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考虑采空区矸石非均匀充填影响的倾斜煤层沿空留巷稳定性分析

Stability analysis of inclined coal seam roadway along goaf considering non-uniform filling of gob gangue

  • 摘要: 倾斜煤层开采后,由于采空区顶板冒落矸石在重力作用下向下运动堆积充填采空区,使得倾斜煤层沿空留巷矿压显现规律与水平煤层不尽相同。为研究倾斜煤层采空区矸石非均匀充填对沿空留巷围岩稳定性的影响,以四川龙门峡南煤矿3131运输巷为工程背景,对采空区垮落矸石充填分区长度进行量化,并采用双屈服模型反演得到采空区矸石分区压实特性参数;并以此为基础建立数值计算模型,重点研究了倾斜煤层沿空留巷全服务周期内围岩应力场环境和塑性区分布形态的演化特征,以及承载状态下巷旁充填体的应力状态和支护性能。研究结果表明:3131工作面采空区的充填压实区、完全充填区以及部分充填区的倾向长度分别为57.20、72.18、10.62 m;对于考虑采空区分区压实特性的倾斜煤层沿空留巷而言,其工作面前方支承压力和采空区残余支承压力沿煤层倾向随深度增加而增大;相比于一次采动,二次采动时工作面前方支承压力峰值和影响范围明显增大,侧向支承压力集中程度也明显提高;留巷阶段采空区垮落带矸石对巷道顶板岩层具有一定的支撑作用,侧向支承压力有明显的应力集中;受重复采动影响,两帮塑性区破坏范围发生顺层扩展现象,且巷道顶板与采空区顶板的塑性区相贯通,巷道靠近高帮侧顶板和两帮围岩破碎较为严重,稳定性较差;矿方现用的巷旁充填体采空区侧承载应力明显大于巷道侧,且水平应力大于垂直应力,巷旁充填体能够满足强度要求,但抗倾覆性能较弱。在此基础之上,分析了现有支护条件下巷道围岩稳定性的控制效果,并针对性地提出了3131运输巷围岩补强支护方案。

     

    Abstract: After the mining of inclined coal seam, the roof falling gangue of goaf moves downward to fill the goaf due to gravity, which makes the strata behavior law of gob-side entry retaining in inclined coal seam different from that in horizontal coal seam. In order to study the influence of non - uniform filling of gangue on surrounding rock stability of gob - side entry retaining in inclined coal seam, taking No.3131 machine roadway of Longmenxia South Coal Mine in Sichuan as engineering background. The filling zone length of caving rock in goaf was quantified, and the compaction parameters of rock in quantified goaf were obtained by double yield model inversion. On this basis, a numerical calculation model was established to study the evolution characteristics of surrounding rock stress field and the distribution pattern of plastic zone in the whole service cycle of gob-side entry retaining in inclined coal seam, as well as the stress state and support performance of roadside filling body under bearing state. The results showed that the inclined lengths of filling compaction zone, complete filling zone and partial filling zone in goaf of 3131 working face were 57.20 m, 72.18 m and 10.62 m, respectively. For the gob-side entry retaining of inclined coal seam considering the zoning compaction characteristics of goaf, the abutment pressure in front of working face and the residual abutment pressure in goaf increase with the increase of depth. Compared with the first mining, the peak value and influence range of the abutment pressure in front of the working face under the second mining were significantly increased, and the concentration degree of the lateral abutment pressure was also significantly improved. The rock in the caving zone of goaf had a certain supporting effect on the roof strata of roadway, and the lateral abutment pressure had obvious stress concentration. Affected by repeated mining, the failure range of the plastic zone of the two sides extended along the layer, the plastic zone of roadway roof and goaf roof was connected, and the roof near the high sidewall and the surrounding rock of the two sidewalls were seriously broken and the stability was poor. The bearing stress of gob side of roadside backfill used in the mine was significantly greater than that of roadway side, and the horizontal stress was greater than the vertical stress. The roadside filling body can meet the strength requirements, but the anti-tilting performance was weak. On this basis, the control effect of roadway surrounding rock stability under existing support conditions was analyzed, and the reinforcement support scheme of 3131 machine roadway surrounding rock was put forward.

     

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