高应力矿柱在动力扰动下力学响应研究

Study on Mechanical Response of Highly-stressed Pillars under Dynamic Disturbance

针对高应力矿柱在遭受爆破、震动、远场地震等外界动力扰动时,往往发生整体失稳,甚至坍塌的现象,对深部矿山二步骤回采预留矿柱进行简化并建立了地质和力学模型,并对应力波在矿柱中传播进行了力学分析;进而采用FLAC3D数值模拟的方法研究了高径比为4的典型圆柱形矿柱分别在20 MPa、30 MPa、40 MPa静应力作用下竖向应力和塑性区的分布以及在此基础上分别受到峰值为10 MPa、20 MPa、30 MPa动力扰动时的力学响应特性。研究结果表明:矿柱在40 MPa高静应力作用下依然处于弹性变形阶段,可以保持自身的稳定;而高应力矿柱在遭到外界动力扰动时,会产生不同程度的塑性区,稳定性变差;静应力越大,动力的峰值越高,矿柱的稳定性越差,越容易失稳。得到了它们之间的定量关系并给出了保护矿柱稳定性的建议。

In view of the phenomenon that the highly-stressed pillars often suffer from overall instability,even collapse when encountering external disturbance such as explosion,shock,far field earthquake,etc,this paper simplifies and establishes the geological and mechanical model of the pillars reserved in the two-step mining,then analyzes the propagation of stress wave in the pillars on the aspect of mechanics. By the method of FLAC3 Dnumerical simulation,the paper studies the distribution of the vertical stress and plastic zones of cylindrical pillars with a ratio 4 of height to diameter under the static pressure of 20 MPa,30 MPa and 40 MPa and mechanical response characteristics of pillars suffering from dynamic disturbance with peaks of 10 MPa,20 MPa and 30 MPa. The result shows that the cylindrical pillars is still in the stage of elastic deformation and can maintain its own stability under 40 MPa static stress. Yet the highly-stressed pillars produce different degrees of plastic zones,their stability being weak when suffering from dynamic disturbance. The larger the static stress,the higher the peak of dynamic power is,the more unstable and fragile pillars become. The quantitative relationship among stability of pillars,static stress and dynamic power are obtained and several suggestions of protecting stability of pillars are given.