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.
RESUME
Des tests de cisaillement directs ont reveles que la rigidite et la resistance d'un joint rempli de glace est fonction a la fois de la contrainte normale et de la temperature (Davies et al., 2000). La comparaison de ces donnees avec les resultats d'experiences semblables conduites sur des joints non geles indique qu'a basse temperature et pour des contraintes normales identiques, la resistance d'un joint rempli de glace peut etre plus elevee d'une maniere significative que celle d'un joint non gele. Toutefois, en l'absence d'une pression de fermeture suffisante, la resistance d'un tel joint rempli de glace peut etre significativement moindre que celle d'une fissure non gelee. Ceci implique que si la stabilite de la pente est maintenue par des joints remplis de glace, son facteur de securite sera reduit avec l'augmentation de la temperature. Cette hypothese suggere qu'une pente de roches fissurees 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 a basse temperature, deviendra instable quand la glace s'echauffe. Des resultats obtenus par des tests ont confirme ce resultat. Copyright © 2001 John Wiley & Sons, Ltd.
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