基于DSR时间扫描的沥青常应力疲劳演化规律分析

发布时间：2018-05-10 10:51

本文选题：道路工程 + 疲劳寿命　；参考：《公路交通科技》2017年11期

【摘要】：为了研究沥青疲劳特性在常应力模式下的演变规律,采用动态剪切流变仪(Dynamic Shear Rheometer,DSR),在应力控制模式下对70#基质沥青和SBS改性沥青进行时间扫描试验,获得复数剪切模量(G*)、耗散能变化率(DR)和累计耗散能比(DER)3种物理指标随荷载作用次数的变化曲线,通过分析3种曲线变化规律确定沥青疲劳寿命:(1)G*值下降到初始值50%时对应的荷载作用次数(NG*);(2)DR-N曲线转折点对应的加载次数(NDR);(3)DER-N曲线转折点(70#基质沥青)和曲线偏离DER=N直线20%时(SBS改性沥青)对应的加载次数(NDER),并建立沥青疲劳破坏方程。结果表明:NG*处于复数剪切模量加速下降阶段,而NDR和NDER处于沥青缓慢破坏和加速破坏转折阶段,NG*是根据经验所确定,而NDR和NDER是根据曲线转折点定义,物理意义明确;70#基质沥青和SBS改性沥青疲劳寿命(NG*、NDR和NDER)与应力在双对数坐标中表现出良好的线性关系;70#基质沥青疲劳破坏规律性强,疲劳曲线有明显的转折点,能明确定义沥青疲劳寿命;而改性沥青由于改性剂的作用,沥青弹性恢复能力增强,沥青疲劳曲线变化规律不明显;相同分析方法下,SBS改性沥青疲劳寿命明显优于70#基质沥青;随着加载应力提高,两种沥青的疲劳寿命均下降。
[Abstract]:In order to study the evolution of asphalt fatigue characteristics under constant stress mode, dynamic Shear rheometer was used to test 70# matrix asphalt and SBS modified asphalt under stress control mode. The curves of complex shear modulus, dissipation energy change rate (DRN) and accumulative dissipation energy ratio (DERN) with the number of loads are obtained. Through analysis of three curves, it is determined that the fatigue life of asphalt decreases to the initial value of 50 and the loading times corresponding to the turning point of the DR-N curve are higher than that of the turning point of the DR-N curve, and the curve deviates from the DER=N of the base asphalt (the turning point of the DER-N curve is the turning point of the DER-N curve) and the curve deviates from the DER=N. The loading times of SBS modified asphalt were calculated and the fatigue failure equation of asphalt was established. The results show that the complex shear modulus of NDR * and NDER are at the stage of accelerated decrease of complex shear modulus, while NDR and NDER are determined by experience, while NDR and NDER are defined according to the curve turning point. The physical meaning is clear. The fatigue life of Y70# matrix asphalt and SBS modified asphalt shows a good linear relationship with the stress in the double logarithmic coordinate. The fatigue failure regularity of the 70# matrix asphalt is strong, and the fatigue curve has obvious turning point. The fatigue life of SBS modified asphalt is obviously better than that of 70# base asphalt under the same analytical method, and the elastic recovery ability of modified asphalt is enhanced and the change law of asphalt fatigue curve is not obvious. With the increase of loading stress, the fatigue life of both kinds of asphalt decreases.
【作者单位】：山区道路结构与材料重庆市市级重点实验室;重庆交通大学土木工程学院;广西交通规划勘察设计研究院有限公司;
【基金】：国家自然科学基金项目(50808189)
【分类号】：U414

【相似文献】