摘要
孔周破碎-裂隙煤体注浆后形成注浆体与破碎煤体复合的组合煤体,其渗透特性是影响钻孔抽采瓦斯效果的关键因素。为探究这类组合煤体的渗透特性,采用改进的LFTD1812型三轴渗透仪,开展了双组合煤体下位级配与上位高度变化的三轴逆序渗透试验,系统分析了孔隙率、流速、渗透率及其在多级加载下的变化规律。研究表明:随着渗透压升高,上位煤体对渗透速度的抑制能力呈现出强抑制、过渡和弱抑制3个阶段,且该抑制能力为试样的固有属性。轴压对组合体试样渗透的抑制作用弱于上位煤体,但随着上位煤体高度h的增加,轴压的抑制效果显著增强。组合体试样渗透过程受渗透压影响较大,其随着渗透压增大存在线性减小和指数型降低两种趋势。渗透基质颗粒越大,阻塞区域范围越广,“水塞”效应越明显,但当渗透压超过一定阈值后,“水塞”效应消失。此外,组合体下位Talbol指数n2与标准试样Talbol指数对渗透规律的影响不同,n2增大会导致试样渗透率降低且变化范围缩小,使渗透过程趋于稳定,表现为显著的渗透抑制作用。
After grouting in the fragmented and fractured coal mass,a composite coal mass comprising the grouting body and the fractured coal body around the borehole will be formed.The permeability characteristics of this composite coal mass are key factors affecting the efficiency of gas extraction from the borehole.To explore the permeability characteristics of such a composite coal mass,triaxial reverseorder permeability tests were performed on dual composite coal mass samples characterized by a variable height of the upper coal mass and a variable gradation of the lower coal mass with the aid of an improved LFTD1812 triaxial permeability apparatus.On this basis,the porosity,flow velocity,and permeability of the composite coal mass,as well as their variations under multi-stage loading,were analyzed.The study led to the following findings:Due to the increase in permeation pressure,the upper coal mass exhibits three stages of permeation velocity suppression,namely strong suppression,transition,and weak suppression,and the suppression ability is an intrinsic property of the sample.The suppression effect of axial pressure on the permeability of the composite sample is weaker than that of the upper coal mass itself,and raising the height h of the upper coal mass can enhance the suppression effect of axial pressure during the permeation process.The permeation process of the composite sample is considerably affected by the permeation pressure.As the permeation pressure rises,two variation trends,i.e.,linear decrease and exponential decrease,are observed in the permeation process.Larger sizes of permeation matrix particles correspond to a wider blockage area and a more pronounced"water plug"effect.However,when the permeation pressure rises to a certain value,the"water plug"effect will disappear.The Talbol index n2 of the lower coal mass is different from the Talbol index of the standard sample in terms of their influences on the permeation behavior.An increase in the Talbol index n2 of the lower coal mass leads to a decrease in the sample permeability and a shrinkage of the permeability variation range.Consequently,the permeation process weakens and tends to stabilize.That is,its increase exerts an inhibitory effect on permeability.
作者
张磊
曹妍
张尧
杨世华
初雨航
张天军
ZHANG Lei;CAO Yan;ZHANG Yao;YANG Shihua;CHU Yuhang;ZHANG Tianjun(College of Safety Science and Engineering,Xi'an University of Science and Technology,Xi'an,Shaanxi 710054,China)
出处
《采矿与安全工程学报》
北大核心
2025年第3期648-659,共12页
Journal of Mining & Safety Engineering
基金
国家自然科学基金面上项目(52374228)
国家自然科学基金青年项目(52104216)。
关键词
渗透率
组合煤体
注浆范围
气体渗透
“水塞”效应
permeability
composite coal mass
grouting range
gas permeation
"water plug"effect
