断层对采动应力的影响数值模拟研究

Numerical Simulation Study on Influence of Faults on Mining Stress

为研究断层对采动应力演化控制作用及发生滑移特征,利用FLAC3D软件对断层带两盘的接触状态以库仑剪切模型的接触面单元代替,模拟随着工作面沿断层倾向和沿断层走向推进时断层接触面上法向应力和剪切应力的演化特征、断层滑移危险性演化规律。结果表明:断层面上法向应力和剪切应力的演化具有明显的时空特征,且断层面上剪切应力对采动影响的敏感性强于法向应力;当工作面沿断层倾向或断层走向推进时,开采层上方断层先于开采层下方断层“活化”,开采层上方附近断层在采空区距离断层20 m时最容易出现“活化”,开采层下方断层在采空区距离断层小于10 m时滑移危险性最高;相比之下,工作面沿断层走向推进时开采扰动对开采层附近断层产生的影响较工作面沿断层倾向推进时大。

To study the controlling effect of faults on the evolution of mining stress and the characteristics of slip occurrence,an interface element with a Coulomb shear model was used to simulate the interface at the fault by using FLAC3D numerical simulation software and the processes of face mining along fault trend and fault dip were simulated respectively.The development of normal stress and shear stress as well as slip risk at the fault was studied.Simulation results showed that:the development of normal stress and shear stress at the fault has obvious spatial-temporal features and the sensitivity of shear stress on the fault surface is stronger than the normal stress.Fault above mining layer activates sooner than fault below mining layer when face advances along the fault trend or fault dip.Fault near the upper side of mining layer activates easiest when the distance of minedout area and fault is 20 m and the slip risk of fault near the below of mining layer is highest when the distance of mined-out area and fault is less 10 m.By contrast with face advancing along the fault trend,mining disturbance makes a larger effect on fault near mining layer when face advances along the fault dip.