柔性隔离层下单漏斗散体矿岩力链演化特征模拟

Simulation on evolution characteristics of force chain in granular ore rock with single funnel under flexible isolation layer

开展柔性隔离层下单漏斗散体矿岩力链演化特征模拟研究,对于进一步揭示柔性隔离层下散体介质流动规律的内部作用机理具有重要意义。基于大量放矿同步充填留矿法数值试验模型,利用PFC强大的数据处理及图片输出功能,结合接触力学及统计力学相关知识,对单漏斗放矿过程散体介质体系内力链长度、数量、强度、方向、准直系数等的演化特征进行量化研究。结果表明:在柔性隔离层下单漏斗放矿过程,随着放矿次数的增加强接触占比逐渐由37%减小到32%,并在放矿后期逐渐保持稳定,力链接触作为强接触自组织而成的结构,其接触占比在放矿过程稳定在17%左右。力链总数随着放矿次数的增加逐渐减少,并在放矿后期稳定在810条左右,且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式递减;随着放矿次数增大力链强度的概率分布先呈指数式上升,再呈指数式下降,在0.7 F(F为平均接触力)处出现一峰值。放矿初始阶段,力链主要沿垂直方向分布,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,力链方向分布形态由花生状逐渐变为椭圆最终演变成花瓣状形态,力链分布主方向由一个演变为三个(垂直及与水平方向呈±30o夹角的方向)。力链准直系数在第9次放矿结束后达到顶峰,随后逐渐下降并保持稳定。

It is of great significance to carry out the simulation on the evolution characteristics of the force chain in granular ore rock with a single funnel under a flexible isolation layer so as to further reveal the internal mechanism of the flow law of the granular medium under the flexible isolation layer.Based on the numerical test model of the mass draw and synchronous filling with shrinkage stoping method,the evolution characteristics of the force chain length,quantity,intensity,direction and collinear coefficient in the granular medium system with a single funnel during ore drawing process are quantitatively studied by using the powerful data processing and image output functions of PFC and combining with the relevant knowledge of contact mechanics and statistical mechanics.The results show that in the ore drawing process with a single funnel under a flexible isolation layer,the ratio of strong contact gradually decreases from 37%to 32%with the increase of ore drawing times,and gradually remains stable in the later stage of ore drawing.As a structure of strong contact self-organization,the contact ratio of force chain contact is stable at about 17%in the ore drawing process.The total number of force chains gradually decreases with the increase of the number of ore drawing,and stabilizes at about 810 in the later period of ore drawing.The probability distribution of force chain length under different times of ore drawing is almost the same,which decreases exponentially with the increase of the length of the force chain.The probability distribution of force chain strength under different times of ore drawing firstly increases exponentially and then decreases exponentially,and a peak value appears at 0.7 F(F is the average contact force).In the initial stage of ore drawing,the force chain is mainly distributed along the vertical direction,and its distribution pattern is similar to that of peanut,with the increase of ore particles sustained drawn,the direction of the force chain distribution from peanut shape gradually into elliptical form eventually evolved into a petal shape form,and the main direction of force chain distribution evolved from one to three(the vertical direction and the direction with±30 o angle to the horizontal direction).The collimation coefficient of the force chain reached its peak after the 9 th ore drawing,and then gradually declined and remained stable.