Vacuum and surcharge combined three-dimensional consolidation of soft clayey soils

A vacuum, surcharge, and vacuum-surcharge combined preloading are prevailed Three-Dimensional Consolidation Model in which a new test apparatus is manufactured and applied to the soil sample. The apparatus allows monitoring of excess pore-water pressure, axial strain (settlement), and volumetric strain during consolidation. Three sets of tests are performed using the apparatus on undisturbed clay soil samples, which were collected from Wen Zhou, Zhe Jiang Province - China at natural water content 76%. It is demonstrated from the experiments that three-dimensional vacuum-surcharge consolidation model describes the consolidation behavior of soils well. The consolidation behaviour of the clay has no rigorous difference, whether they are consolidated under the vacuum preloading, under surcharge preloading, or even under vacuum-surcharge combined preloading. The study concluded that the consolidation characteristics of the soil obtained from the conventional consolidation tests can be used in the design of vacuum preloading system provided that axi-symmetrical stress condition prevails.