Progressive failure mechanisms in a slope prone to toppling

Abstract

The Checkerboard Creek rock slope is located upstream of the Revelstoke hydroelectric dam, British Columbia, Canada. Annual surface movements of approximately 10 mm have been recorded over the past 25 years. The movement is occurring within a 60-m-deep weathered zone. A numerical modelling methodology based on a discrete element framework was used to investigate progressive failure of the slope that lacks a basal rupture surface but does contain discontinuous joints and shears. The methodology, which assigns internal micro-structure to the intact rock allows for both shear and tensile failure through intact rock bridges and for slip along existing discontinuities. The progressive failure modelling methodology was used to estimate the effect of continued weathering on the stability of the slope. A velocity boundary condition was also applied to the slope surface to estimate the time to failure. The simulations predicted that slope instability would localize at the steepest part of the slope but could take nearly 200 years to occur, assuming the current deformation rate of 10 mm/year, continues.