EXPERIMENTS ON SUBAQUEOUS GRAVITY FLOWS OF LIQUEFIED SAND IN A DRUM CENTRIFUGE －EFFECTS OF VOLUME OF SEDIMENT

Abstract

 This paper examines the behaviour of subaqueous gravity flows of liquefied sand in a set of centrifuge model tests. A series of flow tests was performed under centrifugal accelerations of 30 or 50 gravities, in variation of thickness of initial sediment. The sediment having a thickness was liquefied and fluidized by upward seepage flow, and the gravity flow generated following opening the gate set in the channel. Sediment gravity flow with a velocity of 2.0 m/s, following liquefaction of 5 m-thick sand bed on the prototype scale, was observed. As progress of the gravity flow, the head of flow unstabilized followed by the gravity flow of slow speed in association with dilution of sediment. It is also observed that the gravity flow with much volume of sediment maintains high velocity from the start of flow to 50 m distance.