路面层状结构低频介电增强特性

Dielectric enhancement of layered pavement at low frequencies

为减小因介电增强特性带来的路面检测误差,借助模拟路面层状结构的'双电层'模型,对路面层状结构的介电增强特性进行分析。通过Debye模型推导双电层模型介电常数计算公式,采用有限差分算法对模拟路面层状结构的双电层模型建模仿真;根据仿真结果,讨论了路面层状结构中电性参数对介电增强的影响,并基于电容器原理,设计了一款平行板电容器,在低频段对不同膜层的双电层模型进行测量。研究结果表明:双电层模拟的路面层状结构在低频段存在介电增强,其主要受界面层的电导率、厚度等参数影响;面层和基层材料的电性参数只影响路面层状结构的弛豫频率和时间,不影响介电增强;采用增大界面层电导率,限定界面层厚度的方法能减小路面检测中因界面层中各参数差异产生的介电增强,提高测量精度。

To reduce the pavement measurement error caused by dielectric enhancement, dielectric enhancement of layered pavement was analyzed with electric double layer （EDL） model. Firstly, the dielectric constant formula of EDL was derived from Debye model. Secondly, EDL model a- bout layered pavement was established and simulated by FDM software. The influence of EDL parameters on dielectric enhancement was discussed. Finally, a parallel plate capacitor was de- signed, and used to measure EDL admittance with different membranes at low frequencies. The results show that the layered pavement simulated by EDL has dielectric enhancement at low fre- quencies, which is affected by the conductivity and thickness of pavement interface. The electrical parameters on surface and base pavement only affect relaxation frequency and time, but have no effect on amplitude of dielectric enhancement. Increasing conductivity and limiting thickness of the interface layer can reduce dielectric enhancement of layered pavement in pavement detection so as to improve measurement accuracy. 1 tab, 10 figs, 13 refs.