Experimental studies on soft marine clay under combined vacuum and surcharge preloading with PVD

A large-scale three-dimensional cell is designed, manufactured and assembled for applying designated vacuum and surcharge preload and allows for the measurement of settlement and excess porewater pressure. Six experiments were performed with post- arid pre-installation of prefabricated vertical drain to study the effect of smear on reconstituted samples of Mumbai marine clay. The effective stresses (40-180 kPa) are applied with six different combinations of surcharge preload (20-80 kPa) and vacuum pressure (0-100 kPa). The study concluded that the coefficient of radial consolidation (c(h)) increases from 4.60% to 20.07% higher than one-dimensional coefficient of consolidation. The addition of vacuum pressure tends to increase the horizontal coefficient of consolidation leads to shorten the preloading time by 15-63% depending on the vacuum pressure magnitude. The increase in shear strength due to vacuum pressure is more significant than a surcharge preload.