力学损伤混凝土热传导行为细观研究

为研究力学损伤对温度传导行为的影响，考虑混凝土细观结构的非均质性，将其视为由骨料、砂浆和界面过渡区组成的三相复合材料，提出并建立了力学-热学单向耦合作用研究的细观数值方法与模型。方法的思想是:首先对非均质混凝土在荷载作用下开裂损伤力学行为模拟分析，获得其内部的损伤分布情况；然后，将力学分析结果作为初始输入条件，结合复合材料均匀化理论，获得损伤混凝土各细观单元的导热性能，从而实现了力学-热学单向耦合作用的数值模拟。以单轴压缩加载为例，通过与试验结果的对比，验证细观方法的合理性与有效性。基于该套细观数值模拟方法，对荷载作用后混凝土试件的宏观有效导热系数与温度场分布进行了细观计算分析，对比了不同复合材料力学模型的影响，探讨分析了压缩荷载水平的影响规律。

MESO-SCALE INVESTIGATION ON THERMAL CONDUCTION BEHAVIOR IN CONCRETE WITH MECHANICAL DAMAGE

To investigate the effect of mechanical damage on thermal conduction, a mesoscopic method was proposed in the present work considering the heterogeneity of meso-structure. In this study, concrete was considered as a three-phase composite material consisting of aggregate, mortar matrix and interfacial transition zones (ITZs) between them. The mechanical analysis was conducted first to study the damage distribution within the concrete. Subsequently, the outcomes of mechanical computation were used as the initial input data in the thermal conduction computation. The current thermal conductivity of damaged element was homogenized by a composite mechanical method based on damage and the initial thermal conductivity of sound material. It is in this way that the mechanical and thermal behavior were coupled. The present model was calibrated by comparing the numerical results with available experimental data. Based on the verified simulation method, effective thermal conductivity (ETC) and temperature field of concrete subjected to compressive loadings were calculated. In addition, the effects of different composite mechanical models were analyzed and the influence of compressive loading levels was explored.