ABSTRACT
Hydraulic fracturing experiments were conducted to estimate the width of the fracture using granite, sandstone, and andesite specimens. Water was injected into the borehole drilled at the center of the specimen at three different injection rates. Larger surface displacement was observed at the larger injection rate and at the LVDT near to the borehole. AE events were observed corresponding to change of injection flux, suggesting that the propagation of the fracture is possible to estimate by monitoring AE events as well as the measurement of the surface displacement. In the andesite sample, although variation was large, as well as the granite and sandstone samples, the fractured plane estimated from AE locations coincided with the plane by the visual observation when the experiment was finished.
