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温度对黏土力学特性具有重要影响,温度变化将引起黏土的体积变形发生变化,并对其前期固结应力、剪切强度、弹性模量等具有重要影响。基于黏土“热陷”特性,引入热屈服面以描述不同超固结比的黏土在温度升高时所产生的塑性变形,并进一步开展以下工作:(1)建立考虑温度影响的下加载面模型,由于保留了下加载面模型对超固结黏土应力–应变特性优异的描述能力,并考虑了温度对黏土的2种作用(即温度使超固结黏土的超固结比降低和温度塑性应变对屈服面的硬化效应),该模型可以描述温度变化对不同黏土力学特性的复杂影响;(2)证明了所提出的模型严格满足热力学第一、第二定律;(3)采用该模型模拟Pontida clay和MC clay在不同压力下的排水加热试验和在不同温度下的三轴排水/不排水试验,模拟结果与试验结果对比分析表明,模型能合理地描述不同超固结比的黏土在温度变化时产生的体积变形以及温度对黏土强度的影响等。
Temperature has an important influence on the mechanical properties of the clay. The temperature change will cause the volume deformation of the clay to change, and has an important influence on the consolidation stress, shear strength and elastic modulus in the early stage. Based on the characteristics of clay “hot slump ”, the hot yield surface was introduced to describe the plastic deformation of clay with different overconsolidation ratios at elevated temperature. The following work was further carried out: (1) Surface model retains the ability of describing the stress-strain behavior of overconsolidated clay under the loading surface model and takes into account the two effects of temperature on the clay (ie, the temperature decreases the overconsolidation ratio of the overconsolidated clay and the temperature (2) It is proved that the proposed model strictly satisfies the first and second laws of thermodynamics; (3) The model is applied to simulate the effect of plastic deformation on yield surface. Drainage heating tests of Pontida clay and MC clay under different pressures and triaxial drainage / undrained tests at different temperatures were simulated. Comparing the simulation results with the experimental results, the model can reasonably describe that the clay with different overconsolidation ratios The volume of deformation caused by temperature changes and the effect of temperature on the strength of clay.