特厚煤层大采高综放工作面矿压及顶板破断特征

针对大采高综放工作面覆岩活动空间大、开采扰动强烈的特点,以不连沟煤矿特厚煤层大采高综放开采为背景,采用现场实测和理论分析等方法对大采高综放采场矿压及顶板运移破断特征进行分析,建立了大采高综放采场周期来压岩层破断的力学模型,得出了液压支架工作阻力的计算方法。结果表明:大采高综放工作面来压时安全阀开启频繁、顶板快速下沉,额定工作阻力13 800 kN的液压支架不能满足顶板控制的需要;开采空间的增大、直接顶厚度增大,低位基本顶转化为直接顶成为悬臂结构、高位基本顶形成砌体梁,二者形成"上位砌体梁-下位倒台阶组合悬臂结构";工作面来压强烈、动载明显、持续时间短的矿压现象是由于高位砌体梁结构滑落失稳造成的,据其力学特征确定了液压支架的工作阻力。

Analysis of ground pressure and roof movement in fully-mechanized top-coal caving with large mining height in ultra-thick seam

In terms of lager space of overlying strata movement and strong mining disturbance in working face of top coal caving with large mining height，this paper investigated the ultra-thick seam at Buliangou Coal Mine.The ground pressure behavior and roof movement characteristics of top coal caving with large mining height were analyzed using the methods such as in-situ observation，and theoretical analysis，etc.The mechanical model of the periodic weighting rock failure of main roof of top coal caving with large mining height was established，and the calculation method of hydraulic support working resistance was obtained.The results show that the hydraulic safety valve opens frequently and the roof subsidence speed is fast when the roof periodic weighting occurs，the rated resistance 13 800 kN hydraulic support cannot meet the requirements of roof control.The larger mining space，the thicker immediate roof，and then，the low main roof becomes immediate roof as a cantilever beam and the high main roof forms masonry beam，which called “Up Masonry Beam and Down Inverted Step Combination of Cantilever Beam”.The phenomena of intensive ground pressure，dynamic loads and short duration are due to the structure of “Masonry Beam” sliding instability，which determines the hydraulic support working resistance.