基于TTS本构模型真三轴条件下的热蠕变研究  

Simulation of thermal creep under true triaxial conditions based on TTS constitutive model

作　　者：刘子琪 程晓辉[1] LIU Ziqi;CHENG Xiaohui(Department of Civil Engineering,Tsinghua University,Beijing 100084,P.R.China)

机构地区：[1]清华大学土木工程系,北京100084

出　　处：《深圳大学学报（理工版）》2023年第1期74-82,共9页Journal of Shenzhen University(Science and Engineering)

基　　金：国家自然科学基金资助项目(51778338,52078274)。

摘　　要：真三轴条件下单调和循环温度荷载显著影响土体轴向、径向变形和侧压力系数,对能源地下结构抗裂、沉降控制及承载力设计提出了挑战.基于清华热力学岩土(Tsinghua thermodynamical soil,TTS)本构模型及Matlab点源求解程序,开展一维压缩和平面应变状态下饱和黏土和粉土的排水热蠕变模拟.分析一维侧限条件下超固结比(over consolidated ratio,OCR)和温度循环对热蠕变的影响;预测OCR及温度循环次数对侧压力系数的影响;模拟真三轴应力条件下各个主应力方向的热蠕变.TTS本构模型模拟的Bonny粉土真三轴排水条件下热蠕变方向和大小与试验结果符合,预测的相同试验条件下Bangkok软黏土温度蠕变幅值更大.结果表明,TTS本构模型可以合理描述真三轴条件下各主应力方向收缩或膨胀的热蠕变及温度剪应变.研究可为能源桩侧摩阻承载力设计提供参考.Monotonic and cyclic thermal loading significantly affect the axial and radial deformation,and lateral pressure coefficient of soil under true triaxial conditions,which poses new challenges to the crack resistance,settlement control and bearing capacity design of underground energy structures.Thermal creep simulation is carried out for saturated clay and silt under 1D compression and plane strain in drained situation based on the Tsinghua thermodynamical soil(TTS)constitutive model and its Matlab model driver.The effect of over consolidated ratio(OCR)and thermal cycles on thermal creep and lateral earth pressure coefficient under 1D confined condition is predicted,and the effect of true triaxial stress conditions on thermal creep of different principal stress direction is simulated.The simulated thermal creep direction and magnitude of bonny silt by TTS under true triaxial drained condition are consistent with the test results.The temperature creep amplitude of Bangkok soft clay is greater than that of Bonny silt under the same test condition.The results show that the thermal shrinkage or expansion creep in each principal stress direction and temperature shear strain under true triaxial condition can be reasonably described by TTS.The research can provide reference for the design of the side friction bearing capacity of energy piles.

关 键 词：岩土工程 平面应变 热蠕变 温度循环 应力历史 清华热力学岩土本构模型 

分 类 号：TU432[建筑科学—岩土工程]