针对特厚煤层分层综采工作面，采用理论分析及现场试验相结合的方法，对于巨厚直接顶下区段煤柱失稳机理及控制技术展开研究。首先分析各分层工作面沿空侧覆岩运移规律，通过建立覆岩结构力学模型，得到中、底分层工作面沿空侧覆岩载荷计算公式，其次基于弹塑性理论，得到窄煤柱及宽煤柱内部任意一点应力的解析解，并代入实际工程参数，分析不同尺寸煤柱内部应力分布规律，最后给出中、下分层工作面区段煤柱围岩控制关键技术，进行现场工业性试验。研究表明：中、下分层开采期间，上覆巨厚直接顶会形成“低位短悬臂梁+砌体梁+高位弯曲下沉带”的覆岩结构；将分层开采煤柱受力状态分为“宽煤柱弹性区应力叠加型”和“窄煤柱峰值应力叠加型”2种形式，分别求得宽煤柱内任意一点三向应力及窄煤柱内任意一点垂直应力的解析公式，其中覆岩应力集中系数、煤柱高度及煤柱宽度是主要影响因素；小于15 m的特厚煤层依然适合留设窄煤柱，其内部垂直应力峰值随煤柱高度增大而降低，再受到分层多次采动影响，窄煤柱内实际残余强度更低，更易失稳，而大于15 m的特厚及巨厚煤层不易留设窄煤柱；给出留设合理区段煤柱尺寸的方法，并提出“及时主动+2次被动+3次关键部位锚索注浆加强支护”的围岩控制方案，现场应用效果明显。

Aiming at the slicing fully mechanized mining face in extra-thick coal seams,a combination of theoretical analysis and field test is used to study the instability mechanism and control technology of coal pillars under super thick direct roof. Firstly,analyze the movement law of the overburden along goaf of each slicing faces,and obtain the calculation formula for the overburden load along goaf of the middle and bottom slicing faces by establishing the mechanical model of the overburden structure. Secondly,based on the theory of elastic-plastic,an analytical solution of the stress at any point in the narrow coal pillar and wide coal pillar is obtained,and the actual engineering parameters are substituted into it to analyze the stress distribution law of coal pillars of different sizes. Finally,the key technology of coal pillar surrounding rock control in the middle and bottom slicing face sections is given,and field industrial tests are carried out. Research shows：During the middle and bottom slicing mining,the overburden with huge thickness will form a structure of " low-level short cantilever beam + masonry beam + high-level bending subsidence zone ". The stress state of the coal pillar in slicing mining is divided into two types："the stress superposition in elastic zone of wide coal pillar" and "the peak stress superposition in narrow coal pillar". The analytical formulas for the three-dimensional stress at any point in the wide coal pillar and the vertical stress at any point in the narrow coal pillar are respectively obtained. The overlying rock stress concentration factor,the height of the coal pillar and the width of the coal pillar are the main influencing factors. The extra-thick coal seam less than 15 m is still suitable for setting narrow coal pillars,and its internal vertical stress peak value decreases as the height of the coal pillar increases. Affected by multiple mining of slicing mining,the actual residual strength in the narrow coal pillar is lower,and it is more prone to instability. However,it is not easy to set narrow coal pillars in extra-thick and huge-thick coal seams greater than 15 m. The method of setting reasonable section coal pillar size is given,and the surrounding rock control scheme of " timely active support + secondary passive support + three times grouting of anchor cable in key parts to strengthen support" is put forward.

1 工程背景

   1.1 地质生产条件

   1.2 垂直分层巷道围岩变形特征

2 分层开采区段煤柱失稳机理

   2.1 沿空侧覆岩载荷传递机制

   2.2 煤柱应力状态

   2.3 煤柱应力分布规律

   2.4 重叠式分层开采煤柱失稳机理

3 区段煤柱控制关键技术

   3.1 合理区段煤柱尺寸留设

   3.2 区段煤柱加强支护控制

4 工程应用

5 结论