Study On The Effect Of Mining And Activation On The Secondary Fault In The Bottom Plate

In this paper, the activation law of the main fault under the influence of the secondary fault and the problem of the protection of the coal pillar are studied. The numerical simulation method and the orthogonal experiment are used to analyze the main fault inclination, the secondary fault dip, the primary and secondary fault spacing, The influence of the secondary fault on the stress change, the activation degree and the coal pillar width of the main fault is studied. The paper summarizes the prevention and control measures of the water inrush from the bottom plate. The main conclusions are as follows:1) the main fault interval increases, the main fault normal stress, tangential stress peak gradually become smaller, and gradually move to the deep, the secondary fault on the main fault stress and activation of the degree of influence and the impact of the scope is gradually smaller, The width of the pillars to be retained increases first and then decreases;2) The increase of the dip angle of the main fault and the influence of the secondary fault on the normal stress and the tangential stress on the main fault near the coal seam are reduced,and the influence degree of the other faults is different. The effect of the secondary fault on the activation of the main fault becomes smaller and the width of the coal pillars to be retained decreases, and the influence of the secondary fault on the width of the coal pillar Diminishes;3) The dip angle of the secondary fault decreases, and the influence of the secondary fault on the normal stress and tangential stress of the secondary fault is not changed, and the influence of the secondary fault on the normal stress and tangential stress of the main fault is increased The effect of the fault on the activation of the main fault is gradually increased. With the increase of the dip angle of the secondary fault, the width of the pillar is also increased.When the dip angle of the secondary fault is greater than 150 °, The increase in the width of the pillars to be retained is not significant;4) The distance between the secondary fault and the coal seam floor increases, the normal stress and the tangential stress gradually move toward the deep, and the influence of the secondary fault on the normal stress and tangential stress of the main fault gradually moves to the deep The influence of the secondary fault on the normal stress and tangential stress of the main fault is getting smaller and smaller, and the influence degree of the secondary fault on the activation of the main fault increases first and then decreases. Increase and decrease;5) The influence of the above four factors on the width of the coal pillar is: the dip angle of the secondary fault> the inclination of the main fault> the distance between the upper end of the secondary fault and the coal seam> the primary and secondary fault spacing.The research results have some reference significance for the prevention and control of water inrush from floor fault in the case of secondary fault.