软岩巷道底鼓机理及其稳定性控制研究

Floor heave mechanism and stability control in soft rock roadway

为探究双巷布置工作面下区段巷道底鼓的发生机理及相应围岩控制技术,以韩城桑树坪二号井的3309运输巷作为工程背景,通过朗肯土理论建立采空区邻近巷道底板力学模型,研究了双巷布置的工作面回采时采动应力分布规律及塑性区范围,结果表明:邻近工作面在工作面前方210 m处开始底鼓,工作面前方40 m处底鼓位移量增加速率升高,拉底前的最大底鼓量达到662 mm;根据对力学模型计算得到巷道底板的破坏与巷道两帮应力集中系数呈线性相关,且煤柱帮应力集中系数K′轴斜率Δ1为6.520,煤壁帮应力集中系数K轴斜率Δ2为2.173;根据数值模拟结果,3309工作面底板塑性区深度维持在3 m左右,由于受到采动影响导致相邻巷道帮部塑性区贯通,最大可达10 m,且工作面后方煤柱最大垂直应力达到44.5 MPa。最后基于采空区邻近巷道底鼓发生机理,提出采用爆破预裂切顶卸压技术对巷道变形进行控制,并且取得了良好的应用效果。

In order to investigate the mechanism of floor heave in the lower section of the working face with double lane arrangement and propose the corresponding control technology,the 3309 transport lane of Hancheng Sangshuping No.2 Mine was taken as the engineering background,the mechanical model of the neighboring lane floor in the mining area was established through Rankine soil theory,and the distribution of mining stress and the range of plastic zone is studied when the working face with double lane arrangement was mined.The research results show that:in the adjacent working face floor heave occurred at 210 m ahead of the working face,and the rising rate of floor heave displacement increased at 40 m ahead,the maximum floor heave reached 662 mm before dinting.According to the mechanical model calculation,the damage of roadway floor was linearly related to the stress concentration coefficient of the roadway sidewalls,and the slope of the coal pillar gang stress concentration coefficient K′axisΔ1 was 6.520.According to the numerical simulation results,the depth of the floor plastic zone in the working face was maintained at about 3 m,and the maximum vertical stress of the coal pillar behind the working face reached 44.5 MPa due to the mining influence,leading to the penetration of the plastic zone of the neighboring roadway sidewalls.Based on the floor heave mechanism in the neighboring roadway in the mining area,the pre-cracking roof cutting and pressure relief technology was proposed to control the deformation of the roadway,and favorable results were achieved.