钢桥面沥青混合料铺装应变动态响应实测研究

Field measurements of dynamic strain responses of asphalt pavement on steel deck bridge

掌握钢桥面沥青混合料铺装层在车载作用下的真实力学特性对桥面铺装体系设计有重要意义,而现阶段现场桥面铺装层的力学实测数据仍偏少,尤其缺乏对铺装层不同温度下服役时力学特性的长期监测。为此,该研究对钢桥面双层SMA混合料铺装进行现场实桥加载试验,实测铺装层在低温、中温、高温3种服役温度下的应变响应数据。试验结果表明,钢桥梯形肋正上方铺装层混合料在中低温服役状态下主要承受压应变的作用,而在高温服役时则主要承受拉应变的作用;动载作用过程中铺装层底纵向应变会出现拉压应变交替作用的现象,而横向应变只体现为拉应变或压应变的形式;加载车行驶速度对混合料的应变极值均有明显的影响,加载车低速行驶时混合料层底横向及纵向变形最为显著。同时,研究利用加载试验中铺装层应变响应时程曲线,计算不同加载状态下混合料对应的加载频率数值,计算结果可为钢桥面铺装混合料室内试验中加载频率参数的确定提供参考。

The mechanical response of steel deck asphalt pavement under load provides essential reference for the improvement of pavement design methods.However,there is extremely limited research focusing on the field mechanical measurements of steel deck pavement.To be more specific,the mechanical properties of steel deck pavement under different loading temperatures are still unknown.A field test was conducted to investigate the dynamic strain responses of a kind of double-layer SMA pavement at different temperatures and loading speeds.Test results show that the mixture of the pavement is mainly subjected to compressive strain under medium and relatively low loading temperature.However,the mixture is mainly subjected to tensile strain at high loading temperature.The longitudinal strain at the bottom of the pavement alternates in compression-tension cycles while the transverse one is constantly compressive strain.The speed of loading truck has a significant influence on the strain values of the mixture.The deformation of the mixture at low loading speed is significantly larger than that at high speed.Moreover,the equivalent loading frequency of the mixture under different loading conditions is calculated based on the strain response pulse of the pavement.The research results can provide reference for determining the proper loading frequency values of some specific laboratory tests.