基于平均应力集度差的近距离煤层下位煤巷围岩应力弱化研究

Study on Stress Weakening of Surrounding Rock in Lower Coal Roadway of Close Distance Coal Seam Based on Average Stress Concentration Difference

针对近距离煤层下位煤巷在进行沿空留巷时的应力集中以及巷道大变形难以支护等问题,采用理论分析、数值模拟和工程试验等方法,开展近距离采空区、实体煤和煤柱下煤巷围岩应力弱化研究。通过建立侧向支承应力数学模型,确定了平均应力集度差这一新的应力弱化评价指标;通过FLAC^(3D)数值模拟结果计算得到了平均应力集度差的变化规律,确定了采空区最佳切顶角度为90°,最佳切顶高度为10 m,实体煤段和煤柱段最佳切顶角度为90°,切顶高度为8 m;现场试验后围岩变形量显著减小。

Aiming at the problems of stress concentration and difficult support of large deformation of roadway during gob-side entry retaining in lower coal roadway of close distance coal seam,use theoretical analysis,numerical simulation and engineering test to carry out research on stress weakening of surrounding rock of coal roadway under close goaf,solid coal and coal pillar.By establishing the mathematical model of lateral support stress,the new stress weakening evaluation index of average stress concentration difference is determined.The variation law of average stress concentration difference is calculated by FLAC^(3D) numerical simulation results,and the best roof cutting angle of goaf is 90°,the best roof cutting height is 10 m,the best roof cutting angle of solid coal section and coal pillar section is 90°,the best roof cutting height is 8 m;the deformation of surrounding rock is significantly reduced after field test.