【作者】 田莉；

【导师】 沙爱民；

【作者基本信息】 长安大学 ， 交通运输工程， 2008， 博士

【摘要】 一直以来,由于分析工具的限制,有关沥青混合料的研究均局限于基于现象学的经验方法,即通过大量的假设及实验,从宏观角度分析和研究沥青混合料的各种性能。这种方法不仅耗时耗资,且结果的变异性较大,再现性差,使沥青混合料路用性能与材料设计体系之间存在较大差距。本文将沥青混合料作为由碎石料和沥青玛蹄脂(矿粉+沥青+空隙)组成的两相体系,从沥青玛蹄脂的力学特性研究出发,以基于虚拟试验的沥青混合料微观力学分析为目标,采用离散单元方法,根据各相的几何及物理信息,运用随机生成多面体(三维)或多边形(二维)技术重构其微观结构,建立微观力学模型,进行沥青玛蹄脂、级配矿料及沥青混合料的力学试验研究,以获得模型参数及验证微观结构模型的可靠性,通过数值模拟预测沥青混合料的劲度模量和各参数对其力学性质的影响。本文方法克服了传统数字重构的局限性,实现了采用不规则多边形和多面体单元模拟级配矿料,进而模拟沥青混合料微观结构组成;利用自定义粘弹性接触模型模拟沥青玛蹄脂及沥青混合料中的粘弹性接触作用,从微观尺度分析了沥青玛蹄脂粘弹性力学特性,实现了常规试验与一般力学方法难以达到的目标;通过对级配矿料室内静三轴试验,校准了虚拟试验结果,对级配矿料的回弹模量力学特性进行了评价;通过室内动态模量试验,校准了离散元模型参数,提出了基于虚拟试验的沥青混合料动态模量预测方法,并与试验结果及其他预估模型结果比较分析,结果表明采用离散元微观力学方法能够达到更高的预测精度。本研究创新性地从沥青混合料的微观结构出发,应用离散元方法,对沥青混合料进行了深入研究,从微观尺度深入分析了沥青混合料在外力作用下的内部力学响应,为沥青混合料设计方法及分析沥青路面破坏机理开辟了一条崭新的途径。更多还原

【Abstract】 Research on asphalt mixture has limited by analysis tools and only empirical methods have been commonly used for a long time. These empirical methods were based on phenomenology, where the macroscale performances of asphalt mixtures were analyzed through laboratory or field tests and making a lot of hypothesises. Obviously, these methods are expensive and time-consuming, and their results are variant and unrepeatable. A direct result from these methods is the seperate beween the design system and road performances of asphalt mixtures. The overall macro- mechanical behaviors of the asphalt mixture are determined by the micromechanics within the cemented particulate system. Based on the heterogeneous multiphase nature of aspahlt material, it appears that a micromechanical model would be best suited to properly simulate such a material. Therefore, this dissertation research presents a micromechanical methodology to predict asphalt mixture stiffness and analyze the effects of its macro-scale properties on the overall mechanical performances of the mixture with discrete element method. Asphalt mastic (fine aggregates, fines, asphalt binder, and air voids) and aggregates are considered as the two basic constituents of asphalt mixture. Random polygon (2D) and polyhedron (3D) algorithms were developed to build the microstructure of asphalt mixture, where the randomly created polygon or polyhedron particles represent aggregates, and the inter-place of aggregate particles is filled with the uniformed balls bonded with viscoelastic contact model to represent asphalt mastics. Laboratory tests were completed including DSR (Dynamic Shear Rheology) tests of asphalt mastic and Uniaxial compressive dynamic modulus tests of asphalt mixtures to serve two purposes: (1) privide input parameters for discrete element simulation; and (2) calibrate simulation results with tests of asphalt mixtures.The contributions of his dissertation work include: (1) an algorithm was developed for randomly creating the irregular polygon or polyhedron particles, with which gradation, shape and distribution of aggregates can be considered. (2) the micromechanical model of asphalt mixture were developed, where the user-written Burger’s model and contact stiffness model are employed to represent viscoelastic behaviors of asphalt mastic and the elastic properties of aggregates respectively, and the flip and bonding models are used to consider the strength properties at contact points. (3) Static tri-axial tests of graded stones were simulated and calibrated. The micromechanical properties of graded stones were evaluated by calculating the standard parameter: resilient moduli (MR). (4) Review of the research on dynamic modulus of asphalt mixtures was conducted. The research history, current efforts and commonly used methods were summarized in this dissertation paper. (5) Simulation of asphalt mixtures was conducted, and the dynamic modulus and phase angles were predicted. The process of the dynamic modulus virtual tests can be monitored with the software developed in this research.The performances of asphalt mixtures were investigated with discrete element method by analysis of microstructure in this dissertation work. This research effort cuts a new way for mixture design and damage mechanism analysis of asphalt pavement: not only avoids a lot of laboratory tests, but also gives a more detailed analysis on the micro-scale behaviors under the outer loading conditions.更多还原