Behaviors of Embankment on PVD-Improved Haiphong Clay

Abstract

This paper presents the behaviors of embankments on clay deposits improved by prefabricated vertical drains (PVD) in the north-east coastal plain of Vietnam. The deposit consists of soft Holocene clay (approximately 20 m) and stiff Pleistocene clay (approximately 20 m) on a thick sand layer. PVDs with various spacing were fully installed into the soft clay. Settlement behaviors mostly show a reverse-S curve that consists of three phases: small recompression, rapid and large settlement, and delayed settlement. When the spacing is smaller than 1.0 m, the recompression behavior disappears because of soil disturbance during installation. A nearly elastic behavior is observed during construction; thus, the ratios of lateral displacement to settlement (0.02-0.13) and of the excess pore pressure to the applied pressure (0.1-0.7) are significantly small.