| 1. | This paper introduces four kinds of mehtods that is used to investigate crack in underground rock stratum : borehole core method , ultrasonic imaging method , borehole television method , and borehole discharge well logging method 摘要本文介绍了地下岩层裂隙的4种勘察研究方法:钻孔岩芯法、超声成像法、钻孔电视法、钻孔流量测井法。 |