Centrifuge-model tests on pore water pressure combined with vacuum and embankment loading

Abstract

Vacuum consolidation is a ground-improvement method in which negative pressure is applied to drain materials placed in a soft ground to consolidate the ground. Using the vacuum consolidation method, a soft ground can be consolidated without the shear deformation of the ground, and the combination of this method along with embankment loading enables the stable construction of the embankment and the suppression of the displacement of the surrounding ground. In this study, centrifuge-model experiments were conducted under a gravitational acceleration of 50g for the purpose of investigating the pore water pressure of the ground during both vacuum consolidation and embankment loading. Embankment loading was reproduced by a loading device consisting of an air cylinder and a loading plate, and vacuum consolidation was reproduced by depressurising the inside of a model drain using a vacuum pump. Three experimental cases were conducted: one case with only embankment loading and two cases with a combination of vacuum consolidation and embankment loading. From the experimental results, it was confirmed that in the ground where vacuum consolidation was applied, large negative pressure propagated near the drain material, and the increase in pore water pressure due to embankment loading was suppressed.