基于虚拟裂缝模型的混凝土双K断裂参数

Fracture Parameter of Concrete Based on the Ficititious Crack Model

本文将虚拟裂缝模型与线弹性断裂力学相结合，利用楔入劈拉试件在实验中测得的最大荷载Ｐｍａｘ及对应的裂缝口张开位移ＣＭＯＤｃ，求得了混凝土裂缝亚临界扩展量Δａｃ的解析解，据此计算了最大尺寸为７００×７００×２００ｍｍ的楔入劈拉混凝土试件的起裂断裂韧度ＫｉｎｉＩｃ、失稳断裂韧度ＫｕｎＩｃ及临界裂缝尖端张开位移ＣＴＯＤｃ，并与试验结果进行了比较．研究结果表明，当试件高度ｈ＞４００ｍｍ时，ＫｉｎｉＩｃ、ＫｕｎＩｃ、ＣＴＯＤｃ是一个与试件高度无关的断裂参数．

The pre critical crack propagation length Δa c of concrete is analytically evaluated by using the maximum load and critical crack mouth opening displacement measured in experiments by means of wedge splitting specimens.According to the analytical solution of Δa c ,the initiation fracture toughness K ini Ic ,unstable fracture toughness K un Ic and the critical crack tip opening displacement CTODc of the wedge splitting concrete specimens are analytically determined and compared with the test data.The results show that the K ini Ic ,K un Ic and CTODc are size independent when the specimen height is larger than 400mm,and the double K fracture criterion can well describe the cracking initiation and unstable fracture of concreite structure.