Mechanical and Propagating Behaviors of Single-Flawed Rock Samples with Hydraulic Pressure and Uniaxial Compression Conditions

A large number of discontinuities is frequently encountered in geotechnical engineering that significantly influences the stability of engineering. Therefore, it is important to investigate the mechanical properties and failure modes of a flawed rock mass. For this study, a series of uniaxial compression experiments was carried out on yellow sandstone samples containing a single flaw and mechanical analyses were conducted accordingly. The experimental results suggested that hydraulic pressure can induce a relatively high peak axial strain in the samples. However, the hydraulic pressure had a different influence on the uniaxial compressive strength of samples with flaws at different inclination angles. Moreover, three new types of crack were observed: One was a tensile crack, and the others were lateral cracks that emerged in samples under hydraulic pressure. On the basis of the analytical method, the calculated results were verified by the experimental results. The findings indicated that the crack initiation position moved toward the flaw tip and the crack initiation angles were reduced when the hydraulic pressure acted on the flaw surface. Furthermore, the hydraulic pressure induced greater initiation strength and strain in the samples, except for the samples with inclination flaws greater than 75 degrees. (C) 2018 American Society of Civil Engineers.