Slope Stability Characteristic of Unsaturated Weathered Granite Soil in Inje considering Antecedent Rainfall

Abstract

Unsaturated geotechnical properties and other factors(rainfall characteristic, geomorphology, etc) have to be considered in order to evaluate the stability of real slope. Even though antecedent rainfall is also an important factor on the slope stability, it is rarely considered in analysis of slope stability. In this paper slope stability analysis for unsaturated weathered granite soil in Inje was conducted considering antecedent rainfall. Effect of antecedent rainfall was considered in analysis by using initial matric suction, which was induced from field measurement. Unsaturated geotechnical properties(soil-water characteristic curve, unsaturated conductivity, unsaturated shear strength) of weathered granite soil in Inje were also investigated. Effects of antecedent rainfall on variation of factor of safety(FS) of slope, failure time and cumulative rainfall were evaluated. For a slope with high initial matric suction, FS slowly decreased and failure time delayed than a slope with low initial matric suction. Numerical analysis also indicated that a slope with wetting SWCC more rapidly approached to failure than a slope with drying SWCC.

Effect of antecedent rainfall conditions and their variations on shallow landslide-triggering rainfall thresholds in South Korea

“…Generally, rainfall-initiated landslides are strongly governed by rainfall characteristics at the time of the rainfall event, but they can also be affected by antecedent rainfall (i.e., rainfall preceding a rainfall event). Antecedent rainfall is an important factor to determine the initial soil matric suction conditions by inducing gradual increases in soil moisture and groundwater level, which can influence the initiation of landslides (Lee et al 2012). Based on realtime monitoring of four slopes in Singapore, Rahardjo et al (2008) demonstrated that the role of antecedent rainfall in the development of the worst pore-water pressure condition was more significant in residual soils with low permeability than in those with high permeability.…”