为研究不同骨料粒径混凝土 Ⅰ型断裂裂缝扩展特性，开展了骨料粒径为10、20、30、40 mm的混凝土三点弯曲梁断裂试验;结合数字图像相关技术(digital image correlation，DIC)测得试件表面计算区域全场位移变化数据;对不同骨料粒径混凝土断裂能、断裂韧度、断裂过程区(fracture process zones，FPZ)变化和发展进行研究，探讨了 FPZ扩展过程与峰后荷载之间的关系。结果表明:随着骨料粒径增大，试件峰值荷载和断裂参数均呈现先增大后减小的趋势，M20试件FPZ长度的变化与峰后荷载的变化有很强的关联性，其骨料对微裂缝扩展的约束效果最好;此外，通过分析不同骨料粒径混凝土试件FPZ的发展规律，可知，骨料粒径为20 mm的混凝土试件，其峰后局部变形能力得到了改善，断裂能及断裂韧度得到了提高，在断裂过程中具有比其他骨料粒径混凝土更高的承载力和更小的FPZ，因此，合适的骨料粒径为20 mm。
Influence of aggregate size on the propagation of concrete type Ⅰ fracture cracks
In order to study the propagation characteristics of type Ⅰ fractures of concrete with different aggregate sizes,concrete three-point bending beam fracture tests with the maximum aggregate size of 10,20,30,40 mm were carried out,and the data of full-field strain and displacement changes in the calculated area on the specimen surface were measured by using digital image correlation techniques to investigate the changes and development of fracture energy,fracture toughness and fracture process zone of concrete with different aggregate sizes.The relationship between the FPZ extension process and the post-peak loading was investigated.The results show that with the increase of the aggregate size,the compressive strength,peak load and fracture parameters of the specimens show a trend of increasing first and then decreasing,and the change of FPZ length of M20 specimens has a strong correlation with post-peak load,and the aggregate has the best restraint effect on microcracks,In addition,by analyzing the development law of FPZ of concrete specimens with different aggregate sizes,it can be learned that specimens with the aggregate size of 20 mm have an improved local deformation capacity after peaking,enhanced fracture energy and fracture toughness,higher bearing capacity and smaller FPZ in the fracture process than other aggregate sizes concrete;therefore,the suitable aggregate size is 20 mm.
fractureaggregate sizedigital image correlationfracture process zone
万方数据
维普
