保护层开采过程中围岩应力演化规律研究

Study on the Stress Evolution Rule of Surrounding Rock in the Process of the Protected Coal Seam

分析了冲击煤层上保护层开采过程中围岩应力演化规律。研究表明:在工作面开采前方0～20 m范围煤岩体内纵向压力处于增长阶段,应力集中系数达到2.0。在20～60 m为纵向压力逐步恢复阶段,应力集中系数达到1.7,应力集中峰值出现在工作面前方5 m处左右。工作面开采50 m之后,超前支撑压力有规律地呈现两次应力集中和两次应力释放现象。分析了保护层采空区及工作面下覆不同垂直高度处围岩应力随煤层开采进度演化规律,指出采空区纵向应力随采空区深入,呈现逐步增大趋势。在采空区两侧下方被保护层应力值升高幅度要大于其中间区域,保护层工作面的压实作用传递到被保护层工作面在空间上稍微滞后,这个滞后的距离在30～40 m。

Analyzed the evolution rule of surrounding rock stress during the process of protected coal seam,studies show：the longitudinal pressure on the coal and rock in the growth stage ahead of the coal face 0 ～ 20 m.The longitudinal pressure on the coal and rock gradually recovery phase in 20 ～ 60 m,the stress concentration factor reaches 2,Peak stress concentration at the working face in front of the 5 m or so,the stress concentration factor reaches 1.7,after the working face mining 50 m,advance support stress regularly present two stress concentration and stress release twice ＂two up two down＂ phenomenon.Analyzed the evolution rule of different heigt surrounding rock stress along with the coal seam mining progress in protective coat and the cove under working face,pointed out that the mined-out area longitudinal stress has gradually increased with goaf deep.The supporting layer compaction is transferred to the protected layer working face in time slightly lag,this lag distance is about 30 ～40 m.