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Geomechanics and Engineering
  Volume 19, Number 1, September20 2019 , pages 1-9

Stability analysis of an unsaturated expansive soil slope subjected to rainfall infiltration
Shunchao Qi, Sai K. Vanapalli, Xing-guo Yang, Jia-wen Zhou and Gong-da Lu

    Shallow failures occur frequently in both engineered and natural slopes in expansive soils. Rainfall infiltration is the most predominant triggering factor that contributes to slope failures in both expansive soils and clayey soils. However, slope failures in expansive soils have some distinct characteristics in comparison to slopes in conventional clayey soils. They typically undergo shallow failures with gentle sliding retrogression characteristics. The shallow sliding mass near the slope surface is typically in a state of unsaturated condition and will exhibit significant volume changes with increasing water content during rainfall periods. Many other properties or characteristics change such as the shear strength, matric suction including stress distribution change with respect to depth and time. All these parameters have a significant contribution to the expansive soil slopes instability and are difficult to take into consideration in slope stability analysis using traditional slope stability analysis methods based on principles of saturated soil mechanics. In this paper, commercial software VADOSE/W that can account for climatic factors is used to predict variation of matric suction with respect to time for an expansive soil cut slope in China, which is reported in the literature. The variation of factor of safety with respect to time for this slope is computed using SLOPE/W by taking account of shear strength reduction associated with loss of matric suction extending state-of-the art understanding of the mechanics of unsaturated soils.
Key Words
    expansive soils; slope stability; unsaturated soils mechanics; case study
Shunchao Qi and Jia-wen Zhou: State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu, Sichuan 610065, PR China

Sai K. Vanapalli: Department of Civil Engineering, University of Ottawa, Ottawa, ON, K1N 6N5, Canada

Xing-guo Yang and Gong-da Lu: College of Water Resource and Hydropower, Sichuan University, Chengdu, Sichuan 610065, PR China

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