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中南大学学报(自然科学版)

Journal of Central South University

第46卷    第7期    总第251期    2015年7月

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文章编号:1672-7207(2015)07-2658-07
基于旅行时修正的钻孔雷达层析成像改进
朱自强,彭凌星,密士文

(中南大学 地球科学与信息物理学院,湖南 长沙,410083)

摘 要: 基于钻孔雷达的波幅采用速度层析成像时,大收发角度雷达波幅因其信噪比低,旅行时提取较困难等问题,钻孔雷达雷达波幅层析成像精度不高。通过计算证明电磁波能量是从发射天线中心点传播至末端,再由接收天线末端传播至其中心。依据此传播路径采用互相关函数对旅行时的提取进行优化,并得到相应的电磁波波速。利用优化后的旅行时与波速得到旅行时的修正值,并根据修正后的旅行时进行速度层析成像,将进行旅行时修正的层析成像图与未进行旅行时修正的层析成像图进行对比。研究结果表明:经过旅行时修正后得到的层析成像结果更加精确,证明对钻孔雷达层析成像的改进方法是可行的。

 

关键词: 钻孔雷达;初至波旅行时;互相关函数;旅行时修正;层析成像

Improved borehole-GPR tomography based on travel-time correction
ZHU Ziqiang, PENG Lingxing, MI Shiwen

School of Geoscience and Info-Physics, Central South University, Changsha 410083, China

Abstract:In the course of borehole GPR tomography processing, the first-arrival time at high transmitter-receive angles is often very difficult to pick by using common tools because of low ratio of signal and noise in the data. The accuracy of borehole radar tomography is not high. It was verified by calculation that the propagation path of electromagnetic wave energy in velocity tomography goes from the center of the transmitter antenna to the end of the transmitter antenna, then to the end of the receiver antenna, and finally to the center of the transmitter antenna. Depending on the true propagation path of electromagnetic wave, the cross-correlation function was used to optimize the extraction of travel time, and then the optimized velocity was obtained. The value of travel-time correction was obtained by calculating the average velocity along each ray and optimized time-picking using cross-correlation, and the optimized velocity tomography was obtained. The results show that compared with the tomography without correction, the optimized tomography is more precise, which verifies the feasibility of the proposed method.

 

Key words: borehole radar; first-arrival time; cross-correlation function; travel-time correction; tomography

中南大学学报(自然科学版)
  ISSN 1672-7207
CN 43-1426/N
ZDXZAC
中南大学学报(英文版)
  ISSN 2095-2899
CN 43-1516/TB
JCSTFT
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