As projects advance to deeper areas, rockbursts occur more frequently. This failure mode is particularly problematic, as the rock mass fails abruptly, releasing high amounts of energy, endangering the life of workers and damaging equipment. The hazard mode is highly influenced by the grain-level structure of the rock. The authors demonstrate this by comparing the grain-level structure of different rocks to their failure mechanism. For this an extensive laboratory program was performed, including uniaxial compression tests (incl. post-failure tests to evaluate the failure energy), acoustic emission testing (to monitor the cracking activity) and Object Based Image Analysis (OBIA) to analyze rock’s structure at grain scale using thin sections taken before and after the compression test. The results allow a better understanding of the underlying mechanism and emphasize the usefulness of petrographic information within rockburst risk analysis.
Modern tunnelling and mining projects are exploring deeper areas than ever before, greatly increasing the likelihood of rockburst. This failure is extremely dangerous as it occurs very suddenly and is capable of releasing high amounts of energy. This poses a high risk to the life of workers and equipment used. Therefore, it is very important to fully understand rockbursts and develop methods to predict them. Laboratory tests and observations in tunnels and mines with high overburden have shown that certain rock types have a high potential for storing elastic energy and are hence more susceptible to rockburst. Although rockburst has been studied extensively in the past, the details of the failure mechanisms, including the fracture initiation, propagation and coalescence, are not yet fully understood. Many researchers (e.g. [1, 2]) suspect that rock’s structure at grain-scale plays an important role in this failure mode.
As part of a research project funded by the Austrian Research Promotion Agency (FFG) the Graz University of Technology, the University of Salzburg, the RHI AG and the University of Texas at Austin investigated the influence of rock’s (micro-) structure on the failure mechanism "rockburst" within a multidisciplinary study. For this study, different up-to-date methods were used, such as Object-Based Image Analysis (OBIA), Micro Computer Tomography (μCT) and Acoustic Emission Testing (AET), and combined with state-of-the-art rock mechanical laboratory tests [3].