沥青混合料动态压-拉双模量及其在路面响应分析中的应用

Dynamic compressive-tensile moduli of asphalt mixture and its applications to pavement response prediction

沥青混合料层模量是沥青路面响应分析的必备参数,其数值的准确性关乎路面设计结果的可靠性。受骨料嵌挤作用的影响,沥青混合料在承受压应力与拉应力时模量表现不同。文章旨在从双模量的角度分析沥青混合料的动态压-拉模量特征,并将压-拉双模量用于路面响应预测,探讨双模量体系下的路面响应特点。首先,基于双模量框架下的有限元模型,建立间接拉伸试验中沥青混合料压-拉双模量、泊松比的计算方法;其次,以一种密级配混合料(AC-13)为例,分析沥青混合料在不同温度与加载频率下动态压-拉双模量、压-拉泊松比与单模量、单泊松之间的差异性;最后,将所确定的压-拉模量及泊松比用于路面沥青层力学响应预测,并与现有的单模量体系下的预测结果进行对比,分析单、双模量两类体系下路面力学响应的特点及其联系。研究表明,AC-13混合料压模量主曲线在全频域内均明显高于拉模量主曲线;单模量体系计算的模量主曲线更接近于压模量主曲线,且所计算的泊松比在中高温时失效;混合料压-拉模量比值分布在1.6~4.0,随温度升高而升高。与双模量体系下路面响应计算结果相比,现有单模量体系模型低估了柔性路面沥青层应变响应及柔性/半刚性路面沥青层的最大剪应力响应,而弯沉响应计算结果具有较好的一致性。研究成果可为考虑材料压、拉模量差异性的路面设计提供参考。

The modulus of the asphalt layer is one of the essential parameters used for pavement response prediction.The determination of asphalt layer modulus directly affects pavement design results.Due to the effect of aggregate interlock,asphalt mixture subjected to compressive and tensile stresses exhibits bi-modulus properties.This research aimed at investigating the dynamic compressive-tensile moduli of asphalt mixture and applying the asphalt mixture’s compressive-tensile moduli to analyzing the pavement response.Firstly,a calculation method based on the FE model with bi-modulus theory was established to calculate the compressive-tensile moduli of the asphalt mixture in indirect tensile test.Secondly,one dense graded asphalt mixture named AC-13 was used to demonstrate the differences of compressive-tensile bi-modulus and single moduli and the differences of compressive-tensile Poisson’s ratio and single Poisson’s ratio.Finally,the compressive-tensile moduli and Poisson’s ratios were applied for the pavement response prediction,and the corresponding prediction results were compared to those from the current single-modulus method so that the pavement response characteristics from the two types of modulus methods and their relationships can be analyzed.The research results disclose that in the whole frequency domain,the master curve of compressive modulus of mixture is evidently greaterthan that of tensile one;the modulus calculated from the single-modulus model is close to the compressive modulus compared to the tensile one,and the single-modulus model failed to predict the Poisson’s ratio of the mixture at intermediate and high temperatures;the compressive-to-tensile modulus ratio for asphalt mixture ranges from 1.6 to 4.0,and the ratio may increase with the temperature.Compared to the bi-modulus system,the single modulus system may underestimate the strain response of flexible pavement and the maximum shear stress response of flexible/semi-rigid pavement,but the deflection responses predicted from the two systems are generally consistent.This research may provide references for improving the pavement design in which the difference of compressive modulus and tensile modulus of asphalt mixture shall be taken into account.