单一粗颗粒影响下的矿岩颗粒体系三维力链演化特征

Evolution characteristics of three dimensional force chain in particle system of caved ore and rock under influence of single coarse particle

针对现有放矿研究中未充分考虑粗颗粒影响的问题,基于滚动阻抗模型开展放矿数值试验,对不同粒径和位置单一粗颗粒影响下的矿岩颗粒体系三维力链宏观分布、数量、平均强度、准直性、长度以及方向等演化特征进行量化研究。研究结果表明:1)针对0.3~0.8 m的三维矿岩细颗粒体系,仅当粗细颗粒粒径比大于6.0且粗颗粒处于矿岩颗粒剪切带区域时,单一粗颗粒的存在才会导致粗颗粒一侧的松动体形态产生明显变异,引起局域细颗粒的提前移动。2)粗颗粒能够产生力链聚集效应,显著提高其四周局域内力链分布密度、力链接触数占比以及力链平均强度,而对力链准直性无显著影响。3)无论是否存在粗颗粒,在各放矿阶段局域内力链概率均随其长度增加而呈负指数函数形式减小;从统计意义的角度而言,力链最大长度均不超过10。4)当粗颗粒及其四周细颗粒未产生松动时,粗颗粒的存在可显著提高局域力链方向各向异性程度;当粗颗粒及其四周细颗粒产生松动后,其局域力链方向各向同性程度不断提高,局域力链方向逐渐向放矿口方向集中。

Aiming at the problem that the influence of coarse particles is not fully considered in the existing draw research,based on the rolling resistance model numerical draw tests containing coarse particle with different size and spatial position were conducted,and the macroscopic distribution,number,average strength,collimation,length and direction of three dimensional force chain in particle system of caved ore and rock under the influence of single coarse particle were quantitatively studied.The results are shown as follows.1) In view of the three dimensional particle system of caved ore and rock with size of 0.3-0.8 m,only when the particle size ratio of coarse and fine particles is greater than 6.0 and the coarse particle is in the shear zone,can the existence of single coarse particle lead to the obvious variation of the IMZ(isolated movement zone) on the side of the coarse particle and lead to the advance movement of the local fine particles.2) Coarse particle can produce force chain aggregation effect,significantly improve the distribution density of local force chain,the proportion of contact number of force chain and the average strength of force chain,but have no significant effect on the collimation of force chain.3) Regardless of the existence of coarse particle,the probability of local internal force chain decreases with the increase of its length in the form of negative exponential function.And from the point of view of statistical significance,the maximum length of force chain is not more than 10.4) When coarse particle and its surrounding fine particles remain stationary,the existence of coarse particle can significantly improve the anisotropy of local force chain direction.When coarse particle and its surrounding fine particles have moved,the isotropy degree of local force chain direction increases,and the local force chain direction concentrates gradually towards the direction of drawpoint.