煤层底板区域治理后断层突水原因及探讨

Causes and discussion of fault water inrush after regional treatment in coal seam floor

以桃园煤矿底板区域改造后Ⅱ1028工作面F28断层突水为背景,阐述了突水过程;根据水位、水质和水温分析了突水水源和通道,通过理论公式计算了断层带的底板破坏深度和承压水导升带高度,阐明了突水的原因;利用地面定向孔灌注骨料和水泥封堵了突水通道,探讨了区域治理钻孔布置、注浆方式和材料配比。结果表明:区域治理虽有效封堵了奥灰导水通道,避免了灾害性突水,但粉煤灰-水泥浆在断层带不凝固、钻孔穿陷落柱且在末端对断层的注浆有效压力低,治理效果差,采动断层活化导致突水;对于将受采掘扰动的断层、破碎带等应注入高强度的水泥单液浆提高强度;注浆沿程压力损失量随孔深先大后小,损失速率随孔深递减,注浆钻孔不宜太长;中途分流“短路”压力会整体降低,孔内无压段长度随分流量增大,注浆钻孔经异常构造、巷道底板应进行试压,避免注浆“短路”现象。

Based on the water inrush from F28 fault ofⅡ1028 working face in Taoyuan Coal Mine,the process of water inrush is described.The water inrush source and channel are analyzed according to the water level,water quality and water temperature.The failure depth and the height of confined water lift zone in fault zone are calculated by theoretical formula,the reasons of water inrush is illustrated,and the water inrush channel was blocked by grouting aggregate and cement through directional holes on the ground.The layout of regional control drilling hole,grouting method and material ratio were discussed.The results show that regional governance effectively blocked the water channel of Ordovician limestone and avoided the disastrous water inrush,the fly ash-cement slurry was not solidified in the fault zone,the effective grouting pressure of drilling through the collapse column and at the end of the fault was low,so the governance effect was poor,and the mining fault activation led to the water inrush.High strength cement slurry should be injected into the fault and broken zone disturbed by mining to improve the strength;the pressure loss rate along the grouting path decreases with hole depth.The grouting holes should not be too long.The pressure of“short circuit”in the middle of the diversion will decrease as a whole,and the length of the section without pressure in the hole increases with the amount of diversion.Pressure test should be carried out through the abnormal structure and roadway floor to avoid the phenomenon of“short circuit”of grouting.