Research on Stress Response Characteristics of Surrounding Rock in Stope Under Repeated Mining
In order to study the stress response and deformation failure law of surrounding rock in stope under close distance coal seam group repeated mining,taking the multi coal seam mining of Pan'er Mine as the engineering background,on-site investigation and numerical simulation methods are used to analyze the stress response characteristics and plastic zone evolution law of surrounding rock in different coal seam working faces under repeated mining of multi coal seams.The research shows that during the stoping of the 18126 working face,the larger the spacing between coal seams,the smaller the influence of mining on the vertical stress of coal seams;Due to the excavation unloading impact of the 7-1 coal seam and the 18126 working face,the unloading size of the 5-2 coal is greater than that of the 4-1 coal,and the unloading range of the 4-1 coal is greater than that of the 5-2 coal;Affected by the mining of the 18225 working face,the floor of the 5-1 coal seam undergoes unloading failure again,and the plastic zone of the floor develops to a vertical distance of 59 m between the bottom and the 5-1 coal;The expansion of the plastic zone along the coal seam dip direction of the 4-1 coal occurs again,with a maximum concentrated stress of 16.34 MPa,a minimum unloading stress of 9.56 MPa,and a stress difference of 6.78 MPa.The unloading range of the 4-1 coal along the dip direction is mainly concentrated in 183-266 m and 543-615 m.After the mining of the 18125 working face,the maximum concentrated stress of the 4-1 coal is 19.0 MPa,the minimum unloading stress is 7.44 MPa,and the stress difference is 11.56 MPa,located in the excavation unloading area of the 18126 working face.
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