Stability Analysis Of Surrounding Rock Under Continuous Mining And Filling In Huangbaici Coal Mine

Huangbaici 12#coal seam belongs to shallow coal seam,and it is easy to cause surface subsidence and ground fissure when fully mechanized mining at one time.At the same time,fully mechanized mining will result in large roof settlement,and frequent periodic pressure phenomenon constantly causes disturbance to the roadway roof.In order to control the subsidence of overlying strata,reduce the surface subsidence and protect the structure of overlying strata in the process of coal mining,this paper studies the control effect of continuous mining,continuous filling and filling mining method on the stability of surrounding rock in Huangbaici Coal Mine by means of field investigation,theoretical analysis,laboratory test,numerical simulation and field application.(1)Due to the full-height mining method of fully mechanized mining at one time,the roof of roadway in No.12 coal seam fell and deformed,and was disturbed by periodic pressure at the same time,resulting in the continuous increase of roof subsidence.The roof of the roadway is continuously deformed and damaged under the influence of strong pressure.(2)The physical and mechanical tests were carried out on the 011207 working face of 12#coal seam with samples taken from the old roof,direct roof and coal seam.The average compressive strength of the old roof reached 35.58MPa,the average compressive strength of the direct roof reached 33.55MPa,and the average compressive strength of the coal seam reached 19.58MPa.The roof strength can provide conditions for filling mining.(3)In the process of backfill mining,"coal pillar and backfill body" transitions from the limit state to the subcritical state according to the dangerous state,and then maintains the stable state after temporarily maintaining the sub-stable state.The roof stress in the stable state is 4.27MPa,and the minimum strength of the backfill reaches 4.13MPa through analysis,which can meet the needs of supporting the roof.By analyzing the caving step distance of fully mechanized mining face,it is determined that the width of backfill mining roadway and coal pillar are both 5m.(4)According to the roadway width and coal pillar width of 5m,the numerical simulation of non-filling and continuous mining and filling was carried out.The results show that the maximum settlement and maximum stress of the odd roadway filling mining are 5.32mm and 5.55MPa,and the maximum settlement and maximum vertical stress of the even roadway filling mining are 10.21mm and 5.51MPa,respectively.Compared with the condition without filling,the displacement in the two stages decreases by 70.9%and 44.3%respectively,and the vertical stress decreases by 33.8%and 34.2%respectively.It can be found that continuous mining and filling can improve the stability of surrounding rock.(5)The field engineering application is carried out according to the simulation scheme of continuous mining and filling.The continuous mining and filling method of dividing strips,interval jumping mining and instant filling is adopted in the working face.The monitoring results of 011207 working face show that the maximum subsidence of the working face is 10.5mm,the stress of the working face remains extremely low,and the surface has no deformation basically.It is proved that the continuous mining and filling mining method has a good control effect on the surrounding rock.