Experimental investigation and numerical simulation analysis of non-penetrating spatial crack propagation and coalescence behaviors

Abstract

This study employs a comprehensive approach integrating experimental analysis and numerical simulation to systematically examine the propagation characteristics of non-penetrating spatial cracks during rock fracturing processes. The results reveal significant differences between the propagation modes of non-penetrating and penetrating cracks. Surface observations demonstrate that anti-wing cracks, as a typical three-dimensional propagation feature, although not necessarily initiating from pre-existing crack tips, predominantly propagate along the loading direction and frequently coalesce with wing cracks to induce localized surface spalling. Internal analysis indicates that crack inclination angle critically influences adjacent crack paths: when the angle between cracks and loading direction increases, micro-cracks preferentially nucleate at edge regions, which subsequently affects both crack propagation behavior and specimen strength. The wrapping effect of wing cracks governs the internal-external connection sequence of adjacent cracks, creating discontinuous propagation patterns through self-inhibition mechanisms until crack coalescence occurs. Peak strength analysis shows a non-monotonic relationship with inclination angles, exhibiting fluctuations at 15° and 45° before reaching maximum values at 90°. Notably, wrapping phenomena persist universally across specimens (including surface-cracked specimens) except at 0° and 90° inclinations, confirming their prevalence in rock fracture processes. Under these special inclination conditions, newly formed cracks exhibit distinct directional propagation characteristics. These findings elucidate the three-dimensional evolution mechanisms of non-penetrating spatial cracks and establish a theoretical foundation for fracture prediction in rock engineering.