Small-scale laboratory flowslides

Abstract

Loose cohesionless slopes are susceptible to liquefaction and subsequent flowsliding. Small scale sub-aerial laboratory flowslides have been obtained by inducing the collapse of loose deposits of saturated fine quartz sand. Failure mechanisms resembled field cases and other laboratory experiments. A detailed set of results is presented, illustrating the temporal and longitudinal variation of both surface velocity and the elevations of flowing and static material. Initially, the flowside accelerated under the influence of gravity. Movement was not arrested ‘en masse’, but unsteady deposition of sand and pore fluid occurred, being dependent on deceleration of the flowslide that propagated downstream. As a result, the slope over which the flowing material was moving increased with time. Excess pore water pressures were measured during flowslide motion, the magnitudes of which were reasonably predicted using the Coulomb failure criterion and assuming equilibrium of driving and resisting forces. This was despite the observance of unsteady flow and the limitations of experimental measurement.