Causes for rockburst and control of gob side entry in deep two soft coal seams

For the geological conditions of two soft coal seams, mechanical models for rockburst occurring in two soft coal seams. Mechanical analysis and field practice of these models show that the main causes for rockburst in deep two soft coal seams are the stress concentration and energy accumulation in the soft alluvium that is clamped in the upper force source layer and the lower stable layer, and the energy accumulated from mining activities which releases to crushing mitigation areas, causing instantaneous ejection of coal and rock blocks and forming the rock burst. Through the researches on stress, energy, material conditions and inducing factors for burst of deep two soft coal seams, the prevention measures for rockburst of block structure of the roof support structure such as transferring stress, maintaining the stability of chain pillars, strengthening coal side, and loosening working slope are formulated. Field practice is made so as to realize the safe and high-efficiency non-impact mining at working faces.