沥青混合料弯曲疲劳损伤强度的多尺度研究

Multi-scale study on bending fatigue damage strength of asphalt mixture

目的为了验证多尺度数值试验模拟方法在预测沥青混合料半圆弯曲试验疲劳损伤过程中弯拉强度参数变化规律的有效性问题。方法基于多尺度算法思想和半圆弯曲试验,通过对沥青混合料试件进行细观结构分析,得到内部集料颗粒的几何特征分布规律;在此基础上,对沥青混合料划分5个微观区域尺度,并构建相应尺度下半圆弯曲试件的有限元(FEM)数值模型,结合多尺度迭代运算来预测各级沥青混合料计算在0%Nf,20%Nf,50%Nf,65%Nf,80%Nf(Nf为疲劳寿命)不同半圆弯拉疲劳损伤程度下的弯拉强度。将室内半圆弯曲试验获得不同粒径的沥青混合料的弯拉强度参数作为宏观验证试验,与通过多尺度算法数值模拟试验所得的弯拉强度进行对比分析研究。结果结果表明:在沥青混合料的疲劳损伤过程中,前期材料的抗弯拉强度衰减速率较为缓慢,当在中后期时,抗弯拉强度进入了急剧衰减阶段,多尺度数值模拟试验与室内试验得到的衰减规律相吻合,且弯拉强度相对误差的绝对值控制在8%以内。结论多尺度数值模拟用于预测疲劳过程中沥青混合料的抗弯拉强度参数是有效的,该算法可以为类似的实际工程提供一定的参考意义。

Objectives To validate the effectiveness of multi-scale numerical simulation methods in predicting the variation of flexural strength parameters during the fatigue damage process of asphalt mixtures in semi-circular bending tests.Methods Based on the multi-scale algorithm concept and the semi-circular bending test,a micro-structure analysis of asphalt mixture specimens is conducted to determine the distribution pattern of geometric characteristics of internal aggregate particles;on this basis,the asphalt mixture was divided into five micro-region scales,and finite element models(FEM)of the semi-circular bending specimens at these scales were constructed.The multi-scale iterative calculation was then used to predict the flexural strength of asphalt mixtures at different semi-circular bending fatigue damage levels of 0%Nf,20%Nf,50%Nf,65%Nf,and 80%Nf(Nf denotes the fatigue life).The flexural strength parameters of asphalt mixtures with different particle sizes obtained from indoor semi-circular bending tests were used as macroscopic verification experiments,and a comparative analysis was conducted with the flexural strength obtained from multi-scale algorithm numerical simulation experiments.Results The results show that in the fatigue damage process of asphalt mixtures,the decay rate of flexural strength is relatively slow in the early stage,but enters a rapid decline phase in the middle and later stages,the decay patterns obtained from the multi-scale numerical simulation tests are consistent with those from indoor tests,with the absolute value of the relative error in flexural strength controlled within 8%.Conclusions The multi-scale numerical simulation is effective in predicting the flexural strength parameters of asphalt mixtures during the fatigue process.This algorithm can provide a reference for similar practical engineering projects.