Numerical simulation of infiltration and evaporation for unsaturated infinite soil slopes

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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Rainfall triggered landslides are common natural hazards with significant consequences all over the world, including Turkey. Majority of available methods for predicting rainfall-induced slope instability are based on regional statistical data of past slope failures and rainfall records rather than a physically-based model that takes the mechanism of the problem into account. Current study aims to define a numerical model for typical slopes in the region (Northern Turkey), use unsaturated soil properties an...
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Ahmadi-adli, Mohammad; Huvaj Sarıhan, Nejan; Toker, Nabi Kartal (2017-09-22)
Rainfall triggered landslides are common natural hazards with significant consequences all over the world. In this study, laboratory model tests are conducted which aims to obtain the rainfall intensity-duration threshold to trigger landslides in a slope composed of unsaturated soil in a flume setup. Sixteen laboratory model tests are conducted to obtain the rainfall intensityduration threshold. Some of the conclusions in this study are: (1) rainfall intensity-duration (I-D) thresholds that would trigger a ...
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Ahmadi-Adli, Mohammad; Huvaj Sarıhan, Nejan; Toker, Nabi Kartal (2017-11-01)
Extreme and/or prolonged rainfall events frequently cause landslides in many parts of the world. In this study, infiltration of rainfall into an unsaturated soil slope and triggering of landslides is studied through laboratory model (flume) tests, with the goal of obtaining the triggering rainfall intensity-duration (I-D) threshold. Flume tests with fine sand at two different relative densities (34 and 48%) and at slope angle of 56.5 degrees are prepared, and rainfall (intensity in the range of 18 to 64 mm/...
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Earthquakes are among the most destructive natural disasters affecting urban populations. Structural damage caused by the earthquakes varies depending not only on the seismic source and propagation properties but also on the soil properties. The amplitude and frequency content of seismic shear waves reaching the earth’s surface is dependent on local soil conditions. It is well known that the soft sediments on top of hard bedrock can greatly amplify the ground motion and cause severe structural damage. When ...
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.