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原状Q_3黄土在加载和湿陷过程中细观结构动态演化的CT–三轴试验研究 被引量:27
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作者 朱元青 陈正汉 《岩土工程学报》 EI CAS CSCD 北大核心 2009年第8期1219-1228,共10页
为了揭示原状Q3黄土在加载和湿陷过程中的细观结构变化,将湿陷三轴仪与医用CT机相配套,进行了一系列控制吸力的CT-三轴湿陷试验,不仅得到了加载过程和湿陷过程中的宏观反应曲线,而且得到了相对应的CT扫描图像。结果表明:原状湿陷性黄土... 为了揭示原状Q3黄土在加载和湿陷过程中的细观结构变化,将湿陷三轴仪与医用CT机相配套,进行了一系列控制吸力的CT-三轴湿陷试验,不仅得到了加载过程和湿陷过程中的宏观反应曲线,而且得到了相对应的CT扫描图像。结果表明:原状湿陷性黄土具有较强的初始结构性;加载过程中,较大的孔洞先扩展后闭合,小孔洞逐渐闭合;湿陷过程中,大部分孔洞逐渐闭合且断面的密度分布趋于均匀;湿陷过程中大孔洞闭合与否取决于浸水时的应力状态。通过宏细观试验资料的分析,确定了原状湿陷性黄土的结构屈服应力,提出了一个基于CT数均值的结构性参数,分别定义了加载和湿陷过程中的结构损伤变量,研究了它们的变化规律,建立了结构损伤演化方程。 展开更多
关键词 原状湿陷性黄土 湿陷三轴仪 CT扫描 细观结构 结构性参数 结构损伤变量 结构损伤演化方程
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A plastic damage model for concrete structure cracks with two damage variables 被引量:6
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作者 ZHENG FuGang WU ZhongRu +2 位作者 GU ChongShi BAO TengFei HU Jiang 《Science China(Technological Sciences)》 SCIE EI CAS 2012年第11期2971-2980,共10页
Based on the concepts of continuum damage theory,a new plastic damage model for concrete crack failure is developed through studying the basic damage mechanics.Two damage variables,tensile damage variable for tensile ... Based on the concepts of continuum damage theory,a new plastic damage model for concrete crack failure is developed through studying the basic damage mechanics.Two damage variables,tensile damage variable for tensile damage and shear damage variable for compressive damage,are adopted to represent the influence of microscopic damage on material macromechanics properties under tensile and compressive loadings.The yield criteria and flow rule determining the plasticity of concrete are established in the effective stress space,which is convenient to decouple the damage process from the plastic process and calibrate material parameters with experimental results.Meanwhile,the plastic part of the proposed model can be implemented by back-Euler implicit algorithm,and the damage part is explicit.Consequently,there exist robust algorithms for integrating the constitutive relations using finite element method.Comparison with several experimental results shows that the model is capable of simulating the nonlinear performance of concrete under multiaxial stress state and can be applied to practical concrete structures. 展开更多
关键词 CONCRETE cracks plastic damage constitutive relation damage variable
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