非等宽复合柱采区中部遗煤开采可行性分析

Feasibility analysis of residual coal mining in the middle of unequal width composite pillar mining area

选取非等宽复合柱采区中部遗煤的开采为研究对象,采用数值模拟、相似模拟和理论分析相结合的方法,从遗留煤柱稳定性、围岩应力分布环境及岩体结构稳定性3个角度出发,系统分析了非等宽复合柱采区中部遗煤开采的可行性。结果表明:复合采动影响下残采区遗留宽煤柱的稳定性强于窄煤柱,中部遗煤开采过程中超前支承压力会与遗留煤柱内集中应力相互叠加,导致窄煤柱发生超前失稳,并强化宽煤柱的应力集中程度。复合柱式开采后采场会形成"遗留煤柱-上位控制层"倒置连续梁岩体结构和"下位承载层-遗留煤柱"连续梁岩体结构。中部遗煤开采过程中,上位层间岩层中的"控制层"结构会逐步发生破断失稳,尤其在通过宽煤柱时会发生切落式失稳,引发"遗留煤柱-上位控制层"倒置连续梁耦合承载结构的破坏,并导致强矿压显现;"下位承载层-遗留煤柱"连续梁耦合承载结构在中部遗煤开采过程中能够保持整体稳定。晋华宫煤矿非等宽复合柱采区中部遗煤开采可行性良好,当工作面通过复合柱采区重叠式遗留煤柱对应的高应力区域时,需要采取柱旁充填、煤柱预裂或切顶卸压等超前防控技术来削减采场强矿压。本研究可以为非等宽复合柱采区中部遗煤的安全高效开采提供良好的理论支持。

The mining of middle residual coal seam in the unequal width composite pillar mining area was selected as the as research object.With the coupled methods of numerical simulation,similar simulation and mechanical analysis,the feasibility of residual coal mining in the middle of unequal width composite pillar mining area was systematically analyzed from three aspects including the stability of residual coal pillar,surrounding rock stress distribution,and rock structure stability.The results showed that:the stability of wide coal pillars in the residual mining area was stronger than that of narrow coal pillars under the composite mining influences.During the mining process of the middle coal seam,the abutment pressure superimposed with the concentrated stress in the residual coal pillar,which led to the pre-failure of narrow coal pillars and strengthening of stress concentration of wide coal pillars.After the composite pillar mining,the"residual coal pillars and upper control layer"inverted continuous beam rock mass structure and the"residual coal pillars and bottom bearing layer"continuous beam rock mass structure were formed.During the mining process of middle coal seam,the control layer in the upper interburden strata gradually broken and failed.Especially when the workface passed the wide coal pillar,the interbueden strata cut off,which would induce the system failure of the"residual coal pillars and upper control layer"inverted continuous beam structure and the strong strata pressure behavior.Moreover,the stability of"residual coal pillars and bottom bearing layer"continuous beam rock mass structure could be maintained overall.The residual coal mining in the middle of unequal width composite pillar mining area could achieve good feasibility.When the working face passed through the high stress area corresponding to overlapping residual coal pillar in the composite pillar mining area,it is necessary to adopt the prevention and control technical measures such as backfilling along the coal pillars,pre-splitting of residual coal pillar and roof strata to reduce the strong mining pressure.This study can provide good theoretical support for safe and high-efficient mining of residual coal mining in the middle of unequal width composite pillar mining area.