沥青混合料黏弹性表征及细观力学预测

发布时间：2018-08-21 12:21

【摘要】：沥青混合料是一种典型的颗粒填充复合材料。在大多数车轮荷载作用下,它仅产生非常小的应变,工程上可将其假设为线性黏弹性材料。基于此假设,美国2002版力学-经验路面设计指南(MEPDG)采用以Sigmoida丨函数表示的单轴沥青混合料动态模量(|E*|)主曲线作为沥青结构层的基本材料表征参数之一。动态模量的使用代表了沥青路面设计从弹性方法到黏弹性方法的过渡。但从本质上看,MEPDG仍然是基于层状体系理论的弹性设计方法,这是因为代表沥青结构层刚度的动态模量仅能表征沥青混合料的频率和温度依赖性,而不能考虑其现实存在的与加载历史相关的力学行为。为了实现完全意义上的黏弹性沥青路面设计,需要进行系统化的沥青混合料黏弹性表征方法及细观力学复数模量(E*)预测方法研究。为此,本文主要开展了以下工作:(1)针对两种沥青混合料进行了不同温度、不同加载频率下的单轴小应变复数模量试验。在全面分析动态模量、相位角、储能模量和损耗模量特征的基础上,建立了一种基于Havriliak-Negami(HN)复数模量模型的沥青混合料黏弹性表征方法。分别采用直接法和Wicket图法确定了 HN模型的参数,并将拟合结果与传统Sigmoidal方法的计算结果进行了详细的比较分析,证明了 HN方法的优势。(2)鉴于广义Maxwell模型和广义Voigt模型显著的计算效率,在构建HN复数模量主曲线的基础上,结合沥青混合料试验数据的自身特征,给出了确定黏弹性离散时间谱和连续时间谱的统一算法。结果表明,所建立的这两种方法均能精确地表征沥青混合料在时域和频域内的线性黏弹性行为。基于实用性的考虑,本文还讨论了如何将连续时间谱方便地转换为相应的离散时间谱,并给出了一种确定缩减主曲线的计算方法。(3)为了更好地表征沥青混合料在三轴应力状态下的黏弹性行为,本文深入研究了围压对沥青混合料复数模量和时间-温度移位因子的影响。基于推导出的HN连续松弛谱模型和一个存在的平衡模量模型,建立了一个围压依赖的三轴HN复数模量模型。结果表明,建立的三轴HN模型不仅能够在频域内精确、完整地表征三轴复数模量的所有分量,还可以方便地转换为时域内对应的三轴松弛模量主曲线,而无需进行相对复杂的变换运算。(4)另外,考虑到沥青结合料(或胶浆)流变学特性对于沥青混合料性能预测的重要性,建立了一个统一的能够快速合并来自弯曲梁流变仪(BBR)和动态剪切流变仪(DSR)两种不同温区、不同加载模式下的流变试验线性黏弹性信息的方法,从而实现了材料在完整路面服务温度和加载频率范围内的黏弹性表征。(5)最后,详细分析了集料嵌锁增强效应对于沥青混合料复数模量各分量主曲线的影响,阐述了传统的细观力学方法在预测沥青混合料复数模量方面的缺点。在此基础上,建立了一个在传统沥青混合料细观力学复数模量预测模型中考虑集料嵌锁效应的方法。结果表明,该方法有效地克服了传统模型在高温、低频加载条件下预测值偏低的缺点;此外,由于没有改变任何原有模型的几何结构,建立的方法保留了传统细观力学模型简单、实用的优势。
[Abstract]:Asphalt mixture is a typical particle-filled composite material. Under most wheel loads, it produces very small strain and can be assumed to be a linear viscoelastic material in engineering. Based on this assumption, the Mechanics-Empirical Pavement Design Guidelines (MEPDG) 2002 in the United States adopts the Sigmoida_ function for single-axis asphalt mixture. Dynamic modulus (| E * |) principal curve is one of the basic material characterization parameters of asphalt structure layer. The use of dynamic modulus represents the transition of asphalt pavement design from elastic method to viscoelastic method. Modulus can only characterize the frequency and temperature dependence of asphalt mixture, but can not consider its actual mechanical behavior related to loading history. In order to achieve a full sense of viscoelastic asphalt pavement design, it is necessary to systematically study the viscoelastic characterization method of asphalt mixture and the prediction method of meso-mechanical complex modulus (E*). In this paper, the following work has been carried out: (1) Uniaxial small strain complex modulus tests of two kinds of asphalt mixtures at different temperatures and loading frequencies have been carried out. Viscoelastic characterization of asphalt mixtures. The parameters of HN model were determined by direct method and Wicket diagram method respectively, and the fitting results were compared with those calculated by traditional Sigmoidal method in detail. The advantages of HN method were proved. (2) In view of the remarkable computational efficiency of generalized Maxwell model and generalized Voigt model, HN model was constructed. Based on the complex modulus principal curve and the characteristics of asphalt mixture test data, a unified algorithm for determining the viscoelastic discrete time spectrum and continuous time spectrum is presented. The results show that both methods can accurately characterize the linear viscoelastic behavior of asphalt mixture in time domain and frequency domain. Considering the effect of confining pressure on the complex modulus and time-temperature of asphalt mixture under triaxial stress, this paper also discusses how to convert the continuous time spectrum into the corresponding discrete time spectrum conveniently and gives a calculation method for determining the reduced principal curve. Based on the derived HN continuous relaxation spectrum model and an existing equilibrium modulus model, a tri-axial HN complex modulus model with confining pressure dependence is established. The results show that the tri-axial HN model can not only accurately characterize all components of tri-axial complex modulus in frequency domain, but also conveniently transform them. In addition, considering the importance of the rheological properties of asphalt binder (or mortar) for predicting the performance of asphalt mixtures, a unified rapid combination of bending beam rheometer (BBR) and dynamic shear rheometer (DSR) was established. The linear viscoelastic information method of rheological test in two different temperature zones and different loading modes is used to realize the viscoelastic characterization of materials in the range of service temperature and loading frequency. (5) Finally, the influence of aggregate interlocking reinforcement effect on the principal curves of complex modulus components of asphalt mixture is analyzed in detail, and the transmission is expounded. Based on the shortcomings of traditional meso-mechanics methods in predicting the complex modulus of asphalt mixture, a method considering aggregate interlocking effect in traditional meso-mechanics complex modulus prediction model of asphalt mixture is established. The results show that this method can effectively overcome the bias of traditional models under high temperature and low frequency loading conditions. In addition, the proposed method retains the advantages of simplicity and practicality of the traditional meso-mechanical model because it does not change the geometric structure of any original model.
【学位授予单位】：大连理工大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：U414

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