Pre-reclamation in situ testing of soft soil

A. Arulrajah, M. W. Bo, H. Nikraz and R. Hashim

The Changi East Reclamation Project in the Republic of Singapore comprises the ground improvement of marine clay with the installation of prefabricated vertical drains and subsequent preloading. Prior to the commencement of land reclamation works, a series of in situ tests were conducted under marine conditions with the help of various in situ testing equipment. The In Situ Testing Site was located in the northern part of the project where the thickest compressible marine clay existed. The in situ tests carried out were with the field vane, piezocone, flat dilatometer, self-boring pressuremeter and BAT permeameter. In situ tests were conducted to determine the undrained shear strength, overconsolidation ratio, soil stiffness and coefficient of consolidation and permeability of the marine clay. In situ dissipation tests provide a means of evaluating the in situ coefficient of consolidation and hydraulic conductivity due to horizontal flow of soft soil and were used to estimate these properties of Singapore marine clay at Changi.