Abstract
Landslides are often triggered by catastrophic events, among which earthquakes and rainfall are the most depicted. However, very few studies have focused on the effect of atmospheric pressure on slope stability, even though weather events such as typhoons are associated with significant atmospheric pressure changes. Indeed, both atmospheric pressure changes and rainfall-induced groundwater level change can generate pore pressure changes with similar amplitude. In this paper, we assess the respective impacts of atmospheric effects and rainfall over the stability of a hillslope. An analytical model of transient groundwater dynamics is developed to compute slope stability for finite hillslopes. Slope stability is evaluated through a safety factor based on the Mohr-Coulomb failure criterion. Both rainfall infiltration and atmospheric pressure variations, which impact slope stability by modifying the pore pressure of the media, are described by diffusion equations. The models have then been forced by weather data from different typhoons that were recorded over Taiwan. While rainfall infiltration can induce pore pressure change up to hundred kPa, its effects is delayed in time due to diffusion. To the contrary, atmospheric pressure change induces pore pressure changes not exceeding a few kPa, but its effect is instantaneous. Moreover, the effect of rainfall infiltration on slope stability decreases towards the toe of the hillslope and is cancelled where the water table reaches the surface, leaving atmospheric pressure change as the main driver of slope instability. This study allows for a better insight of slope stability through pore pressure analysis, and shows that atmospheric effects shouldn’t always be neglected.
Highlights
In mountainous areas, landslides represent a major erosional process that contribute to landscape dynamics and frequently cause significant damage and losses when catastrophic failures occur (Keefer, 1994; Malamud et al, 2004)
We developed a model to assess the respective role of hydrological and atmospheric forcing on slope stability
We 500 used 1D diffusion equations to simulate pore pressure variations induced by rainfall and atmospheric perturbations
Summary
Landslides represent a major erosional process that contribute to landscape dynamics and frequently cause significant damage and losses when catastrophic failures occur (Keefer, 1994; Malamud et al, 2004). Typhoons and major storms can yield atmospheric drop of tens of hPa, which could in turn significantly alter the stability of slopes In this context, groundwater plays a crucial role in converting both atmospheric and rainfall-induced effects into mechanical pressure changes. Since landslides are not evenly distributed along hillslopes (Meunier et al, 2008), this work presents a 2D analytical model based on a hydrological model applied to a hillslope and a mechanistic safety factor to evaluate atmospheric and rainfall effects on slope stability We use this model in this paper to investigate the role of pore pressure changes induced by rainfall and atmospheric pressure changes during major storms on slope stability, while accounting for groundwater level, pre-conditioned by seasonal rainfall and compare it to the rainfall forcing. We discuss about the results and the relevance of the model
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have