Mechanical behavior and damage mechanism of loaded coal and rock

Abstract

PurposeThe purpose of this paper is to obtain the mechanical behavior and damage mechanism of the coal and rock near the stope under the stress state and stress paths of the surrounding rock with the dynamic mining.Design/methodology/approachThrough the three-axial compression test and the uniaxial compression test by meso experiment device, the mechanical behavior and fracture evolution process of coal and rock were studied, and the acoustic emission (AE) characteristics under uniaxial compression of the coal and rock were contrasted.FindingsUnder the three-axial compression, the strength of coal and rock enhance significantly by confining pressure. The volume of outburst coal shows obvious stages: compression is followed by expansion. The coal first appear to undergo compaction under vertical stress due to volume decrease, but with the development of micro- and macro-cracks, the specimens appeared to expand; under the uniaxial compression, through the comparison of stress–strain relationship and the crack propagation process, stress drop and fracture of coal have obvious correlation. The destruction of coal was gradual due to the slow and steady accumulation of internal damage. Due to the influence of the end effect, the specimens show the “conjugate double shear failure”. The failure process of the coal and rock and the characteristics of the AEs have a corresponding relationship: the failure causes a large number of AE events. Before the events peak, there was an initial stage, calm growth stage and explosive growth stage. There were some differences between the rock and coal in the characteristics of the AE.Originality/valueThese research studies are conducted to provide guidance on the basis of mine disaster prevention and control.