Factor of Safety of Geosynthetic-Reinforced Slope in Unsaturated Soils

Abstract

Matric suction tends to exert important effects on the stability of geosynthetic-reinforced soil slopes; however, it is usually neglected in the previously published literature. To quantitatively evaluate the increment in soil cohesions due to the existence of soil suction in unsaturated soils, five nonlinear estimation formulas relating unsaturated shear strength to soil-water characteristic curve (SWCC) models were adopted in this study. Based on the upper-bound theorem of limit analysis, this study investigated the stability of a three-dimensional geosynthetic-reinforced slope in unsaturated soils. The influences of three different reinforcement distribution patterns, reinforcement strength, and the nonlinearity of unsaturated shear strength under SWCCs were considered. The results showed that SWCC models with various unsaturated properties can lead to highly divergent performance of the slope. The applicability of different nonlinear shear strength equations is discussed. It was found that the factor of safety (FS) increased almost linearly as the reinforcement strength increased. Among the three different reinforcement distribution patterns, downwardly strong triangular distribution was the most effective means to enhance the safety of the three-dimensional geosynthetic-reinforced slope.