Three-dimensional upper bound stability analysis of slopes with weak interlayer based on rotational-translational mechanisms

The slope stability is greatly affected by the weak interlayer and pore-water pressure, which can change the failure mechanism of the slope as well. Compared to the two-dimensional method for the slope stability analysis, the three-dimensional method can reflect the actual slope condition better. Based on the upper bound theorem, a three-dimensional combined rotational-translational mechanism is proposed to study the stability of slopes with the weak interlayer and pore-water pressure in this paper. The proposed mechanism consists of the curvilinear cone rotational mechanism and the cone translational mechanism. The combined mechanism can be expended longitudinally by the plane inserted, so that the method can be used to analyze the slope stability with different lengths. The distribution of the pore-water pressure obtained from the two-dimensional seepage finite element analysis is incorporated into the limit analysis. Case studies were carried out by the upper bound limit analysis method with the proposed mechanism and results were compared with those by the limit equilibrium method in the literature. Comparisons demonstrate the reliability of the proposed rotational-translational failure mechanism for slopes with the weak interlayer, which can be used as a simple method for preliminary evaluation of slope stability in practical application.