基于DIC的聚丙烯纤维增强混凝土断裂过程分析

Fracture process analysis of polypropylene fiber reinforced concrete based on DIC

为探究聚丙烯纤维对混凝土断裂过程的影响,以纤维掺量和长径比为控制变量,共制备9组聚丙烯纤维增强混凝土(PPFRC)预制裂缝梁进行三点弯曲试验,并采用数字图像相关技术(DIC)对裂缝扩展过程进行分析.结果表明:聚丙烯纤维延长了混凝土弹性阶段,有效提高起裂荷载、峰值荷载和断裂耗能;降低荷载下降速率,使得混凝土具有较强裂后承载能力;聚丙烯纤维减小了混凝土开裂软化尺寸,效果与粗纤维掺量呈正相关,与细纤维掺量呈负相关,与长径比呈正相关;聚丙烯纤维大幅提高了断裂过程区(FPZ)极值长度,降低了裂缝扩展面积.

In order to investigate the influence of polypropylene fibers on the fracture process of concrete,nine groups of polypropylene fiber reinforced concrete(PPFRC)notched beams were prepared and tested under three-point bending with the content and length/diameter ratio of fibers as control variables,and the crack propagation process was analyzed by digital image correlation(DIC)technology.The results show that polypropylene fiber prolongs the elastic stage of concrete and effectively increases the initial crack load,peak load and fracture energy consumption.Moreover,polypropylene fiber reduces the rate of load decline,which makes concrete have a strong post-crack bearing capacity,and reduces the cracking and softening size of concrete,whose effect is positively related to the amount of macro fiber,negatively related to the amount of micro fiber,and positively related to the length/diameter ratio.Polypropylene fiber greatly increases the extreme length of the fracture process zone(FPZ)and reduces the crack extension area.