STABILITY ANALYSIS OF SLOPES WITH GENERAL SLIP SURFACE

Abstract

Slope stability analyses with reference to sliding surface procedure have been reviewed. A procedure, based on limit equilibrium analysis, has been developed to compute lower bound factor of safety considering a general slip surface in a non-homogeneous soil mass. The statical indeterminacy of the problem has been eliminated by assuming a normal stress distri-bution along the slip surface and satisfying the boundary con-ditions. All the three statical equilibrium conditions have been satisfied and the equations have been solved with the help of Newton Raphson method. A computer programme has also been developed to obtain critical surface and factor of safety by using Steepest Descent method. Results of the proposed method are compared with three other procedures: (i) Bishop's short (ii) Janbu's (approximate and exact) and (iii) Morgenstern and Price's methods. Factors of safety obtained for circular slip from Janbu's method (exact) was found to be in a maximum error of 15%, Morgenstern and Price's 9% and proposed method 3% over Bishop's short method. Further the solution by Morgenstern and Price's method required approximately true values of F and L. The upstream slope of Hirakud Dam has been analysed and compa-red with Bishop's short method to check the reliability of Swedish method of slices which has been found to be in an error of 17%. -