深部承压水上底抽巷围岩破坏特征及合理位置

Surrounding rock's failure characteristic and rational location of floor gas drainage roadway above deep confined water

针对赵固二矿区域瓦斯治理需开掘底抽巷与承压水上开掘底抽巷易引发底板突水之间的矛盾,通过承压水影响下的圆形巷道围岩塑性区边界方程,分析了底抽巷围岩塑性区的分布特征与底板突水危险性之间的关系;采用数值模拟研究了工作面开挖后的底板应力分布状态及底抽巷布置在不同位置时的围岩破坏特征及相应的突水危险性。结果表明:底抽巷围岩塑性区的非均匀分布会显著减小底板隔水层厚度,增加底板突水危险;工作面开挖后底板应力根据其双向应力比值大小及应力加卸载状态可分为4个区域且按对底板突水危险的影响程度可排序为:卸压高应力比值区>卸压应力比值稳定区>增压低应力比值区>原岩应力比值区。据此提出了赵固二矿底抽巷的合理位置为沿待采工作面法向布置,并在规划的煤柱中部下方的L9灰岩上部砂质泥岩层中沿底掘进。

Aiming at the contradiction between the needs of driving floor gas drainage roadway at Zhaogu No.2 coal mine to control gas and the risk of floor water inrush caused by driving the floor gas drainage roadway above the confined aquifers,by using the boundary equation of plastic zone in circular roadway surrounding rock under the influence of confined aquifers,the relationship between the distribution characteristics of the plastic zone of the surrounding rock and the risk of the floor water inrush is analyzed.By using the numerical simulation,two facts are studied:the stress distribution in the floor after working face excavation,the failure characteristics of surrounding rock and the corresponding risk of floor water inrush when the floor gas drainage roadway is arranged at different positions.The results show that the non-uniform distribution of plastic zone of the floor gas drainage roadway’s surrounding rock will significantly reduce the thickness of the floor aquiclude and increase the risk of floor water inrush.After the working face excavated,the stress of the floor can be divided into four regions according to the ratio of the two-way stress and the stress loading and unloading state.According to the impact on the floor water inrush,the danger can be ranked as:high and unloading stress ratio area>;stable and unloading stress ratio area>;low and loading stress ratio area>;original rock stress ratio area.In view of the above,the rational location of the floor gas drainage roadway in Zhagou No.2 coal mine should be arranged along the normal direction of the working face and driven under the middle of coal pillar and along the sandy mudstone layer’s bottom which is above the L 9 limestone.