The effect of rise in mean annual temperature on the stability of rock slopes containing ice‐filled discontinuities

Abstract

Direct shear box tests have revealed that the stiffness and strength of an ice‐filled joint are a function of both normal stress and temperature. Comparison of these data with the results of similar experiments conducted on unfrozen joints indicates that at low temperatures and normal stresses the strength of an ice‐filled joint can be significantly higher than that of an unfrozen joint. However, in the absence of sufficient closure pressure, the strength of an ice‐filled joint can be significantly less than that of an unfrozen joint. This implies that if the stability of a slope is maintained by ice‐filled joints, its factor of safety will reduce with temperature rise. This hypothesis suggests that a jointed rock slope that is stable when there is no ice in the joints and is also stable when ice in the joints is at low temperatures will become unstable as the ice warms. Results from the model tests have confirmed this hypothesis. Copyright © 2001 John Wiley & Sons, Ltd.RÉSUMÉDes tests de cisaillement directs ont révélés que la rigidité et la résistance d'un joint rempli de glace est fonction à la fois de la contrainte normale et de la température (Davies et al., 2000). La comparaison de ces données avec les résultats d'expériences semblables conduites sur des joints non gelés indique qu'à basse température et pour des contraintes normales identiques, la résistance d'un joint rempli de glace peut être plus élevée d'une manière significative que celle d'un joint non gelé. Toutefois, en l'absence d'une pression de fermeture suffisante, la résistance d'un tel joint rempli de glace peut être significativement moindre que celle d'une fissure non gelée. Ceci implique que si la stabilité de la pente est maintenue par des joints remplis de glace, son facteur de sécurité sera réduit avec l'augmentation de la température. Cette hypothèse suggère qu'une pente de roches fissurées qui est stable quand il n'y a pas de glace dans les joints et est aussi stable quand la glace dans les joints est à basse température, deviendra instable quand la glace s'échauffe. Des résultats obtenus par des tests ont confirmé ce résultat. Copyright © 2001 John Wiley & Sons, Ltd.

Exposure dating and reinterpretation of coarse debris accumulations (‘rock glaciers’) in the Cairngorm Mountains, Scotland

“…The possibility that failure was triggered by warming of ice in bedrock joints reducing the stability of the rock mass (e.g. Dramis et al, 1995;Haeberli et al, 1997;Davies et al, 2001;Fischer et al, 2006;Gruber and Haeberli, 2007) seems unlikely as failure occurred during cold periods associated with widespread permafrost, but cannot be excluded owing to the low precision of the exposure ages.…”

Modeling the temperature evolution of Svalbard permafrost during the 20th and 21st century

“…On one hand, this effect buffers ground warming, on the other hand it may cause a non-linear ground temperature response if completely thawed. Resulting increases in ALT may in certain areas of Svalbard be associated with unprecedented thaw settlement as ice-rich soils thaw (Nelson et al, 2001), and in consequence, a marked increase in slope instability (Harris et al, , 2009Davis et al, 2001;Gruber and Haeberli, 2007). An important geomorphological consequence for bedrock in coastal areas is coastal erosion.…”

Monitoring topographic changes in a periglacial high‐mountain face using high‐resolution DTMs, Monte Rosa East Face, Italian Alps

“…Changes in the distribution and temperature of permafrost and surface ice have affected the stability of steep high-mountain faces by influencing the thermal and stress fields in both rock and ice, their geotechnical properties and their groundwater regimes (Haeberli et al, 1997;Davies et al, 2001;Harris et al, 2009;Fischer et al, 2010). The coexistence of permafrost and hanging glaciers in a high-mountain face can give rise to deepseated geothermal anomalies and extremely complex hydrological/hydraulic conditions (Wegmann et al, 1998;Haeberli et al, 2004;Huggel, 2009).…”