Centrifuge model tests on soft clay improved by fabri-packed sand drain

A sea reclamation has been performed using dredged clay for the Haneda International Airport expansion project. Since the thick ground has an extremely high water content, fabri-packed sand drains, which are sand drains wrapped by envelopes of geotextile, are planned to be used. A series of centrifuge tests was performed changing the tensile rigidity of the geotextile to investigate the effect on the consolidation behavior of the ground. The study shows that the fabri-packed sand drain functions well as a drain even in the extremely soft soil. And also revealed is that the anticipated concentration of the fill pressure remains small if an appropriate geotextile is selected.