This thesis comprehensively uses the methods of theoretical analysis,numerical calculation,field test and engineering practice to systematically study the relationship between the stress distribution of the surrounding rock of the stope and the rockburst,the pressure relief mechanism of the boreholes,the pressure relief region of the boreholes,and the layout parameters of the boreholes.According to the "three-factor" mechanism of rock burst,it is believed that the stress of coal and rock mass is a key factor of rock burst.Due to factors such as the depth of mining,the properties of the coal and roof,the local stress concentration of surrounding rock easily induce rockburst under dynamic disturbance.Therefore,the prevention measures for rockburst should also be built around the stress.The weakened zone in the coal body,destroys the bearing structure of the coal of roadway,causes the redistribution of stress in the coal and rock mass.The weakened zone plays an energy-absorbing protective role against instability of deep coal and rock mass,reducing the risk of rockburst,and thus preventing the occurrence of rockburst.Based on the elasto-plastic mechanics,the boundary equations of the pressure relief zone around the borehole are deduced,and the distribution of the pressure relief zone of the borehole is related to the vertical stress,lateral pressure coefficient,borehole diameter,cohesive force and internal friction angle of the coal.As the coal cohesion and internal friction angle,the lateral pressure coefficient decrease or the vertical stress of the drill hole increases,the pressure relief area of the borehole increases,and the angle between the direction of the maximum radius and the horizontal direction increases,and the shape of the pressure relief zone boundary changes from an ellipse shape to an “X” shape,which explains the poor pressure relief effect of hard coal.Using theoretical analysis and field tests,it is concluded that in the high-stress concentrated coal body,the pressure relief zone is in an “X” shape,and the maximum radius of the pressure relief zone is at a certain angle with the horizontal directionThrough the numerical simulation method,the effect of the drilling arrangement and the inter-row distance on the pressure relief effect is analyzed.It is proposed that the formation of the weakened zone in the coal body and the height of the weakened zone directly affect the pressure relief effect of the boreholes.The higher the weakened zone,the better the pressure relief effect.According to the thickness of the coal seam and the degree of rockburst hazard,the arrangement of the boreholes for the first time pressure relief and repeated pressure relief is determined.The inter-row distance between the boreholes should make the pressure relief zone of the boreholes penetrate each other.The determination of the borehole diameter needs comprehensive consideration of the thickness of the coal seam,the degree of rockburst hazard,and the construction conditions.The depth of borehole should ensure that the roadway coal doesn’t affected by the instability of the coal in the deep area.A comprehensive analysis was made of the causes of rockburst in the mining gateway of a mine.It is proposed that borehole relief pressure change the properties of coal,control the generation of high stress,and prevent the rockburst of coal and rock mass.Through the practice of the 311103 working face in the mine,the rationality of the method proposed in the thesis for determining the boreholes arrangement was verified. |