Impact of the Rate of Heating on the Thermal Consolidation of Compacted Silt

摘要

This study involves an evaluation of the impact of the heating rate on the volume change of compacted silt. A temperature-regulated oedometer refurbished as part of this study was used to measure thermally induced volume changes. It was found that the impact of heating rates on the thermally induced volume change in soils lies in the difference between the drained and undrained behavior of soils. When a soil is heated in undrained conditions, the particles and water will expand at the same rate as the rate of heating. In addition, the difference in the coefficients of thermal expansion of the soil particles and the water during heating will result in the generation of excess pore water pressures. If drainage is allowed to occur, these excess pore water pressures will dissipate, leading to a time-dependent consolidation of the soil.The dissipation of thermally induced excess pore water pressure was found to depend on the rate of heating. If the rate of heating is slow, the excess pore water pressures will be able to dissipate at a constant rate, leading to a corresponding decrease in volume. The rate of consolidation will be greater than the rate of thermal expansion of the soil particles and water. If a soil is heated quickly, the particles and water will expand much faster than the dissipation of excess pore water pressure. In this case, the thermally induced excess pore water pressures will be generated instantaneously and a consolidation process will occur afterward. In this case, the amount of thermal consolidation was found to be greater than the amount of thermal expansion, leading to a greater net volume change than in the case of slow heating.