Physical modelling of the effect of climate change on rock slope stability

摘要

The presence of ice in the joints of rock slopes can contribute to maintaining slope stability. Recent laboratory studies have revealed that the stiffness and strength of an ice filled rock joint is a function of both normal stress and temperature and, in the absence of sufficient closure pressure, its shear strength can be significantly less than that of an unfrozen joint (Davies et al. 2000). This suggests that a jointed rock slope that is stable when there is no ice in the joints and when ice in the joints is at low temperatures will become unstable as the ice warms. This leads to the hypothesis that the stability of rock slopes located in permafrost regions that contain ice filled discontinuities may be sensitive to changes in the thermal environment, for example the impact of climate change. To investigate this hypothesis a series of geotechnical centrifuge model tests was conducted in which the effect of a rise in ambient temperature on a rock alope containing a single ice filled discontinuity was simulated. Measurement of temperature thorough the profile of the model together with boundary displacements permitted an assessment of the relationship between temperature distribution and slope movements prior to failure and allowed trigger mechanisms to be identified.