Vacuum consolidation of dredged slurry improved by horizontal drainage-enhanced geotextile

The vacuum consolidation behavior of dredged slurry improved by horizontal drainage-enhanced geotextile (HDeG) application was investigated. For comparison, vacuum consolidation tests using a prefabricated vertical drain (PVD) and layered prefabricated horizontal drains (PHDs) were conducted. Based on the test results, it was found that by using HDeG, the consolidation rate of the dredged slurry was significantly increased. Thus, the effectiveness of the HDeG method was verified. The nonwoven geotextile sheet of HDeG could provide a sufficient vacuum pressure and drainage and therefore greatly shorten the drainage path. The HDeG-induced consolidation settlement generally matched the calculated 1D consolidation settlement well using a representative coefficient of consolidation. The analysis of scanning electron microscopy images shows that after the vacuum consolidation test, the porosity of the PHD filter (vacuum PHD treatment) was only 11% (21.1% of the initial porosity), while the porosity of the PHD filter of the HDeG was 22.16% (42.6% of the initial porosity), suggesting that the geotextile effectively reduced the apparent clogging of the drains.