Improved Statically Solvable Slice Method for Slope Stability Analysis

Although slice methods are simple and effective slope stability analysis approaches, they are statically indeterminate. Several modifications of the slice method, such as the Spencer, Morgenstern-Price, and Chen-Morgenstern methods, are statically determinate and solvable as they assume the inter-slice force inclination angle; however, there is a small gap between the assumptions and actual landslide stability analysis. Through reasonable theoretical analysis, the Su slice method provides a reliable approach for determining the inter-slice force inclination angle that can be used in slice analysis to accurately analyse, calculate, and evaluate the stability of landslides. However, the Su slice method requires further research and analysis, especially in terms of the parameter values $ \sin {{\lambda }}_{{b}{i}} $ and $ {\rho } $. In this study, we investigated more accurate methods for calculating the parameters $ \sin {{\lambda }}_{{b}{i}} $ and $ {\rho } $. In addition, an adjustment coefficient ($ {\mu } $) was introduced to improve the solution method for the inter-slice force inclination angle. The inter-slice force inclination and safety factors of three landslides with arc-shaped slip surfaces and one landslide with a polyline-shaped slip surface were analysed and compared using the different slice methods. The improved inter-slice force inclination not only satisfies the calculation of static force equilibrium condition but also satisfies the calculation of both the force and moment equilibrium conditions. The improved method for calculating inter-slice force inclination presented the best correlation. The safety factors calculated using the improved Su slice method were close to those obtained using numerical simulations and the Morgenstern-Price method. Despite negligible differences among the safety factors calculated using the Su slice, improved Su slice, and M-P methods, the accuracy of the improved Su slice method was better than the M-P method in terms of inter-slice force inclination angles which can be useful to improve protection engineering design.