Micro Polarimetric Borehole Radar for Subsurface Fracture Measurement

用于地下裂缝测量的微偏振钻孔雷达

• 批准号: 10450389
• 负责人: SATO Motoyuki
• 金额: $ 8.13万
• 依托单位: TOHOKU UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 1998
• 资助国家: 日本
• 起止时间: 1998 至 1999
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10450389/
• 关键词: Radar Polarimetry; Borehole Radar; Cross-hole radar; Optical Analog signal link; Civil Engineering; Rock Stability Monitoring; Fracture Imaging; Fracture Characterization; ステップ周波数レーダ; 光アナログ信号伝達

Polarimetric borehole radar has a good potential for detecting and evaluating radar targets beyond the radar resolution determined by the wavelength. This is a great advantage for borehole radar, which is often used I lossy subsurface material. In this research project, we have developed a polarimetric borehole radar system which operates under 200MHz, and can be installed in boreholes having a diameter less than 5cm.In order to have a thin down hole sonde, we have developed a optical analog signal link which is equipped in a cylindrical casing of 2cm in diameter. The completed polarimetric borehole radar system has a diameter of 41 mm. This system was evaluated in field test and could show it can acquire polarimetric radar signal. At the same time, we found that the signal acquired by borehole radar, whose diameter is much smaller than that of a borehole is unstable, and we need additional equipment to set the down hole sonde at the center of the borehole.Polarimetric borehole radar measurements were carried out in several test sites including Mirror Lake, USA, Asse, Germany and Hirabayashi, Japan. We showed that he full-polarimetric borehole radar profiles can be used for classification of subsurface fractures. Under certain conditions, we found that the water permeability is related to the surface roughness of the subsurface fractures, and the polarimetric borehole radar can evaluate them.By using the cross-hole borehole radar measurement, we proposed a imaging technique based on migration. This technique can achieve higher resolution that the conventional tomography analysis.

极化钻孔雷达在探测和评估超出波长决定的雷达分辨率的雷达目标方面具有很好的潜力。这对于井下雷达来说是一个很大的优势，因为井下雷达经常被用于有损耗的地下材料。在本研究项目中，我们研制了一套工作在200 MHz以下、可以安装在直径小于5厘米的钻孔中的极化钻孔雷达系统。为了获得薄的井下探头，我们研制了一种安装在直径为2厘米的圆柱形外壳中的光学模拟信号链路。完成的极化钻孔雷达系统直径为41 mm。对该系统进行了现场测试，结果表明该系统能够捕获极化雷达信号。同时，我们发现，直径远小于钻孔直径的钻孔雷达获取的信号不稳定，需要额外的设备将井下探头放置在钻孔中心。在美国镜湖、德国阿塞和日本平林等几个试验点进行了极化钻孔雷达测量。结果表明，全极化钻孔雷达剖面可用于地下裂缝的分类。在一定条件下，发现渗透率与地下裂缝的表面粗糙度有关，利用极化钻孔雷达可以对其进行评价，提出了一种基于偏移的成像技术。与传统的层析分析相比，该技术可以获得更高的分辨率。

项目成果

M.Sato and M.Takeshita: "Polarimetric Borehole Radar Approach to Subsurface Fracture Classification"Proceedings of the 8th Int. Conference on Ground Penetrating Radar. (印刷中). (2000)

M.Sato 和 M.Takeshita：“极化钻孔雷达方法进行地下裂缝分类”第八届探地雷达国际会议论文集（2000 年）。

H. Zhou and M. Sato: "Fracture Imaging and Saline Tracer Detection by Crosshole Borehole Radar Data Migration"Proceedings of the 8th Int. Conference on Ground Penetrating Radar, Gold Coast, Australia. (2000)

H. Zhou 和 M. Sato：“通过跨孔钻孔雷达数据迁移进行裂缝成像和盐水示踪剂检测”第八届国际会议论文集。

H.Zhou and M.Sato: "Estimation of Subsurface Fracture Extension by Using Cross-hole Radar Measurement"信学技報. SANE99-73. 81-85 (1999)

H.Zhou 和 M.Sato：“使用跨孔雷达测量估计地下裂缝延伸”SANE99-73 (1999)。

M.Sato and T.Miwa: "Polarimetric Borehole Radar System for Fracture Measurement"Subsurface Sensing Technologies and Applications. 1. 161-174 (2000)

M.Sato 和 T.Miwa：“用于裂缝测量的极化钻孔雷达系统”地下传感技术和应用。

M. Sato: "Polarimetric Borehole Radar Approach to Subsurface Fracture Classification"Proc. Three-Dimensional Electromagnetics, Salt Lake City. 259-262. 26-29 (1999)

M. Sato：“极化钻孔雷达地下裂缝分类方法”Proc。