Large-Scale Self-Weight Consolidation Testing

Syncrude Canada Ltd. has developed self-weight consolidation tests with specimens 10 m high and 1 m in diameter. Used in a research and development program on oil sand waste slurry disposal, these large-scale tests determine whether or not the slurry material properties measured in large-strain slurry consolidation cells and in 2-m-high consolidation tests (when used in the finite-strain consolidation mathematical model) can predict the consolidation behavior of deep deposits of waste slurry such as those deposited in the field. The consolidation equipment and testing methods used in this research program are described, and typical test results are shown. Among the phenomena observed are the effective stress wave which travels up the cylinder during sedimentation, the development of thixotropic strength during the initial period of consolidation, the full pore pressure and total stress profile for the height of the cylinders at any time, and the consolidation with time and depth as shown by pore pressure dissipation and by the increase in solids content. The rate of consolidation in the 10-m cylinders as shown by the settlement of the water-sludge interface is in good agreement with theory and indicates the validity of the test methods.