多相离散随机介质探地雷达三维数值模拟

沥青混凝土是典型的多相离散随机介质, 为了研究探地雷达波在这种介质中的传播特征, 基于随机介质模型理论与统计学方法, 研究了沥青混凝土芯样的空间随机分布统计特征、各组成物质体积百分比、自相关函数及其特征参数(如自相关长度、自相关角度等), 基于量化约束多相离散随机介质模型建模算法, 构建了与之对应的多相离散随机介质三维模型.采用时域有限差分法建立了商用探地雷达蝶形天线的三维模型, 开展了多相离散随机介质探地雷达三维数值模拟.研究结果表明:多相离散随机介质模型不仅能全面、准确地描述沥青混凝土的介质特征, 而且可用于描述其他的复杂非均质混合物, 其模拟剖面与实测剖面相符, 有利于指导探地雷达沥青混凝土质量无损检测实测剖面的数据解译.

Three dimensional numerical simulation of ground penetrating radar based on multiphase discrete random medium

Bituminous concrete is a typical multiphase discrete random medium. In order to study the propagation characteristics of ground penetrating radar wave in such medium, we based on random medium model theory and statistical method to study the spatial random distribution characteristic statistic, the volume percentage of material composition, autocorrelation function and its characteristic parameter (like autocorrelation length, autocorrelation angle) by core samples of bituminous concrete, and built corresponding three-dimensional models based on the modeling algorithm of multiphase discrete random medium under quantization constrain developed in the paper. According to a commercial ground penetrating radar bow-tie antenna, the paper built its realistic three-dimensional model by using finite difference time domain, and carried out three-dimensional numerical based on multiphase discrete random medium. The result shows that the multiphase discrete random medium model not only completely and accurately describes bituminous concrete, but also describes other complex heterogeneous mixtures. Forward section of multiphase discrete random medium is consistent with the measured profiles and is conductive to the interpretation of the ground penetrating radar profile data in nondestructive testing of bituminous concrete.