Abstract
Abstract. The effect of preferential flow on the stability of landslides is studied through numerical simulation of two types of rainfall events on a hypothetical hillslope. A model is developed that consists of two parts. The first part is a model for combined saturated/unsaturated subsurface flow and is used to compute the spatial and temporal water pressure response to rainfall. Preferential flow is simulated with a dual-permeability continuum model consisting of a matrix domain coupled to a preferential flow domain. The second part is a soil mechanics model and is used to compute the spatial and temporal distribution of the local factor of safety based on the water pressure distribution computed with the subsurface flow model. Two types of rainfall events were considered: long-duration, low-intensity rainfall, and short-duration, high-intensity rainfall. The effect of preferential flow on slope stability is assessed through comparison of the failure area when subsurface flow is simulated with the dual-permeability model as compared to a single-permeability model (no preferential flow). For the low-intensity rainfall case, preferential flow has a positive effect on drainage of the hillslope resulting in a smaller failure area. For the high-intensity rainfall case, preferential flow has a negative effect on the slope stability as the majority of rainfall infiltrates into the preferential flow domain when rainfall intensity exceeds the infiltration capacity of the matrix domain, resulting in larger water pressure and a larger failure area.
Highlights
IntroductionHydrological models can be integrated with slope stability analysis methods to calculate the factor of safety and predict the time and magnitude of landslides (Crosta and Frattini, 2008; Shuin et al, 2012; Aleotti and Chowdhury, 1999; Westen et al, 2006)
Landslides are commonly triggered by rainfall events
For the highintensity rainfall case, preferential flow has a negative effect on the slope stability as the majority of rainfall infiltrates into the preferential flow domain when rainfall intensity exceeds the infiltration capacity of the matrix domain, resulting in larger water pressure and a larger failure area
Summary
Hydrological models can be integrated with slope stability analysis methods to calculate the factor of safety and predict the time and magnitude of landslides (Crosta and Frattini, 2008; Shuin et al, 2012; Aleotti and Chowdhury, 1999; Westen et al, 2006). The limit equilibrium method or infinite slope stability approach is frequently integrated with Richards’ equation (Lanni et al, 2013; Ng and Shi, 1998; Godt et al, 2008; Shuin et al, 2012; Wilkinson et al, 2002; Talebi et al, 2008; Greco et al, 2013) or conceptual models (Arnone et al, 2011; Simoni et al, 2008; Qiu et al, 2007) for landslide hazard evaluation. The underlying assumptions of the slope failure mechanism have limitations (Huang and Jia, 2009; Griffiths et al, 2011), the simplified slope stability analysis method has low computational demand and is widely used for geotechnical analyses at the slope scale
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