Analytical approach for stability of 3D two-stage slope in non-uniform and unsaturated soils

• Published in: Engineering geology Vol. 292; p. 106243
• Main Authors: Yang, Xiao-Li, Wei, Jia-Jing
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-10-2021
• Subjects: Factor of safety; Gravity increase method; Two-stage slopes; Uniform soils; Unsaturated soils; Upper bound; Two-stage slopes; Upper bound; Uniform soils; Unsaturated soils; Gravity increase method; Factor of safety
• ISSN: 0013-7952; 1872-6917
• DOI: 10.1016/j.enggeo.2021.106243

In geological engineering, the unsaturation and non-uniformity of soil have significant influence on slope stability. However, they were common neglected in published literature. Based on the three-dimensional (3D) rotational failure mechanism, this paper introduces a method that combines the gravity increase method and the upper bound theorem, to evaluate the factor of safety (FS) of 3D stepped slope in non-uniform and unsaturated soils. The soil cohesion increases linearly with depth, and three nonlinear unsaturated shear strength models are adopted in this study. After the calculations of internal energy dissipation rate and external work rate, the analytical formula of FS is derived, and the lowest FS value is obtained through optimization. To prove the validity of the proposed method, the present results are compared with previously published solutions. A parametric study is carried out, and the influences of a number of factors on FS are discussed. For non-uniform and unsaturated soils, the new formula for calculating the FS of 3D two-stage slopes is presented for practical use in geological engineering.
•New formula for calculating the FS of 3D two-stage slopes is derived.•GIM is introduced to evaluate FS of 3D stepped slopes in inhomogeneous and unsaturated soils.•Validity of the analytical solutions obtained in this study is verified.