隔水煤柱采动渗流耦合失效特征及其合理宽度  

Failure characteristics and reasonable width of water-resisting pillar under the coupling effect of mining and seepage

作　　者：李竹 樊建宇 冯国瑞[1,2] 张宏 祁承恩[1,2] 张靖宇 LI Zhu;FAN Jianyu;FENG Guorui;ZHANG Hong;QI Chengen;ZHANG Jingyu(College of Mining Engineering,Taiyuan University of Technology,Taiyuan 030024,China;Key Laboratory of Shanxi Province for Mine Rock Strata Control and Disaster Prevention,Taiyuan University of Technology,Taiyuan 030024,China)

机构地区：[1]太原理工大学矿业工程学院,山西太原030024 [2]太原理工大学矿山岩层控制与灾害防控山西省重点实验室,山西太原030024

出　　处：《煤炭学报》2023年第11期4011-4023,共13页Journal of China Coal Society

基　　金：国家自然科学基金联合基金资助项目(U22A20169);国家杰出青年科学基金资助项目(51925402);山西省科技重大专项资助项目(20201102004)。

摘　　要：采空区遗留隔水煤柱水浸软化及采动影响下的耦合失效,是诱发同层回采工作面突水事故的常见原因之一,探究采空区积水隔水煤柱失效特征及其合理宽度,对于矿井水害防治具有重要意义。以甘肃华亭砚北煤矿250209工作面同层上覆关闭采空区隔水煤柱安全宽度为研究对象,通过理论分析及FLAC_(3D)数值仿真研究,分析了浸水侧煤体局部失效、坍塌及总宽度不足时隔水煤柱整体失稳灾变过程,揭示了水浸弱化、采动、渗流复杂影响下隔水煤柱内应力场、塑性区、渗流场耦合特征,掌握了不同煤柱宽度条件下隔水煤柱阻水能力及稳定性演化规律,提出了“渗水区+弹性压密阻水区+塑性区”3区联合型隔水煤柱宽度确定方法。结果表明:(1)隔水煤柱在覆岩载荷及采空区积水水压叠加作用下浸水侧下部煤体率先剪切塑性破坏,随着积水侵蚀渗透范围的扩张及不同程度浸泡弱化,诱发该区域煤体承载能力劣化及坍塌,最终导致隔水煤柱偏心压缩不均衡承载的倾倒失稳。(2) 3个阶段中隔水煤柱上部、中部、下部塑性区发育宽度不同,均呈现出沿煤柱高度方向自上而下逐步增加的现象,即隔水煤柱浸水侧下部塑性区扩展范围相对中部及上部更大,表明隔水煤柱底部区域更易形成导水通道,与理论分析相一致。(3)隔水煤柱中塑性区体积占据了渗水区总体积83%以上,是隔水煤柱导水的主要区域,弹性区体积占据了渗水区总体积的17%,尽管其占比较小,但其决定了渗水区范围的最大扩展边界,且弹性渗水区呈现出“高应力低渗透小范围”和“低应力高渗透大范围”应力渗透耦合特征。(4)隔水煤柱阻水能力取决于浸水侧渗水区与采动侧塑性区范围及其连通特性,隔水煤柱宽度为110和120 m时,渗水区与塑性区完全连通;隔水煤柱宽度为130、140和150 m时,渗水区与塑性区不连通,两者之间弹性压The coupling failure induced by the influence of mining practice and the water immersion softening of the waterresisting coal pillars in old goaf is one of the common causes of water inrush accidents in the same seam working face.Exploring the failure characteristics and reasonable width of the water-resisting coal pillars in the old goaf is of great significance for the prevention and control of mine water damage.The safe width of the water-resisting coal pillars in the closed overlying goaf in the same layer of the No.250209 working face of the Yanbei Coal Mine in Huating,Gansu Province is taken as the research object.The theoretical analysis and the FLAC_(3D) numerical simulation are conducted to analyze the whole instability disaster process of water-resisting coal pillars as the occurrence of partial failure of the immersed coal blocks,collapse,and insufficient total width.The coupling characteristics of the stress field,plastic area and seepage field in the water-resisting coal pillars under the complex influence of water immersion weakening,mining and seepage have been revealed and the water blocking capacity and stability evolution law of water-resisting coal pillars with different coal pillar widths are obtained.Accordingly,a method for determining the width of the water-resisting coal pillars of threezone combined type of“water seepage zone+elastic compaction water resisting zone+plastic zone”is proposed.The results show that①the plastic failure firstly occurs in the lower coal at the immersed side of the water-resisting coal pillar under the superimposed action of overburden load and water pressure in the goaf.And with the expansion of the seepage scope of water erosion and the gradual immersion-induced weakening,the deterioration and collapse of the bearing capacity of the coal in this area are induced,which ultimately leads to the eccentric axial compression and collapse of the waterresisting coal pillar.②In the three stages,the development width of the plastic zone at the upper,middle and lo

关 键 词：隔水煤柱 水浸软化 流固耦合 偏心压缩 弹性压密阻水区 

分 类 号：TD745[矿业工程—矿井通风与安全]