Abstract

Rock masses are usually discontinuous in nature, as a result of various geological processes they havegation and coalescence processes mainlycause rock failures in tunnels. In this study, we focused on th e crack initiation, propagation and coalescenceprocess of rock materials containing two pre-existing open crac uniaxial compression, wing crack initiation stress, wing crack propagation angle, and crack coalescencestress of Diastone gypsum and Yeosan Marble specimens were exam ined. And crack initiation, propagation,ed (shear+tensile) types of crack coalescenceoccurred. To compare the experimental results with Ashby & Hall am model, crack coalescence stress wasnormalized and it generally agreed with the experimental result s.