On the Behavior of Thermally Driven Creeping Landslides

Rapid, giant landslides are usually preceded by prolonged periods of accelerating creep. The prolonged creep of a slide might trigger the excess pore pressure generation due to the friction-induced temperature rise (i.e. thermal pressurization). Past this point, the phenomenon evolves explosively, until the moment where the pore pressure reaches its maximum value (the value of the normal stress) and the strength of the gouge drops to zero, explaining the catastrophic accelerations that these landslides obtain during their final collapse.

In this study we expand the model presented Veveakis et al.,2007 to provide stability criteria for thermally driven landslides. The landslide is modeled using a rigid block that slides over a clayey zone of finite width and a thermal softening and velocity strengthening constitutive law for the friction coefficient of the basal clay material. As time progresses, the sliding process enters and irreversible, highly unstable procedure, when the heat dissipation at the base of the slide starts localizing towards an infinitesimally small shear band of the order of mm. The influence of this transition to the stability of the slide is explored by applying this model in the landslide of the Vaiont Valley (Northern Italy) and in the Shuping landslide (Three Gorges Reservoir, China). The two models are calibrated upon the real velocity data of the slide using both a constant basal shear stress approach (creep), and a variable shear stress with the water table variations.

This physical mechanism of heat production in the slip surface managed to reproduce with great accuracy the observed behavior of the sliding rock mass, as well as the variations of the lake level that were performed in order to control the slide. Thus, the analysis verifies that the onset of the localization of dissipation is also a stability threshold for deep seated thermally driven landslides.

References

Veveakis, E., Vardoulakis, I., and Di Toro, G., 2007. Thermoporomechanics of creeping landslides: The 1963 Vaiont slide, northern Italy. Journal of Geophysical Research, 112, F03026, doi:10.1029/2006JF000702.