沥青混合料铺装层现场模量探究-以钢桥面铺装为例

A case study on evaluating in-situ layer modulus of asphalt pavement

沥青混合料铺装层在荷载作用下的力学响应为铺装体系的设计提供必要的指导,在铺装层力学响应的计算中,各层模量是一个重要的输入参数。过往研究中,研究人员主要通过室内试验的方法确定铺装层混合料的模量值,但忽略了混合料的室内试验模量值与其现场模量值可能存在的偏差。针对以上问题,文章以一处钢桥面铺装工程为例,介绍一种确定沥青混合料铺装层现场模量主曲线的方法:基于不同加载工况下铺装层底部的应变实测数据,利用有限元模型对铺装层混合料的现场模量进行反算,拟合得到相应的混合料现场模量主曲线并验证其适用性。此外,将反算得到的混合料现场模量与其室内试验模量进行对比,分析两类模量之间的差异性。研究结果表明,反算得到的铺装层混合料的现场模量在不同加载工况下变化显著,其数值随加载温度的增加而减小,随加载频率的增加而增大,表现出黏弹性的特征;利用不同加载工况下的混合料现场模量值可以较好地拟合得到混合料的现场模量主曲线,且该模量主曲线经过验证后证明有效。对比铺装层混合料的单轴压缩试验模量与现场模量发现:混合料的室内模量值与现场模量值在不同加载工况下并不完全匹配,其现场模量值普遍要小于对应的室内压缩模量值;两类模量对应的模量主曲线之间也有较大偏差,在加载频率较高或较低时,主曲线间的偏差更为显著;可采用幂函数对两类混合料的室内模量进行修正,使修正后的室内模量能够反映铺装层混合料的现场模量特征。

The mechanical response of the steel deck asphalt pavement under loading provides essential references for the design of the pavement.The layer modulus of the pavement is one of the essential parameters for the mechanical response calculation of the pavement.In the past,most researchers are used to determine the modulus of the pavement layer based on the laboratory test,in which the difference between the tested modulus tested laboratory and the in-situ values of the pavement layers are neglected.To solve this problem,a method for determining the in-situ modulus of asphalt pavement layer is studied via a case study on one steel deck pavement.Firstly,the layer modulus of pavement is backcalculated based on the field measured strain using the finite element method.Secondly,the master curve of layer modulus is obtained and then validated.The back-calculated modulus of the pavement layer is compared to the corresponding laboratory modulus.It is found that the in-situ layer modulus of field pavement varies significantly at different loading conditions.The magnitude of the in-situ modulus increases with the loading frequencies but decreases with the loading temperatures,which indicates that the filed mixtures behave viscoelastically.The comparison between the laboratory and in-situ moduli of the pavement asphalt mixture shows that these two types of modulus do not accurately match under different loading conditions,and the in-situ modulus is lower than the corresponding laboratory modulus for most cases.The deviation between master curves of laboratory and in-situ moduli is more obvious when the loading frequency is relatively high or low.It is also found that the power function can be used to modify the laboratory modulus of the pavement layer,and the revised value is able to reflect the modulus characteristics of the field pavement.