铁尾矿的渗透特性试验研究

Testing study on the permeability features of iron tailings

尾矿坝的渗流状态是影响上游法筑坝尾矿库安全稳定性的重要因素之一。以阜新地区阿哈来铁尾矿和同乃铁尾矿为研究对象,探讨了尾矿坝渗透系数的合理取值问题。通过室内试验得出阿哈来铁尾矿和同乃铁尾矿的基本物理性质。两种铁尾矿均级配不良,同乃铁尾矿属于含砂低液限粉土,阿哈来铁尾矿属于粉土质砂。使用自行研制的"固结-渗透联合测定装置"进行试验,得出了"固结压力-孔隙比-渗透系数"的定量变化规律。结果表明,阿哈来铁尾矿渗透系数较大。随着固结压力的增大铁尾矿的孔隙比减小,渗透系数也在减小且减小程度很大。在孔隙比减小的初期,渗透系数减小较快;而在孔隙比减小的后期,渗透系数减小速度放缓。在铁尾矿固结压缩过程中,渗透系数随着孔隙比的减小呈高斯曲线关系降低。

The present essay is to report our testing study results on the permeability features of iron tailings by taking Ahalai and Tongnai in Fuxin as a study sample.In this essay,we have mainly chosen to discuss the reasonable permeability value for analyzing the seepage within tailing dam,state of which is one of the important factors influencing the security and stability of tailings pond constructed on the upstream of the mining site.For our research purpose,first of all,we have measured the basic physical properties of the samples through laboratory tests.The results of our analysis indicates that both of the two samples belong to poor grade.The Tongnai iron tailings belong to sand silt with lower liquid limit whereas the Ahalai iron tailings is silty sand by nature.By using a self-developed osmotic oedometer of ours,we have determined the permeability coefficients of the two samples under different quantitative and homogeneous consolidation pressure.The self-developed osmotic oedometer is in a position to simplify the permeability test mentioned in the Standard for Soil Test Method.Due to the higher permeability coefficient of the Ahalai sample,it has made us able to use the coarse sand filter and metal net instead of permeable stone and filter paper in our testing process.What is more,the osmotic oedometer helped us to increase testing accuracy of the permeability coefficient.It has enabled us to finish the testing and measurement of the relationship among the consolidation pressure,the void ratio and the permeability coefficient quantitatively as a result of our testing measurement.The results show that the void ratio and the permeability turn to decrease with the consolidation whereas the permeability coefficient may enjoy a higher degree tolerable to the reduction.Therefore,in the decreasing period of the void ratio,the decreasing speed of the permeability coefficient can be made faster at first and then slower.In the process of consolidation and compression,it is possible for the permeability coefficient to get lower with the decrease of the void ratio,which fits the relationship of Gauss curve which we have found and first proposed.The conclusion provides the scientific basis of parameter determination which turns to be more tally in seepage and stability with the actual situation in mining tailing analysis.