基于离散元的充填散体与岩柱相互作用规律数值模拟研究

Numerical Simulation Research of the Interaction Law Between Granular Backfill and Rock Based on Discrete Element Method

金属矿山的充填采场在上覆岩层的挤压作用下,充填散体与围岩或矿柱产生强烈相互作用,认清这种相互作用规律及其影响因素对评价覆岩变形具有重要指导意义。本研究采用颗粒流数值软件PFC^(2D)构建了充填散体与岩柱相互作用模型,通过室内试验对模型细观参数进行标定并开展充填散体侧向约束下岩柱轴向压缩数值模拟试验,再现充填散体与岩柱相互作用演化过程,分析充填散体颗粒大小、级配和弹性模量等散体结构参数对其相互作用的影响。模拟结果表明:岩柱的侧向变形挤压充填散体,散体反作用于岩柱,并对其提供被动侧压力;随着岩柱侧向变形的增大,充填散体内部颗粒之间接触力链强度逐渐增强,充填散体岩柱之间相互作用逐渐增大,从而使岩柱峰值抗压强度得到提升;同时,由于充填散体的被动约束作用,岩柱发生变形破坏后仍具有残余抗压强度。此外,这种相互作用剧烈程度随充填散体颗粒粒径增大而减小,随充填散体密实度和弹性模量的增大而增大。

In the filling stope of metal mines,under the compression of the overlying strata,the granular backfill interacts strongly with the surrounding rock or ore pillars.Recognizing the law of this interaction and its influencing factors has important guiding significance for evaluating the deformation of the overlying rock.In this paper,the particle flow numerical software PFC^(2D)is used to construct the interaction model between the granular backfill and the rock column,and the microscopic parameters of the model are calibrated through laboratory tests.The evolution process of the interaction between the body and the rock column is analyzed,and the influence of the granular backfill structure parameters such as particle size,gradation and elastic modulus of the granular backfill on its interaction is analyzed.The simulation results show that:the lateral deformation of the rock pillar squeezes the granular backfill,and the scattered body reacts to the rock pillar and provides passive lateral pressure;The strength of the force chain is gradually increased,and the interaction between the granular backfill rock columns increases gradually,so that the peak compressive strength of the rock column is improved;At the same time,due to the passive restraint of the granular backfill,the rock column still has residual after deformation and failure.Compressive strength.In addition,the intensity of this interaction decreases with the increase of the particle size of the granular backfill,and increases with the increase of the density and elastic modulus of the granular backfill.