LAUSR

A 3D internal open-type flaw inside gypsum rock-like specimens is prepared using a volume-loss method. It has three types of flaw inclinations and four types of flaw strike lengths. Uniaxial compression and acoustic emission monitoring tests show a small range of secondary local failures are initially distributed near the internal flaw. The area of these secondary failures remains stable and does not extend to other positions until the uniaxial compression strength status of specimens is reached. To explain the special test results, which have rarely been seen in previous 2D fractured rock studies, the surrounding rock of the internal open-type fracture is simplified as a rectangular board model with fixed boundary conditions on four sides. Theoretical calculations prove that a Destruction Region (secondary tensile failures) occurs in the central parts of the internal free surface as built from the internal flaw and is surrounded by a circular Anti-destruction Region. (The rock is under triaxial compression, and tensile failure cannot develop.) Once rock in the Anti-destruction Region reaches its triaxial compressive strength, the constraining effects on the secondary tensile failures disappear. These theoretical analysis results are consistent with experimental phenomena and provide an important reference for geotechnical engineering under similar conditions.