基于基本顶关键岩块B断裂线位置的窄煤柱合理宽度的确定

Rational width of narrow coal pillar based on the fracture line location of key rock B in main roof

为掌握基本顶断裂结构对窄煤柱稳定性的影响规律,建立沿空掘巷围岩结构力学模型,提出了沿空巷道上覆基本顶3种断裂结构形式,对基本顶断裂结构与窄煤柱稳定性的相关性进行了分析。研究表明,基本顶断裂线位于不同位置时,巷道围岩应力、煤柱应力及应变差异较大。当基本顶断裂线位于巷道正上方时,靠近采空区侧围岩变形量较靠近实体煤壁侧的大,巷道顶板应力降低快导致围岩破碎可锚性差,煤柱应力和变形增速最快,围岩稳定后作用在煤柱上的载荷最大,煤柱持续变形速度也最大,导致巷道后期维护困难。当基本顶断裂线位于沿空巷道外侧时,煤柱变形在合理范围内,同时具有较强的支承能力,对巷道维护有利。研究成果在燕家河煤矿8105综放面成功应用,并取得了满意的技术经济效益。

In this paper, to master the influence law of the main roof’s fracture structure on the stability of narrow coal pillar, the mechanical model of surrounding rock structure in gob-side entry was built, three fracture forms of the overlying main roof in gob-side entry were put forward, and the correlation between the fracture structure of main roof and the stability of narrow coal pillar was analyzed. The results show that there are great differences in the stress of roadway surrounding rock, and the stress and strain in coal pillar while the fracture line of main roof locates in different places. When the fracture line of main roof locates just at the top of the roadway, the surrounding rock deformation closed to the goaf is larger than that closed to the entity coal wall. The stress in the roadway roof is reduced fast, the surrounding rock is crushed and its anchoring ability is pool. The stress and deformation in pillar are increased fast, and the loads on the pillar are the largest when the surrounding rock is stable. Meanwhile, the continuous deformation speed of coal pillar is also the largest, which leads to the difficult later maintenance of roadway. When the fracture line of main roof locates in the lateral of roadway, the pillar deformation is in a reasonable scope, and the supporting capacity is strong, which is beneficial to the maintenance of roadway. The research results have been applied successfully in the No.8105 fully mechanized face with sub-level caving of Yanjiahe Coal Mine, and satisfactory technical and economic effects are achieved.