An alternative shear strength reduction approach for the stability analysis of undeground excavations

Abstract

Conventional shear strength reduction methods are widely used in the numerical stability analysis of various geotechnical problems. They allow modelling the associated failure mechanisms as well as computing a stability indicator, the factor of safety. Nonetheless, due to the uniform and monotonic reduction scheme integrated in this method, it is not possible to identify the zones which are prone to failure more than others, and faster than others. Consequently, a kinetic shear strength reduction method that accounts for the influence of the physical behaviour of the model on its failure is proposed. The scheme of reduction is called kinetic since it is neither applied uniformly on the model zones, nor incremented monotonically along the calculation steps. The reduction depends on the accumulation of the strains. This method is implemented in the stability study of a braced excavation. Results are compared with those obtained using the conventional method. Results obtained show the applicability of the proposed method which in turn provides a better understanding of the evolution of the strain mechanisms, development of failure, and localization of the weak zones. The kinetic method can be generalized and used in the stability analysis of different geotechnical applications.