近直立特厚煤层分段综放夹持煤柱冲击机理

Impact mechanism of clamped coal pillar in sublevel fully mechanized top coal caving in the near vertical extra thick coal seam

以窑街三矿近直立特厚煤层水平分段综放开采为背景,建立了倾向剖面“夹持岩梁”力学模型与走向剖面“U-λ”岩板力学模型,揭示了近直立煤层水平分段开采的顶底板夹持煤柱冲击地压机理,分析了应力分布与塑性区演化规律,对工作面微震事件进行定性监测与时空定量监测。研究表明:当顶板岩层形成的“悬臂”结构达到一定长度极限,“U-λ”岩板断裂,对下方煤体产生冲击载荷,造成强烈的矿压显现;随着工作面不断向深部开采,煤柱所受水平应力增加,积聚在煤体中的弹性变形能释放,工作面下方煤体形成一定深度的剪切挤压张裂带破坏区;工作面下部为巨厚的底煤积聚大量的弹性应变能,产生塑性变形释放弹性能,导致底板突然底鼓、支架工作阻力升高。随着工作面向前推进,顶煤与其上方松散破碎煤岩体发生垮落,岩块在滑落和回转失稳过程中释放大量能量,对工作面造成动载扰动。

Based on the horizontal sublevel caving mining of the near vertical extra thick coal seam in Yaojie No.3 coal mine,the mechanical model of“clamped rock beam”in dip section and“U-λ”rock plate in strike section were established in this paper.The mechanism of the rock burst of the coal pillar clamped by the roof and floor in the horizontal sublevel mining of the near vertical coal seam was revealed.The stress distribution and the evolution law of plastic zone were analyzed.Furthermore,qualitative monitoring and space-time quantitative monitoring of microseisms in the working face were carried out.The research showed that,when the“cantilever”structure formed by the roof slate layer reached a certain length limit,the“U-λ”rock plate was fractured that produced impact load on the coal body below,resulting in strong ground pressure behavior.The horizontal stress on the coal pillar increased with the continuous mining of the working face to the deep.The elastic deformation energy accumulated in the coal body was released that made the coal body below the working face form a certain depth of shear compression tension fracture zone damage area.The lower part of the working face was a huge thick bottom coal,that accumulated a large amount of elastic strain energy.It produced plastic deformation and released its elastic property,resulting in sudden floor heave of the bottom plate and the increase of the support resistance.With the advance of the working face,the top coal and the loose broken coal and rock mass above it collapsed.As a result,the rock block released a lot of energy in the process of sliding and rotating instability,causing dynamic load disturbance to the working face.