The limit equilibrium methods of slices

the safety factors are computed from force equilibrium

have been widely used for analyzing and designing slope stability. However

because the assumptions regarding the inter-slice forces are different

the solving formulations of every method are different. It does not facilitate the compiling of the program and the understanding among the advantages and disadvantages of different procedures. In this paper

the assumptions for the inter-slice forces made by the existing limit equilibrium methods of slices that the safety factors are computed from force equilibrium are expressed into the unified formulation for the first time; the simple and clear recurrence equation of the inter-slice forces is derived based on force equilibrium. The unified solving formulation for the safety factors based on force equilibrium in the context of conventional methods of slices is developed based on the recurrence equation of the inter-slice forces. It makes the calculating principle to be clearer and the calculating process to be simpler. On this basis

if inter-slice moment equilibrium equation that rigorous Janbu method satisfies is expressed into the assumption regarding the inter-slice forces

rigorous Janbu method can also adopt the unified solving formulation for the safety factor based on force equilibrium.