水-温-荷载耦合作用下沥青路面疲劳寿命预估

Prediction on Fatigue Life of Asphalt Pavement under Water-Temperature-Load Coupling

为精准预测沥青路面的疲劳使用寿命,基于累积疲劳损伤理论,提出路面结构内水、温度以及轴载分布耦合作用下沥青混合料疲劳寿命预测方法。通过间接拉伸疲劳试验确定路面结构下面层沥青混合料在冻融和未冻融两种条件下应变疲劳方程。依托十堰—天水高速试验段,计算设计年限内9种不同温度和10种不同轴载(共计90种)条件下设计轴载的作用次数,同时结合路面结构层底拉应变计算程序进行计算,进而得到更加精确的拉应变。基于疲劳累积损伤理论,计算沥青路面经过冻融和未冻融条件下的疲劳累积损伤,进而得到沥青路面在无水和有水影响下的疲劳寿命。研究结果表明:十天高速公路沥青路面在受水影响和不受水影响下疲劳寿命分别为8.56年和12.12年,相较于设计寿命分别降低了19.2%和42.9%,为沥青路面在结构设计中考虑水、温度以及车辆荷载影响因素提供了可靠依据。

In order to predict accurately the fatigue life of asphalt pavement,a fatigue life prediction method of asphalt mixture that considers the coupling action of water,temperature and axle load distribution in pavement structure is proposed based on cumulative fatigue damage theory.The strain fatigue equations of freeze-thaw and unfreeze-thaw two kinds of asphalt mixture under pavement structure are determined by indirect tensile fatigue test.Relying on the Shiyan-Tianshui Expressway test section,the action times of design axle load under 90types of conditions for 9different temperatures and 10 different axle loads in the design life are calculated which are introduced to the calculation process of the tensile strain at the bottom of the pavement structure layer and make the calculation more accurate.Based on the fatigue cumulative damage theory,the fatigue cumulative damage of freeze-thaw and non-freezethaw two kinds of asphalt mixture are calculated,and then the fatigue life of asphalt pavement under the influence of water and no water is obtained.The studies show that the fatigue life of the influence of water asphalt pavement and without the influence of water asphalt pavement of Shiyan-Tianshui Expressway is 8.56years and 12.12years respectively,which is 19.2%and 42.9%lower than the design life,which provide a reliable basis for considering the influence factors of water,temperature and vehicle load in the structural design of asphalt pavement.