Experimental testing reveals that faster lateral unloading accelerates brittle failure in coal-rock combinations, highlighting the mechanics of deep mining rock bursts.
Key Points
To investigate how different lateral confining pressure unloading rates influence energy evolution, acoustic emission characteristics, and structural damage in coal-rock combinations.
Conducted triaxial unloading tests on coal-rock combination specimens under constant axial stress.
Applied four confining pressure unloading rates: 0.02, 0.06, 0.10, and 0.14 MPa/s alongside continuous acoustic emission monitoring.
Elastic energy primarily accumulated during initial loading, whereas lateral unloading triggered rapid energy dissipation and mechanical instability.
Increasing the unloading rate significantly accelerated damage accumulation, reduced energy storage capacity, and produced intensified acoustic emission activity.
Failure mechanics shifted from progressive, gradual damage to abrupt, brittle failure as the lateral unloading rate increased.