考虑加载速度影响的沥青混合料疲劳方程

FATIGUE EQUATION OF ASPHALT MIXTURE CONSIDERING THE INFLUENCE OF LOADING RATE

为了建立沥青混合料强度与疲劳行为之间的联系,通过不同加载速率下的沥青混合料直接拉伸强度试验,揭示了强度随加载速率的幂函数变化规律;基于不同加载速率下的强度值,得到了与疲劳加载速率对应的沥青混合料疲劳真实应力比;通过疲劳试验,创建了基于名义应力比和真实应力比的沥青混合料疲劳方程,基于名义应力比的疲劳方程后延后与横坐标的交点远比1大,不具有后延性,而基于真实应力比的疲劳方程可以后延到疲劳寿命为1的强度破坏点,统一了强度破坏与疲劳破坏行为;据此推导了沥青路面抗拉强度结构系数计算新方法;研究结果可为我国公路沥青路面设计规范的修订提供理论依据。

In order to establish the relationship between the strength and fatigue behavior of asphalt mixture, the direct tensile strength tests under different loading rates are presented and the power function rule between the strength and loading rate is revealed. Basing on the strength values under different loading rates, the real stress ratios corresponding to the fatigue loading rates of asphalt mixture are obtained. The asphalt mixture fatigue equations based on nominal and real stress ratio are created by fatigue tests. The intersection of fatigue curve characterized by the .nominal stress ratio and abscissa axis is much larger than 1. The fatigue curve based on a nominal stress ratio cannot be extended. But the fatigue curve characterized by a real stress ratio can be extended to the strength failure point, whose fatigue life is 1. The strength and fatigue failure behavior are unified. The structure coefficient of tensile strength of asphalt pavement is deduced. The results of the research provide a theoretical foundation for revising the specifications for the design of highway asphalt pavement in our country.