Limit Analysis of Unsaturated Soil Slope Stability Considering Intermediate Principal Stress and Strength Nonlinearity

Abstract

Natural and man-made slopes are mostly in unsaturated soils, and the saturated or dry condition is just a particular case. This paper investigates the stability of unsaturated soil slopes. The influence of intermediate principal stress is considered by introducing the unified shear strength formulation, and the strength nonlinearity of unsaturated soils is addressed by means of two different methods. Based on the upper bound theorem of limit analysis, analytical expressions of the critical height of slope are deduced. Relevant numerical solutions are obtained through optimization and parametric analysis is then conducted. It is found that: the critical height of slope increases with the increase of UST parameter b or matric suction, while it decreases with the increase of slope angles. Besides, as regards the strength nonlinearity, it’s suggested to adopt Method II when parameter $$m$$ can be reasonably determined.