摘要
应力-损伤-渗流耦合作用下弱胶结地层采动覆岩渗透性演化是影响矿井保水开采的重要因素。以新疆伊犁四矿21103工作面弱胶结地层条件为背景,选取侏罗系弱胶结泥岩、砂岩,在分析全应力应变过程中弱胶结岩石渗透率变化规律的基础上,明确了弱胶结岩石孔隙结构、矿物组成对其渗透性的影响机理,建立了弱胶结岩石应力-损伤-渗流耦合模型,研究了采动弱胶结覆岩渗透性演化规律。结果表明:围压5 MPa内,弱胶结岩石初始渗透率高,压密阶段渗透率大幅下降,最大降幅达91.5%,这与其初始孔隙率高、孔径大直接相关。同时,弱胶结岩石最大渗透率及残余渗透率与初始渗透率相比增幅较小,最大比值分别为4.51和4.17,这与岩石中高岭石、蒙脱石等水敏矿物遇水膨胀泥化造成部分导水裂隙弥合有关;基于弱胶结岩石基质可压缩融合、破裂等假设,定义了损伤变量D,建立了弱胶结岩石应力-损伤-渗流耦合模型,有效表征了弱胶结岩石初始渗透率高而残余渗透率增幅较小的渗透特性;工程尺度下,弱胶结地层采空区在工作面回采后快速压实闭合,出现渗透率恢复区,且该区域渗透率仅为初始地层的1.1~1.2倍。当工作面连续推进长度大于面长时,覆岩渗透率增高区由“马鞍形”演化为“双V形”,并集中分布于开切眼前方及工作面后方25~30 m范围。研究结果可为弱胶结地层保水开采提供指导。
The permeability evolution of mining-induced overburden in weakly cemented strata under stress-damage-seepage coupling is an important factor affecting water-conserved mining.Considering the conditions of weakly cemented strata in the 21103 coalface of Ili No.4 Coal Mine in Xinjiang,the Jurassic weakly cemented mudstone and sandstone were selected for analysis in this study.First,the permeability evolution of weakly cemented rock during the full stress-strain process was analyzed.On this basis,the influence mechanism of pore structure and mineral composition of weakly cemented rock on its permeability was clarified,and the stress-damage-seepage coupling model of weakly cemented rock was established.Finally,the permeability evolution of weakly cemented overburden was studied.The results disclose that within a confining pressure of 5 MPa,the initial permeability of weakly cemented rock is high,and the permeability decreases significantly in the compaction stage,with a maximum decrease of 91.5%,which is directly related to its high initial porosity and large pore size.At the same time,the maximum permeability and residual permeability of weakly cemented rock increase slightly compared with the initial permeability,the maximum ratios being only 4.51 times and 4.17 times,respectively.This is attributed to the closure of partial water-conducting fractures caused by the expansion and argillization of water-sensitive minerals such as kaolinite and montmorillonite in the weakly cemented rock.Based on the assumptions of compressible fusion and fracture of weakly cemented rock matrix,the damage variable D was defined and the stress-damage-seepage coupling model of weakly cemented rock was established,which effectively characterized the permeability characteristics,high initial permeability and small increase in residual permeability,of weakly cemented rock.At the engineering scale,the weakly cemented strata in the goaf are rapidly compacted and closed after coalface mining,resulting in the emergence of a permeability recove
作者
张世忠
范钢伟
张东升
李文平
范张磊
ZHANG Shizhong;FAN Gangwei;ZHANG Dongsheng;LI Wenping;FAN Zhanglei(School of Mines,China University of Mining and Technology,Xuzhou,Jiangsuu221116,China;School of Resources and Geosciences,China University of Mining and Technology,Xuzhou,Jiangsu 221116,China)
出处
《采矿与安全工程学报》
EI
CSCD
北大核心
2024年第6期1230-1240,共11页
Journal of Mining & Safety Engineering
基金
国家自然科学基金项目(52204161)
国家重点基础研究发展计划项目(2015CB251600)
山西省揭榜招标项目(20201101009)。
关键词
保水开采
弱胶结地层
应力-损伤-渗流耦合
采动覆岩
岩石渗透率
water-conserved mining
weakly cemented strata
stress-damage-seepage coupling
mining-induced overburden
rock permeability
