The hydraulic conductivity of Singapore Marine Clay at Changi

Abstract

Abstract The hydraulic conductivity of Singapore Marine Clay at Changi was studied by both in situ and laboratory methods. In situ tests, such as the Cone Penetration Test (CPT), Dilatometer Test (DMT), Self-boring Pressuremeter Test (SBPT) and BAT permeameter test were carried out. Rowe Cells and oedometers were used to determine the horizontal hydraulic conductivity and vertical hydraulic conductivity respectively. Hydraulic conductivity values were found to range between 10 -10 m/s and 10 -9 m/s. Hydraulic conductivity values in the horizontal direction measured from laboratory Rowe Cell tests were found to be about twice the vertical hydraulic conductivity from oedometer tests. Horizontal hydraulic conductivity values measured from Rowe Cell tests were also higher than those measured from BAT and SBPT but about the same order as values obtained from CPTU and DMT. Most hydraulic conductivity values evaluated indirectly from in situ dissipation tests were higher than direct measured values from BAT permeameter tests. DMT and CPTU gave the highest horizontal hydraulic conductivity values and SBPT yielded values in between. However CPTU, DMT and SBPT dissipation tests were found to be suitable alternative methods for estimating the hydraulic conductivity of clay. The variation of vertical hydraulic conductivity was characterized by the relationship between void ratio and hydraulic conductivity change index which, based on oedometer results, is only C kv =0.3e 0 .