On the Strength and Crack Propagation Process of the Pre-Cracked Rock-Like Specimens under Uniaxial Compression

The pre-cracked cylindrical specimens of rock-like materials are experimentally tested under compressive loading (using specially made rock-like specimens from portland pozzolana cement). The stress-strain and strength of the specimens are measured showing the decreasing effects of the cracks and their orientation on the final breakage stress of the specimen. The crack initiation and coalescence stresses during the crack propagation process are observed. The breakage process of the specimens is studied by inserting single and double cracks with different inclination angles at the center and applying uniaxial compressive stress at both ends of the specimen. The wing cracks are produced at the first stage of loading and start their propagation toward the direction of uniaxial compressive loading. The secondary cracks may also be produced in form of quasicoplanar and/or oblique cracks in a stable manner. The secondary cracks may eventually continue their propagation in the direction of the maximum principle stress. The same specimens are numerically simulated by an indirect boundary element method known as displacement discontinuity method. One may validate the results by the numerical and experimental results given in this study.