Analysis of PVD-enhanced consolidation with soil disturbance

Abstract

Soil disturbance caused by the installation of prefabricated vertical drains (PVDs) in soft soil deposits has a detrimental effect on the rate of consolidation. The current practice of accelerating consolidation using PVDs captures the effect of soil disturbance typically by reducing the in situ hydraulic conductivity in the disturbed zone, and by assuming that the hydraulic conductivity is spatially constant over the entire disturbed zone and that preloading is instantaneous. Through recent laboratory and field studies it has been shown that the hydraulic conductivity varies spatially in the disturbed zone surrounding a PVD. Based on the data available in the literature, four possible profiles were identified for the spatial variation of the hydraulic conductivity in the disturbed zone. Analytical solutions were developed for the rate of consolidation considering these hydraulic conductivity profiles for instantaneous and time-dependent preloading. This paper shows that the consolidation rate depends not only on the hydraulic conductivity profile in the disturbed zone but also on the preloading rate.