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本文采用尺寸为 40 0mm× 40 0mm× 2 0 0mm ,初始缝高比分别为 0 2、 0 4、 0 5、 0 6的楔入劈拉试件 ,应用线性渐近叠加原理 ,利用试验中测得的最大荷载Pmax及对应的裂缝口张开位移CMODc 计算了混凝土裂缝的亚临界扩展量Δac,在此基础上利用虚拟裂缝模型并结合线弹性断裂理论 ,采用不同的闭合力方程计算了混凝土起裂断裂韧度KiniIc、失稳断裂韧度KunIc及临界裂缝尖端张开位移CTODc.结果表明 ,采用不同闭合力方程所计算的混凝土KiniIc值有所差异 ,但当试件缝高比大于或等于 0 4时KiniIc及CTODc 均与试件初始缝高比无关 ,而KunIc值则与初始缝高比无关 ,这表明双K断裂参数及CTODc 可以作为描述混凝土裂缝起裂、稳定扩展及失稳破坏全过程的材料常数 .
In this paper, a wedge-splitting tensile test specimen with a size of 40 0 mm × 40 0 mm × 200 mm and an initial seam height ratio of 0 2, 0 4, 0 5, 0 6 respectively was used. By using the principle of linear asymptotic superposition, Obtained the maximum load Pmax and the corresponding open crack displacement CMODc calculated the sub-critical expansion of the concrete crack Δac, based on the use of virtual crack model and combined with linear elastic fracture theory, using different closure force equation calculated concrete The fracture toughness KiniIc, the instability fracture toughness KunIc and the critical crack tip open displacement CTODc.The results show that the calculated KiniIc values of concrete with different closing force equations are different, but when the specimen seam height-height ratio is greater than or equal to 0 4 KiniIc and CTODc all have nothing to do with the initial seam height ratio of the specimen, but KunIc value has nothing to do with the initial seam height ratio, which shows that the double K fracture parameters and CTODc can be used to describe the whole process of crack initiation, stability expansion and failure of concrete Material constant.