基于干涉成像条件的探地雷达衰减补偿逆时偏移成像  

Attenuation compensated reverse time migration of ground penetrating radar data based on interferometric imaging condition

作　　者：席宇何 王洪华[1] 龚俊波 王欲成 XI YuHe;WANG HongHua;GONG JunBo;WANG YuCheng(College of Earth Sciences,Guilin University of Technology,Guilin 541004,China)

机构地区：[1]桂林理工大学地球科学学院,桂林541004

出　　处：《地球物理学进展》2023年第2期880-890,共11页Progress in Geophysics

基　　金：国家自然科学基金项目(41604102);广西自然科学基金项(2020GXNSFAA159121)联合资助。

摘　　要：探地雷达(GPR)衰减补偿逆时偏移方法采用互相关成像条件对实际地下结构成像时,由介质小尺度不均匀所产生的散射波和噪声能量在电磁波衰减补偿逆时外推中会急剧增大,严重影响成像分辨率.为此,本文提出一种基于干涉成像条件的GPR衰减补偿逆时偏移方法.该方法通过在逆时外推过程中,人为改变电磁波动方程中衰减项前的正负号,以保持逆时外推的时间对称性,补偿衰减的电磁波能量;干涉成像条件利用Wigner分布函数(WDF)对所有时刻的逆时外推电磁波场进行滤波,以有效压制逆时偏移剖面中的低频噪声及成像伪影.数值试验结果表明:相比于互相关成像条件,干涉成像条件可有效压制衰减补偿逆时偏移过程中由于背景小尺度不均匀性所产生的散射波和低频噪声,且几乎不影响目标体的成像能量;在计算效率相当的同时,成像分辨率更高.When the Ground Penetrating Radar(GPR)attenuation compensated reverse time migration method based on cross-correlation imaging condition is used to image real underground media, the scattering wave and noise energy generated by the small scale heterogeneity of the medium would be increased sharply in the attenuation compensation reverse time extrapolation, which seriously affects the imaging resolution. Therefore, a GPR attenuation compensated reverse time migration method based on interferometric imaging condition is proposed in this paper. In the process of electromagnetic wave reverse time extrapolation, the time symmetry invariance is kept by artificially changing the sign of the attenuation term of electromagnetic equation, to compensate for the attenuation of electromagnetic energy. The interferometric imaging condition based on the Wigner distribution function is used to filter the reverse time extrapolated electromagnetic wave field at all times, which can effectively suppress the low-frequency noise and imaging artifacts in the reverse time migration profile. The numerical simulation results certified that, compared with the cross-correlation imaging condition, the interferometric imaging condition can effectively suppress the scattering wave and low-frequency noise caused by the small scale heterogeneity of the background during the attenuation compensated reverse time migration process, and hardly affects the imaging energy of the target. It has higher imaging resolution while ensuring computational efficiency.

关 键 词：探地雷达 干涉成像条件 衰减补偿逆时偏移 WIGNER分布函数 

分 类 号：P631[天文地球—地质矿产勘探]