预掘回撤通道末采围岩破坏机制研究

为保证工作面安全高效回撤,通过理论分析及现场观测法,研究综采工作面末采期间回撤通道围岩应力分布及破坏特征,提出垛架支撑力控制顶板围岩破坏机制及方法,得到垛架最小支撑力计算方法.结果表明:回撤通道围岩集中应力与工作面前方支承压力逐步叠加,导致剩余煤柱由两侧向中部逐渐破坏,当两侧破坏区连通时,煤柱上方直接顶跨距增加为原来的...

Study on failure mechanism of withdrawal channel's surrounding rock during last mining period

In order to make the working face withdrawal safe and efficient,the stress distribution and failure characteristics of withdrawal channel's surrounding rock in fully-mechanized area during last mining period were studies through theoretical analysis and field observation.Then,failure mechanism and method for roof surrounding rock control by supporting force of cog timbering were proposed,and calculation method of minimum initial support force of cog timbering was obtained.The results show that concentrated stress of the withdrawal channel's surrounding rock is gradually superimposed with the bearing pressure in front of working face,which leads to the gradual failure of remaining coal pillar from both sides to the middle.When the failure areas on both sides are connected,the direct top span above coal pillar is increased by 2 times,and the load is large.When the stress and span meet the instability conditions of direct roof,the latter is damaged before working face is cut through,thus leading to roof fall before penetration.Adjusting the initial support force of cog timbering can reduce superimposed stress value of coal pillar at the side of withdrawal channel,corresponding coal pillar width when remaining coal pillar loses stability and the span of direct roof,thus avoiding shear failure and ensuring smooth withdrawal.