Abstract: To investigate the deformation and failure mechanisms of deep coal seam floors,we compared and analyzed the stress-strain behavior,acoustic emission energy events,and strength variations of sandstone samples subjected to different initial confining pressures and varying loading and unloading rates. We also examined changes in damage factor,Elastic modulus,and Poisson’s ratio under these conditions. The results indicate that,at an unloading rate of 0. 06 MPa/s,the onset of elastic modulus degradation under an initial confining pressure of 40 MPa occurs earlier than the change in Poisson’s ratio,whereas the opposite trend is observed at an initial confining pressure of 25 MPa. When the confining pressure is unloaded at 0. 04 MPa/s,regardless of whether the initial confining pressure is 25 MPa or 40 MPa,the sandstone undergoes rapid crack propagation as a result of significant internal energy accumulation. This process is accompanied by a sudden drop in stress and is classified as energy-driven damage. Under an initial confining pressure of 25 MPa and an unloading rate of 0. 06 MPa/s,internal cracks in the sandstone fully develop,allowing accumulated energy to be released gradually,resulting in a more stable stress response. This behavior is defined as damage deterioration-driven failure. In contrast,at an initial confining pressure of 40 MPa and the same unloading rate,the sandstone first experiences a rapid stress drop due to the sudden release of internal energy. Subsequently,the failure mode shifts to crack propagation and deformation, influenced by confining pressure and axial compression, marking a transition from energy-driven damage to damage degradation-driven failure.