Experimental study on crack penetration mechanism and filling enhancement effect in complex fissured rock mass

This study delves into the mechanical properties and crack propagation mechanisms in complex fissured rock masses, utilizing advanced 3D printing and digital image correlation (DIC) technologies. The research focuses on the impact of different filling materials—specifically HIPS and low-strength gypsum—on the stability and failure modes of rock-like specimens. Through uniaxial compression tests, the study examines how these materials influence the stress-strain behavior, crack initiation, and propagation patterns. Key findings reveal that HIPS filling significantly enhances the peak strength and modulus of elasticity of the specimens, while low-strength gypsum filling also improves these properties but to a lesser extent. The study highlights the time-sensitive nature of crack propagation near different fissures, with outer fissures typically developing first and forming penetration cracks. The main penetration cracks are found to be parallel to the stress loading direction, and their formation is influenced by the strength of the filler materials. As the filler strength increases, the main penetration crack area shifts from the center to the sides of the specimen. The research concludes that the lengths and angles of pre-existing fissures forming the main penetration regions fall within specific intervals, with the standard deviation of these parameters correlating positively with the peak stress and strain of the specimens. This comprehensive analysis provides valuable insights into the mechanical behavior of complex fissured rock masses and the effectiveness of different filling materials in enhancing their stability.