Effect of temperature in soil mechanics for energy and the environment
Geotechnical engineering may play an important role in responding to global climate change by reducing emissions of greenhouse gases into the atmosphere (Mitigation) and adapting to life in changing climate (Adaptation). In this seminar, Dr. Anh Minh Tang will present his research works related to the effect of temperature on soil mechanical behaviour in order to develop geostructures for energy and to increase the resilience of geostructures. Four examples, covering a wide range of temperature, will be analysed. First, in the concept of geological high-level radioactive waste disposal, soil surrounding the waste canisters may be heated from the initial state (around 10 °C) up to approximately 80 °C. This heating would modify the stress state in soil by increasing pore water pressure and altering soil mechanical properties. Second, in the case of energy geostructures (foundations or buried geotechnical structures which have been equipped with heat transfer pipes so that they may act as ground heat exchanger, part of a ground source heat pump system for heating or cooling of residential, commercial and industrial buildings), soil surrounding geostructures may be cooled down to few °C in winter (for heating demand of the buildings) and heated up to 30 °C in summer (for cooling demand of the buildings). In these conditions, the effect of temperature on soil mechanical properties would be negligible but soil/structure interactions related to thermal dilation/contraction of the structure would be significant. Third, natural gas hydrates abundantly exist within sediment layers along the world’s continental margins (few °C above zero), and within and beneath Arctic permafrost (few °C below zero). Any small change in temperature (due to global warming) would cause this ice-like solid to abruptly separate into water and gas and significantly modify the mechanical properties of the sediment layers. Fourth, for road pavement subgrade in cold region, freeze-thaw cycles related to seasonal change in temperature (variation around 0 °C) can induce degradation by formation of ice lenses related to cryo-suction.