Analytical model for consolidation of soft ground improved by PVDs with air-boosted system

Abstract

Vacuum preloading is widely used in soft soil improvement projects. However, conventional vacuum preloading may cause clogging of the PVDs, consequently resulting in the reduction of their drainage capacity. To overcome this disadvantage, a new technology referred to as air-boosted vacuum preloading (AVP) has been proposed by introducing an array of pre-buried air-boosted pipes to enhance the water head differences between the PVDs and surrounding soil, which is beneficial to accelerating the consolidation rate of soft soils. Nevertheless, almost no analytical theories of the consolidation with AVP are available in the literature. To fill this gap, a new analytical model including both the air booster and the PVDs in the unit cell is proposed to predict the coupled radial-vertical consolidation of soils improved by AVP. The equal volumetric strain assumption, together with the effect of well resistance and smear effect are considered to obtain analytical solutions under instantaneously loading. Then the solution is applied to a field test to verify the reasonability of the proposed analytical model. Furthermore, the present solution is compared to the analytical model of conventional vacuum consolidation, and the results indicate that AVP can accelerate the consolidation more effectively. Finally, a parametric analysis of AVP consolidation is carried out to investigate the impacts of various parameters on the consolidation behavior.