In-situ stress measurements using oriented core - A comparison of uniaxial vs triaxial Acoustic Emission results

This paper describes the results from a number of laboratory testing experiments conducted under uniaxial and triaxial conditions. A high speed AE monitoring system was used to record the maximum amplitude and waveform for the AE signals with no major loss of events, even for AE event rates of the order of several thousands of events per second, such as they are normally observed before a catastrophic full scale rock mass failure event. The detailed damaging process as stress was increased was determined by monitoring the complete spacio-temporal distribution of microcracking events. The results showed that for samples of similar orientation and collected immediately adjacent to each other, the magnitude of the stress field determined using a triaxial testing set-up is similar to the stress level determined using uniaxial samples.