Abstract:
As the basic mechanical mechanism of coal bump in coalmine, energy accumulation and release has become one of the focuses in the academic and engineering fields in recent years. How to break through the present situation of deformation energy induced disaster mechanism based on traditional stress-strain curve, and research the kinetic energy driving mechanism, is a bottleneck of learning coal bump scientifically. According to the change of abutment pressure caused by mining and the rationale of mining disturbance, authors deduced a calculation method of mining kinetic energy, obtained the relationship between kinetic energy and depth, width of plastic zone, and advancing degree, and put forward a risk assessment index of mining kinetic energy. It was found that the release of high strain energy caused by concentrated abutment pressure is only a necessary condition for coal failure, the release and transformation of strain energy into kinetic energy is a sufficient condition for coal dynamic failure or coal bump. By deducing the kinetic energy calculation formula caused by abutment pressure change when advance of coal face is less than or greater than width of plastic zone. It was found that kinetic energy will be generated when mining advance is larger than 0.8 times the width of plastic zone. When mining advance is as a constant, the greater the width of plastic zone, the less the kinetic energy transferred. Therefore, such means to increase the plastic zone width as loose blasting, large diameter borehole pressure releasing and others, are conducive to the reduction of kinetic energy. The larger the mining advance, the higher the transferred kinetic energy. Therefore, reducing mining advance is conducive to reducing the transferred kinetic energy. The larger the mining advance is, the higher the kinetic energy transferred, thus, the reduction of mining velocity or the reduction of mining advance is beneficial to reduce kinetic energy. It provides a quantitative method for determining allowable advance of coal seam with different coal bump degree. The ratio of the kinetic energy per unit volume of coal to the elastic strain energy was defined as a risk assessment index of kinetic energy impact, which emphasizes driving mechanism of kinetic energy and is more conducive to judge the risk degree of coal bump.