基于开裂应变能平衡原理的纤维水泥稳定破碎卵石增韧研究  

Toughening of Fiber Reinforced Cement Treated Crushed Pebble Based on Cracking Strain Energy Equilibrium Principle

作　　者：张裕卿[1] 顾章义 李辉[1] 罗雪[2] ZHANG Yu-qing;GU Zhang-yi;LI Hui;LUO Xue(School of Transportation,Southeast University,Nanjing 211189,Jiangsu,China;College of Civil Engineering and Architecture,Zhejiang University,Hangzhou 310058,Zhejiang,China)

机构地区：[1]东南大学交通学院,江苏南京211189 [2]浙江大学建筑工程学院,浙江杭州310058

出　　处：《中国公路学报》2023年第12期197-208,共12页China Journal of Highway and Transport

基　　金：国家重点研发计划项目(2019YFE0117600);国家自然科学基金项目(52108423);浙江省自然科学基金项目(LZ21E080002)。

摘　　要：为了降低水泥稳定碎石基层对矿石资源过多的消耗,并探究纤维对水泥稳定碎石抗疲劳开裂的增韧作用,采用破碎卵石替代石灰岩集料,基于开裂应变能平衡原理建立疲劳裂纹长度预测模型,分析纤维增韧水泥稳定破碎卵石疲劳开裂性能。选取不同长度(10、15、20 mm)和掺量(0.9、2.0、3.0 kg·m^(-3))的聚丙烯纤维,设计了纤维增韧水泥稳定破碎卵石间接拉伸疲劳试验,采集应变、模量以及裂纹长度等信息。利用所提出的模型获取疲劳开裂扩展规律,并与传统基于模量衰减的疲劳开裂模型预测结果及试验实测裂纹长度进行对比分析。结果表明:基于应变能疲劳损伤模型预测的裂纹长度与实测裂纹长度更为接近,说明所提出的模型能更好地表征纤维增韧水泥稳定破碎卵石的疲劳开裂特性。损伤密度在稳定发展阶段增长速率随纤维长度的增加呈下降趋势,随纤维掺量的提高先减小后增加,表明掺量对水泥稳定破碎卵石抗疲劳开裂性能的提升更加明显,但掺量过高反而会降低纤维水泥稳定破碎卵石的抗裂性能,在长度20 mm、掺量2.0 kg·m^(-3)时疲劳寿命提升最佳(3倍左右),建议纤维长度取15~20 mm,掺量范围为0.9~2.0 kg·m^(-3)。利用疲劳损伤密度区分纤维增韧效果更加清晰,评价损伤程度更为精准,研究结果可为纤维增韧材料设计提供新的评价指标。To reduce the excessive consumption of mineral resources in the construction of cement-treated bases and explore the toughening effect of fibers on the fatigue cracking resistance of cement-treated aggregates,crushed pebbles are used to replace limestone aggregates,and a model for predicting the fatigue crack length is proposed based on the cracking strain energy equilibrium principle.The fatigue cracking performance of fiber-reinforced cement-treated crushed pebbles(F-CTCPs)was analyzed.Polypropylene(PP)fibers with different lengths(10 mm,15 mm and 20 mm)and contents(0.9,2.0 and 3.0 kg·m^(-3))were selected.Indirect tensile fatigue tests(IDT)of the F-CTCP were designed to record the strain,modulus,and crack length.Fatigue crack propagation features were obtained using the proposed model,and the prediction results were compared with those of the traditional fatigue model based on the modulus degradation and measured crack length of the tests.The results show that the predicted crack lengths based on the proposed model match the measured results well,indicating that the proposed model is more suitable for predicting fatigue cracking in F-CTCP.The growth rate of the damage density at the stable development stage gradually decreases with the increase in fiber length and decreases,followed by an increase,as the fiber content increases,which indicates that the fiber content has a more significant effect on improving the fatigue cracking resistance of F-CTCP.However,excessive fiber content reduced the crack resistance of F-CTCP.The fatigue life of F-CTCP increased by three times with optimum proportions(fiber length of 20 mm and fiber content of 2.0 kg·m^(-3)).The recommended fiber length and content were determined as 15-20 mm and 0.9-2.0 kg·m^(-3).The fatigue damage density was used to clearly distinguish the toughening effect of the fibers and accurately evaluate the degree of damage,which can be regarded as a new evaluation indicator for the design of fiber-reinforced materials.

关 键 词：路面工程 纤维水泥稳定破碎卵石 间接拉伸疲劳试验 疲劳开裂 损伤密度 

分 类 号：U414[交通运输工程—道路与铁道工程]