基于界面剪切试验的沥青混合料集料切向弹性刚度研究

目前仍缺乏沥青混合料颗粒接触界面参数的有效获取方法，导致基于离散元法的沥青混合料数值分析手段无法精确模拟材料的力学行为。针对"切向弹性刚度"参数无法准确获取的难题，基于自主开发的"沥青混合料颗粒剪切分析系统"开展沥青混合料的颗粒界面剪切试验研究，确定合理试验参数。在此基础上开展3种级配和3种集料的沥青混合料单轴贯入试验，分析不同试验方法得到的剪切模量相关性。试验结果表明：在60℃试验温度和0.02 mm·s^-1剪切速度条件下可获得较为稳定的试验结果；剪切应力曲线表现出典型的"预剪切阶段"、"剪切稳定阶段"和"剪切破坏阶段"三段式增长；级配对界面剪切力有显著影响，AC-13、SMA-13和OGFC-13混合料的峰值均值分别约为100，50，90 N；同一级配下，采用玻璃珠和铁珠的混合料的界面剪切力分别为75，70 N；集料的材料类型是影响界面切向弹性刚度的关键因素，采用玻璃珠和铁珠的界面切向弹性刚度分别是0.17×10⁶ N·m^-1和0.22×10⁶ N·m^-1，而花岗岩集料则达到0.66×10⁶ N·m^-1以上；贯入试验结果表明级配和集料类型决定了混合料的剪切模量大小，采用花岗岩集料的AC-13型混合料的剪切模量达到18.88 MPa，OGFC-13混合料最小，仅为8.95 MPa；界面剪切试验得到的剪切模量与贯入试验结果的相关系数达0.89。所提出的集料接触界面剪切试验可分辨级配和集料类型对切向弹性刚度的影响。

Tangential Elastic Stiffness of Asphalt Mixture Aggregate Based on Interfacial Shear Test

Owing to a lack of effective methods for obtaining the contact interface parameters of asphalt mixture particles, the discrete element method fails to accurately simulate the mechanical behavior of the asphalt mixture. Based on the self-developed "asphalt mixture particle shear analysis system", this study aims to address the difficulties that arise in obtaining the parameters of "tangential elastic stiffness" accurately to carry out the particle interface shear test of the asphalt mixture. On this basis, uniaxial penetration tests of asphalt mixture with three gradations and three aggregates were carried out to analyze the correlation of the values of shear modulus obtained through these different testing methods. It was concluded that stable results could be obtained at 60℃ and 0.02 mm·s^-1 shear speed in the particle interface shear test. The shear stress curve obtained appeared to be a typical three-stage growth of "pre-shear stage", "shear stability stage" and "shear failure stage". The calculated mean values of the interfacial shear stress of AC-13, SMA-13 and OGFC-13 mixtures were 100 N, 50 N and 90 N, respectively. With the same gradation, the interfacial shear stress of the mixtures with glass balls and iron balls were found to be 75 N and 70 N, respectively. It was observed that the material types of aggregates are the key factors that influence the tangential elastic stiffness of the interface. The tangential elastic stiffness of glass ball mixture and iron ball mixture are 0.17×10⁶ N·m^-1 and 0.22×10⁶ N·m^-1, respectively, whereas that of the granite aggregate mixtures are above 0.66×10⁶ N·m^-1. The uniaxial penetration test results reveal that the gradation and aggregate type determines the shear modulus of the mixture. The shear modulus of AC-13 mixture with granite aggregate was 18.88 MPa, and that of OGFC-13 mixture was 8.95 MPa. The results of correlation analysis indicate that the correlation coefficient between the values of shear modulus obtained from the interfacial shear test and those acquired from the uniaxial penetration test is 0.89. In this study, the influence of the type of gradation and aggregate on tangential elastic stiffness is distinguished using the proposed particle interface shear test.