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类型 基础研究 预答辩日期 2018-02-28
开始(开题)日期 2015-11-04 论文结束日期 2017-12-14
地点 逸夫楼交通设计院会议室 论文选题来源 非立项    论文字数 8.9 (万字)
题目 基于细观结构的纤维沥青混凝土疲劳损伤机制研究
主题词 玄武岩纤维,沥青混凝土,细观结构,粘弹变形,疲劳损伤
摘要 随着我国高等级公路建设的快速发展以及路网的不断完善,作为实际公路的主要形式,沥青路面现阶段养护工作已十分繁重,其工程耐久性面临挑战,特别是疲劳耐久性研究已成为重要课题。而纤维作为提高路面材料疲劳耐久性的重要添加剂也已得到广泛应用,但其中的内在作用机制和理论研究有待进一步开展。本文通过多尺度细观结构建模、有限元模拟及室内试验验证相结合的手段,开展了纤维改善沥青混凝土粘弹力学特性及其抗疲劳损伤机制的研究。 首先,在沥青砂浆层面,提出了一个纤维三维随机分布算法,利用MATLAB编程实现了纤维数值模型的生成,并在ABAQUS有限元中建立了纤维与砂浆基体两相复合有限元模型,实施了纤维砂浆梁试件的弯拉流变模拟。通过分析纤维不同取向、含量、长径比及类型等因素的影响,结果表明纤维的添加能有效吸收砂浆基体应力,使纤维起到加筋效果而降低砂浆弯拉流变,纤维含量提高、长径比增大以及纤维沿砂浆试件水平方向分布增多都能有效提高加筋作用而进一步降低弯拉流变,且玄武岩纤维效果要好于软钢丝纤维,其中加0.3%含量的这两种纤维试件在3600s时的流变较控制试件降低近61.7%和44.0%。进一步通过敏感性分析,建立了纤维特征(纤维含量、长径比和模量)与砂浆Burgers粘弹参数的关系方程。 其次,在混合料层面,利用图像切片扫描及其处理技术获取了粗集料和砂浆两相复合二维细观结构,在ABAQUS中实现了细观试件蠕变模拟。结果表明,较均质试件内部应力场的均匀梯度变化,细观试件有明显应力集中现象,且相比普通细观试件,加纤维后砂浆组分模量提高,使混合料整体模量增大,进而抗蠕变能力增强,如0.3%含量玄武岩纤维和软钢丝纤维试样在1800s时变形降幅达36.1%和19.3%。进一步数值分析集料模量、纤维特征等因素的影响,表明纤维和粗集料模量对混合料粘弹参数影响可忽略,而纤维其他特征下的砂浆与混合料两尺度间的粘弹变形呈正相关,得到了砂浆与混合料对应粘弹参数间的定量关系,进而建立了纤维特征(纤维含量和长径比)与混合料粘弹参数的敏感性关系方程。 最后,对加0.3%含量纤维与不加纤维混合料试件实施应力控制疲劳试验,结果表明纤维的添加能明显提高试件疲劳寿命,如4kN荷载水平下玄武岩纤维和软钢丝纤维试件寿命提高近63.4%和25.0%。基于纤维特征与混合料性能的关系方程所得参数,推导了循环荷载下的变形演化方程,得到纤维试件变形值较控制试件更小,并与疲劳试验变形规律相同;耦合粘弹变形与损伤,建立了疲劳损伤演化模型,结果表明加纤维试件在同循环数下的损伤明显降低,如玄武岩纤维和软钢丝纤维试件在6000次循环数下损伤降幅达47.8%和26.2%,使疲劳损伤演化过程延长,进而疲劳寿命提高,也揭示了纤维通过降低混合料粘弹变形改善疲劳性能的内在机制。此外,通过对所推导的变形演化结果的分析,提出了一个表征纤维对疲劳寿命影响的特征斜率,得到了相应的修正疲劳方程; 进一步对不同纤维特征下的疲劳损伤研究表明,在保证纤维均匀分散前提下提高纤维含量和长径比有利于疲劳损伤的降低,如2MPa应力水平下加载10000循环数的0.3%、0.2%含量玄武岩纤维试件较0.1%含量纤维下损伤降幅近20.7%和13.7%,而长径比Ld为50、40、30较Ld为20的降幅约8.3%、4.3%和2.0%。 本文从纤维复合材料多尺度细观结构入手,研究了纤维加筋沥青砂浆进而降低混合料宏观粘弹变形的内在机理,也揭示了加纤维对沥青混凝土抗疲劳损伤的作用机制,对沥青混凝土中合理利用纤维具有重要指导意义。
英文题目 Research on the fatigue damage mechanism of fiber asphalt concrete and its mesostructure
英文主题词 basalt fiber,asphalt concrete,mesostructure,viscoelastic deformation,fatigue damage
英文摘要 The maintenance of asphalt pavements, which currently make up several highways in China, has become a complex task at this stage of construction and load network development. Durability, especially fatigue durability, has become a major engineering challenge. Fibers are currently used as an important additive to improve the fatigue durability of pavement materials. However, theoretical research on the inner mechanism, particularly between fiber and asphalt-like materials, need to be further investigated. In this study, improvements to the viscoelastic properties and anti-fatigue damage mechanism are explored. Then, the fiber effect on asphalt concrete is determined by means of mesostructure modeling based on the multi-scale method, finite element simulation, and laboratory test verification. The first part of the study focused on the scale of the asphalt mortar. A random 3D distribution algorithm of the fiber is proposed and a fiber numerical model is generated using MATLAB programming to be imported to the ABAQUS finite element software. Then, a finite element composite model of the fiber-reinforced asphalt mortar, which corresponds to the fiber and asphalt mortar matrix phase, is established for flexural–tensile rheological simulation. The numerical analysis of the fiber-reinforced asphalt mortar model considered different factors, such as orientation, content, aspect ratio, and fiber type. The fiber can effectively absorb the stress of the mortar matrix. Results indicate that the flexural–tensile rheological value of the asphalt mortar is reduced to the level of reinforcement effect. Moreover, the flexural–tensile rheological values are reduced with the increase in fiber content, aspect ratio, and fiber distribution along the horizontal direction of the mortar specimens. The result of the basalt fiber is less than that of the steel fiber. In particular, the rheological values of the mortar with 0.3% content of basalt fiber or steel fiber at 3600s are reduced by 61.7% or 44.0% compared with that of the control, respectively. Finally, the relationship equation between fiber factors (content, aspect ratio, and modulus) from sensitivity analysis and the parameters of the Burgers constitutive model for the asphalt mortar is established. The second part of the study focused on the mixture scale. A typical 2D mesostructure consisting of coarse aggregate and asphalt mortar is obtained using image slice scanning and digital image processing technology. Then, the creep of the mesostructure specimen is simulated in ABAQUS. Results of simulation showed that the stress field of the mesostructure specimen exhibited an apparent stress concentration in contrast to the stress field of the homogeneous specimen with gradient variations. Furthermore, in contrast to the microstructure specimen control, the modulus of adding fiber into the mortar in the microstructure specimens increased. Thus, the mixture modulus also increased and its resistance deformation capacity is enhanced when the creep deformations of the asphalt mixture with 0.3% content of basalt fiber or steel fiber at 1800s are reduced by 36.1% or 19.3%, respectively. A numerical analysis of the influencing factors (fiber and coarse aggregate modulus) is also conducted, and results show a non-significant effect of the fiber modulus and coarse aggregate modulus on the viscoelastic parameters. Thus, the modulus effects of fiber and coarse aggregate can be ignored, which further imply that the viscoelastic deformation between the mortar and mixture scale is positively related considering the influence of other fiber factors. On the basis of these results, the quantitative relationship between the mortar and mixture is obtained, and the relationship equation between the fiber factors (fiber content and aspect ratio) and viscoelastic parameters of the mixture is established. In the last part of the study, fatigue tests in stress control mode are initially conducted on the asphalt mixture specimens with 0.3% content of fiber and control. Results show that adding fiber can significantly improve the fatigue life of specimens. The fatigue life of mixture specimens with basalt fiber and steel fiber under 4kN loading increased by 63.4% and 25.0%, respectively. Then, the parameters of the relationship equation between the fiber factors and viscoelastic properties of the mixture are considered, and the evolution equation of the viscoelastic deformation under cyclic loading for the fatigue specimens is deduced. Results indicate that the deformation value of the fiber mixture is less than that of the control, which is similar to the deformation result of the fatigue test. Subsequently, viscoelastic deformation and damage are coupled, and the damage evolution model of the fatigue specimen is established. The damage of the fiber mixture specimen is reduced in contrast to the control given the same cyclic numbers. The values of the basalt fiber mixture and steel fiber mixture in 6,000 cycles are reduced by 47.8% and 26.2% in contrast to the control, respectively. Thus, the fatigue damage evolution is prolonged and fatigue life is increased. Findings also reveal the capability of the inner mechanism of the fiber to improve fatigue performance by reducing the viscoelastic deformation of asphalt mixture materials. Furthermore, the evolution of viscoelastic deformation is analyzed by theoretical derivation, and the slope characteristics of the evolution equation to describe the effect of fiber factors on fatigue life is proposed, i.e., the fatigue equation is modified in relation to fiber factors. Then, the effect of different fiber factors on fatigue damage is studied. Results show that increases in fiber content and aspect ratio are both conducive to the reduction of fatigue damage under uniformly dispersing fiber conditions. In particular, the damage value of 0.3% and 0.2% contents of basalt fiber mixture are reduced by 20.7% and 13.7% in 10,000 cycles with 2MPa stress level in contrast to 0.1% of fiber content, respectively. Furthermore, the 50, 40, and 30 fiber aspect ratios are reduced by 8.3%, 4.3%, and 2.0% in contrast to the 20 fiber aspect ratio, respectively. This study initially explores the mesostructure of the fiber-reinforced asphalt concrete composite. Then, the internal mechanism of the fiber-reinforced mortar is investigated by the multiscale method. The viscoelastic deformation of the asphalt concrete is reduced. This result reveals the advantageous mechanism of the fiber-reinforced asphalt concrete to counteract fatigue damage. This study therefore offers a significant guide for the rational usage of fibers in asphalt concrete.
学术讨论
主办单位时间地点报告人报告主题
东南大学 2014年 道桥实验室会议室 张小元 纤维沥青砂浆流变性能评价
东南大学 2015年 中山院 Tom Scarpas State of the Art of Pavement Engineering in Netherlands
东南大学 2015年 道桥实验室会议室 张小元 3D modeling of fiber distribution in matrix materials
东南大学 2015年 中山院 John Haddock Modifying Laboratory Mixture Design to Improve Field Compaction
东南大学 2016年 道桥实验室会议室 张小元 Simulation of Rheological Behaviors of Fiber Reinforced Asphalt Mortar
东南大学 2016年 道桥实验室会议室 张小元 Fatigue performance and fatigue laboratory test of Fiber asphalt concrete
东南大学 2017年 道桥实验室会议室 蔡宜長 Smart City Transportation Asset Management and Safety Analysis
东南大学 2017年 道桥实验室会议室 石鲜明 Sustainable Transportation Infrastructure: Innovative Materials and Practices
     
学术会议
会议名称时间地点本人报告本人报告题目
The 2nd International Symposium on Frontiers of Road and Airport Engineering 2015年 上海同济大学嘉定校区 Study on Properties of Fiber-reinforced Asphalt Mastic Based on the Multi-scale Method
95th Transportation Research Board Annual Meeting 2016年 美国华盛顿 Laboratory Investigation on Performances of Basalt Fiber Reinforced Asphalt Chip Seal
Transportation Research Congress (TRC) 2016年 北京国家会议中心 Mechanism and Behavior of Fiber-Reinforced Asphalt Mastic at High Temperature
World Transport Convention 2017 2017年 北京国家会议中心 三维随机分布纤维加筋沥青砂浆弯拉流变模拟
     
代表作
论文名称
3D numerical model to investigate the rheological properties of basalt fiber reinforced asphalt-lik
Experiment and simulation of creep performance of basalt fibre asphalt mortar under uniaxial compres
玄武岩纤维沥青碎石封层性能及合理材料用量
Study on the Properties of Fiber-Reinforced Asphalt Mastic Based on the Multi-Scale Method
 
答辩委员会组成信息
姓名职称导师类别工作单位是否主席备注
钱振东 正高 教授 博导 东南大学
赵永利 正高 博导 东南大学
杨群 正高 教授 博导 同济大学
王声乐 正高 教授 博导 东南大学
茅荃 正高 教授级高工 其他 江苏高速公路工程养护技术有限公司
      
答辩秘书信息
姓名职称工作单位备注
于斌 副高 副教授 东南大学