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Influence of Rainfall-induced Wetting on Unsaturated Weathered Slopes  

Jeong Sang-Seom (School of Civil & Environmental Engrg., Yonsei Univ.)
Kim Jae-Hong (Dept. of Civil Engrg, Univ. of Colorado)
Park Seong-Wan (Dept. of Civil & Environmental Engrg., Dankook Univ.)
Publication Information
Journal of the Korean Geotechnical Society / v.20, no.7, 2004 , pp. 159-169 More about this Journal
Abstract
Surface failures of slopes in weathered soil are caused by infiltration due to prolonged rainfall. These failures are mainly triggered by the deepening of the wetting band accompanied by a decrease in suction induced by the infiltrating water. This paper reports trends of rainfall-induced wetting band depth in two types of weathered soils that are commonly found in Korea. Both theoretical and numerical analyses are presented based on the soil-water characteristic curve (SWCC) obtained using filter paper as well as tensiometer tests. It is found that the magnitude of wetting front suction plays a key role in the stability of slopes in weathered soils. Theoretical analysis based on modified Green and Ampt model tends to underestimate the wetting band depth for typical Korean weathered soils. It was also deduced that for Korean weathered soils, the factor of safety drops rapidly once the wetting band depth of 1.2 m is reached.
Keywords
Infiltration; Rainfall; Slope stability; Unsaturated soils; Wetting front suction;
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