摘要
钻孔抽采是煤矿井下瓦斯抽采的主要方式,孔周煤岩体在荷载作用下具有明显的塑性软化、扩容特征,为准确获取煤层钻孔孔周应力分布特征及影响因素,基于Hoek-Brown准则,建立了煤层钻孔弹塑性软化及扩容力学理论模型。该理论模型将沿巷道壁钻进的钻孔,分为应力叠加区和原岩应力区2段,研究结果表明:随着煤体GSI值减小,埋深增大,孔周卸压范围及塑性区范围均增大,影响钻孔正常钻进和抽采,出现塌孔、堵孔及卡钻等现象;孔径小范围变化对孔周应力影响不大,后期抽采可采用水力措施大幅度增大有效抽采段孔径;应力叠加区孔周塑性区范围较原岩应力区大,在此处封孔应考虑支护孔周塑性区煤体,减小塑性区范围,防止形成抽采漏气通道。
The borehole serves as a primary method for underground coalbed methane extraction,holding significant importance in this context.Considering the plastic softening and dilatancy characteristics of coal,a theoretical model based on the Hoek-Brown criterion has been established to study the stress distribution around the borehole and its influencing factors.This theoretical model divides the borehole drilled along the tunnel wall into two segments:the stress superposition zone and the original rock stress zone.Research findings indicate that with a decrease in the GSI value of the coal body and an increase in burial depth,both the range of stress relief and the plastic zone around the borehole increase.This can adversely affect normal drilling and extraction operations,leading to issues such as borehole collapse,blockage,and bit jamming.Furthermore,small variations in borehole diameter have minimal impact on the stress around the borehole.In later extraction phases,hydraulic measures can be employed to significantly increase the effective extraction segment diameter.Additionally,the plastic zone around the borehole in the stress superposition area is larger than that in the original rock stress zone.Therefore,when sealing the borehole in this area,it is crucial to consider the support of the coal body in the plastic zone to reduce the plastic zone′s extent and prevent the formation of gas leakage pathways during extraction.
作者
刘利平
马海潮
韩超
LIU Liping;MA Haichao;HAN Chao(Jungar Banner Yunfei Mining Co.,Ltd.,Ordos 010400,China;School of Emergency Management and Safety Engineering,China University of Mining and Technology-Beijing,Bejing 100083,China)
出处
《煤炭技术》
2025年第9期163-168,共6页
Coal Technology
