中文摘要：

沥青混凝土是典型的多相离散随机介质,为了研究沥青混凝土各结构层的空隙率与探地雷达波场特征之间的关系,本文基于沥青混凝土各结构层对应的多相离散随机介质模型参数,应用量化约束多相离散随机介质模型建模算法,构建了不同空隙率的多相离散随机介质三维模型,并基于商用屏蔽型蝶形天线三维模型数值模拟了探地雷达波在其中的传播特征,研究了多相离散随机介质空隙率与探地雷达波场特征之间的关系.研究结果表明：在半无限空间中,多相离散随机介质的空隙率越大,探地雷达波散射越强烈、地面直达波正相位振幅越强;对于上、中、下面层厚度分别为4 cm、6 cm、8 cm的层状多相离散随机介质,地面直达波正相位振幅强度主要取决于上面层多相离散随机介质空隙率大小,受中面层多相离散随机介质空隙率的影响较小;地面直达波负相位的振幅强度主要与中面层多相离散随机介质空隙率大小相关,其振幅强度随空隙率的增大而增强,且地面直达波正、负相位振幅强度与下面层多相离散随机介质空隙率无关;下面层多相离散随机介质的空隙率与下层介质分界面之间的反射波振幅强度成正比例关系.研究结果为探地雷达定量估算沥青混凝土各结构层的空隙率提供了理论依据.

英文摘要：

Asphalt concrete is a typical multiphase discrete random medium,while the porosity is an important index for evaluating the construction quality of asphalt concrete pavement. In order to research the correlation between the porosity of each layer of asphalt concrete and the GPR wave-field characteristics,in this paper,based on the statistics and estimation results of the multiphase discrete random medium model parameters of each asphalt concrete layer,we used modeling algorithm to build 3D models of multiphase discrete random medium with different porosities; On the other hand,we built the 3D model of commercial GPR bow-tie antenna using FDTD method,and studied the propagation characteristics of GPR wave in such medium by numerical simulation,so as to figure out the correlation between the porosity of each asphalt concrete layer and the GPR wave-field characteristics. The numerical simulation results show that in a semi-infinite space, a larger porosity normally represents a more intensive GPR wave scattering,and a stronger amplitude of direct wave in positive phase; Among the multiphase discrete random medium layers with layer thicknesses of 4 cm（ upper layer）,6 cm（ middle layer）,8 cm（ lower layer）,respectively,the amplitude of direct wave in positive phase is slightly related to the middle layer porosity but mainly related to the upper layer porosity; The amplitude of direct wave in negative phase is mainly proportional to the middle layer porosity; moreover the amplitude of direct wave in positive or negative phase are not related to the lower layer porosity; However the porosity of multiphase discrete random medium lower layer is in positive correlation with the amplitude of reflected wave between lower layer medium interface. The research results show there is a significant corresponding change rule between the porosity of each asphalt concrete layer and the GPR wave-field characteristics, which provides theoretical basis for the quantitative estimation of the porosity of each asphalt concrete la