Thermomechanical Behavior of Soil: Energy Extraction through Pile Foundation

能源需求的增加、化石燃料储量的减少以及对碳排放有害影响的日益关注，使得有必要寻找替代的、可再生的和清洁的能源。地热能是一种清洁的可再生能源，可以通过桩基础（能源桩）经济地提取。据估计，在住宅和商业建筑中使用地热能可以减少45-80%的二氧化碳排放，节省18-56%的成本。通过能源桩提取地热能在加拿大是非常可行的，特别是在冬季，因为地球表面以下几英尺的温度在20°-35°c的狭窄范围内保持稳定。**使用能源桩的主要问题是缺乏精确的设计方法，因为基于力学的合理设计方程无法用于能源桩。关于能量桩的荷载传递机制以及土的热-力行为如何影响能量桩-土的相互作用，目前尚无明确的资料。因此，能源桩的可靠性在桩业中还没有得到很好的确立，从而限制了能源桩的使用。**建议的研究将通过(1)通过室内试验研究土壤和土-混凝土界面的热力学行为，(2)基于室内试验开发热塑性非等温土本构模型，(3)通过使用解析和数值框架分析能源桩，将土壤和土-桩界面的热力学特性与能源桩响应联系起来。(4)在分析的基础上提出合理的设计方程。提出的研究计划将为能源桩的分析和设计建立一个开创性的、合理的框架。由于专业人士将认识到研究的价值，该框架将在实践中采用，这将有助于加拿大民用基础设施的可持续发展与清洁能源技术。****

Increasing energy demands, dwindling fossil fuel reserves and a heightened concern for the detrimental effects of carbon emissions have made it necessary to search for alternate, renewable and clean energy sources. Geothermal energy is a form of clean and renewable energy that can be extracted economically through pile foundations (energy piles). It is estimated that the use of geothermal energy in residential and commercial buildings may lead to 45-80% reduction in CO2 emissions and to 18-56% cost savings. The extraction of geothermal energy through energy piles is very viable in Canada, particularly during the winter months, because the temperature at a few feet below the earth's surface remains stable within a narrow range of 20°-35°C.** The main concern in using energy piles is the lack of a precise design method because mechanics-based rational design equations are not available for energy piles. There is no definitive information available regarding the load transfer mechanism of energy piles and regarding how the thermo-mechanical behavior of soil affects the energy pile-soil interaction. Thus, the reliability of energy piles is not well established in the piling industry resulting in their restricted use.** The proposed research will address this issue by (1) investigating the thermo-mechanical behavior of soil and soil-concrete interface using laboratory tests, (2) developing a thermoplastic, non-isothermal soil constitutive model based on the laboratory experiments, (3) relating the thermo-mechanical properties of soil and soil-pile interface to energy pile response by analyzing energy piles using an analytical and numerical framework, and (4) proposing rational design equations based on the analysis. The proposed research program will establish a pioneering, rational framework for the analysis and design of energy piles. As the profession will recognize the value of the research, the framework will be adopted in practice, which will contribute to the sustainable development of civil infrastructure in Canada with a clean energy technology.****