Analysis of mechanical response mechanism and energy evolution characteristics of saturated coal with a single pre-existing hole

Abstract

It is very important to elucidate the mechanical mechanism of the effect of water injection and large-diameter borehole pressure relief on coal rock deformation and failure for improving the pertinence and effectiveness of coal mine dynamic disaster prevention measures. In order to obtain the mechanical response mechanism and energy evolution characteristics of saturated coal with a single pre-existing hole, uniaxial compression test was carried out, and the failure process and acoustic emission characteristics of coal were monitored by using high-speed camera and acoustic emission monitoring system. The results show that the strength of coal samples deteriorated by 23.49%, 9.47% and 47.95% respectively by water saturation, single pre-existing holemeasures and the coupling effect of the two measures. The final failure mode of coal samples with different measures is shear failure mode. The law of fracture development and expansion and energy accumulation and release in different coal samples is roughly the same, but the speed of energy accumulation and release in different stages is different. Water saturation and single pre-existing hole measures can affect the impact risk of coal samples, and water saturation can significantly reduce the impact tendency of coal samples, and reduce the impact energy index of complete coal samples by 56.59%. The impact tendency index of natural coal sample is slightly increased by single pre-existing hole measures, and the impact energy index of intact coal sample is reduced by 46.78% by the coupling of saturated water and cavity measures. It can provide technical support for coal mine power disaster prevention and control.