裂缝宽度探地雷达波场响应的数值研究

Numerical study on response of ground penetrating radar wave field to crack width

裂缝是沥青混凝土公路路面的常见病害,为了研究沥青混凝土中隐含裂缝的宽度与其探地雷达波场之间的对应变化关系,本文基于各结构层沥青混凝土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,构建了与公路各结构层实际情况更相符的多相离散随机介质三维模型,并基于商用探地雷达蝶形天线三维模型,数值模拟与对比分析了探地雷达波在多相离散随机介质和均匀介质中的传播特征,研究了探地雷达波场随裂缝宽度变化的函数关系.研究结果表明:探地雷达波在多相离散随机介质中发生了散射,致使其数值模拟剖面具有明显的随机扰动特征和"噪声",降低了探地雷达对裂缝的成像能力;随着裂缝宽度由窄变宽,其在探地雷达剖面图上的横向异常宽度差异较小,但裂缝顶端绕射波振幅强度与裂缝宽度之间具有明显的规律性,这为探地雷达定量估算公路结构层隐含裂缝宽度提供了理论依据.

Cracks are common diseases in asphalt concrete pavement. In order to analyze the corresponding relation between crack width and GPR wave field,in this paper,based on the multiphase discrete random medium（ MDRM） model parameters of each asphalt concrete layer,we built 3D MDRM models which were more compatible with each asphalt concrete layer using quantitative constraint MDRM modeling algorithm. Based on the 3D model of commercial GPR bow-tie antenna, we conducted numerical simulation and comparative analysis of GPR wave propagation characteristics between in multiphase discrete random medium and in homogeneous medium,as well as analyzed the functional relation between GPR wave-field and crack width. The results show that GPR wave is scattering in multiphase discrete random medium,leading to significant random perturbation and＂noise＂in the profile of numerical simulation,and the imaging capability to crack in GPR profile decreased; with the increase of the width of crack,there is less difference in the width of transverse anomalies which caused by cracks,and the width of crack is not able to be measured directly from GPR image. But,the amplitude of diffracted wave at crack top has obvious rules related to crack width,which provides theoretical basis for quantitatively estimation the width of hidden cracks in highway structural layer from GPR data.