Thermoporomechanics of creeping landslides: The 1963 Vaiont slide, northern Italy

Abstract

[1] The catastrophic Vaiont landslide (Southern Alps, Italy) of 9 October 1963 moved 2.7 Â 10 8 m 3 of rock that collapsed in an artificial lake, causing a giant wave that killed 1917 people. The landslide was preceded by 2-3 years of creep that ended with the final collapse of the rock mass slipping at about 30 m s À1 . Assuming that creep was localized in a clay-rich water-saturated layer, in this study we propose shear heating as the primary mechanism for the long-term phase of accelerating creep. We study only the creeping phase of the slide, and we model this phase using a rigid block moving over a thin zone of high shear strain rates. Introducing a thermal softening and velocity strengthening law for the basal material, we reformulate the governing equations of a water-saturated porous material, obtaining an estimate for the collapse time of the slide. Our model is calibrated upon real velocity measurements from the Vaiont landslide and provides an estimation of the critical time of failure up to 169 days before the collapse. We also show that the slide became critical $21 days before the collapse, when shear heating started localizing in the clay-rich layer, inducing a tendency for slip localization and thermal runaway instability in a plane. The total loss of strength in the slipping zone during the last minutes prior to the slide is explained by the onset of thermal pressurization, triggered by the temperature rise within the clay-rich layer.

Failure in shear bands for granular materials: thermo-hydro-chemo-mechanical effects

“…3(b)). Since usually T p %T c , as temperature increases due to shear heating, the shear band would shrink in a thermally controlled process (see also Veveakis et al (2007Veveakis et al ( , 2010). …”

Rock‐and‐soil avalanches: Theory and simulation

“…We have set D c = 5 m, which is consistent with weakening slip distances for the models of rock avalanches with supposed thermal pressurization of the pore fluid [e.g., Chang et al, 2005b;Veveakis et al, 2007]. Nevertheless, the dynamic behavior of the granular hillslope has been analyzed for other threshold distances (1 -10 m); this parameter only affects the response time of avalanche triggering and does not modify the main results of this study.…”

Effects of heat softening on initiation of landslides

“…In such way, the results can be used in other cases whose dimensionless parameters are in the same range. In simulation, the parameters of the slope are determined mainly by reference of Vaiont slide (Veveakis et al 2007;Tika and Hutchinson 1999) which are as follows: E r =1×10 5 Pa, ρ=2.4×10 3 kg/m 3 ,…”

“…As the localized zones are very thin, besides the pore water seepage, thermal effects during rapid slip may be of primary importance (Jean et al 2011). For example, disastrous Vaiont slide happening on 9 October 1963 showed to be a collapse after a long-term creep during which a localized zone was formed in clay-rich layers with 0.005 to 0.175 m thick, embedded in the limestone (Figure 1) (Veveakis et al 2007). The clay-rich layer was heated during creep.…”