土石混合介质中非反应性阴离子运移试验研究

为探讨化学物质在土石混合介质中的运移过程和机理,采用饱和稳态流下的Cl-1混合置换试验,测定水流和溶质运移过程,分析土石混合介质的溶质穿透曲线特征及碎石组成和含量对运移过程的影响。选用CXTFIT2.1的平衡和物理非平衡对流弥散模型,对参数弥散系数D和滞留因子R进行反求。结果显示:不同土石比的D变异较大:0.258~22.31 cm2/h。R的波动范围为0.6~1.54;碎石含量影响土石介质的溶质运移过程表现为平均孔隙流速、弥散系数、弥散度均与土石比成负指数的幂函数关系。对碎石粒径与溶质运移参数进行相关分析发现,小粒径的碎石含量增加,则孔隙流速和弥散系数有减少的趋势,而大于10 mm的碎石有利于溶质的运移。通过土石介质的非反应性阴离子的混合置换试验研究,可以为非均一介质中化学物质运移提供参考。

Experimental study of non-reactive anion transport in the soil-stone mixture

To make known the process and the mechanism of the chemical transport in the soil-stone mixture,we measured the process of the water and solute transport,based on the displacement experiments using Cl- during the saturated and steady flow in the soil containing rock fragments,and stuied the effect of different content and constitutes of rock fragments on the breakthrough curves of the solute. The parameters(D,R)of classic CDE were fitted to the measured BTCs using CXTFIT211 at the given pore velocities. The results show that:D values varied from 0.258 cm2·h-1 to 22.31 cm2·h-1,and R values from 0.6 to 1.54.The relations between the soil-stone ratios and the averaged pore velocities,the dispersion coefficients and the dispersivitis all fit the power functions repeatedly. After correlate analyses,the effect of size and constitutes of rock frag-ments on the parameters is expressed in the content of rock fragment. When the content of rock fragments smaller than 5mm increases,the pore velocity and the D have decreasing trend;while the rock fragments bigger than 10mm in diameter are favorable to the solute transport. The result of transport of the non-reactive anion in this paper may provide important data and be useful for better understanding of the solute transport in the heterogeneous porous media.