A Stability Analysis of the Ancient Site of Liye Based on the Strength Reduction Method

Due to the effects of time and space, there is a continuous deterioration of the surface layers of earthen sites and a corresponding decline in soil stability. Evaluating the stability of these sites is very important for potential site restoration. In this study, we analyze, evaluate, and summarize the factors that adversely affect the ancient moat site in Liye, a town of Longshan County, Hunan Province, China, through on-site investigation, sampling, and testing. An X-ray diffractometer and a scanning electron microscope were used to analyze the chemical composition and microstructure of the soil sample of the trench, and the ABAQUS software was used to produce two-dimensional models of seriously damaged areas. Using the strength reduction method, we obtained the minimum safety factor of the trench under its natural state and after rainfall; thus, the stability of the trench was examined under different working conditions. Additionally, we evaluated the safety and stability performance of the more dangerous sections to provide a basis for the safety evaluation, protection, and repair of the trench. The results show that rain erosion, freeze–thaw cycles, and man-made damage are the primary factors contributing to a deterioration of the soil site. The safety factor of the trench is found to decrease with increases in water content; thus, water has an impact on the strength of the site wall. The wall soil has larger pores and more initial cracks than does the trench soil, which is easy to peel off. As a result, there is a high probability of a secondary deformation of the wall slope. Our results identify the real state of the existing site and provide both a basis for stability evaluation and a scientific formulation for restoration schemes.