大温差干旱地区复合式基层沥青路面应变响应现场试验

Field Test Strain Response of Composite Base Asphalt Pavement in Arid Area with Large Temperature Difference

针对大温差干旱地区路面结构病害多发现状,以内蒙古中西部地区为例,深入调研气候环境特征与路面病害特征,在新建高速公路复合式基层沥青路面结构中埋设光纤光栅传感器,通过现场加载试验探究路面结构不同方向、深度应变响应规律,并根据实测结果计算路面结构疲劳寿命,验证复合式基层结构实际应用效果。结果表明,内蒙古中西部地区日温差、年较差超过全国84%地区,年降雨量低于全国87.4%地区,路面病害以反射裂缝为主,裂缝间距仅10~20 m。车辆荷载作用下,复合式基层路面结构下面层、上基层底面应变变化显著,横向应变较纵向波动更大、恢复更慢,以致荷载-温度综合作用下路面结构主导病害表现为横向开裂。加入ATB-25上基层后,结构层在标准轴载作用下的应变值降低40%~50%,应变峰值为39με,路面结构计算疲劳寿命为24 368×10^(6)次,可在控制建设成本同时避免运营期疲劳开裂风险。

In view of the frequent occurrence of pavement diseases in arid areas with large temperature difference,the central and western regions of Inner Mongolia was taken as an example,and the characteristics of environment and pavement diseases were deeply investigated.Fiber grating sensors were embedded in the composite base asphalt pavement structure of the new expressway.The strain response of different directions and depths of the pavement structure were investigated through field loading tests.The fatigue life of the pavement structure was calculated according to the measured results to verify the practical application effect of the composite base structure.Results show that the daily temperature difference and annual difference in the central and western regions of Inner Mongolia exceed 84%of the whole country,and the annual rainfall is lower than 87.4%of the whole country.The primary pavement disease is reflective cracking,and the crack spacing is only 10~20 m.The strain changes of the bottom surface layer and the upper base layer of the composite base pavement structure under traffic load are obvious,and the lateral strain fluctuates more and recovers slower than the longitudinal strain,thus the dominant disease of the pavement structure under the combined effects of load and temperature is lateral cracking.After adding the ATB-25 upper base layer,the strain under the standard axial load is reduced by 40%~50%,and the peak strain is 39με.The calculated fatigue life of the pavement structure is 24368×10^(6) times,which can control the construction cost and avoid the risk of fatigue cracking in the operation period.