Frictional heat and strength loss in some rapid landslides

Abstract

Frictional heat generated within fluid-saturated landslide slip zones can create an increase in pore fluid pressure. This rise in fluid pressure is enhanced by large values of friction coefficient, initial porosity and slide displacement, and by small values of slip zone thickness and compressibility. If maintained under conditions of fast slip, and small wall rock permeability and shear dilatancy, fluid pressure rise can induce rapid frictional strength loss during sliding. Moderate sliding can thereby be converted under certain conditions into catastrophic descent. The rate of temperature rise within a slip zone diminishes as pore fluid pressures rise. Vaporization seems possible only under restricted conditions, and results suggest that large gas pockets are not generally produced. However, rock melting or dissociation may be relatively common under portions of large slides. Frictional heat-induced fluid pressure enhancement is proposed as a possible explanation for the problem of low kinetic friction posed by the Vaiont slide. La chaleur de friction engendrée à l'intérieur des zones de glissement de terrain saturées de fluide peut créer une augmentation de la pression du fluide interstitielle. Cette augmentation de la pression du fluide est rehaussée par des valeurs élevées du coefficient de frottement, de la porosité initiale et du déplacement de glissement, et aussi par des valeurs basses de l'épaisseur et de la compressibilité de la zone de glissement. Si elle est maintenue sous des conditions de glissement rapide, de perméabilité réduite du mur de roche et de dilatance de cisaillement, l'augmentation de la pression du fluide peut causer une perte rapide de la résistance par frottement pendant le glissement. Comme résultat, sous de certaines conditions du glissement modéré peut se convertir en affaissement catastrophique. La rapidité de l'augmentation de temptéature à l'intéieur d'une zone de glissement diminuit à mesure que les pressions du fluide interstitielles s'accroissent. Il semble que la vaporisation soit possible seulement sous des conditions restreintes, et les résu1tats donnent l'impression que de grandes poches de gaz ne se produisent pas généralement. Cependant, la dissolution ou la disassociation de la roche peut se produire relativement souvent sous des parties de grands glissements de terrain. L'augmentation de la pression du fluide causée par la chaleur de frottement est proposée comme explication du problème de la friction cinétique réduite posé par le glissement de terrain qui eut lieu à Vaiont.

Dynamic thermo-poro-mechanical analysis of catastrophic landslides

“…Curves (1) correspond to the case of a perfectly plastic soil (zero softening) show the same behaviour, and also make it clear that thermal pressurisation alone could lead to catastrophic accelerations (cf. Voight & Faust, 1982). Curves (3) correspond to the clay softening model, as discussed in our paper (weakly coupled displacement and velocity softening).…”

Rockslide and Impulse Wave Modelling in the Vajont Reservoir by DEM-CFD Analyses

“…According to the discussion by Sitar et al (2005) and Caloi (1966), part of the slide mass has moved more than 400 m in less than 60 s. Previously published papers indicate that the average maximum slide velocity can range from 20 to 50 m/s (Hendron and Patton 1987). Several hypotheses have been proposed to explain the unusual high velocity, including the reduction of shear strength, weak layer beneath the slope, disintegration of the slide mass (Hendron and Patton 1987;Voight and Faust 1982;Sitar et al 2005). In this paper, we have investigated the slope velocity by the DEM simulations.…”

“…30 m/s) (Ciabatti 1964;Chen et al 2006;Crosta et al 2013) is still an important research subject. Many theories and assumptions have been proposed in the attempt to explain the apparent high mobility of rock and debris avalanches, and in particular, for the Vajont rockslide these theories include the thermo-poro-mechanical effects at the clay layer due to heating (Voight and Faust 1982;Vardoulakis 2002;Alonso and Pinyol 2010;Pinyol and Alonso 2010), high shearing rate-induced friction loss (Tika and Hutchinson 1999;Ferri et al 2011) and disintegration of the rockslide mass during the failure (Sitar et al 2005).…”

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

“…Temperature increase in the slipping zone may also have led to pressurization of pore water with the same effect [Anderson, 1980;Voight and Faust, 1982;Vardoulakis, 2000Vardoulakis, , 2002a. Total loss of strength by thermal pressurization has also been claimed for the Jiufengershan rock and soil avalanche triggered by the Chi-Chi (Taiwan) 1999 earthquake [Chang et al, 2005a[Chang et al, , 2005b.…”