Indoor simulation test of step vacuum preloading for high-clay content dredger fill

ABSTRACTVacuum preloading is a soft ground improvement method that has been successfully used by geotechnical engineers and specialists to accelerate the rate of consolidation. However, consolidation efficiency is low when dealing with newly reclaimed high-clay content dredger fills because of sludge plugging of the prefabricated vertical drains. In this study, step vacuum preloading was proposed to reinforce a high-clay content dredger fill by applying the vacuum load gradually to consolidate the dredger fill fully and to reduce the migration of fine particles. An indoor simulation test was conducted, and monitoring data were obtained. Results showed that the settlements increased gradually, the pore water pressures and flow velocities decreased over time, and all the changes tended to be stable by the end of the test. The settlements at each stage were more than that at the previous stage, illustrating that changing the method of drainage consolidation in a timely manner, or increasing the vacuum pressu...