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国内外的大量研究结果表明,混凝土的断裂机理与金属材料的断裂机理有着明显的不同。为了描述混凝土断裂的随机性和实验表明的断裂韧度K_(IC)所存在的尺寸效应现象,本文首先对所收集的十三批(235根,尺寸为100×100×515mm)混凝土三点弯曲试件的断裂韧度K_(IC)的实验观测值进行了分布假设检验,结果表明,混凝土断裂韧度K_(IC)实验值服从Weibull分布。在此基础上,作者给出了描述混凝土断裂韧度K_(IC)尺寸效应规律的计算公式。计算结果与国内外所收集到的实验结果符合得较好。最后,作者应用上述研究结果对大尺寸混凝土试件断裂韧度K_(IC)统计分布进行了推断,从而计算了某混凝土坝裂缝发生脆性断裂的相对失效概率。
A large number of research results at home and abroad show that the fracture mechanism of concrete is obviously different from the fracture mechanism of metal materials. In order to describe the randomness of the concrete fracture and the size effect phenomenon of the experimentally demonstrated fracture toughness K_(IC), this paper first of all points to the 13 batches (235 roots, size 100×100×515mm) concrete three-point bending. The experimental observations of the fracture toughness K_(IC) of the specimen were tested by the distribution hypothesis. The results showed that the experimental value of the fracture toughness K_(IC) of the specimen follows the Weibull distribution. On this basis, the author gives the formula for describing the law of size effect of fracture toughness K_(IC) of concrete. The calculated results are in good agreement with the experimental results collected at home and abroad. Finally, the author applied the above research results to infer the statistical distribution of fracture toughness K_ (IC) of large-size concrete specimens, and calculated the relative failure probability of brittle fracture of a concrete dam crack.