ARMA 12-571 A Numerical Approach of Failure Mechanism of Transversely Isotropic Rocks

摘要

Stress-induced rock failures occur during the construction of underground structures, which draws a considerable attention of geotechnical, mining, and petroleum engineers to understand the failure mechanism of rocks. This paper presents a numerical experiment for evaluating the strength and deformation characteristics of transversely isotropic rock specimen, 5 cm in diameter and 10 cm in height, using advanced finite element software PLAXIS. A mesh refinement study was conducted to select the appropriate finite element mesh for the proposed study to ensure that the computed responses are independent of the finite element mesh. Seven orientations of bedding plane (15, 30, 45, 60,75 and 90°) and four confining pressures (0, 2.5, 5 and 10 MPa) were considered in this study. The Mohr-Coulomb failure criterion was employed for each isotropic layer joined by an interface bonding. The results indicate that the failure strength is, in general, dependent on confining pressure and bedding plane orientation. The largest failure strength is obtained for case with maximum bedding plane, and the smallest strength is obtained when the bedding plane angle is between 40° and 60°. The predicted ultimate strengths are compared with the experimental results of Yi Shao et al. (1999). A reasonable match between the numerical and experimental approaches is observed, especially at low confining pressure.