考虑冻结粘性土结构损伤特性的本构模型

发布时间：2018-02-22 22:20

本文关键词： 冻结粘性土结构性损伤特性影响因子蠕变损伤本构模型蠕变损伤本构模型　出处：《安徽理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：冻土是种十分特殊的材料,而冻土结构性的研究也经历了漫长曲折的探索过程,随着科技的发展,人工冻土技术的应用越来越多,对冻土结构性的研究依然重要,不管是理论的建立还是经验的累计,随着对冻土结构性研究的发展,工程建设将更加安全和科学。本文通过对重塑土人工冻结并进行单轴压缩试验和单轴蠕变试验,通过考虑不同的含水率及温度,分析冻土的物理力学性质并研究冻土的结构性。将计算机统计出的实时数据进行截面积修正,考虑泊松比对试验数据的影响,为之后的研究工作提供更符合实际的试验数据。根据单轴压缩试验得到损伤起始条件(应力损伤门阀值和应变损伤门阀值)并找出其与温度、含水率之间的关系;确定损伤变量D,从而得到冻土损伤本构模型,对不同试验条件下的单轴压缩曲线进行拟合,证明了此模型能够很好的描述冻结粘性土的应力-应变曲线特征。根据单轴蠕变试验分析冻结粘性土的蠕变特性,分析不同流变模型的应用,从而建立考虑结构损伤的流变模型,并将理论值与实验值比较,证明了此模型可以很好的描述冻结粘性土的蠕变特性。分析蠕变对冻土单轴抗压强度的影响,并用损伤本构模型进行拟合,结果表明,此损伤本构模型可以很好的描述预压后冻土应力-应变曲线中的弹性阶段以及应变较大时的损伤阶段,而只在弹性段结束后,损伤开始阶段初期与实验值有较大差异。
[Abstract]:Frozen soil is a very special material, and the study of frozen soil structure has also experienced a long and tortuous exploration process. With the development of science and technology, the application of artificial frozen soil technology is more and more, and the study of frozen soil structure is still important. With the development of structural research on frozen soil, engineering construction will be safer and more scientific, no matter whether the theory is established or the accumulated experience is accumulated. In this paper, uniaxial compression test and uniaxial creep test are carried out on remolded soil by artificial freezing, and uniaxial compression test and uniaxial creep test. By considering different moisture content and temperature, the physical and mechanical properties of frozen soil are analyzed and the structure of frozen soil is studied. According to the uniaxial compression test, the damage initiation conditions (stress damage threshold value and strain damage threshold value) are obtained and the relationship between the damage threshold and temperature and moisture content is found out. According to the damage variable D, the damage constitutive model of frozen soil is obtained, and the uniaxial compression curve under different experimental conditions is fitted. It is proved that this model can well describe the stress-strain curve of frozen clay. According to uniaxial creep test, the creep characteristics of frozen clay are analyzed, and the application of different rheological models is analyzed. Thus a rheological model considering structural damage is established and compared with experimental data. It is proved that the model can describe the creep characteristics of frozen clay and analyze the influence of creep on uniaxial compressive strength of frozen soil. The damage constitutive model is used to fit the damage constitutive model. The results show that the damage constitutive model can well describe the elastic stage in the stress-strain curve of frozen soil after preloading and the damage stage when the strain is large, but only after the end of the elastic section. There was significant difference between the initial stage of injury and the experimental value.
【学位授予单位】：安徽理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU445

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