Mechanical responses of bedding coals under uniaxial compression: Insights from deformation, energy and acoustic emission characteristics

To evaluate the mechanical anisotropy and acoustic emission characteristics of bedded coal samples under uniaxial compression, this research makes use of both an acoustic emission system and a rock mechanics system. The findings indicate that there is a large anisotropy in the mechanical characteristics of the coal. The uniaxial compressive strength of the coal samples shows a trend of first decreasing and then increasing with changes in bedding angle. The average compressive strengths of coal samples with bedding angles of 0 degrees, 30 degrees, 60 degrees, and 90 degrees are 14.5 MPa, 10.7 MPa, 3.5 MPa, and 4.6 MPa, respectively, with the lowest value occurring at 60 degrees.Data from AE have been used to develop patterns of the progression of bedded coal degradation over time. The coal sample with a bedding angle of 60 degrees fails in 105.5 s approximately 40.4 % faster than the 177 s required for the sample with a bedding angle of 0 degrees.The total energy, elastic strain energy, and dissipated energy of the coal drop, and then they grow again. The coal sample with a bedding angle of 60 degrees has the smallest dissipated energy, accounting for 18.05 %, and is the most likely to fail under energy-driven conditions. The levels of difficulty associated with deformation and failure follow a pattern that may be described as tough, easy, and challenging when energy is the driving force. Through the process of constant fracture development, samples with a bedding angle of 0 degrees fail, while those with angles of 30 degrees and 45 degrees experience a transition from gradual to unstable propagation. Bedding angles of 60 degrees and 90 degrees lead to sudden and unstable failure.