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根据混凝土四点剪切加载和两端切口半边对称加载这2种Ⅱ型混凝土试件断裂试验的结果,计算分析了它们的断裂韧度KⅡC及其相互关系。采用有限元方法,基于数值模拟,利用ANSYS软件计算分析了2种Ⅱ型混凝土试件断裂试验加载阶段各荷载步的应力场和应变场,用位移外推法分别计算了四点剪切加载和两端切口半边对称加载Ⅱ型断裂数值模拟试验的断裂韧度,并与试验结果进行了比较。由于两端切口半边对称加载条件下试件受力均匀,容易保证整个试验过程中试件断裂过程区切应力占据主导地位,而四点剪切加载条件下则不可避免出现张拉和扭转等现象,从而导致试件断裂破坏过程中并不总是纯剪切的Ⅱ型断裂,这可能是这2种Ⅱ型混凝土试件断裂韧度KⅡC值有所不同的原因所在。
According to the results of the fracture tests of two types of concrete specimens with four-point shear load and half-symmetrical load at both ends of the concrete, their fracture toughness KⅡC and their correlation were calculated and analyzed. The finite element method was used to calculate the stress field and the strain field of each type Ⅱ type concrete specimen during the loading test. The displacement extrapolation method was used to calculate the four-point shear loading The fracture toughness of the Ⅱ-type fracture numerical simulation experiment was symmetrically loaded on both sides of the incision, and compared with the experimental results. Because of the uniform stress of specimen under half-symmetric loading, it is easy to ensure that the shear stress in the specimen rupture area occupies a dominant position during the whole test. However, under four-point shear loading, tension and torsion inevitably occur. Which leads to the Type II fracture which is not always pure shear during the fracture failure of the specimen, which may be the reason for the difference in the fracture toughness KⅡC between the two Type Ⅱ concrete specimens.