SIMULATION OF TIME-DEPENDENT MOVEMENTS IN SYNCRUDE TAILINGS DYKE FOUNDATION

Foundation movements at the Syncrude tailings dyke continued over seve ral years in response to the construction of the dyke. Major movements have been observed in a relatively narrow layer of previously sheared clay-shale material of the Clearwater Formation. The residual strengt h of this highly plastic clay increases with the rate of shear. By rev iewing the existing literature on the rate effects on residual strengt h and using data from new experiments on Clearwater Clay Shale, a gene ral correlation between soil plasticity and rate effects is found. Thi s rate dependence of the residual strength of Clearwater clay shale ha s been incorporated into a deformation analysis, which made it possibl e to compute time-dependent movements of the foundation soil to a sati sfactory level. By using a rate-dependent plasticity model, a predicti on of anticipated foundation velocities and how I,hey decrease with ti me may be achieved.