摘要
This paper analyzed the pore structure, quantified the pore fractal dimension, calculated the grading index(GI) of mixed aggregate, and studied the relationship among GI, pore structure, and strength to describe the cross-scale characteristics of backfill, which is made from stone powder and cemented tailing. A series of experiments were conducted on stone powder cement tailings backfill(SPCTB). The GI formulas for mixed aggregates, containing stone powder and tailings, were derived based on the Füller theory. The nuclear magnetic resonance(NMR) fractal dimensions of backfills were derived using fractal geometry principles. Compared to the mesopore and macropore fractal dimensions, the correlation between micropore fractal dimension and macro-properties in terms of NMR porosity, pore structure complexity, uniaxial compression strength(UCS), and GI is the most significant. Macropore fractal dimension is generally correlated with UCS and GI and the other properties such as the shape of mixed aggregates also have an impact on fractal dimension. However, mesopore fractal dimension has no obvious relationship with macro-properties. Finally, the relationship between GI and UCS was studied, which contributed to improving backfill’s strength and optimizing gradation.
分析石粉水泥尾矿充填体的孔隙结构,量化孔隙的分形维数,计算混合骨料的分级指数(GI),并研究分级指数、孔隙结构与强度之间的关系,以描述其跨尺度特征。同时,对石粉水泥尾矿充填体进行一系列室内实验。基于Füller理论推导混合骨料(石粉和水泥尾矿)的GI公式。通过分形几何原理推导充填体的核磁共振(NMR)分形维数。与中孔和大孔分形维数相比,微孔分形维数与NMR孔隙率、孔结构复杂性、单轴抗压强度(UCS)和GI等宏观特性之间的相关性最为显著。大孔分形维数通常与UCS和GI相关,而其他属性(如混合骨料的形状)也影响分形维数。但中孔分形维数与宏观特性无明显关系。最后,研究GI和UCS之间的关系,这有助于改善充填体的强度和优化级配效果。
基金
Project(41672298)supported by the National Natural Science Foundation of China
Project(2017YFC0602901)supported by the National Key Research and Development Program of China。
作者简介
Corresponding author:Dong-jie YANG,Tel:+86-18684911183,E-mail:yangdjxx@csu.edu.cn。
