“三硬”薄煤层沿空留巷围岩破坏特征及控制技术研究

Study on surrounding rock failure characteristics and control technology of gob-side entry retaining in"three hard"thin coal seam

为解决薄煤层沿空留巷应力条件复杂、留巷难度大以及巷道围岩长时稳定性的难题,以陕西汇森煤业凉水井煤矿4301工作面为研究对象,采用理论分析、数值模拟、工程实践等方法,对浅埋“三硬”薄煤层沿空留巷围岩破坏特征及控制对策进行研究,分析巷旁支护体结构参数对于巷道稳定性的影响。结果表明:给顶板提供充足的支护强度以及合适的可缩量,是巷旁充填体整体稳定的前提;高水充填材料单轴加压下的力学行为可分为“均匀压密、弹性变形、动态失稳、劣化破坏”4个阶段;在充填体宽度增加过程中,最大应力表现为先增后减再增的趋势,在充填体1.6 m宽时出现稳定承载应力核;理论计算的切顶最佳高度为10.7 m。工程实践表明,工作面后方60 m范围无大变形和明显应力集中,围岩整体控制效果良好、结构稳定,留巷效果达到设计要求。

This study aims to address existing problems of complex stress conditions and difficulties in retaining roadway so as to achieve long-term stability of roadway surrounding rock in gob-side entry in thin coal seam.Specifically,we investigated the 4301 working face of Liangshuijing Coal Mine in Huisen Coal Industry of Shaanxi Province through theoretical analysis,numerical simulation and engineering practice,with an aim to study the failure characteristics and control countermeasures of surrounding rock of gob-side entry retaining in shallow buried"triple hard"thin coal seam,and analyse the influence of structural parameters of roadside support on roadway stability.The results show that 1)maintaining the roadway through roadside filling body requires sufficient support strength and appropriate shrinkage to the roof and ensuring the overall stability of the roadway;2)the mechanical behaviour of high water filling material under uniaxial compression can be divided into four stages:"uniform compaction,elastic deformation,dynamic instability and deterioration failure".The numerical simulation results show that in increasing the width of the filling body,the maximum stress first increases,then decreases and then increases,and a stable bearing stress core appears at 1.6 m.Theoretical calculation shows that the optimal height of roof cutting is 10.7 m,and it offers the roof cutting scheme and parameters of shaped blasting.Engineering practice shows that there is no large deformation and no obvious stress concentration in the 60 m range behind the working face.The surrounding rock exhibits good overall control effect and stable structure,and the effect of retaining roadway meets the design requirements.