Brittle failure geometry analysis based on acoustic emission locations in the Khibiny deposit rock samples

This study investigated the process of failure of the Khibiny deposit rocks in a hydrostatic pressure chamber with acoustic emission recording. In order to solve the tasks set, MTS 815 4600 kN testing complex was used, consisting of a press system, a hydraulic pump station and a recording system. The discussed method of analyzing hypocenters of acoustic emission events allowed studying fracture at the scale of microcrack formation and tracing the evolution of the process. The coordinates of the hypocenters of acoustic emission events were calculated throughout the experiment, the process of catastrophic macro-fracture image formation was analyzed and the accompanying stresses were determined. As a result of the study, it is found that the dominant geometry of brittle rock failure is a diagonal macro-fracture. It is also determined that failure occurs not instantly but evolves over time with the development of a fracture source. The failure process analysis through location of hypocenters of acoustic emission events shows that localization of a future macro-fracture begins at the stresses equal to 0.99 of the fracture strength. The study has a significant practical importance in terms of mining safety as it aims to timely detect a critical fracture stage. The results obtained can be used to describe the multi-stage process of rock failure to identify precursors of rock bursts. To further study the development of a fracture source by stages, it is necessary to improve the quality of recording acoustic emission events and refine methods for analyzing patterns of acoustic emission hypocenters.