Some observations of the effects of pore fluids on the triaxial behaviour of a sand

This paper describes unusual stress-strain behaviour, involving deviatoric stress, axial strain and pore pressure jumps, observed during undrained triaxial compression testing of Leighton Buzzard sand when using syrup and silicon oil pore fluids. The materials, pore fluids, specimen preparation and test methods are described, as are the results of a suite of triaxial tests in a temperature controlled cell in which deviatoric stress, pore pressure and local strain were measured. The results are compared with the some existing data showing similar effects, and possible causes of the strain jumps are postulated. The results suggest that specimen formation in the way used here, in a viscous fluid, could suppress dilatancy.