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该文以各组分体积不变为准则建立了考虑温度影响的混凝土三相微观断裂球体模型。将混凝土组成简化为骨料,水及水泥浆体,并以模型中各层模拟;认为高温下混凝土的断裂为模型中间层水汽蒸发逸出的结果。通过气体状态方程分析了模型内部气压随温度的变化,并研究了骨料和水泥浆体层的应力状态。分析了含圆盘形裂纹的混凝土的可释放弹性能和表面能,并根据Griffith断裂准则给出了混凝土断裂韧性随温度的变化规律。对该文模型进行数值模拟,并与相关试验结果对比,结果证明了该文模型能够有效地计算高温下和高温后混凝土的断裂韧性。同时分析发现:随着温度的升高,混凝土可释放弹性能增大而开裂时的裂纹初始长度将减小。
In this paper, a three-phase microscopic fracture sphere model of concrete considering temperature influence was established based on the constant volume of each component. The concrete composition is simplified as aggregate, water and cement paste, and simulated in every layer of the model. It is considered that the fracture of concrete at high temperature is the result of the evaporation of water vapor in the model middle layer. The change of pressure inside the model with temperature was analyzed by gas equation of state, and the stress state of aggregate and cement slurry was studied. The release elastic energy and surface energy of concrete with disc-shaped crack were analyzed. According to Griffith criterion, the fracture toughness of concrete with temperature was given. The numerical simulation of the model is carried out and compared with the related experimental results. The results show that the model can effectively calculate the fracture toughness of concrete after high temperature and high temperature. Simultaneously, it is found that as the temperature increases, the elastic properties of concrete can be increased and the initial crack length will decrease.