Soil improvement works for Changi East reclamation project

Reclamation in Changi East, Singapore involved the formation of 2000 ha of land. The use of prefabricated vertical drains, combined with surcharge, was required to accelerate the consolidation settlement of the underlying soft compressible soil throughout most of the area. The fill used was marine dredged sand which was placed mainly by hydraulic means and densified by various deep compaction methods such as dynamic compaction, vibroflotation and Müller resonance compaction. A comprehensive instrumentation scheme was used to monitor the process of consolidation. The various methods used for assessing the performance of the soil improvement works, namely soil instrumentation, in situ tests and laboratory tests, are also discussed. The soil improvement works, which included the treatment of a siltpond filled with ultrasoft soil and three pilot tests associated with the use of vertical drains, are also described and discussed.