Research and consideration on deep coal mining and critical mining depth

Based on characteristics of a series of engineering disasters such as rock burst,coal and gas outburst,roof weighting,water outburst with increasing depth,a quantitative difference between shallow and deep depth was discussed.Furthermore,based on demand on reserves capacity for sustainable mining and technological development,the concept and limit of critical mining depth were also proposed within the framework of the air temperature of mining face,control of tunnel deformation and mining-induced strain energy accumulation of surrounding rocks.