Numerical simulation of infiltration and evaporation for unsaturated infinite soil slopes

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2017
Kenanoğlu, Melih Birhan
Rainfall triggered landslides are common threat in many regions of the world and cause loss of lives and properties. These are shallow failures (typically 3-5 m depths from the ground surface) that occur along a plane parallel to the ground surface where the groundwater level is located at significant depths below, and they are triggered after a heavy rainfall in a short time or after days of lower intensity rainfall (Huvaj et al., 2013). Considering a failure plane oriented parallel to the ground surface, infinite slope models are used to analyse stability of these landslides after rainfall infiltration in general. In this study, a numerical model was developed to simulate the infiltration and evaporation in the unsaturated infinite soil slopes by considering the effect of wetting-drying hysteresis, as well as transitions between the two regimes. The scanning curve model fits the general shape of retention curves found in the literature. The incremental form of Darcy’s equation was used to evaluate water flow within the infinite slope in case of both infiltration and evaporation. The proposed numerical model was validated with results of infiltration column test. The flow model was used with infinite slope analysis (without coupling hydraulic and mechanical behavior at the element scale), and a parametric study was conducted to obtain suction and water content profiles, as well as rainfall intensity-duration thresholds for failure. Three distinct mechanisms that led to instability was observed, depending on soil proporties and rainfall intensity. The understanding of various mechanisms of landslide trigger due to rainfall may eventually pave the road for areal models and early warning systems to mitigate the hazard of such landslides. The proposed hydraulic model can also be used in incremental form to predict suction in different hydromechanical frameworks for other physical problems.  

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Citation Formats
M. B. Kenanoğlu, “Numerical simulation of infiltration and evaporation for unsaturated infinite soil slopes,” M.S. - Master of Science, Middle East Technical University, 2017.