基于细观力学模型的混凝土温度裂缝研究

Study of concrete temperature cracking based on mesomechanics

建立了混凝土的细观力学模型,考虑骨料、砂浆和界面的3相组成,利用Weibull概率分布对各相材料的力学参数进行随机赋值,体现出材料的细观特征和不均质特性.基于混凝土弹脆性损伤模型,对混凝土开裂进行数值模拟,以单轴压缩和3点弯曲梁实验对该方法进行了验证,同时提出了通过宏观性质演算细观参数的方法,最后,模拟了寒潮工况下早龄期混凝土在不同保温条件下的开裂.结果表明:该方法能较好地模拟混凝土材料中微裂纹的萌发和扩展,能较好地反应混凝土材料在温度荷载下开裂的全过程.

Concrete is a kind of composite material with highly heterogeneity.Its cracking propagation process is closely related to the distribution of micro fissures in it.This paper simulates the aggregate,cement mortar and the interface between them,by establishing a three-phase mesomechanical model.The parameters are randomly valued on the Weibull distribution,in order to reflect the micro characters and heterogeneity of concrete.Based on the elastic brittle damage model,the complete process of concrete cracking propagation is analyzed by numerical simulation.This method is verified by simulating uniaxial tension and three-point bending beam test,and the inversion of micro parameters based on macro parameters is introduced.Finally,concrete structure cracking at early age during a cold spell is simulated under different surface insulation conditions.The results show that this method can simulate the cracking initiation and propagation effectively and reflect the whole process of concrete cracking under temperature load.