Study On Disturbance Failure Law And Water Inrush Prediction Of Coal Seam Floor In Pingmei No.9 Mine

At present,the depth and intensity of coal mining are getting bigger and bigger,and the geological conditions are becoming more and more complex.and the stability of the coalseam floor strata is relatively poor.In the process of coal mine production in China,the problem of water inrush from floor is very prominent and widespread,which seriously threatens the mining of coal seam.This paper combines theoretical analysis with numerical simulation,the disturbance and failure law of No.2₁ coal seam in Ji16-17-22011 working face of Pingmei No.9 Coal Mine is studied,and the prediction of water inrush from coal seam floor was carried out.The following results were achieved:（1）The vertical stress of the rock mass of the floor is obviously changed:As the working surface continues to advance,the vertical stress of the bottom plate becomes larger and larger,and tends to be stable after reaching the maximum value.When the work is forward to 360m,the vertical stress reaches a maximum of 37.35MPa,and then tends to be stable.（2）The plasticity of the top and bottom of the working surface changes with progress:When the forward propulsion length is 210m,the depth of damage of the bottom plate reaches a maximum of 21.45m;When the forward propulsion length is 260 m,the roof damage of the height reaches a maximum of 40.14 m.（3）The vertical displacement of the top and bottom plates changes regularly with the advancement of the working surface:When propelling from 10m to 280m,the vertical displacement of the top plate is increased from 0.31cm to 4.59cm.When propelled to 310m,the vertical displacement of the bottom plate increases from 0.21cm to 2.57cm and does not increase.（4）The vulnerability of water inrush from coal floor is gradually increased from south to north.Vulnerable areas,more vulnerable areas and transition areas are concentrated in the northern,central and central parts of the minefield;The safer zone and the relatively safe zone are concentrated in the southeast and northwest of the mine.Their proportion in the entire mining area is 3.69%,17.22%,37.88%and 41.21%.The non-pressure zone is located near the southern boundary of the mine and is a safe area.