Study on triaxial compression failure mechanism of fractured coal and rock in 4-2 coal seam of Yuhua Mine

Abstract

In this paper, the TAW-1000 triaxial test system is used to carry out the triaxial compression test of the complete and single fractured coals under different confining pressures, and the acoustic emission monitoring system is used. This paper analyzes the failure mechanism of fractured coal and rock based on the fracture diagram of fractured coal and the relationship between stress and strain. The results show that: the stress of single fracture coal is more complex than that of intact coal. The stress concentration at the tip of the fracture leads to the formation of micro cracks and the development of connectivity, which makes the coal enter the plastic stage earlier and leads to the significant deterioration of the strength and elastic modulus of coal. The results show that the lateral deformation of fractured coal and rock is more significant than that of intact coal and rock under higher confining pressure; with the increase of confining pressure, the fracture mode of 45° fractured coal and rock presents an excessive failure mode from direct shear failure to oblique shear failure; the stress-strain curve of 60° fractured coal and rock presents a plateform softening, and the change of elastic modulus is not obvious with the increase of confining pressure; under the same confining pressure, with the increase of fracture angle, the mechanical parameters of fractured coal and rock deteriorate significantly with the increase of fracture degree. The fracture dip angle is positively correlated with the ringing number.

Keywords

• fractured coal
• triaxial compression
• failure mechanism
• acoustic emission
• stress concentration