大倾角煤层走向长壁开采支架稳定性力学分析

Mechanical analysis of support stability in longwall mining of steeply dipping seam

大倾角煤层走向长壁工作面安全高效开采的关键是对围岩的有效控制,而围岩控制的难点在于“支架-围岩”系统的稳定性控制。在综合厘定与研究工作面“顶板-支架-底板”系统相互作用关系的基础上,采用理论分析方法,将底板假设为弹性地基,构建支架倾向力学模型,研究顶板载荷作用下支架的行为响应,并探讨采高、底板物理力学属性和架间作用等因素对支架稳定性的影响。结果显示,在大倾角煤层走向长壁开采中,工作面顶板在其自重及上覆岩层载荷作用下,沿着渐进于重力方向的曲线处于非连续运动状态中;受工作面顶板非连续运动影响,其对支架的作用载荷处于渐进累积过程,支架亦会随着顶板的运动而运动,且其运动幅度处于非连续渐进累积过程;支架稳定性随着顶板法向载荷的增大、顶板切向载荷的减小、顶板载荷偏载程度的减小、底板硬度的增大、采高的减小和支架侧护板千斤顶刚度的增大而增强;顶板法向载荷、底板地基系数、采高和支架侧护板千斤顶刚度仅能在一定程度上增大或减小支架的运动幅度,而顶板切向载荷和顶板载荷作用位置不仅能影响支架的运动幅度,亦会改变其运动方向,且较其它因素而言,其对支架稳定性影响较显著。严控工作面倾斜中上部区域顶板稳定并及时调整支架位态,以减小工作面顶板对支架的切向载荷和顶板载荷的偏载程度,是控制支架稳定的有效途径。

The key of safe and high efficiency mining in the longwall mining of steeply dipping seam is the effective control of surrounding rock,and the difficult point in surrounding rock control lies in the stability control of “support-surrounding rock” system.Based on the comprehensive definition and research on the interaction relationship of “roof-support-floor” system in the working face,a mechanical model of support in inclined direction is established to model the behavior response of support under roof load.Besides the influence of mining height,the floor physical and mechanical properties and interaction between supports on the stability of supports are discussed.Results show that under the load of self weight and overlying strata,the roof of the working face is in a state of discontinuous motion in steeply dipping seam mining,and the motion direction is along the curve in the direction of gravity.As a result,the support will also move with the movement of the roof of working face,and the motion amplitude of support is in a discontinuous progressive accumulation process.The stability of the support increases with the increase of normal roof load,the decrease of the tangential roof load,the decrease of the partial roof loading degree,the increase of floor hardness,the decrease of the mining height and the increase of jack stiffness of side protecting plate of support.The normal load of roof,foundation coefficient of floor,the mining height and jack stiffness of side protecting plate of support can only increase or decrease the movement amplitude of the support to a certain extent.However,the tangential load of roof and the roof load location can not only affect the movement amplitude of the support,but also change the direction of its movement.Compared with other factors,it has a significant impact on the stability of the support.Therefore,there is an effective way to control the stability of the support by strictly controlling the stability of the roof in the middle and upper parts of the inclined working face and timely adjusting the position of the support,so as to reduce the tangential roof load and its eccentric degree.