| 基于激发振幅成像条件的探地雷达逆时偏移成像 |
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| 引用本文： | 王敏玲,王洪华,张智,徐志锋.基于激发振幅成像条件的探地雷达逆时偏移成像[J].地球物理学报,2018,61(8):3435-3445. |
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| 作者姓名： | 王敏玲 王洪华 张智 徐志锋 |
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| 作者单位： | 1. 桂林理工大学地球科学学院, 广西桂林 541004;2. 广西隐伏金属矿产勘查重点实验室, 广西桂林 541004 |
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| 基金项目： | 国家自然科学基金项目（41604039，41604102，41574078，41274070），广西自然科学基金项目（2016GXNSFBA380215，2016GXNSFBA380082，2015GXNSFAA139238，2014GXNSFAA118305），广西中青年教师基础能力提升项目（KY2016YB199）资助. |
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| 摘 要： | 针对基于互相关成像条件的探地雷达（GPR）逆时偏移计算效率低、存储量大及易产生低频假象的不足，本文将激发振幅成像条件应用于GPR逆时偏移成像中.通过在源点电磁波场正向传播过程计算每个网格点的能量密度，并保存最大能量密度的时刻和相应的电磁波场值；在接收点电磁波场逆向传播过程提取每个网格点最大能量密度时刻及对应的电磁波场值，并利用保存的最大能量源点电磁波场及走时做归一化，从而获得了依赖反射系数成像剖面，避免了源点正向传播电磁波场的存储和重建.此外，为了提高电磁波场的模拟精度，采用了基于三角形剖分的时间域有限单元法（FETD）计算电磁波正向和逆向传播过程.最后通过模型试算表明：激发振幅成像条件相比于归一化互相关成像条件，成像结果低频噪声更弱，空间分辨率更高，计算效率提高了近2倍.
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| 关 键 词： | 探地雷达 逆时偏移 激发振幅成像条件 能量密度 归一化互相关成像条件 |
| 收稿时间： | 2017-04-28 |
Reverse time migration in Ground Penetrating Radar based on the excitation amplitude imaging condition |
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| WANG MinLing,WANG HongHua,ZHANG Zhi,XU ZhiFeng.Reverse time migration in Ground Penetrating Radar based on the excitation amplitude imaging condition[J].Chinese Journal of Geophysics,2018,61(8):3435-3445. |
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| Authors: | WANG MinLing WANG HongHua ZHANG Zhi XU ZhiFeng |
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| Institution: | 1. College of Earth Sciences, Guilin University of Technology, Guangxi Guilin 541004, China;2. Guangxi Key Laboratory of Hidden Metallic Ore Deposits Exploration, Guangxi Guilin 541004, China |
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| Abstract: | In order to overcome the shortcoming of lower calculation efficiency, larger storage and low frequency illusion, which can be easily produced in Ground Penetrating Radar (GPR) reverse time migration (RTM) based on normalized correlation imaging condition, a stable excitation amplitude imaging condition for GPR reverse time migration is proposed. In the propagation of the source electromagnetic wave filed extrapolation along a positive time axis, the energy density for total grids are computed at each time step, and the travel time as well as electromagnetic wavefiled values corresponding to the maximum energy density are stored to extract and normalize the receiver electromagnetic wave field, the imaging profile which rely on reflectance can be obtained. Compared to the normalized cross-correlation (NC) imaging condition, this strategy will save a great amount of memory resource and significantly improve the computational efficiency for RTM. In order to improve the simulation accuracy of electromagnetic wavefield, the finite element time domain (FETD) method based on triangulation is used to calculate the forward and reverse propagation process of electromagnetic wave. At last the feasibility and accuracy of the proposed GPR RTM algorithm are validated by numerical tests of inclined model and fluctuation interface model by compared with the results of RTM based on the NC imaging condition. The compared results demonstrated that the RTM based on the excitation imaging condition has a higher spatial resolution and can produce less low-frequency artifacts compared with the RTM results based on NC imaging condition. Moreover, the calculation efficiency of the excitation imaging condition has improved nearly 2 times because computer storage capacity due to that it needs not to store source electromagnetic field. |
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| Keywords: | Ground Penetrating Radar (GPR) Reverse Time Migration (RTM) The excitation amplitude imaging condition Energy density The normalized correlation imaging condition |
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