Influence of thermomechanics in the catastrophic collapse of planar landslides

Frictional heating has long been considered a mechanism responsible for the high velocities and long run-out of some large-scale landslides. In this work a landslide model is presented, applicable to large-scale planar landslides occurring in a coherent fashion. The model accounts for temperature rise in the slip zone due to the heat produced by friction, leading to water expansion, thermoplastic collapse of the soil skeleton, and subsequently to an increase of pore-water pressure. The landslide model, comprising equations that describe heat and pore pressure diffusion and the dynamics of the moving mass, is used to analyse the evolution of the Jiufengershan planar landslide as an example. Further, its parameter space is systematically and efficiently explored using a Taguchi parametric analysis in an attempt to quantify dominant parameters. It is shown that the process of sliding is dominated by the softening properties of the material, as expected, but also by the permeability of the slip zone and the thickness of the sliding mass. It is worth noting that the latter two parameters do not enter traditional stability analyses of uniform slopes.