Mechanical Properties and Damage Characteristics of Coal-Rock Combination with Different Dip Angles

The effect of the dip angle of an interlayer coal seam on rock mass mechanical behavior and damage characteristics is seldom discussed. To address the lack of the existing research, a numerical simulation was conducted using the Particle Flow Code (PFC2D), and its damage to mechanical behavior, acoustic emission (AE)characteristics, and damage characteristics were analyzed. The outcomes exhibit the peak strength and elastic modulus of coal-rock combinations are between that of rock and coal. As the coal inclination angle rises, the elastic modulus and peak strength gradually decrease. AE model experiences the initial growth period, stable growth period, and rapid decline period. The value of AE hits and the generation of the AE signal is affected by the size of the inclination angle. The degree of damage to the coal-rock combination gradually rises as the angle rises. The damage process of the coal and rock composite sample encompasses an initial damage phase, damage stable evolution phase, accelerated damage phase, and a failure phase. The damage values of the stable evolution stage for varying dip angle models are also different. As the inclination angle increases, the damage value gradually increases, while the strain at the same damage value gradually decreases.