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倾斜板状体探地雷达波形特征研究

2021-04-06李远强

城市地质 2021年1期

李远强

摘 要:探地雷达方法在地质勘探、工程勘探及其他勘探工作中,经常会遇到地下倾斜板状体的探测,其异常特征为沿反射波同相轴的一条斜线,倾角的解释也是依据图像倾角读取。在实际工作中发现,其数值与实际有时会存在很大的偏差,当板状体的倾向与测线方向一致时,倾斜板状体真倾角大多是大于图像倾角的;当板状体的倾向与测线方向不一致时,倾斜板状体真倾角也是大于图像倾角的,其反演计算更为复杂一些。倾角越大,偏差值也越大;倾角越小,偏差值也越小,并给出了校准计算公式。

关键词:倾斜板状体;探地雷达;倾角

Abstract: In geological, engineering geophysical and other explorations, GPR method often encounters the exploration of oblique boards. The abnormal characteristic is the existence of an oblique line along the reflection phase axis and the dip-angle is interpreted in terms of image obliquity. In practice, it is discovered that there is sometimes a great discrepancy between the actual value and the interpreted value. When the inclination of the board is the same as the line direction, the true obliquity of the oblique board is greater than the image obliquity. The true obliquity of the oblique board is also greater than the image obliquity when the inclination of the board is not the same as the line direction, and the inverse calculation is more complicated. The larger the dip-angle is, the larger the discrepancy is, and vice versa. The calibration formula is presented here.

Keywords: oblique board; GPR; dip-angle

自20世纪80年代以来,探地雷达较成功的应用于地质勘探、工程勘探、水文勘探、考古勘探、军事勘探等领域,解决了不少地下勘探问题,如地层划分、管线探测、道路质量检测、隧道开挖超前预报、不良地质体(岩溶等)勘探、土壤含水率探测、考古探测、地下未爆物探测等(JOL,2009;王惠濂,1993;李大心,1994;曾昭发等,2006)。在实际工作中经常会遇到地下目标体为倾斜板状体的情况(陈从新等,2007;郭石礼等,2013;恩和得力海等,2017),而板状体探地雷达反射波的同相轴的倾角与实际板状体真倾角有一定的差异。从理论上分析了倾斜板状体环境条件下的探地雷达探测中电磁波的传播路径(王杰,2018),数值模拟了不同倾角情况下真倾角与图像倾角的关系,并采用探地雷达进行了室内试验,在工作实例中,应用该方法对倾斜板状体的倾角进行了校正解释。……

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