柔性隔离层下多漏斗散体矿岩力链演化特征的离散元模拟

Discrete element simulation for evolution characteristics of multi-funnel mineral-rock force chain under flexible isolation layer

为进一步揭示柔性隔离层下散体介质流动过程的内部作用机理,基于离散元软件PFC开展了柔性隔离层下散体介质流力链演化特征的数值试验研究.结合接触力学及统计力学相关知识,对多漏斗放矿过程中散体介质体系内力链长度、数量、强度、方向和准直系数等的演化特征进行了量化研究.研究发现:多漏斗放矿过程中,强接触及力链接触占比均比较稳定,其中强接触占比稳定在33%左右,力链接触占比稳定在16%左右,上下波动幅度均不超过2%;力链总数随着放矿次数的增加不断波动减少,并在放矿后期稳定在790条左右;不同放矿次数下力链长度的概率分布几乎一致,均随着力链长度的增加呈指数形式递减;力链强度的概率分布随着放矿次数的增加先呈指数形式上升再呈指数形式下降,并在0.7■(■为平均接触力)处出现一峰值;放矿初始阶段,力链主要沿铅垂方向分布,力链方向分布形态近似花生状;此后随着矿石颗粒的持续放出,散体介质体系内部局部应力集中现象明显,力链分布主方向由1个演变为4个(铅垂方向、水平方向及与水平方向呈±60°夹角方向);力链准直系数随着放矿次数的增加呈指数形式增长并逐渐保持稳定.

To further reveal the internal mechanism of the granular media flow process under the flexible isolation layer, numerical experiments on the evolution characteristics of bulk media flow force chain under the flexible isolation layer were carried out based on the discrete element software PFC. Based on a combination of contact mechanics and statistical mechanics, the evolution characteristics of the force chain length, quantity, strength, direction, and the collimation coefficient of the internal bulk medium system in the multifunnel ore drawing process were quantitatively studied. It is found that the proportions of the strong contact and the force chain contact is found to be relatively stable in the multi-funnel ore drawing process;the proportion of strong contact is stable at about 33%, that of the force chain contact is stable at about 16%, and the fluctuation amplitude is not more than 2%. The total number of force chains decreases with the increase in ore drawing times, and it is stable at 790 strips in the later stage of ore drawing. The probability distribution of the force chain length is almost the same under different ore drawing times, and it decreases exponentially with the increase in the force chain length. The probability distribution of the force chain strength first increases exponentially with the increase in the ore drawing times and then decreases exponentially;it reaches a peak value at 0.7■(■is the average contact force).In the initial ore drawing stage,the force chain is mainly distributed along the vertical direction, and the force chain direction distribution is similar to a peanut shape.After that, with the continuous release of ore particles, the phenomenon of local stress concentration in the granular media system becomes remarkable, and the main direction of the force chain distribution changes to become four(vertical direction, horizontal direction, and angles of ±60° to the horizontal). The force chain collimation coefficient increases exponentially with the increase in drawing times and gradually becomes stable.