Computational and experimental study of a hydro-dynamical landslide model based on laboratory flume tests

Abstract

Hydrological factors such as volumetric water content (VWC) and pore-water content (PWC) have been cited widely as significant factors that trigger slope failures especially shallow landslides and debris flows. Over the years, researchers have studied these processes using a range of physically-based models which in many occasions are either too complex incorporating very many parameters or fail to mimic real field conditions. The principal objective of this study was to derive and incorporate a set of physically-based equations that describe the dependence of slope failures at laboratory scale on VWC into a factor of safety expression herein referred to as the hydro-dynamical landslide model. The model was validated by a series of physical tests on soil samples in the laboratory using the Chep-flume. Results showed a close agreement between computational and experimental data, confirming the hypothesis that cohesion, internal friction angle and pore-water pressure are modulated by VWC especially for slopes with sandy-loam soils. More so, rapid change of soil water content was observed to accelerate build-up of negative pore-water pressures (PWP) which triggers slope failure. Apart from giving a simplified expression for the factor of safety, the proposed model circumvents the difficulties associated with tedious procedures employed in the measurement of cohesive stress by limiting the tests to only three sets of parameters i.e. VWC, PWP and displacement.