Experimental Investigation on Mechanical and Acoustic Emission Characteristics of Gassy Coal under Different Stress Paths

Abstract

Coal mining leads to stress loading–unloading variation in front of the working face, which influences the occurrence of disasters. In order to study the influence mechanism of stress loading–unloading to the coal failure, a series of experiments of gas-bearing coal deformation and failure under triaxial stress were conducted and acoustic emission (AE) was monitored. In this study, the effect of gas pressure on the mechanical behavior of gas-bearing coal in conventional triaxial stress (CTS) experiments and fixed axial stress and unloading confining stress (FASUCS) experiments was analyzed, and the damage evolution rules of gas-bearing coal in the CTS experiments and FASUCS experiments were determined using AE. The results show that with the increasing of gas pressure, the peak strength and peak strain of gas-bearing coal in the CTS experiments and FASUCS experiments gradually decrease, and the peak of AE ring-down counts lags behind the peak strength. Compared with the CTS experiments, the strength of gas-bearing coal in the FASUCS experiments is lower and the precursor information appears later. The trends in calculated stress and damage coefficient D are consistent with the stress path during unloading, and both begin to rise sharply after the sample enters the plastic stage. Therefore, AE ring-down counts, damage coefficient D, and calculated stress can be used as precursor information for failure of coal and rock, which has great significance for the further study of coal-rock material and for early hazard warning.

Analysis of Acoustic Emission Characteristics and Failure Mode of Deep Surrounding Rock of Sanshandao Gold Mine

“…Due to economic growth, the need for resources, especially mineral resources, is increasing. The depth of mining engineering has also been increasing [ 1 , 2 ]. As the depth of mining increases, rock deformation and the failure of deep roadway become the main causes of mining safety accidents [ 3 , 4 ].…”

Influence of Confining Pressure on Nonlinear Failure Characteristics of Coal Subjected to Triaxial Compression

“…Fractures in natural rocks play an important role in determining the strength, deformability, and failure behavior of rock masses; to increase the strength of fractured rock masses, rock-reinforcement methods are always used in underground mining [4][5][6][7][8][9]. Frequent coal mining accidents seriously threaten people's lives and property safety [10][11][12][13][14]. Therefore, a comprehensive analysis of the effect of the confining stress on the deformation and failure characteristics of coal and rock can help to better understand the complex deformation and failure process of deep coal rock.…”