Abstract
Water was injected into a borehole and generated a crack in a biaxial loaded granite specimen. After that, regarding the crack as a preexisting joint, the maximum loading direction was turned with 90 degree and viscous oil having 80 times larger viscosity than that of water was injected into the borehole. Located sources of acoustic emission indicated that a new crack was generated in the direction normal to the preexisting joint after water remaining in the borehole seeped into the preexisting joint with several small pressure drops. The results clarify the possibility to measure stress state generating a new crack by using viscous fracturing fluid, even in a rock mass having preexisting joints.
