水-温作用下沥青混合料疲劳性能分析

Fatigue property analysis of asphalt mixture in water-temperature action

针对我国南方湿热多雨的气候条件,采用冻融循环的试验方法模拟湿热地区沥青混合料的水-温作用,通过CRT-NU14气动伺服沥青材料试验机对高速公路沥青路面下面层常用AC-25沥青混合料进行间接拉伸疲劳试验,得到不同水-温条件下的疲劳曲线和疲劳方程,并从疲劳寿命、力学性能、疲劳特征参数和疲劳破坏特征4个方面分析水-温作用下沥青混合料的疲劳规律。研究结果表明:不同水-温条件下沥青混合料的应力与疲劳寿命在双对数坐标中均呈良好的线性关系,可为沥青路面疲劳寿命预估提供依据;水作用和温度升高对沥青混凝土的疲劳寿命和力学性能影响显著,可使混合料的抗疲劳特性大幅衰减;水-温作用下试件疲劳破坏表现为剪切和劈裂联合作用形式,证明用冻融循环处理条件模拟沥青混凝土处于水-温作用的合理性。

Given the hot and humid weather conditions in Southern China,the water-temperature action of asphalt mixture was simulated by freeze-thaw cycle test method and the indirect tensile fatigue test of commonly used AC-25 asphalt mixture was carried out through CRT-NU14 pneumatic servo asphalt material testing machine at various stress levels.Then,fatigue curves and fatigue equations of different water-temperature conditions were obtained and the influencing factors of fatigue life,mechanical properties,fatigue characteristic parameters and fatigue failure features were analyzed.The results indicate that there is good linear relationship between stress level and fatigue life in double-logarithm coordinates which can serve as a basis to forecast fatigue life,and water action and temperature rise can significantly impact on fatigue life and mechanical properties of asphalt mixture which decline anti-fatigue properties of mixture in a large extent.Also,the fatigue failure features of shear and splitting combined effect in water-temperature action fully prove that it is reasonable to use freeze-thaw cycling simulate hot and humid environment.