Experimental and molecular dynamics studies on the consolidation of Hong Kong marine deposits under heating and vacuum preloading

Consolidation of marine soft soils with prefabricated vertical drains (PVDs) and vacuum preloading is a hot spot of research in marine geotechnical engineering. Marine soft soils usually have low permeability and the consolidation is time-consuming. To accelerate the consolidation of marine soft soils, elevating the temperature with heating-aided PVDs in soils has been an attractive option. In this study, a series of laboratory tests were conducted to investigate the influence of heating on Hong Kong marine deposits (HKMD). Through the oedometer tests, the effects of heating on the compression and consolidation behavior are quantified. In the two physical model tests with vacuum preloading, it is indicated that increasing the temperature to 40 °C in HKMD can significantly speed up the consolidation process, reduce vacuum loss and increase the settlements and effective stress in a shorter period. To reveal the mechanism of thermal effect on HKMD, the molecular dynamics simulation was performed with three typical mineral elements, and the thermal effect on the different responses of minerals in HKMD is interpreted. Furthermore, theoretical analysis with Hansbo’s theory and simplified Hypothesis B method is also conducted for calculating the consolidation settlements of the model tests, with a quantified smear factor accounting for the combined effects of non-uniform consolidation, clogging, and temperature during vacuum-heat preloading.