Thermo-mechanical consolidation of soft Bangkok clay: innovative technique using PVD

Previous research works in literature show that subjecting the saturated fine-grained soils to temperature less than water boiling point (100 degrees C) induces volumetric and shear strength changes depend on the stress history. These alterations of the soil properties have been attributed to the thermo-physico-chemical changes at the microscopic level. Recently, intensive experimental program has been conducted to investigate the effect of temperature, up to 90 degrees C, on the engineering properties of soft Bangkok clay. In the range of temperatures investigated, normally consolidated soft Bangkok clay exhibited irreversible contraction temperature induced volume change, stiffening, and increased hydraulic permeability with increasing temperature as well as apparent overconsolidation state after subjecting to heating/cooling cycle. These findings encourage further research towards employing the thermal load only, up to 90 degrees C, or in combination with mechanical loading as ground improvement technique. This paper study the applicability of this technique through series of large oedometer tests conducted on reconstituted soft Bangkok clay specimens. Heating was conducted using flexible wire heater attached to the PVD point or separate line heat source. The tested specimens have been subjected to either thermal load or thermo-mechanical load. The test results show that the combination between the thermal load and the mechanical load gives promising results since it accelerates the rate of consolidation and increase the amount of total settlement.