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针对基于虚拟裂缝扩展粘聚力的解析方法确定双K断裂参数时 ,起裂韧度 KiniIc和选定的混凝土软化本构曲线形状有关的问题 ,指出对于双线性软化本构曲线而言 ,其拐点坐标 (ws,σs)的取值大小对 KiniIc有一定影响。当取 ws等于临界裂缝尖端张开位移 ,并引入一个反映混凝土变形性能的参量λ时 ,λ的大小将直接影响 KiniIc的确定。通过将三点弯曲梁断裂试验取得的 KiniIc实测结果与选择不同混凝土软化本构曲线形状得到的解析解进行对比 ,得到了使两者吻合的参量 λ和软化本构曲线形状 ,为确定双 K断裂参数中的起裂韧度 KiniIc提供了适合的双线性软化本构曲线。
In order to solve the problem of double-K fracture parameters based on analytic method of virtual crack expansion cohesion, the relationship between KiniIc of fracture initiation and selected concrete softening constitutive curve shape is pointed out. For bilinear softening constitutive curve, The value of inflection point coordinates (ws, σs) has an impact on KiniIc. When taking ws equal to the critical crack tip opening displacement and introducing a parameter λ which reflects the deformation performance of concrete, the size of λ will directly affect the determination of KiniIc. By comparing the results of KiniIc obtained from the three-point bending test with those obtained from the softening constitutive curves of different concrete structures, the parameter λ and softening constitutive curve that agree well with each other are obtained. In order to determine the double K-fracture KiniIc in the parameters provides a suitable bilinear softening constitutive curve.