Deformation of Athabasca oil sand at low effective stresses under varying boundary conditions

The stress-strain responses of Athabasca oil sand at low effective stresses have been studied using drained triaxial compression tests. It is found that the behavioural characteristics such as initial Young's modulus, dilation rate, postpeak softening rate, and peak and residual strengths are very sensitive to the specimen slenderness ratio and end platen conditions. The magnetic resonance imaging results of the sheared specimens show that the internal homogeneity of shear deformation is much improved in tests with short specimens and lubricated ends. The postpeak features such as postpeak softening rate and residual strength are dependent on the degree of shear deformation homogeneity developed within the sheared specimen.