Estimation of rock burst grade using acoustic emission technique

Estimation of rock burst grades is an important basis for rock burst prevention measures, and the AE (acoustic emission) features of rocks could reflect the rock burst grades. Taking a railway tunnel in western China as an example, the original rock cores with different rock burst grades were obtained by core drilling method; the cylindrical specimens in a diameter of 50 mm with a height of 100 mm were made from different directions (transverse, oblique, longitudinal) of the original rock cores. The AE features of different directions specimens during indoor uniaxial compression test were obtained. Using the ratio of the cumulative AE energy Eq before the main fracture to the cumulative AE energy E after the final fracture of specimens in different directions, the corresponding new methods for estimating the rock burst grade were proposed respectively; the estimation results were compared with the actual rock burst grades and the estimation results of the traditional rock burst estimation methods. It shows that the estimation accuracy of the method based on Eq/E of specimens in different directions reaches 80%, which is in good agreement with the actual rock burst grades; compared with the traditional rock burst estimation methods, the estimation results of Eq/E-based rock burst estimation methods are more reliable; when Eq/E of specimens in different directions is used to estimate rock burst grades, the reliability of the estimated results from high to low is longitudinal, oblique, and transverse specimen. The results presented herein are important for the prevention and control of rock burst.