基于FBG的沥青混合料横向流动变形评价

Evaluation of lateral flow deformation of asphalt mixture based on FBG

为了分析沥青混合料横向流动变形,进行了沥青混合料的车辙试验,利用布设于沥青混合料板表面的光纤布拉格光栅传感器,研究了沥青混合料表面的横向应变规律;以最大应变和蠕变稳定阶段横向应变速率绝对值为评价指标,分析了沥青混合料横向流动变形。分析结果表明:横向流动变形随沥青混合料的最大应变和横向应变速率绝对值的减小而降低;横向流动变形在循环轮载作用下不断发展,测试点距离轮载愈近其流动变形愈剧烈;当胶粉掺量分别为0、15%、18%时,距离轮载63mm的测试点横向应变速率分别为6.8×10^-6、4.0×10^-7、6.4×10^-6 min^-1,因此,掺15%胶粉的沥青混合料具有较大的抵抗高温横向流动变形的能力;对于15%胶粉掺量的沥青混合料,当其集料级配分别为AC-13粗级配和AC-13细级配时,距离轮载28mm的测试点横向应变速率分别为6.0×10^-7、7.7×10^-6 min^-1,因此,AC-13粗级配沥青混合料高温抗横向流动变形能力优于AC-13细级配;胶粉改性沥青混合料最大应变为1.96×10^-4,而胶粉和抗车辙剂复合改性沥青混合料最大应变只有1.22×10^-4,说明在高温情况下,胶粉和抗车辙剂复合改性沥青混合料整体结构强度较大,能够承受来自轮载的直接作用而不向轮迹两边产生横向推移致使发生较大的横向流动变形。基于光纤布拉格光栅横向应变的沥青混合料横向流动变形评价能较好地说明不同材料和级配对沥青路面产生侧向流动变形规律的影响。

In order to analyze the lateral flow deformation of asphalt mixture,a rutting test of asphalt mixture was conducted,and the law of lateral strain on the surface of asphalt mixture was researched by using the fiber Bragg grating(FBG)sensor installed on the slab surface of asphalt mixture.With the maximum strain and the absolute value of lateral strain rate in creep stability stage as evaluation indexes,the lateral flow deformation of asphalt mixture was analyzed. Analysis result indicates that the lateral flow deformation decreases with the decreases of both the maximum strain of asphalt mixture and the absolute value of lateral strain rate.The lateral flow deformation develops continuously under the action of cyclic loading.The nearer the test point to the wheel,the heavier its flow deformation is.When the rubber powder contents are 0,15%and 18%,the lateral strain rates at test point with a distance of 63mm to the wheel are 6.8×10^-6, 4.0×10^-7 and 6.4×10^-6 min-1,respectively.Therefore,the asphalt mixture with 15%rubber powder content has larger capacity to resist lateral flow deformation in high temperature.For the asphalt mixtures with 15%rubber powder content,when their aggregate gradations are selected as coarse gradation of AC-13and fine gradation of AC-13,the lateral strain rates at test point with a distance of 28mm to the wheel are 6.0×10^-7 and 7.7×10^-6 min^-1,respectively,so the anti-lateral flow deformation capability of AC-13coarse-graded mixture in high temperature is better than that of AC-13fine-graded mixture.The maximum strain of rubber powder modified asphalt mixture is 1.96×10^-4,but for the asphalt mixture modified by rubber powder and rutting resistance additive,the value is only 1.22×10^-4,which shows that under the condition of high temperature,the asphalt mixture modified by rubber powder and rutting resistance additive has higher overall structural strength and can bear the direct effect from the wheel load without lateral movement to both sides,which could cause larger lateral flow deformation.The evaluation of lateral flow deformation to asphalt mixture based on the FBG lateral strain can well illustrate the effect of different material and gradation characteristics on the lateral flow deformation of asphalt pavement.7tabs,10figs,30refs.