西鞍山铁矿深部立井围岩稳定性数值模拟分析

Numerical simulation analysis of the stability of the surrounding rocks in the deep vertical shaft of the West Anshan Iron Mine

针对西鞍山铁矿辅助井开挖诱致井筒围岩变形破坏问题,以700~1000m深度范围辅助井掘进为依托,运用FLAC3D有限差分模拟软件对竖井开挖过程进行了三维数值分析,阐明了不同深度辅助井开挖诱致井筒围岩变形破坏演化特征,揭示了辅助井掘进过程井筒掘进工作面支护效应下围岩应力及位移释放规律,分析获得了辅助井掘进诱致井筒围岩弹性应变能积聚、迁移与释放演化机理。研究表明:在辅助井开挖过程中,井筒围岩塑性区破坏方式以剪切破坏为主,塑性区范围随着竖井掘进深部的增加不断增加,且最大主应力峰值位置位于井筒围岩弹、塑性区交界处;井筒围岩径向位移随深度呈线性增加,最大径向位移值为90.64 mm,且最小水平主应力方向围岩位移大于最大水平主应力方向;随着竖井掘进深度增加,井筒掘进工作面以上距其2m位置井筒围岩应力释放率达到95%,且井筒围岩径向位移随距井筒掘进工作面距离增加呈非线性增加,并在距井筒掘进工作面24m处径向位移达到最大;受开挖扰动影响,井筒围岩弹性应变能密度呈非线性增加,并根据岩爆判据预测竖井掘进至1050m处井筒围岩存在岩爆发生可能性。

Aiming at the problem of shaft surrounding rock deformation and failure caused by auxiliary shaft excavation in West Anshan Iron Mine,based on the auxiliary shaft excavation at the depth of 700 m to 1000 m,the three-dimensional numerical analysis of vertical shaft excavation process is carried out by using FLAC3D finite difference simulation software,and the evolution characteristics of shaft surrounding rock deformation and failure caused by auxiliary shaft excavation at different depths are expounded.The stress and displacement release law of surrounding rock under the support effect of shaft driving face in the process of auxiliary shaft driving is revealed,and the evolution mechanism of elastic strain energy accumulation,migration and release of shaft surrounding rock induced by auxiliary shaft driving is obtained.The study shows that during the excavation of the auxiliary shaft,the failure mode of the plastic zone of the surrounding rock of the shaft is mainly shear failure,and the range of the plastic zone increases with the increase of the depth of the shaft excavation,and the peak value of the maximum principal stress is located at the junction of the elastic and plastic zone of the surrounding rock of the shaft.The radial displacement of wellbore surrounding rock increases linearly with depth,the maximum radial displacement is 90.64 mm,and the displacement of surrounding rock in the direction of minimum horizontal principal stress is larger than that in the direction of maximum horizontal principal stress.With the increase of shaft driving depth,the stress release rate of shaft surrounding rock at 2 m above the shaft heading face reaches 95%,and the radial displacement of shaft surrounding rock increases nonlinearly with the increase of distance from shaft heading face,and reaches the maximum at 24 m from shaft heading face.Affected by the excavation disturbance,the elastic strain energy density of the surrounding rock of the shaft increases nonlinearly,and the possibility of rockburst is predicted according to the rockburst criterion.