开裂混凝土有效导热系数研究:三维模拟与试验验证

发布时间：2018-04-08 23:31

本文选题：开裂混凝土　切入点：有效导热系数　出处：《水利学报》2017年06期

【摘要】：利用三维的细观数值模拟,研究了混凝土在单轴拉伸和压缩破坏过程中有效导热系数(ETC)的变化规律,并分别给出拉伸应变、压缩应变与ETC的定量关系。研究发现:(1)拉伸过程中,混凝土试件的ETC在塑性阶段显著下降(23%),但在软化阶段变化很小;(2)压缩过程中,混凝土试件的ETC在塑性强化阶段前期显著下降(30%),在塑性强化阶段后期趋于稳定,而在下降阶段又开始缓慢地减小;(3)骨料与砂浆间界面开裂所形成的界面热阻是导致混凝土ETC在塑性阶段急剧下降的主要原因;(4)开裂强化了混凝土导热性能的各向异性。随后,对单轴压缩破坏混凝土垂直于裂纹方向ETC(C-ETCV)进行了试验测量。数据表明:在单轴压缩过程塑性强化阶段前期,C-ETCV急剧下降20%~25%;在塑性强化阶段后期逐渐趋于稳定。随后利用模拟结果拟合确定了王家俊模型中的界面热阻因子,比较了王家俊模型与试验结果,两者比较吻合,证明了数值方法和王家俊模型的正确性。
[Abstract]:The variation of effective thermal conductivity (ETC) of concrete during uniaxial tensile and compression failure is studied by using three-dimensional meso-numerical simulation. The quantitative relationships between tensile strain, compressive strain and ETC are given respectively.It is found that the ETC of concrete specimens decreases significantly during the plastic stage, but the change is very small during the softening stage.The ETC of concrete specimens decreased significantly in the early stage of plastic strengthening, and tended to be stable at the later stage of plastic strengthening.The thermal resistance of the interface formed by the interfacial cracking between aggregate and mortar is the main reason for the sharp decline of ETC in the plastic stage. The cracking strengthens the anisotropy of the thermal conductivity of concrete.Then, the test measurement of the concrete under uniaxial compression is carried out, which is perpendicular to the crack direction.The data show that the C-ETCV decreases sharply in the early stage of plastic strengthening during uniaxial compression, and tends to be stable at the later stage of plastic strengthening.Then the interfacial thermal resistance factor of Wang Jia-jun model is determined by fitting the simulation results, and the results of Wang Jia-jun model are compared with the experimental results. It is proved that the numerical method and the Wang Jia-jun model are correct.
【作者单位】：河海大学水利水电学院;河海大学力学与材料学院;
【基金】：国家自然科学基金项目(11132003) 河海大学中央高校基本科研业务费项目(2013/B15020334)
【分类号】：TU528

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