特厚煤层预掘回撤通道稳定性分析

Stability Analysis of Pre-driving Retracement Gateway in Extra-thick Coal Seam

鉴于特厚煤层预掘回撤通道围岩应力分布状态复杂的问题,采用数值模拟计算的方式分析了特厚煤层综放工作面预掘回撤通道采动应力场演化规律:回撤通道同回采工作面间煤柱中的应力呈动态增加态势,并且在净煤柱宽度为35 m左右时,回撤通道侧煤柱应力受到工作面显著影响;末采段煤柱的应力变化同煤柱稳定性有很大的关系,当末采段煤柱宽度为5 m时,应力达到最大值,导致煤柱完全屈服破坏。现场应用结果表明,回撤通道在净煤柱为40 m时变形量开始逐渐增加,当末采段煤柱为7 m左右时,回撤通道两帮的收缩量达到最大,煤柱失稳破坏,现场巷道变形监测结果同数值计算结果具有相同趋势。

In view of complicated stress in pre-driving recovery gateway at fully mechanized caving face of extra-thick coal seam,the method of numerical simulation was used to analyze the stress evolution laws,and the results indicate that stress shows a increasing trend in the pillars between the pre-driving retracement gateway and working face,and the stress in channel side retracement pillar is significantly affected by the working face when the clean coal pillar width is around 35 m; the stress variation closely associated with stability of coal pillar at the last mining stage. At maximum stress,the pillar at last mining stage is completely yield and destroyed when the clean coal pillar width is around 5 m. Field application results show that the deformation of the pre-driving retracement gateway gradually increases when the clean coal pillar width is at around 40 m,and shrinkage of which is maximized when the clean coal pillar width is at around 7 m. The in-situ deformation monitoring results of the pre-driving retracement gateway has the same trend with the numerical results.