面状不良地质体钻孔雷达响应特征及正演研究

依据钻孔地质雷达探测工作中常见的面状不良地质体,利用几何-物理模型分析方法,推导了面状不良地质体的钻孔雷达反射波的传播距离和双程走时公式,研究了不同倾角、不同收发天线距的面状地质体的雷达反射截面特征,分析了面状地质体反射截面倾角随节理裂隙倾角的变化关系,以及钻孔雷达天线收发间距对雷达波传播距离变化的影响。同时,还利用时域有限差分(FDTD)数值模拟方法,对不同宽度的面状不良地质体进行了雷达响应正演研究,为钻孔雷达在岩体工程勘察中的应用及数据解译提供了直观的感性认识和丰富的判读基础。研究钻孔雷达电磁波波在各种地质条件下的传播,对于提高勘察效果和地质解译的准确性具有重要意义。

Study on borehole radar response's characteristics and forward simulation for planar unfavorable geo-bodies

According to the common planar unfavorable geo-bodies in borehole radar exploration, the formula of propagating/reflecting distance and two-way-travel-time of borehole radar wave in rock mass with planar unfavorable geo-bodies was derived by analyzing the method of geometry-physical model.The RCS (radar cross section) characteristics for planar unfavorable geo-bodies with various dip angles and various antenna intervals were studied.The regression curve relation between the dip angle of fissure and radar cross section angle was given, and also the influence of antenna interval on the propagating or reflecting distance is discussed.Furthermore, the borehole radar response fields of various fissure model intersected or non-intersected with borehole were analyzed with the finite difference time domain (FDTD) method.The simulation results provide visualized perceptual knowledge and abundant interpretation material for use of borehole radar in geologic survey, which improves the accuracy of geological interpretation.