裂纹尺寸对混凝土抗压强度的影响规律和动态断裂韧度计算方法研究

Influence Law of the Crack Size on Compressive Strength and the Calculation Method for Dynamic Fracture Toughness of Concrete

目前,学者普遍认为裂纹尺寸对混凝土抗压强度的影响不大,并采用较为复杂的方法计算混凝土动态断裂韧度。为全面分析混凝土内部缺陷对混凝土力学性能的影响,并简化动态断裂韧度的计算方法。文中利用线弹性断裂力学理论,探讨了裂纹尺寸对混凝土抗压强度的影响规律,研究表明,当分支裂纹间距一定时,混凝土抗压强度随裂纹尺寸的增大而降低。基于上述研究,给出了不同含水率下混凝土动态断裂韧度的近似计算方法。模型计算结果与宏观试验现象较为一致,表明文中计算模型可以较好地反映混凝土的动态断裂特性。

Currently ,many researchers think that the crack size has no effect on compressive strength ,and use a complex method to calculate the dynamic fracture toughness .In order to analyze the influence of concrete internal defect on its mechanical behavior and simplify the method of calculating concrete ,dynamic fracture toughness ,the linear elastic frac-ture mechanics theory was used to discuss the influence of crack size on the compressive strength of concrete .This re-search showed that concrete compressive strength decreased with the increasing of the crack size when the intervals be-tween the branching cracks were at a certain value .Based on these findings ,an approximate calculation method for the dynamic fracture toughness of concrete under different water content was proposed .The calculated results agreed well with available experiment data ,This indicates that the proposed method can ,to some extent ,predict the dynamic fracture property of concrete .