Failure mechanism of rock-like specimens under uniaxial compression: Effects of hole-crack spatial relationship and crack number

The geometric characteristics of cracks exert a significant influence on the stability and failure behavior of rock masses, particularly in underground engineering contexts. This study integrated uniaxial compression experiments with numerical simulations using the Particle Flow Code in Two Dimensions (PFC^2D) to systematically investigate the failure modes, acoustic emission (AE) characteristics, and stress distribution patterns of rock-like specimens with varying hole-crack distances and crack numbers. The results indicated that the hole-crack distance had a pronounced impact on the specimen’s peak strength and failure mode. When the distance was 20 mm, the coupling effect between the hole and the crack was most prominent, often triggering boundary-crack-hole penetration failure. As the distance increased, the failure mode transitioned into asymmetric failure. An increase in crack number enhanced crack dominance, driving the failure zone from the specimen boundary toward the central zone, while intensifying stress field disturbance and localized instability. AE analysis showed that when the hole-crack distance was 15–20 mm and the crack number was two, energy release was abrupt and concentrated, frequently leading to severe instability. When the crack number increased to three, the failure process became more gradual, accompanied by greater energy consumption. Stress monitoring and numerical results further revealed that the spatial configuration between holes and cracks, combined with crack quantity, jointly altered stress transmission paths, induced localized stress redistribution, and promoted the development of asymmetric failure zones. These findings contribute to a deeper understanding of the failure mechanisms of fractured rock masses and offer theoretical guidance for the prevention and mitigation of crack-induced hazards in underground engineering.