纤维掺量对PVA纤维混凝土力学参数的影响及压缩韧性指标的计算方法  

Influence of Fiber Content on Mechanical Parameters of PVA Fiber Concrete and Method for Calculating Compression Toughness Index

作　　者：沈才华[1,2] 钱晋 陈晓峰 谢飞 陈伟 郭佳旺 SHEN Caihua;QIAN Jin;CHEN Xiaofeng;XIE Fei;CHEN Wei;GUO Jiawang(College of Civil and Transportation Engineering,Hohai University,Nanjing 210098,China;Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering,Hohai University,Nanjing 210098,China;Zhejiang Provincial Institute of Communications Planning,Design and Research Co.,Ltd.,Hangzhou 310012,China)

机构地区：[1]河海大学土木与交通学院,南京210098 [2]河海大学,岩土力学与堤坝工程教育部重点实验室,南京210098 [3]浙江省交通规划设计研究院有限公司,杭州310012

出　　处：《硅酸盐通报》2020年第10期3152-3160,共9页Bulletin of the Chinese Ceramic Society

基　　金：国家自然科学基金重点项目(41830110);浙江省交通厅科技项目(2015J09,2016008)。

摘　　要：通过聚乙烯醇(PVA)纤维混凝土的力学试验,研究纤维掺量对于混凝土破坏形态、峰值应力、峰值应变、抗折强度以及折压比的影响,依据单轴抗压应力-应变曲线,提出一种适用于普通C40纤维混凝土的压缩韧性指标计算方法,并采用拟合法,建立了损伤变量服从对数正态分布的损伤本构方程。分析表明:由于纤维的桥接作用,纤维混凝土呈现“裂而不碎”的特征,与素混凝土存在较大差异;随着PVA纤维掺量的增加,混凝土的峰值强度、抗折强度和折压比呈现先增加后降低的趋势,峰值应变则持续增长,压缩韧性指数随着PVA纤维掺量的增加提高明显,综合考虑力学性能影响,建议的工程最佳纤维掺量为0.2%(体积分数)。根据试验曲线拟合对比,对数正态分布损伤本构方程优于Weibull分布的损伤本构方程,误差更小,充分反映了PVA纤维掺量对峰后力学特性的影响规律,而且能反映纤维掺入量引起的损伤性质突变现象,对工程优化设计具有重要参考价值。Through the mechanical test of polyvinyl alcohol(PVA)fiber reinforced concrete,the influence of fiber content on concrete failure pattern,peak stress,peak strain,flexural strength and the ratio of flexural-compressive strength were studied.Based on the uniaxial compressive stress-strain curve,a method for calculating the compression toughness index of C40 fiber concrete was presented.The damage constitutive equation with the damage variables obeying logarithmic normal distribution was established by the fitting method.The analysis shows that the fiber concrete presents the characteristic of"crack but not break"due to the joint action of the fiber,which is quite different from the plain concrete.With the increase of PVA fiber content,the peak strength,flexural strength and ratio of flexural-compressive strength of concrete show a trend of increasing first and then decreasing.While the peak strain continues to increase,the compression toughness index increases significantly with the increase of PVA fiber content.Considering the influence of mechanical properties,the recommended optimal engineering fiber content is 0.2%(volume fraction).According to the comparison of test curve and fitting curve,the logarithmic normal distribution damage constitutive equation is better than the Weibull distribution damage constitutive equation,and the error is smaller.So the logarithmic normal distribution damage constitutive equation fully reflects the influence of PVA fiber content on the post-peak mechanical properties.Moreover,it reflects the damage property mutation caused by fiber content,which has important reference value for engineering optimization design.

关 键 词：PVA纤维 峰值应变 对数正态分布 压缩韧性指数 损伤本构 

分 类 号：TU528[建筑科学—建筑技术科学]