Abstract
Present study describes a new method of back calculation of the shear strength adaptable to a heterogeneous slope as well as homogeneous one. Proposed is an iterative method of the variational stability analysis, in which friction-dependent slip lines expressed by some log-spirals are provided. Therefore cohesion and friction angle are determined independently, especially the latter is particulated every different zone. After the verification of the method by the stability analysis results, the effects of the errors of the safety factor or location of the slip line specified as input data of the back analysis on the calculated strength are also examined. Finally the method is shown to be effective by applying it to a problem reported by other researcher.
