Practical application of the dual core-bit tool for drilling stress record cores to stress measurements at Kamioka mine, Japan

Kazuhiko Tezuka, Geophysical Surveying Co., Ltd., Tokyo, Japan, Toshiya Yamamoto, Geophysical Surveying Co., Ltd, Tokyo, Japan, Takatoshi Ito, Tohoku University, Institute of Fluid Science, Sendai, Japan, Tatsuya Yokoyama, OYO Corporation, Tokyo, Japan and Akio Funato, Fukada Geological Institute, Tokyo, Japan