厚煤层下分层综放缩面回撤通道围岩控制

Surrounding rock control of the retreat passage of the fully mechanized caving face under the thick coal seam

针对厚煤层分层开采下分层综放缩面时回撤通道受上分层采动、上分层煤柱产生集中应力、及本工作面采动等多重因素影响下,造成回撤通道巷围岩塑性区和破碎区范围扩大,易引发大面积的冒顶和片帮的问题,采用理论分析得出上分层回采对底板的破坏深度为2.16 m,且下分层缩面过程受上分层煤柱产生集中应力影响较大;采用FLAC^(3D)软件模拟了厚煤层分层开采下分层综放缩面过程,对比分析了主辐回撤通道间煤柱内部不同监测点受力情况,提出了对回撤通道进行分区域治理的思路,同时分析了“锚索+注玛丽散”支护前后顶板塑性区体积的变化,认为该支护方式有助于改善顶板岩性,从而提高其承载能力。结果表明,综放工作面贯通并缩面期间,工作面支架工作阻力仅增加3.3×10^(2)kPa,贯通缩面后液压支架压力又恢复到正常值,未出现异常的矿压显现,说明“锚索+注玛丽散”支护方式在贯通缩面过程中效果良好。

In view of the fact that the withdrawal channel is affected by multiple factors such as upper-slice mining,concentrated stress on the upper-slice coal pillar,and mining in this working face when the lower-slice fully-mechanized caving face shrinks in thick coal seams,the withdrawal channel is caused.The expansion of the plastic zone and fracture zone of the surrounding rock is easy to cause large-area roof fall and slab-side problems.According to theoretical analysis,the damage depth of the upper layer mining to the floor is 2.16 m,and the lower layer shrinkage process is affected by the upper layer.The coal pillars have a greater impact on the concentrated stress;FLAC^(3D)software is used to simulate the process of slicing fully mechanized caving face under slicing mining in thick coal.The idea of regional treatment,and the analysis of the changes in the volume of the plastic zone of the roof before and after the“anchor cable+injection of Mary powder”support is considered,and it is believed that this support method can help improve its bearing capacity.The results show that during the period when the fully mechanized caving face is penetrated and shrunk,the working resistance of the working face support only increases by 33×10^(2)kPa,and the pressure of the hydraulic support returns to the normal value after the pierced and shrunk face.The support method has a good effect in the process of piercing and shrinking the surface.