Evolutionary pattern and control technology of mine pressure when mining face for coal pillars in main roadways passing through abandoned roadways
LI Zhenhua;REN Ziyuan;DU Feng;REN Hao;WANG Wenqiang
河南理工大学 能源科学与工程学院煤炭安全生产与清洁高效利用省部共建协同创新中心河南理工大学 河南省矿井水害防控及水资源利用工程技术研究中心
由于矿井工作面布置方式的调整,煤柱工作面经常会面临通过废弃巷道时覆岩顶板难以控制的情况。
为解决这一问题,以河南赵固二矿二盘区外侧煤柱工作面过空巷为工程背景,采用理论分析、数值模拟和现场试验等方法,研究工作面与空巷覆岩破断组合结构,模拟不同支护强度下顶板应力−位移全周期演化规律,分析工作面矿压显现特征,提出相应的控制技术。
结果表明,基本顶不同破断形式对矿压显现特征影响显著,关键块断裂位置可分为煤柱上方、空巷上方和实体煤上方3种类型。通过建立工作面过空巷力学模型,研究基本顶超前破断力学机理,基本顶受到空巷−煤柱−工作面支护系统支撑作用,形成“砌体梁”稳定承载结构,判定基本顶滑落失稳时空巷支护强度的临界值为4.6 MPa。数值模拟显示,工作面超前支承压力与空巷应力集中产生的叠加效应对煤柱影响显著,当工作面推进至距空巷5 m时,煤柱失稳破坏,基本顶易发生超前破断。在工作面过空巷过程中,煤柱超前支承压力分布特征由“双峰型”转变为“孤峰型”。不同支护强度下的顶板应力分布特征存在明显差异,确定空巷支护强度为4.5 MPa能够防止基本顶超前破断。最后,在研究区二盘区外侧煤柱工作面采用“锚网索”支护方式对空巷顶板进行补强支护,过空巷期间液压支架工作阻力在研究区域处于安全范围内,未发生顶板垮落和压架等事故,解决了二盘区外侧煤柱工作面过空巷技术难题,可为类似工作面提供参考依据。
With the adjustment of the mining face layout in mines, the overburden roof of the mining face for coal pillar recovery is frequently difficult to control when the mining face passes through abandoned roadways.
To address this challenge, this study investigated the coal pillar mining face outside the No.2 panel in the Zhaogu No.2 Coal Mine in Henan Province, which passes through abandoned roadways. Using methods like theoretical analysis, numerical simulation, and in-situ tests, this study examined the composite structure of the mining face and the broken overburden of abandoned roadways, followed by simulation of the full-cycle evolutionary patterns of the stress and displacement of the mining face roof under different support strengths. Finally, it analyzed the mine pressure behavior on the mining face and proposed corresponding control technology.
The results indicate that the breaking forms of the main roof significantly influenced the mine pressure behavior. The breaking of its key blocks might occur above the coal pillar, abandoned roadway, or solid coal. The mechanical mechanisms underlying the advance breaking of the main roof were explored using the established mechanical models of the mining face passing through an abandoned roadway. The main roof was found to be supported by the support system consisting of the abandoned roadway, coal pillar, and mining face, which formed a stable bearing structure in the form of a masonry beam. The critical support strength of the abandoned roadway in the case of the sliding instability of the main roof was determined at 4.6 MPa. The numerical simulation results indicate that the superimposed effects of the advance support pressure of the mining face and the stress concentration in the abandoned roadway significantly affected the coal pillar. As the mining face advanced to 5 m away from the abandoned roadway, the coal pillar experienced instability failure, and the main roof was prone to undergo advance breaking. When the mining face passed through the abandoned roadway, the advance support pressure of the coal pillar shifted from the bimodal to unimodal distribution. The roof stress exhibited varying distribution characteristics under different support strengths, and it was discovered that the support strength of 4.5 MPa of the abandoned roadway could prevent the advance breaking of the main roof. For the coal pillar mining face outside the No.2 panel in the study area, cable anchors were employed as the reinforced support of the abandoned roadway roofs. Consequently, when the mining face passed through the abandoned roadways, the working resistance of hydraulic supports fell within the safe range in the study area, avoiding accidents such as roof collapse and support crushing. This study addressed the technical challenges faced when the coal pillar mining face outside the No.2 panel passed through abandoned roadways, providing a reference for similar mining face.
abandoned roadway;coal pillar;mechanical model;rock burst;numerical simulation;in-situ test
主办单位:煤炭科学研究总院有限公司 中国煤炭学会学术期刊工作委员会