Experimental investigations on progressive rupture and predictive acoustical behavior in brittle rocks

The progressive rupture in brittle rocks is usually observed on both laboratory and field scales. However, there is limited knowledge on the prediction of the progressive rupture due to its multi-path failure mode. This paper applies the statistics to the multi-path failure analysis to explore the predictive acoustical behaviors against the energetic failure in brittle rocks. To this end, a uniaxial compression test with concurrent monitoring of acoustic emission (AE) is conducted on a large population of flawed sandstone specimens. Experimental results show that the damage progression in brittle rocks can be reflected faithfully by the AE event rate characteristics. When the macro-fracturing event occurs, the AE event rate rapidly increases to a quite high level. More importantly, typical AE parameters such as AE energy are found to be strong descriptors that can be used in predicting the energetic failure. Three simple quantitative AE-based criteria are finally established based on the strong discrimination in averaged AE parameters between the micro-cracking-dominated damage stage and the macro-fracturing-dominated damage stage.