为了适应沥青路面新的动态设计方法,加深对改性乳化沥青冷再生混合料动态模量的认识,针对再生剂(rejuvenation agent,RA)、玄武岩纤维(basalt fiber,BF)、布敦岩沥青(Buton rock asphalt,BRA)及聚苯乙烯丁二烯共聚物(SBR)胶乳改性的乳...为了适应沥青路面新的动态设计方法,加深对改性乳化沥青冷再生混合料动态模量的认识,针对再生剂(rejuvenation agent,RA)、玄武岩纤维(basalt fiber,BF)、布敦岩沥青(Buton rock asphalt,BRA)及聚苯乙烯丁二烯共聚物(SBR)胶乳改性的乳化沥青冷再生混合料,开展单轴压缩动态模量与车辙试验,利用时温等效原理将不同温度下的乳化沥青冷再生混合料动态模量平移形成主曲线,并通过图像比对得到乳化沥青冷再生混合料的最佳外掺剂以及最佳掺量,最后基于灰熵理论进行动态模量与动稳定度的关联分析。试验结果表明:乳化沥青冷再生混合料黏弹性质与普通热拌沥青混合料相近;RA可以显著改善乳化沥青冷再生混合料的黏弹特性,并可降低乳化沥青的用量,但RA用量并非越多越好,推荐RA最佳用量为8%。利用Sigmoidal函数确立了7种不同乳化沥青冷再生混合料动态模量主曲线,其总体呈现出S形扁平状曲线特征。在同一级配与油石比条件下,BRA、SBR胶乳改性方式均能提升乳化沥青冷再生混合料的高温性能,而掺量(质量分数,下同)4%、8%、12%的RA改性对其高温性能有负面影响,相比于普通(未改性)乳化沥青冷再生混合料,采用SBR、BRA胶乳改性的冷再生混合料动稳定度分别增加18.6%、5.5%,而BF改性以及掺量为4%、8%、12%的RA改性,冷再生混合料的动稳定度分别下降10.8%、12%、30.1%、51.7%。乳化沥青冷再生混合料动态模量与动稳定度的关联度较好。试验成果可为改性乳化沥青冷再生混合料动态模量提升及其在道路维修设计中的应用提供依据。展开更多
The transition location of a boundary layer depends on the amplitude and characteristic of initial disturbances. The larger the amplitude and the amplification rate of the initial disturbances are,the more upstream th...The transition location of a boundary layer depends on the amplitude and characteristic of initial disturbances. The larger the amplitude and the amplification rate of the initial disturbances are,the more upstream the transition location is. However,the environment surrounding the flying vehicle is variable,so the amplitude and characteristic of the disturbances triggered in the boundary layer through receptivity are also variable. In this paper,how the transition location varies in response to the variation of the initial disturbance amplitudes is studied by using direct numerical simulation. The results show that if the initial disturbance amplitudes become smaller,the transition location moves downstream correspondingly,but there is a time delay compared to the time of arrival of the disturbances with reduced amplitudes. Moreover,the speed of moving downstream is appreciably lower than the propagation speed of the disturbances. On the other hand,if the amplitudes of the initial disturbances recover their original value,the transition would immediately take place whenever the disturbances reach the former transition location,but the laminar flow between the new and old transition locations would not become turbulent immediately. Theoretical explanations are provided based on the transition mechanism found by our group.展开更多
文摘为了适应沥青路面新的动态设计方法,加深对改性乳化沥青冷再生混合料动态模量的认识,针对再生剂(rejuvenation agent,RA)、玄武岩纤维(basalt fiber,BF)、布敦岩沥青(Buton rock asphalt,BRA)及聚苯乙烯丁二烯共聚物(SBR)胶乳改性的乳化沥青冷再生混合料,开展单轴压缩动态模量与车辙试验,利用时温等效原理将不同温度下的乳化沥青冷再生混合料动态模量平移形成主曲线,并通过图像比对得到乳化沥青冷再生混合料的最佳外掺剂以及最佳掺量,最后基于灰熵理论进行动态模量与动稳定度的关联分析。试验结果表明:乳化沥青冷再生混合料黏弹性质与普通热拌沥青混合料相近;RA可以显著改善乳化沥青冷再生混合料的黏弹特性,并可降低乳化沥青的用量,但RA用量并非越多越好,推荐RA最佳用量为8%。利用Sigmoidal函数确立了7种不同乳化沥青冷再生混合料动态模量主曲线,其总体呈现出S形扁平状曲线特征。在同一级配与油石比条件下,BRA、SBR胶乳改性方式均能提升乳化沥青冷再生混合料的高温性能,而掺量(质量分数,下同)4%、8%、12%的RA改性对其高温性能有负面影响,相比于普通(未改性)乳化沥青冷再生混合料,采用SBR、BRA胶乳改性的冷再生混合料动稳定度分别增加18.6%、5.5%,而BF改性以及掺量为4%、8%、12%的RA改性,冷再生混合料的动稳定度分别下降10.8%、12%、30.1%、51.7%。乳化沥青冷再生混合料动态模量与动稳定度的关联度较好。试验成果可为改性乳化沥青冷再生混合料动态模量提升及其在道路维修设计中的应用提供依据。
基金was supported by the National Natural Science Foundation of China (Grant Nos. 10632050 and 90716007)the National Basic Research Program of China (Grant No. 2009CB724103)the Specialized Research Fund for the Doctoral Program of Higher Education
文摘The transition location of a boundary layer depends on the amplitude and characteristic of initial disturbances. The larger the amplitude and the amplification rate of the initial disturbances are,the more upstream the transition location is. However,the environment surrounding the flying vehicle is variable,so the amplitude and characteristic of the disturbances triggered in the boundary layer through receptivity are also variable. In this paper,how the transition location varies in response to the variation of the initial disturbance amplitudes is studied by using direct numerical simulation. The results show that if the initial disturbance amplitudes become smaller,the transition location moves downstream correspondingly,but there is a time delay compared to the time of arrival of the disturbances with reduced amplitudes. Moreover,the speed of moving downstream is appreciably lower than the propagation speed of the disturbances. On the other hand,if the amplitudes of the initial disturbances recover their original value,the transition would immediately take place whenever the disturbances reach the former transition location,but the laminar flow between the new and old transition locations would not become turbulent immediately. Theoretical explanations are provided based on the transition mechanism found by our group.
