Limit Equilibrium Analysis of the Influence of Matric Suction on Unsaturated Soil Slope Stability

In slope engineering, soils are commonly at unsaturated state. The question of how to apply unsaturated soil mechanics theory to the slope stability analysis has become a hot spot in today’s geotechnical engineering research. Based on the experimental research of how shear strength of residual soil varies with water content, reasonable computation modules can be created. By using limit equilibrium analysis, which includes Bishop, Ordinary and Janbu method, the stability of residual soil slope can be calculated under different water content. Extrapolating from soil water characteristic curve obtained from experiments, the influence of matric suction on unsaturated soil slope is obtained. The importance of matric suction is revealed in the slope stability analysis. The result shows that: as matric suction increases, water content decreases, shear strength decreases, and safety factor of soil slope is improved.