Estimation of slope safety factor based on trajectory reduction method

Abstract

Currently, double reduction method (DRM) is widely used in the field of slope stability. However, one of the main challenges of the double reduction method is how to define the comprehensive safety factor based on two reduction parameters. The trajectory reduction method developed by Isakov can be used to ensure the minimum comprehensive safety factor on different conditions. However, its main shortcoming is that the method needs expensive calculation to determine the safety factor for a certain slope configuration. The paper examines the relationship between the comprehensive safety factor and cohesive and internal friction angle of soil, by using the FEM and trajectory method to calculate the minimum safety factor and corresponding reduction factor with respect to different inclinations of the slope. The initial strength effect on double reduction parameters are analyzed accordingly. The result shows for a certain slope configuration; the initial strength has little effect on the critical strength which is related to the minimum comprehensive safety factor. It means that for a slope with a certain inclination, even if the strength of soil is different, the critical strength is identical. The critical strength of soil slope is linear with the inclination of the slope, which means that every inclination corresponds to one critical cohesive and one critical internal friction angle. Consequently, a novel method to calculate the minimum safety factor is proposed in this paper. The result obtained by this method is close to the result which is from the limit equilibrium method, and compared with the original method by Isakov, this alternative method can simplify the calculation, and keep the result as accurate as the limit equilibrium method. Thus, it can be used to analyze the stability of slope