Mechanisms of rockburst and outburst compound disaster in deep mine

To explore the mechanisms leading to the compound disaster of rockburst and outburst,and to provide a the-oretical basis for its effective monitoring and prevention through theoretical analysis and laboratory tests,this study in-vestigates the influence of gas on the mechanical properties and rockburst tendency of coal rock,establishes the rock-burst and outburst compound disaster model of circular roadway,and explores the induced transformation mechanisms of rockburst and outburst. The results show that the strength,elastic modulus and peak strain of coal rock all have a negative correlation with gas pressure. At the same time,the rockburst tendency of coal rock decreases with the in-crease of gas pressure. There exists a critical value of coal rock stress,when the coal rock stress exceeds the critical stress value,the system loses its stability and rockburst and outburst compound disaster occurs. The critical stress in-creases with the increase of gas pressure and coal strength,and it first decreases and then increases with the increase of rockburst tendency. Outburst-induced rockburst occurs mostly in a soft and hard coal seam. Rockburst-induced outburst occurs mostly under a situation which the gas-storing structures,such as a gas-bearing closed fault,exist in the coal body or a high elastic modulus strata exists in floor. Outburst-induced rockburst may also occur in another situa-tion during which the ejection of a fragmentized coal body forms a larger empty support area during the process of out-burst.