A Novel Energy-Based Method to Evaluate Layered Rock Brittleness

Rock brittleness plays an important role in rock engineering, thus it is practically valuable to assess rock brittleness accurately. Many brittleness indices have been developed, but few methods are developed for layered rocks. Based on energy evolution, the authors propose a new index for assessing brittleness of layered rocks. The new index indicates that high rock brittleness means elastic energy accumulated effectively before peak and dissipated abruptly after peak. For the sake of verifying the proposed method, a series of compression tests were performed. The results demonstrate that rock brittleness decreases gradually with increasing confining pressure. As orientation angle increases, rock brittleness weakens and then strengthens overall. The brittleness of the specimen with an orientation angle of 0 degrees is slightly higher than that with an orientation angle of 90 degrees. The new index was compared with three existing brittleness indices, and the results indicate that the proposed method can evaluate brittleness of layered rock effectively.