Abstract: The stability analysis of pile-anchor retaining structure is based on the searching method of the sliding surface and the calculating theory of the safety factor. During the process of analyzing anti-sliding moment, conventional slip circle method of slices has too many assumptions. At the same time, during the process of searching for the most dangerous sliding surface, there are some problems with the grid-search method. If the rough grid is applied, the result will be less accurate. However, if the fine grid is applied, the efficiency will be lower. To solve these problems, the soil strength redundancy method is proposed in order to analyze dynamic stability of foundation pit. Also, adaptive grid-search method is used to ensure accuracy and efficiency. Finally, this paper compareds the soil strength redundancy method, the sliding surface stress method and the slip circle method of slices. The results show that the sliding surface stress method overestimates the overall stability of the foundation pit and that the slip circle method of slices cannot consider the weakening effect on the shear strength of the soil behind the pile caused by excavation. Also, the soil strength redundancy method can reflect the overall stability of the foundation pit.

Key words: excavation engineering, pile-anchor retaining structure, stability, strength redundancy method, adaptive grid-search method