Study on the limit equilibrium slice method considering characteristics of inter-slice normal forces distribution: the improved Spencer method

The limit equilibrium slice method is a universal method to determine the safety factor of a slope. However, the forms of the inter-slice normal forces distribution are not considered in the traditional limit equilibrium slice method, and the influence of different positions of thrust lines on the safety factor is not considered. Thus, an improved Spencer method is developed here, wherein the characteristics of the inter-slice normal forces distribution are considered. The safety factor of a deep concave sliding surface is calculated, and a difference of approximately 20% is found between the safety factors that are obtained using the improved method and those obtained using the traditional method. The influence rule of different forms of the inter-slice normal forces distribution on the safety factor has been studied, and the influences of various factors on the inter-slice forces contribution, the stress state of the slice and the stress state of the slip surface have been analysed. Finally, two case studies are combined to illustrate the impact of the improved method on engineering safety and economic benefits.