张家峁矿近水体煤层群隔水煤柱合理宽度确定

Determination of reasonable width of water-proof coal pillar in coal seams near the water body in Zhangjiamao Mine

针对张家峁常家沟水库近水体煤层开采后覆岩裂隙扩展诱发透水的潜在风险,对煤层开采过程中的覆岩破坏特征及裂隙扩展规律进行了模型试验及数值模拟研究。为合理确定4^(-2)煤层的隔水煤柱宽度,基于矿山支承压力和静水压力对隔水煤柱的不同作用机理,将4^(-2)煤层隔水煤柱划分为矿压影响区和有效隔水区,分别构建了矿压影响区和有效隔水区的煤柱受力分析计算模型,推导了4^(-2)煤层矿压影响区和有效隔水区的理论宽度计算公式。在此基础上,考虑煤层开采边界角与水体下伏不同煤层矿压影响区宽度的关系,提出了“上覆煤柱宽度+矿压影响区”的水体下伏煤层群隔水煤柱宽度确定方法。结果表明:4^(-2)煤层工作面初次来压步距为45~56 m,周期来压步距为13.8~14.9 m,上覆岩层冒落带高度为12~13 m;地表最大下沉量为2.0~2.2 m,下沉系数为0.571~0.629,4^(-2)、4^(-3)、4^(-4)和5^(-2)煤层隔水煤柱的合理宽度分别为25,39,51和87 m。现场实测隔水效果验证了近水体煤柱理论留设宽度的合理性及其工程适用性,为张家峁近水体煤层群安全高效开采提供了技术保障。

Aiming at the potential risk of water permeability induced by the expansion of overlying rock cracks after coal seam mining in Changjiagou Reservoir near the water body of Zhangjiaomao,model tests and numerical simulations were conducted on the overlying rock damage characteristics and crack expansion rules during coal seam mining.In order to reasonably determine the width of the water-proof coal pillar in the 4-2 coal seam,based on the different mechanisms of mine support pressure and static water pressure on the water-proof coal pillar,the water-proof coal pillar in the 4-2 coal seam was divided into pressure affected zone and effective water-proof zone.The force analysis and calculation models of the coal pillar in the pressure affected zone and effective water-proof zone were constructed,and the theoretical width calculation formulas for the pressure affected zone and effective water-proof zone in the 4-2 coal seam were derived.On this basis,considering the relationship between the boundary angle of coal seam mining and the width of different coal seam pressure influence zones under the water body,a method for determining the width of water-proof coal pillars in the coal seam group under the water body was proposed,which includes the width of overlying coal pillars and the pressure influence zone.The results show that the initial pressure step distance of the 4-2 coal seam working face is 45~56 m,the periodic pressure step distance is 13.8~14.9 m,and the height of the overlying rock caving zone is 12~13 m.The maximum surface subsidence is 2.0~2.2 m,with a subsidence coefficient of 0.571~0.629.The reasonable widths of the water-proof coal pillars for coal seams 4-2,4-3,4-4,and 5-2 are 25,39,51 and 87 m,respectively.The on-site measurement of the water blocking effect has verified the rationality and engineering applicability of the theoretical reserved width of coal pillars near the water body,providing technical support for the safe and efficient mining of coal seams near the water body in Zhangjiamao.