In situ dissipation testing of soft soil under reclamation fills

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


In situ dissipation tests provide a means of evaluating the in situ coefficient of consolidation and hydraulic conductivity of soft clays due to horizontal flow. Dissipation tests using piezocone (CPTU), dilatometer (DMT), self-boring pressuremeter (SBPT) and BAT permeameter (BAT) were utilized in the characterization of the coefficient of horizontal consolidation and horizontal hydraulic conductivity of Singapore marine clay at Changi in a land reclamation project. Dissipation tests were carried out to compare the changes in the coefficient of consolidation and hydraulic conductivity due to horizontal flow prior to reclamation and after ground improvement. Tests were carried out in a Vertical Drain Area as well as in an adjacent untreated Control Area, 23 months after preloading for comparison purposes. The purpose of this research is to determine the consolidation parameters of soft soil before reclamation and after 23 months following preloading with and without vertical drains by means of in situ dissipation tests. This should indicate the change in these consolidation parameters associated with void ratio changes caused by the consolidation process under the same magnitude of load at different degrees of consolidation.