New Stability Charts for the Quick Assessment of Soil Slope Stability

ABSTRACT The assessment of slope stability is crucial for the evaluation of the landslide risks. In practice, the engineers may need to perform a quick assessment on slope stability in the field, and the stability chart would provide convenience for this purpose. The original stability number chart is a tool that can provide a quick assessment of the soil slope stability from the slope geometry and soil properties. However, the original stability number chart was proposed mainly based on the hand calculation. With the development in computation, there are much more advanced analysis methods available based on the limit equilibrium method as compared method for stability number chart. In this paper, the method of published stability number chart was reviewed, and the limitation of the original chart is highlighted. Subsequently, the factors of safety for slopes with varying slope geometry and soil properties were evaluated using the limit equilibrium software Slope/W. The discrepancies between the results from Slope/W and the original stability number chart were discussed and then validated by comparing with the published cases. It was observed that the published chart only considered slip surface and factor of safety for certain conditions, while the results from Slope/W indicated three types of slip surface and a comprehensive factor of safety. In addition, the former method required iterative trial calculations while the latter method only required searching for charts of the corresponding parameters. Consequently, the new stability charts were proposed from the results of Slope/W for quick assessment of the soil slope stability.