静态致裂作用下低渗厚煤层瓦斯增透数值模拟研究  

Numerical simulations of enhancing permeability and gas extraction of thick coal seams through static fracturing

作　　者：王新丰 刘文港[1] 王龙 韦友玉 张乔 WANG Xinfeng;LIU Wengang;WANG Long;WEI Youyu;ZHANG Qiao(College of Environment and Resources,Xiangtan University,Xiangtan 411105,China;Key Laboratory of Safety and High-efficiency Coal Mining,Ministry of Education(Anhui University of Science and Technology),Huainan 232001,China)

机构地区：[1]湘潭大学环境与资源学院,湖南湘潭411105 [2]煤矿安全高效开采省部共建教育部重点实验室(安徽理工大学),安徽淮南232001

出　　处：《煤田地质与勘探》2023年第11期1-12,共12页Coal Geology & Exploration

基　　金：国家自然科学基金项目(51904266,52104224);湖南省自然科学基金青年项目(2023JJ40634);湖南省教育厅优秀青年基金项目(21B0144);煤矿安全高效开采省部共建教育部重点实验室开放基金项目(JYBSYS2018203)。

摘　　要：为提高煤层静态致裂井下作业效率,优化致裂布孔参数,以中煤华晋王家岭矿12316综采工作面胶带巷为实验背景,结合煤层变形破坏方程、瓦斯扩散渗流方程和煤层渗透率演化方程,构建煤层破坏及渗透率演化模型;采用FlAC^(3D)-COMSOL Multiphysics对煤体静态致裂增透过程及影响因素进行数值模拟,揭示静态致裂作用下煤层应力分布、塑性扩展与瓦斯压力传递演化规律。通过优化选取致裂工艺参数开展现场试验,定量分析不同孔距下静态致裂过程中煤层瓦斯抽采量的变化特征。结果表明:静态致裂过程中膨胀应力在煤体内部沿致裂孔半径方向向四周均匀传递,单孔致裂过程中形成圆环状应力圈和塑性区;在双孔致裂条件下,两致裂孔内膨胀应力的水平叠加效果优于竖直叠加效果,使煤体水平方向破坏效果较竖直方向显著,且两致裂孔中间区域的煤层先于其他区域破坏。受静态致裂作用范围的限制,增透促抽后煤层内瓦斯压力大小与孔距呈正相关关系,煤层渗透率与孔距间呈负相关关系;现场试验表明,将孔距设为1.6 m以内进行静态致裂增透,在抽采负压为20 kPa条件下抽采30 d,测得致裂后瓦斯抽采纯量提升1倍左右,说明静态致裂对瓦斯抽采具有显著的卸压增透效果。This study seeks to improve the underground operation efficiency and optimize the borehole arrangement parameters for static fracturing of coal seams.To this end,this study conducted tests in the belt roadway of the No.12316 fully mechanized mining face in the Wangjialing Coal Mine,China Coal Huajin Group.By combining the equations for coal seams’deformation and failure,gas diffusion and seepage,and coal seams’permeability evolution,this study constructed a model of the damage and permeability evolution of coal seams.Based on the numerical simulations of the process of static fracturing and permeability enhancement of coals,as well as its influencing factors,using FlAC^(3D) and COMSOL Multiphysics,this study revealed the laws of the stress distribution,plastic expansion,and gas pressure transfer and evolution of coal seams under the action of static fracturing.Furthermore,through field experiments using fracturing parameters selected through optimization,this study quantitatively analyzed the changes in gas flow extracted from coal seams during static fracturing under different borehole spacings.The following findings are obtained.During the static fracturing,the expansion stress in coals was evenly transferred outward along the radial directions of the borehole for fracturing.An annulus stress zone and a plastic zone were formed during single-hole fracturing.In the case of double-hole fracturing,the expansion stress in both holes exhibited better superposition effects in the horizontal direction than in the vertical direction,leading to more significant damage to coals in the horizontal direction than in the vertical direction.Furthermore,zones between both holes were damaged earlier than other zones.After permeability and gas extraction were enhanced by static fracturing,the gas pressure and permeability of coal seams were positively and negatively correlated with the hole spacing,respectively due to the limited static fracturing range.During field tests,static fracturing and permeability enhancement were c

关 键 词：瓦斯抽采 静态致裂 煤层增透 扩散渗流 数值模拟 效果评价 

分 类 号：TD713[矿业工程—矿井通风与安全]