| Generally,wide coal pillars are used for roadway protection between fully mechanized coal mining faces,and the width of section coal pillars is generally20-50 m.Due to the advantage of improving coal resource recovery rate,small coal pillar roadway has attracted the attention of scholars and coal mine enterprises in recent years.But compared with leaving wide coal pillars,the surrounding rock stability is poor due to the small coal pillars protecting the road pillars,especially under the condition of large mining height face,it is more difficult to control the surrounding rock.Based on this,this paper proposes to use the method of pressure relief to control the deformation of surrounding rock and improve the stability of small coal pillars.This paper takes the tunneling along the goaf in the 151106 working face of Fusheng Coal Mine as the research background,and adopts the method of combining laboratory test,theoretical analysis,numerical simulation and industrial test to analyze the overburden rock structure and stability of the roadway with large mining height and small coal pillar.1.The reasonable width of small coal pillars and the surrounding rock control technology are studied.The main results are as follows:(1)Based on the data collection and collation of the actual mining situation of No.15 coal seam in the first mining area of Fusheng Coal Mine,on-site drilling core drilling,peeping and laboratory experiments of physical and mechanical parameters were adopted for the mining conditions of 151102 and151106 working faces The method has mastered the lithology distribution status and coal rock mechanical parameters of No.15 coal seam roof and floor.(2)The law of collapse of overlying strata on the working face with large mining height was analyzed,and the characteristics of each stratum were determined.The influence of the critical block rotation angle on the surrounding rock deformation along the roadway is studied.According to the coal pillar load formula,the relationship between the coal pillar load and the lateral support angle is calculated.(3)Using FLAC3 D software to conduct numerical simulation analysis onthe reasonable width of small coal pillars reserved for roadway with large mining height and small coal pillars,comparatively study the stress distribution characteristics of coal pillars and the deformation law of roadway surrounding rock under different width conditions,combined with theoretical calculations,Finally,the reasonable width of the small coal pillar is 8.0m.(4)In order to further improve the stability of coal pillars,it is proposed to adopt cutting-top pressure relief roadway technology to reduce the load of coal pillars and improve the surrounding rock stress environment of small coal pillar roadways.Based on this,the numerical simulation method is used to study the parameters of cutting pressure relief.By comparing and analyzing the coal pillar stress and the deformation law of roadway surrounding rock under different cutting height and angle conditions,the cutting roof under this geological condition is obtained.The height is 16.0m,and the cutting angle is 0 °.(5)The field practice results show that the cumulative deformation of the roof and floor along the empty roadway and the two gangs are 71 mm and 70 mm respectively,the convergence rate of the roadway section is 3%,and the deformation control of the surrounding rock of the roadway achieves the expected effect.The research results provide a certain reference and guidance for other mines with similar geological conditions,and have significant economic and social benefits. |
PDF Full Text Request