Superposition calculation of double-K fracture parameters of concrete using wedge splitting geometry and boundary effect
Superposition calculation of double-K fracture parameters of concrete using wedge splitting geometry and boundary effect
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发表时间：
2006
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通讯作者：
Xu Shi-lang
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作者：
Xu Shi-lang
对最大尺寸为1 200 mm×1 200 mm×200 mm的混凝土试件进行楔形劈裂断裂试验，根据试验得到的荷载-裂缝口张开位移曲线，基于线性渐近假设，利用应力强度因子叠加原理计算双K断裂参数，其中竖向力和自重对计算双K断裂参数的影响 当楔力、自重和支撑力的垂直分量不共线时，考虑断裂参数。结果表明，试件后边界对断裂过程区发展的限制是混凝土材料断裂韧性产生可观察到的尺寸效应的原因。对于深度小于600 mm的小试件，试件深度越小，断裂过程区的限制越强。 后边界越大，断裂韧性越小。此外，还得出结论，考虑边界限制的影响后，可以获得与尺寸无关的一致断裂韧性。
Wedge splitting fracture tests are performed on concrete specimens with the maximum dimension of 1 200 mm×1 200 mm×200 mm.With the load-crack mouth opening displacement curve obtained from tests,based on linear asymptotic assumption,the double-K fracture parameters are calculated by using superposition principle of the stress intensity factor,in which the effect of vertical force and deadweight on the calculated double-K fracture parameters is taken into account when vertical component of wedge force,deadweight and support force are non-colinear with each other.The results show that the confinement of back boundary of specimen to the development of fracture process zone is responsible for the observable size effect on fracture toughness of concrete material.For small specimens with the depth of less than 600 mm,the smaller the depths of specimen are,the stronger the confinement of back boundary is and the smaller the fracture toughness is.Moreover,it is also concluded that the size-independent consistent fracture toughness can be obtained after the consideration of effect of boundary restriction.