Reduction of smear effects around PVD using thermo-PVD

Abstract

This paper presents the effects of raising the temperature of soft Bangkok clay, up to 90°C, in combination with the performance of prefabricated vertical drains (PVD) during the preloading process called thermo-PVD, as measured in laboratory model tests. For both reconstituted and undisturbed specimens, higher settlements were observed for the soil specimens with thermo-PVD loaded with constant vertical stress. Furthermore, using thermo-PVD, Kh/Ks decreased while the coefficient of horizontal consolidation Ch increased for both the undisturbed and reconstituted specimens, which resulted in an increased rate of consolidation. This behaviour can be attributed to an increase in the hydraulic conductivity of the soil as the soil temperature increased within the smear zone surrounding the PVD. Therefore, using thermo-PVD, which combines a heat source and drainage with the PVD, the drainage performance can be enhanced by reducing the drainage retardation effects in the smear zone around the thermo-PVD.