原状铁尾矿砂渗透特性试验研究

铁尾矿砂渗透特性是影响其坝体稳定性的重要因素之一。而渗透系数是表征其渗透性的重要指标。国内外学者均对渗透系数进行了广泛的研究，分别建立了相应渗透系数的计算公式。但这些公式多适用于粗粒土，其对铁尾矿砂的适用性尚不明确。因此，有必要对现有公式准确性进行验证，并建立适用于铁尾矿砂的渗透系数计算模型。通过室内变水头试验，从FC值、级配、粒径、比表面积和粉粒间孔隙比等多个角度出发，对铁尾矿砂原状样的渗透性质进行了分析。结果表明：原状铁尾矿砂的渗透系数受细粒含量影响明显，细粒含量的阀值在35%左右；应用传统渗透系数计算公式对原状铁尾矿砂渗透系数进行计算，结果并不准确；受细颗粒含量影响，原状铁尾矿砂的渗透系数与不均匀系数Cu、曲率系数Cc、平均粒径、加权平均粒径、体积比表面和粒间孔隙比es之间呈现明显的非线性关系，应用这些参数难以表征细粒含量较大时的渗透系数变化；但是，有效粒径和粉粒间孔隙比与原状铁尾矿砂的渗透系数呈现出了较好的相关性，据此建立铁尾矿砂渗透系数计算公式，其计算结果较为准确。这对陈坑尾矿坝的渗流场分析与稳定性计算具有一定意义。同时，所取尾矿砂试样主要为磁铁矿尾砂，这对类似铁尾砂渗透性计算也有一定借鉴意义。

Experimental Study on Permeability Characteristics of Undisturbed Iron Tailings

The permeability characteristics of iron tailings are one of the important factors affecting the stability of the dam. The permeability coefficient is an important indicator of its permeability. Many formulas for calculating permeability coefficient have been proposed by scholars at home and abroad. However, these formulas are mostly applicable to coarse-grained soil, and its applicability to iron tailings is not clear. It is necessary to verify the accuracy of the these formula and establish a calculation model for the permeability coefficient of iron tailings. The permeability properties of iron tailings sand were analyzed from various angles such as FC value, gradation, particle size, specific surface area and inter-particle void ratio with water head test in laboratory. The results showed that the permeability coefficient of iron tailings sand is affected by the fine content. The threshold of fine content is about 35%. The traditional formula for calculating the permeability coefficient was applied, but the results were inaccurate. The relationship between permeability coefficient of the iron tailings sand and the non-uniform coefficient Cu, the curvature coefficient Cc, the average particle size, the weighted average particle size, the volume ratio surface and the interparticle void ratio es is nonlinear. It is difficult to characterize the change of permeability coefficient when the fine content is large. However, the relationship between permeability coefficient of the iron tailings sand and the effective particle size and inter-particle void ratio is linear. A formula was developed for the determination of permeability coefficient of iron tailings sand by analyzing the effective particle size and inter-particle void ratio data. It is significant for the seepage field analysis and stability calculation of the Chenkeng tailings dam. This can be used to calculate the permeability coefficient of magnetite tailings.