Discussion on the implementing approach of unsaturated matric suction in the slice methods

The study of slope stability is one of the traditional and eternal issues in Geotechnical Engineering. There are a lot of previous achievements on stability of unsaturated soil slope are reviewed in this paper. Firstly, the influence of matric suction impacted on the strength of unsaturated soil is summarized. Secondly, the different treatments of matric suction in some commonly used slice methods such as the Sweden slice method, the simplified Bishop's slice method and the Janbu's slice method are analyzed based on the Bishop's unsaturated strength theory and Fredlund's unsaturated strength theory respectively. Finally, the advantages and disadvantages of these methods in application on the stability analyses of unsaturated soil slope are also discussed. Though these developed and modified slice methods may consider the matric suction in sliding zone, it still can be concluded that these slice methods have to neglect the other matric suction outside of the slip surface, which lead to underestimating the influence of the matric suction in the stability analyses of unsaturated soil slope in fact.