Dynamic disaster mechanism and acoustic emission evolution of deep coal-rock under true triaxial disturbance stress
Jun Lü, Wang Jiang, Heping Xie, Heng Gao, Dongming Zhang
Abstract
In deep underground resources mining engineering, rock mass exists in a three-dimensional environment of high stress, high fluid pressure, and high temperature. With the stress disturbance of mining engineering, it is easy to trigger high-energy coal-rock dynamic disasters, which severely restricts the safe and efficient development of deep resources. To investigate the non-linear fracture evolution process and key precursor laws of the coal-rock mass in the process of deep mining, an experimental study was conducted based on the true three-dimensional disturbance stress simulation experiment system. Results showed that the disturbance disaster process of the coal-rock mass has significant stages, and the corresponding acoustic emission (AE) signals also show regular changes. The necessary condition for the occurrence of coal-rock dynamic disasters is that the coupling of the maximum static stress and disturbance stress amplitude should exceed the damage threshold value, the increase of σ₂ can reduce the occurrence probability of disaster, and the influence of disturbance frequency on disaster intensity is transition. There are obvious stages in the damage accumulation process of stress-disturbed rock mass, including: damage weakening stage, no damage stage, and accelerated damage stage. The brief AE event calm period and the rapid decline of high average frequency value accompanied with the surge in the low-rise time/amplitude value before the disaster can be regarded as the key precursors of the rock dynamic disaster. The research results are crucial for understanding the disaster evolution of rock mass rupture disturbed by three-dimensional stress in deep engineering, and for the early warning and prevention of coal-rock dynamic disasters.