Abstract: Stability analysis is essential in the design of an embankment. A new limit equilibrium based method is proposed to calculate the factor of safety of a newly developed prestressed embankment. It consists of an analytical method for computing additional stresses on a sliding surface and a method for calculating inter-slice forces. First, analytical formulas are derived to approximately calculate the additional stress components on a potential sliding surface using the elastic theory, and the additional normal and shear stresses at any point of the sliding surface are obtained based on stress state analyses. Then, a limit equilibrium method combining the additional stress calculation method, slice method, inter-slice force calculation method, and the loading characteristics of railway subgrades is proposed to analyze the stability of a prestressed embankment. The proposed method is applicable to arbitrary shaped sliding surfaces, the calculation formulas are concise, and the analysis process does not need iteration trial calculations. Example analyses demonstrate that the additional stresses on the potential slip surface of an embankment resulted by the prestress are not all anti-slide, and there are sliding effects in small local areas. Compared with the traditional limit equilibrium method on treating the compressive prestress, the proposed method considers the continuous propagation effects of the prestress, and the analyzed safety factor is biased towards safety. Finally, numerical methods are used to further demonstrate the reliability of the proposed method.

Key words: prestressed embankment, stability, limit equilibrium method, additional stress, inter-slice force