分层开采窄煤柱巷道围岩失稳机理及控制技术研究

Instability mechanism and control technology of surrounding rock of narrow pillar roadway in slicing mining

为合理解决老公营子煤矿中下分层回采巷道大变形的问题,基于5#煤层实际的地质条件,研究覆岩运动与巷道围岩稳定性的联系,揭示巷道围岩失稳机理。指出采动应力的叠加作用是造成首采面巷道围岩失稳的主要因素;覆岩的二次破断形成非对称结构,造成偏载作用显著是影响接续工作面巷道围岩失稳的主要因素,且窄煤柱多次受到回采扰动,塑性破坏严重,承载能力降低是造成巷道围岩失稳的内在因素。以此提出"封闭强化、区别对待"的围岩控制思路,表面喷浆内部注浆提高围岩的自承能力,补强锚索加强围岩局部支护强度。现场实践表明,窄煤柱巷道可以满足工作面回采期间的要求,稳定性较好,为类似巷道围岩控制提高借鉴。

Aiming at the large deformation of the mining roadway in the middle and lower layers of Laogongyingzi Coal Mine,the relationship between the overburden stratum movement and the stability of the surrounding rock is discussed based on the actual geological conditions of the 5#coal seam,and the erratic mechanism of the roadway surrounding rock is revealed.The result indicates that the additive effect of mining stress is the key factor causing the surrounding rock instability in the first mining face;the secondary rupture of the overlying rock forms an asymmetric structure and leads to notable partial loads which is the prominent factor for the surrounding rock instability of the continuous working face;and the bearing capacity of narrow coal pillar decreases under repeated mining disturbance and severe plastic damage,which is the intrinsic factor for the instability.Based on the above analysis,the surrounding rock control idea of“enclosed and strengthened and differentiated treatment”is proposed,which enhances the bearing capacity of the surrounding rock using surface shotcrete and internal grouting,and improve the local surrounding rock support by strengthening the anchor cable support.It’s proved by the field practice that the narrow coal pillar roadway can meet the requirements during the working face mining,and the roadway is stable.