Improved crosshole radar tomography by using direct and reflected arrival times
Improved crosshole radar tomography by using direct and reflected arrival times
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DOI：
10.1016/s0926-9851(01)00050-7
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发表时间：
2001-06-01
影响因子：
2
通讯作者：
Appel, E
中科院分区：
文献类型：
--
作者：
Tronicke, J;Tweeton, DR;Appel, E
通过反演直接到达时间的走时层析成像是跨孔雷达测量中最常见的技术。在标准的跨孔实验中，由于视角范围有限，会产生模糊和模糊的结果，因此反演在数学上是一个非唯一的过程。如果可能，应从数据中提取附加信息或从外部添加附加信息，以改进和约束反演和解释。在低衰减介质中，反射波能量也可以出现在跨孔数据中。反射通常是由众所周知的界面引起的，例如自由地球表面或地下水位。由于它们的行进路径不同，这些反射事件包含有关地下结构和参数分布的附加信息。我们提出了一种技术，将与已知界面相关的反射走时纳入跨孔雷达数据的层析走时反演中。如果在跨孔雷达测量中可以清楚地识别这种反射，则所提出的反演策略会增加射线总数和射线路径角度的范围。对合成和真实现场数据集的应用表明了该方法的实用性和改进。结果表明，与仅使用直接到达的标准跨孔断层扫描相比，水平拖影减少了，局部异常的轮廓也更好了。 (C) 2001 Elsevier Science BN，保留所有权利。
Traveltime tomography by inverting direct arrival times is the most common technique in crosshole radar surveying. In a standard crosshole experiment, the inversion is a mathematically nonunique process due to the limited range of viewing angles producing ambiguous and smeared results. If possible, additional information should be extracted from the data or added from the outside to improve and constrain the inversion and the interpretation. In low attenuation media, reflected wave energy can also be present in the crosshole data. Reflections are often caused by well-known interfaces, such as the free earth surface or the groundwater table. Because of their differing travel paths, these reflected events contain additional information about subsurface structure and parameter distribution. We present a technique to include reflection traveltimes associated with known interfaces into tomographic traveltime inversion of crosshole radar data. If in a crosshole radar survey such reflections can be clearly identified, the total number of rays and the range of raypath angles are increased by the presented inversion strategy. Applications to a synthetic and a real field data set show the practicability and the improvements offered by this method. The results show that horizontal smearing is reduced and local anomalies are better contoured compared to standard crosshole tomography using only direct arrivals. (C) 2001 Elsevier Science BN, All rights reserved.