摘要
针对探地雷达(Ground Penetrating Radar,GPR)在实际检测中因电磁波衰减、噪声干扰及多路径反射导致分辨率受限的问题,本文基于时域有限差分法(Finite-difference Time-domain,FDTD)构建数值模型,结合GPRmax仿真软件,系统研究了不同频率天线(400 MHz/900 MHz)对隧道衬砌脱空、钢筋分布不均等缺陷的垂直与水平分辨率特性及其影响因素。通过精细化建模与物理试验验证,揭示了天线频率、缺陷尺寸及埋深与分辨率之间的内在关联机制。研究通过分层脱空模型和钢筋间距模型开展数值模拟,量化了垂直分辨率与水平分辨率的理论极限。研究表明,高频天线(900 MHz)在浅层可实现λ_(1)/10的垂直分辨率和0.15 m的水平分辨率,而低频天线(400 MHz)虽分辨率下限为λ_(2)/8且水平分辨需0.20 m间距;埋深增加会导致菲涅尔带直径扩展,高频天线(900 MHz)分辨率随深度下降更显著。本文通过FDTD方法实现了隧道衬砌多缺陷模型的电磁场动态响应模拟,揭示了天线频率选择需权衡分辨率与探测深度的矛盾,提出多频数据融合策略以提升复杂工况下的检测精度。
Regarding the limitations in resolution of ground penetrating radar(GPR)caused by electromagnetic wave attenuation,noise interference,and multipath reflection during practical inspections,this study employs the finite-difference time-domain(FDTD)method to construct numerical models.Utilizing GPRmax simulation software,it systematically investigates the vertical and horizontal resolution characteristics—along with influencing factors—of antennas at different frequencies(400 MHz/900 MHz)for detecting tunnel lining defects such as voids and unevenly distributed reinforcement bars.Through refined modeling and physical experimentation,the intrinsic mechanisms among antenna frequency,defect size,burial depth,and resolution are elucidated.The research conducts numerical simulations using stratified void models and reinforcement bar spacing models,quantifying the theoretical limits of vertical and horizontal resolution.Findings reveal that high-frequency antennas(900 MHz)can achieve a vertical resolution of λ_(1)/10 and a horizontal resolution of 0.15 m in shallow layers,whereas low-frequency antennas(400 MHz)have a lower vertical resolution limit of λ_(2)/8 and require a horizontal spacing of 0.20 m.Increased burial depth expands the diameter of the Fresnel zone,and high-frequency antennas(900 MHz)exhibit a more significant decline in resolution with depth.This study simulates the dynamic electromagnetic field responses of multi-defect tunnel lining models via the FDTD method,revealing the trade-off between resolution and detection depth in antenna frequency selection.Besides,it proposes a multi-frequency data fusion strategy to enhance inspection accuracy under complex working conditions.
作者
田云程
刘晓甲
Tian Yuncheng;Liu Xiaojia(China Railway Engineering Consuling Group Co.,Ltd.,Beijing 100055,China)
出处
《工程地球物理学报》
2025年第5期565-573,共9页
Chinese Journal of Engineering Geophysics
基金
中国中铁交通基础设施安全与韧性专业研发中心重点课题(编号:KY2025A014)。
关键词
时域有限差分法(FDTD)
探地雷达
隧道衬砌缺陷
分辨率
数值模拟
finite-difference time-domain(FDTD)
ground penetrating radar(GPR)
tunnel lining defects
resolution
numerical simulation
