A comparative study between infinite slope model and Bishop’s method for the shallow slope stability evaluation

Abstract

Comparative analyses were performed to discuss the difference between the shallow slope safety coefficient calculation method deduced from the infinite slope model (ISM) and the Bishop method to figure out the difference of calculation results between the two different methods for engineering evaluation. The location of the potential slip surface and the factor of safety (FS) based on the same analytical conditions calculated by the two different methods are used as the comparative index. The potential slip surface obtained by ISM is shallower than that obtained by the Bishop method. The FS calculated by ISM is also smaller than that obtained by the Bishop method. While the differences are gradually reduced or even reversed with the increase of the slope inclination, the length to thickness ratio (L/H) of the soil layer, the rainfall intensity and the antecedent rainfall duration, respectively. The critical slip surface location calculated by the ISM is shallower than that of the Bishop method when the L/H is below 5, and deeper when L/H is around 10.