覆岩破坏裂隙发育高度是矿井顶板突水预测及防治的关键要素，而覆岩强度类型和开采强度是覆岩破坏裂隙发育特征的主要影响因素。对覆岩破坏高度进行预计时，覆岩类型划分标准和采煤方法对应的经验公式选择非常重要。采用钻孔冲洗液消耗量和钻孔电视观测相结合的方法，测得了坚硬和软弱地层高强度开采条件下覆岩破坏裂隙发育特征，得出坚硬岩层采动裂隙发育，冲洗液消耗量变化断断续续或者完全漏失，且岩层断裂倾角大，引起岩层采动传播影响角较大。软弱地层遇水易软化、塌孔，钻孔电视成像较为模糊，垮落带难以观测，需采用综合方法进行“两带”顶点的判别。对于近距离特厚煤层开采，下层煤垮落带高度波及到上层煤采空区时，需采用综合采厚计算下分层的导水裂缝带发育高度，《建筑物、水体、铁路及主要井巷煤柱留设与压煤开采指南》中综合采厚公式已不适用。为此通过构建近距离特厚煤层开采垮落带高度与层间距关系数学模型，提出了适合该地质条件的综合采厚计算公式，由于受煤层间距的影响使综合垮落带高度增大，并且上组煤对综合采厚影响较小，造成垮采比明显增大，得出坚硬顶板高强度开采综合垮采比为9.39～9.62，裂采比大于17.80，约为软弱覆岩的2倍，表明覆岩强度类型对高强度开采覆岩破坏裂隙发育特征影响明显，公式适用性强，研究成果可为覆岩破坏高度观测及水害防治现场实践提供参考。

The development height of overburden fractures is a key factor for the prediction and prevention of water inrush from the roof of a mine. The overburden strength type and mining intensity are the main influencing factors for the development characteristics of overburden fractures.When predicting the damage height of overlying strata, it is important to choose the correct classification standard of rock mass and empirical formula for different mining method. The comprehensive methods of water consumption quantity and borehole TV observation were used to test the fracture development characteristics of overlying rock under high-strength mining conditions in hard and weak formations. It is concluded that the hard rock formations have developed mining fractures and the flushing fluid consumption changes intermittentlyor completely leaks, and the inclination of the rock formation fractures is large, which causes a large impact angle of the rock formation mining propagation. However, for the weak strata, the rock is softened and collapsed easily. The TV imaging of the boreholes is blurred, and the collapse zone is difficult to observe. It is necessary to adopt a comprehensive method to distinguish the vertices of the “two zones”. For the short distance and extra-thick coal seam mining, the comprehensive mining thickness is needed to predict the fissure zone height of lower seam. But the formula of comprehensive mining thickness is no longer applicablebased on the “Guidelines for coal pillar retention and coal mining in buildings, water bodies, railways and main shafts”.For this reason, by constructing a mathematical model of the relationship between the height of the caving zone and the interlayer spacing in the short-distance ultra-thick coal seam mining, a comprehensive mining thickness calculation formula suitable for the geological conditions is proposed. Due to the influence of the coal seam spacing, the height of the comprehensive caving zone increases, and the upper group of coal has little effect on the comprehensive mining thickness, resulting in a significant increase in the caving ratio.It is concluded that the comprehensive caving ratio of hard roof high-strength mining is 9.39-9.62 and the proportion of fissure zone height and mining height is more than 17.80 for the hard strata, which is two times of weak strata. It shows that the strength type of the overburden has a significant impact on the development characteristics of the overburden failure cracks in high-strength mining, and the formula has strong applicability. The research results can provide references for the observation of the overburden failure height and the field practice of water damage prevention. 

0 引言

1 高强度采动裂隙发育高度预计方法

   1.1 覆岩类型划分方法

   1.2 厚煤层“两带”发育高度预计方法

2 坚硬覆岩高强度采动裂隙发育特征

   2.1 现场观测区概况

   2.2 现场观测成果

3 软弱覆岩高强度采动裂隙发育特征

   3.1 观测区概况

   3.2 现场观测成果

4 采动裂隙发育特征对比及观测建议

5 结论