An experimental study on deformation and strength anisotropy of transversely isotropic rocks in Korea

摘要

This paper reports the experimental investigation of deformation and strength anisotropy of Asan gneiss, Boryeong shale and Yeoncheon schist in Korea which show clear evidence of the transverse isotropy. For each rock type, three sets of seven cylindrical specimens cored with angles of 0, 15, 30, 45, 60, 75, and 90 degrees with respect to transversely isotropic planes were obtained by using laboratory directional coring system. Five independent elastic constants of transversely isotropic rocks were determined using various combinations of strain measurements obtained from specimens having different coring directions. The applicability of transversely isotropic model to the chosen rocks was quantitatively investigated by comparing the values of apparent elastic moduli with the theoretical ones predicted by tensorial transformation of compliance matrix. The mean prediction error defined as the average relative difference between measured and predicted elastic moduli were low, which indicates that transversely isotropic model is a reasonable assumption for the rock types chosen in this study. The extent of anisotropy in deformation, uniaxial and tensile strength observed in this study is rather significant and this study reconfirms the importance of anisotropy in rock engineering.