Study On Mechanism And Control Technology Of Rock Burst Induced By Mining In Fault Area

With the increase of mining depth, fault structure is significantly increasing during the face mining and tunneling. However, these fault structures are often in a state of unstable equilibrium, which makes it easy to activate fault by mining, and thus induce rock burst.Therefore, the theoretical analysis, numerical simulation and field monitoring methods are used to study mechanism and control technology of rock burst induced by mining in fault. The main achievements are as follows:(1) Based on Mohr-Coulomb law, stress state of fault unit, normal and shear stress state of fault surface are analyzed. And, the law of stress of unit, normal and shear stress are obtained by using of theory analysis. The results show that; the larger the minimum principal stress in rock is, the smaller the upward opening of the maximum principal stress is, and the greater the possibility of rock failure. Both the normal stress and shear stress of fault surface decrease with the increase of fault plane angle, and the degree of reduction increase.(2) The shear stress and normal stress ratio of fault plane have comparison with internal friction angle of tangent value by using the shear instability theory, and the instability characteristics of fault are discussed. At the same time, the amount of energy release and magnitude of fault impact instability are estimated by using cusp catastrophe theory. The results show that: the energy release of fault rock burst is in the form of hyperbolic curve with the ratio of n and the variation of m of rock mass, and decreases with the increase of the ratio n.When the Rock mass homogeneity m is constant, the energy release of the fault rock burst increases gradually with the decrease of the ratio of the pressure, and the larger the width of the fault zone is, the smaller the energy released by the failure of the fault is.(3) The vertical stress and elastic strain energy evolution laws of ahead of face and the junction between mine and fault structure are analyzed by using FLAC numerical simulation software under the influence of reverse fault, fault dip and fault fall, which is discussed its influence on the stability of faults. The results show: In the condition of the same coal rock mass parameters and working face layout, the variation of fault fall has the greatest influence on the vertical stress and elastic strain energy in fault control area, the influence of dip angle is closely followed, and influence of normal and reverse faults is minimum, where gradually decreased rock burst danger in the control area of fault by mining.(4) Based on the geological conditions and mining technical conditions of working face,the comprehensive index method and the probability index method are used to evaluate the rock burst risk of working face and the factors that influence the mining are analyzed. At the same time, the influence of the variation of drilling distance and diameter on the pressure relief effect is analyzed. The results show that: For certain geological conditions the smaller borehole spacing, the larger hole diameter is, the more obvious effects of discharge pressure.After drilling pressure relief, the stress of ends of the borehole is smaller than that of middle part of borehole with single peak change.