侧限条件下充填散体压缩承载和传力特性

充填散体的压缩承载和传力特性对防控充填开采矿山的地表变形具有重要意义。通过河卵石、碎石、尾矿、河砂、尾砂5种散体材料和7组不同粒径河卵石的侧限压缩试验，以及河卵石数值模拟压缩试验，分析了其压实过程和粒径对其变形、承载的影响，揭示了散体压缩过程中的传力特性。结果表明：散体压缩过程可分为空隙压密、颗粒破碎压密和压实固结3个阶段，且散体类型和粒径对其非线性压实过程基本没有影响，但对其内部结构重组过程有较大影响；压缩过程中，存在一个临界密实度使不同粒径河卵石的承载能力次序发生反转，且河卵石散体平均变形模量与颗粒特征因子呈负指数关系；基于河卵石数值模拟压缩试验得到的散体内部力链强度分布和“压力拱”，很好地证实了室内压缩试验中散体垂直应力沿加载方向呈递减的趋势，以及侧向应力在整个散体高度上先增后减这一试验结果。

Compressive bearing and force transmission characteristics of granular backfill under lateral confinement

Compressive bearing and force transmission characteristics of granular backfill are of great significance to control the surface deformation in backfill mining. The compression tests were conducted on five types of granular materials including pebbles, gravel, mine tailings, river sand and tailings, and seven gradations pebbles under lateral confinement. The compaction process and the influence of particle size on deformation and bearing capacity were analyzed. Meanwhile, based on the numerical simulation test of the pebbles, the force transmission characteristics were revealed. The results indicate that the bearing process of granular backfill under lateral confinement can be divided into three stages, i.e. void compaction, particle crushing compaction and granular compaction consolidation. The type of granular material and particle size have no effect on its nonlinear compaction process, but have a remarkable effect on the process of internal structure reorganization. In the process of compression, there is a critical compactness that reverses the order of bearing capacity of pebbles with different gradations, and the average deformation modulus of pebbles and the characteristic factor of particle have a negative exponential relationship. Numerical simulation test of pebbles reveals the strength distribution of the force chain and the “pressure arch” inside granular materials. It confirms the facts that the vertical stress in granular backfill decreases along the loading direction, and lateral pressure first increases and then decreases throughout the filling height.