strack 1979) and discontinuous deformation analysis (DDA) (Chihsen & Bernard 1996) can be used to simulate large block movements in complex geological media consisting of many blocks which can break on presumed fracture planes during the calculation process without any external intervention.