钻孔雷达探测地下裂缝

钻孔雷达是地质雷达的一种特殊模式,与通常的地质雷达比起来,有几个显著的特点。比如,利用钻孔接近地下的某个区域,天线可以相对接近所要测量的地质异常体或目标,从而导致在较深的范围对目标的精确测量。实验场地位于北京西部的一个石灰岩的小山上。该处有一组钻孔,并被大量的裂缝所切割。在这些钻孔中,进行了单孔反射测量和跨孔测量。测量的数据经过处理和解释表明,在该场地雷达的径向探测范围可达30 m,地下裂缝的分布可以形成清晰的图像。可以看到很多裂缝,它们距钻孔的距离及倾角都可以确定下来。在有些情况下,确定裂缝分布的方位是可能的。

Subsurface Fractures Detection by Borehole Radar

Borehole radar is a special mode of Ground Penetrating Radar.It has several distinguished features from surface radar.For examples, by means of borehole access to regions below the surface,the antennas can be located relatively close to the anomalies or targets to be measured,resulting in more precise targets response in deep subsurface applications.The experimental site is located on the top of a granite hill west of Beijing.There is a group of boreholes intersected by many fractures;both single-hole and cross-hole measurements were carried out.The measured data are processed and interpreted.The radial detecting range is more than 30 meters at this site.The subsurface fracture distribution can be imaged very clearly.Many fractures can be "seen",and their distance from borehole and their dip angle can be determined.The azimuth determinations for these fractures are possible in some situations.It is concluded that the borehole radar is an effective tool for subsurface imaging.