富水条件下沥青混凝土疲劳性能试验研究

Test Study on Asphalt Concrete Fatigue Performance Under Rich-water Conditions

根据厚沥青面层自身的受力特点,采用应力控制模式对高速公路沥青路面下面层常用AC-25沥青混凝土进行无水和富水条件下间接拉伸疲劳试验,得到不同应力水平作用下的疲劳试验结果,回归建立了应力-疲劳方程,并从疲劳寿命、疲劳方程特征参数、疲劳破坏形态等方面分析了水对沥青混凝土疲劳性能的影响.研究结果表明,在相同的应力水平作用下,富水沥青混凝土疲劳寿命仅约为无水沥青混凝土的24%～30%;沥青混凝土的应力水平与疲劳寿命在双对数坐标中呈现较好的线性关系,可为沥青路面疲劳寿命预估提供依据;富水状态下试件疲劳破坏表现为剪切和劈裂联合作用形式,充分证明用冻融循环处理条件模拟沥青混凝土富水状态的合理性.

Stress-controlled mode can reflect mechanical response oi m^cr.c~ v carry out indirect tensile fatigue test of commonly used AC-25 asphalt concrete in different test condi- tions which are designed by anhydrous and rich-water respectively. With the fatigue test results by various stress level, the equations of stress-life fatigue for asphalt concrete were obtained. The water impacts on fatigue performance were analyzed from fatigue life, characteristic parameters of fatigue e- quation and fatigue failure modes. The results indicate that the fatigue life of rich-water asphalt con- crete is only about 24~30~ of anhydrous concrete in the same stress level, and there is good linear relationship between stress level and fatigue life in double- logarithm coordinates which can be serve as a basis to forecast fatigue life. At the same time, the fatigue failure form of shear and splitting com bined effect in rich-water condition fully proved that it is reasonable of using freeze-thaw cycling to simulate severely water damage.