Abstract
The acoustic emission (AE) method under a confining pressure has been developed in order to measure in-situ stress that is expected to be close to the uniaxial compressive strength or to estimate the stress from weak rock, which are very difficult to deploy the conventional AE method based on standard uniaxial loading. We have developed a special small pressure vessel by which AE event can be detected under a confining pressure. We tested the ability of the vessel to detect the Kaiser effect of AE occurrence under a confining pressure. Then, we evaluated the AE method under a confining pressure by conducting a simulation test of determination of pre-stress using a soft sedimentary rock from Tono mine in Japan. The result showed that the previous stress could be estimated under a confining pressure with reasonable accuracy of 3.3 % mean error.
