摘要
对不同初始缝高比的自密实混凝土(Self-compacting concrete,SCC)非标准三点弯曲梁开展不同加载速率下的断裂试验,获得其断裂的荷载-裂缝嘴张开口位移曲线及峰值荷载、断裂韧度、临界缝高比增量、弹性模量和柔度系数等断裂参数,结合Pearson相关性检验公式及加载速率效应模型,定量分析初始缝高比、加载速率与断裂参数间的相关性强弱及SCC断裂参数的加载速率效应。结果表明峰值荷载、断裂韧度及弹性模量均存在一定的加载速率效应,柔度系数仅与初始缝高比强相关,弹性模量和断裂韧度是材料的固有属性,不受初始缝高比影响。同时,基于声发射(Acoustic emission,AE)技术对SCC的损伤断裂过程、断裂边界效应及裂缝扩展模式进行分析,结果表明,AE参量能较好地反映混凝土断裂的三阶段特性及边界效应。裂缝的扩展首先以拉伸裂缝为主,剪切裂缝占比随着裂缝扩展过程逐渐增大。
Fracture tests were carried out on non-standard three-point bending self-compacting concrete(SCC)beams with different initial crack-depth ratios under different loading rates. The fracture parameters such as loadcrack mouth opening displacement curve, peak load, fracture toughness, critical crack-depth ratio increment, elastic modulus and flexibility coefficient were obtained. Based on Pearson correlation test formula and loading rate effect model, the correlation between initial crack-depth ratio, loading rate and fracture parameters and the loading rate effect of SCC fracture parameters were quantitatively analyzed. The results show that the peak load, fracture toughness and elastic modulus all have loading rate effect in a certain extent. The flexibility coefficient is only related to the initial crack-depth ratio. The elastic modulus and fracture toughness are inherent properties of the material and are not affected by the initial crack-depth ratio. Meanwhile, the damage and fracture process, fracture boundary effect and crack propagation pattern of the SCC were analyzed based on acoustic emission(AE) technology. The results show that the AE parameters can well reflect the three-stage characteristics and boundary effect of concrete fracture. The propagation of crack is mainly tensile crack at first, and the proportion of shear crack increases with the fracture propagation process.
作者
冯璐
陈徐东
张锦华
袁佳怡
程熙媛
FENG Lu;CHEN Xudong;ZHANG Jinhua;YUAN Jiayi;CHENG Xiyuan(College of Civil and Transportation Engineering,Hohai University,Nanjing 210098,China;Key Laboratory of C&PC Structures,Ministry of Education,Southeast University,Nanjing 210096,China;Engineering Research Center of Explosion Safety Protection,Ministry of Education,Southeast University,Nanjing 211189,China;School of Civil Engineering,Southeast University,Nanjing 211189,China)
出处
《复合材料学报》
EI
CAS
CSCD
北大核心
2021年第2期630-640,共11页
Acta Materiae Compositae Sinica
基金
国家自然科学基金(51979090)
江苏省自然科学优秀青年基金(BK20190075)
中国科协青年人才托举项目(2017QNRC001)
中央高校基本科研业务费专项资金(B200202076)。
关键词
自密实混凝土
非标准三点弯曲梁
断裂试验
加载速率效应
声发射技术
self-compacting concrete
non-standard three-point bending beams
fracture test
loading rate effect
acoustic emission technology
