New approach of vacuum preloading with booster prefabricated vertical drains (PVDs) to improve deep marine clay strata

TLDR

Deep marine clay layers pose challenges for ground improvement, and conventional booster tubes in air‑booster vacuum preloading provide limited inflow channels for compressed air. The authors conducted in‑situ field tests at the Oufei sluice project in Wenzhou, China, monitoring vacuum pressure, pore‑water pressure, settlement, and lateral displacement in over 20 m of marine clay, and analyzed the data to assess ground‑improvement performance. The new air‑booster vacuum preloading technology outperformed conventional vacuum preloading in improving deep marine clay layers.

Abstract

This paper presented a new approach for ground improvement of deep marine clay in which the conventional booster tube in the current air booster vacuum preloading technology was replaced by a booster prefabricated vertical drain (PVD). In comparison to the ordinary PVD, the booster PVD could provide inflow channels for the compressed air when the booster pump was in operation. To examine the performance of this new air booster vacuum preloading technology, in situ field tests were conducted at Oufei sluice project in Wenzhou, China, where the thickness of the soft soil layers (i.e., marine clay) was more than 20 m. An extensive monitoring system was implemented to measure the vacuum pressure, pore-water pressure, settlement, and lateral displacement at this reclamation site. With the collected field monitoring data, a comprehensive data analysis was carried out to evaluate the extent of ground improvement. The study results depicted that this new air booster vacuum preloading technology was more effective for the ground improvement of the deep marine clay layers, in comparison to the conventional vacuum preloading technology.