Rock Brittleness Evaluation Index Based on Ultimate Elastic Strain Energy

Abstract

Brittleness is an essential parameter to determine the deformation and failure behavior of rocks, and it is useful to quantify the brittleness of rocks in numerus engineering practices. A novel energy-based brittleness evaluation index is proposed in this study, which redefines the dissipated proportion of ultimate elastic strain energy relative to post-peak failure energy and residual elastic strain energy. A series of conventional triaxial compression (CTC) tests were performed on shale rock to verify the reliability and accuracy of the brittleness index. The results show that the proposed index can precisely reflect the deformation and failure characteristic of rocks under different confining pressures. Based on the testing data from six types of rocks in previous studies, the universality of the novel index was verified. According to comparison with existing brittleness indices, the new brittleness index can more precisely characterize the brittleness of rock.