清华热力学岩土模型与能源地下结构有限元模拟  

Tsinghua thermodynamic soil model for simulating energy engineering projects

作　　者：程晓辉[1] 赵乃峰 王浩 张志超[1,3] CHENG Xiaohui;ZHAO Naifeng;WANG Hao;ZHANG Zhichao(Department of Civil Engineering,Tsinghua University,Beijing 100084.China;School of Civil and Environmental Engineering,Nanyang Technological University,Singapore 639798.Singapore;School of Civil Engineering,Chongqing University,Chongqing 400045,China)

机构地区：[1]清华大学土木工程系,中国北京100084 [2]新加坡南洋理工大学土木与环境工程学院,新加坡639798 [3]重庆大学土木工程学院,中国重庆400045

出　　处：《清华大学学报（自然科学版）》2020年第9期707-714,共8页Journal of Tsinghua University(Science and Technology)

基　　金：国家自然科学基金面上项目(51778338)。

摘　　要：能源桩是利用建筑桩基础与周围岩土体进行热交换的新型结构和换热构件,具有高效开发利用浅层地温能和节省地下空间等优点。由于对桩周岩土体温度-应力耦合行为认识的匮乏,能源桩的设计和安全服役面临新的挑战。该文首先总结了饱和黏土温度-应力耦合的体积变化规律,简要评述了现有岩土热力耦合本构模型存在的问题;重点阐述了清华热力学岩土本构模型(Tsinghua thermodynamical soil model,TTS模型)的理论框架,给出了模型参数的物理意义和标定方法;最后开展了饱和高岭土升温排水试验和能源基础的有限元分析。基于TTS模型的有限元分析结果表明:升温过程中,能源基础的承载能力有微小降低,界面正应力、切应力均发生衰减;随着基础深度的增大,界面切应力随温度升高呈非线性增加,而界面正应力变化较小;升温降温后,桩土界面的接触减弱,基础沉降有所增大、承载能力有一定降低。Energy piles utilize pile foundations to exchange heat with the surrounding rock and soil to facilitate efficient use of shallow geothermal energy supplies.An energy pile design is given that improves the thermo-mechanical coupling of the soil with the energy pile.Specifically,this paper summaries the influences of temperature and stress on the volume change of saturated clays with evaluations of the thermo-mechanical constitutive models in the literature.A Tsinghua thermodynamic soil(TTS)model is then used in finite element simulations of the thermo-mechanical behavior of elevated temperature oedometer tests of Kaolin clay with an energy pile.The predictions show that heating reduces the bearing capacity of the energy pile foundation,the interfacial normal stress and the shear stress.The results also show that the interfacial shear stress increases with increasing temperature and foundation depth,while the interfacial normal stress changes little.Cooling reduces the energy pile-soil interface interactions,increases foundation settling and reduces the bearing capacity.

关 键 词：能源地下结构 热蠕变试验 非平衡态热力学 温度应力耦合 本构模型 

分 类 号：TU432[建筑科学—岩土工程]