A new practicable approach to the stability analysis of unsaturated expansive soil slope

The contribution of the suctional strength to the stability of unsaturated expansive soil slope should be properly evaluated in order to meet engineering demands in the unsaturated soil area. It is essential to develop a better method to analyze the stability of unsaturated expansive soil slope instead of the slices method commonly used in practice at present. Firstly, some researches on strength theory of unsaturated soil are reviewed and an effective strength formula of unsaturated soil is discussed in three-dimensional effective stress space. Then the implementing of the strength reduction FEM to stability analysis of unsaturated expansive soil slope is analyzed and described. Finally, some cases of stability of an unsaturated expansive soil slope are analyzed in this paper Numerical results not only indicate that the strength reduction FEM developed in this paper is a reliable, applicable and new way for the stability analysis of unsaturated expansive soil slope, but also reveal that the equivalent expansion pressure corresponding with the matric suction has the important effect on stability of the unsaturated expansive soil slope also.