Investigation of moisture variation effects on the compaction, bearing characteristics, and mechanical behavior of fissured coal

This is the authors' abstract. We don't add key points for this paper.

This study explores the effects of moisture content and fissure orientation on the mechanical behaviour of fissured coal and the compaction and load-bearing characteristics of fragmented rock, with direct implications for coal mine safety and stability. Uniaxial compression tests, Acoustic Emission (AE) monitoring, and RA-AF parameter analysis were employed to assess fracture development under varying fissure inclinations (0°, 15°, 30°, and 45°) and moisture conditions. The results reveal that coal peak strength decreases at 0° and 15° but increases at 30° and 45°, while the elastic modulus exhibits a consistent upward trend with increasing fissure angles. Moisture content significantly reduces both peak strength and elastic modulus, delays crack initiation, and promotes more extensive crack propagation within the fracture process zone (FPZ), without altering dominant crack modes. In fragmented rock, increased moisture affects compaction behaviour, stress distribution, and deformation patterns, thereby reducing load-bearing capacity. AE b-values and RA-AF trends indicate a shift from shear to tensile failure mechanisms with higher fissure inclinations. FLAC3D numerical simulations corroborated the experimental observations, accurately reproducing crack propagation and FPZ evolution. These findings provide critical insights into moisture-fissure interactions, supporting improved design and stability control strategies for coal pillars and underground mining structures.