变幅荷载作用下沥青混合料的疲劳损伤试验

Experimental Study on Fatigue Damage of Asphalt Mixture under Variable Amplitude Loading

为了深入研究沥青混合料的疲劳性能,解决现有疲劳性能研究中没有考虑实际路面所受荷载是变幅、重复的加卸载过程这一关键问题,本文通过加载顺序和加载幅值对沥青混合料粘弹性指标的影响进行试验研究,分析了变幅荷载作用下沥青混合料劲度模量、相位角的变化,并选取耗散能作为损伤变量分析了变幅荷载下沥青混合料的疲劳损伤。试验结果表明:劲度模量与应变加载顺序有关;在低高加载顺序中,相位角在两阶段都表现为随着荷载作用次数的增加而增大,在高低加载顺序中,相位角的变化与高低应变的幅值相关;应变在高低顺序加载下累积耗散能要高于低高顺序下的累积耗散能;当采用的前后加载幅值较大时,这种现象更加明显。

In this paper, the experimental study the fatigue performance of asphalt mixture is focused upon the fatigue behavior under variable load amplitude or repeating load during fatigue processing. To make further progress, the changes of stiffness modulus and phased angle of the variable amplitude loading are analyzed by investigating the effects of loading sequence and loading amplitude on viscoelastic-index of the asphalt mixture. It also analyzed that the fatigue damage of asphalt mixture under variable amplitude loading by select dissipated energy as damage variable is also discused. This experimental result indicates that the stiffness modulus is related to the strain loading sequence. In increasing strain loading order, phase angle in the two stages increases with the load number. In decreasing strain loading order, however, the change of phase angle is associated with the amplitude of high and low strain. The accumulative dissipated energy of the strain in decreasing strain loading order is higher than that in increasing strain loading order. This becomes more obvious when the adopted loading amplitude islarger.