Experimental Study On Migration Characteristics Of Sodium Fluoride In Unsaturated Red Clay

With the rapid development of hydropower aluminum industry in Yunnan in recent years,a large number of hydropower aluminum projects have landed in Yunnan.However,the pollution caused by hydropower aluminum has also been widely concerned,especially a large number of hydropower aluminum projects in karst areas.The location of hazardous waste storage and temporary storage has become the key to the project landing,especially the construction of hazardous waste storage in karst area caused potential pollution to soil and groundwater.Therefore,it is of great significance to carry out the study on the permeability of sodium fluoride in unsaturated red clay to assess the risk of soil and groundwater pollution in the karst area of southwest China.In this paper,the characteristics of Na F migration in unsaturated red clay were studied,and the characteristics of Na F migration in unsaturated zone red clay were revealed.The study concluded that:(1)The experimental results show that the hydrodynamic dispersion coefficient and permeability coefficient accord with the exponential relationship,and the hydrodynamic dispersion coefficient increases sharply with the increase of permeability coefficient;(2)When the compaction degree of unsaturated red clay soil is lower,the permeability of soil is better,the migration of fluorine ion in soil is faster,and when the compaction degree of unsaturated red clay is closer to that of saturated red clay,the value of permeability coefficient is closer to that of saturated red clay;(3)When the fluorine ion in the infiltration solution is in the low concentration state,the permeability coefficient will increase,and the migration of fluorine ion in the soil will accelerate;when the concentration of fluorine ion in the infiltration solution in unsaturated red clay is high,the permeability coefficient of the soil will decrease first and then increase,because the change time is relatively short,the migration of fluorine ion in the soil will not have a significant effect;(4)With the decrease of the head height,the infiltration process is mainly divided into three stages: the first stage,the seepage amount of the solution is zero,the seepage velocity is zero;the second stage,the permeability of the soil is from better to more stable,the migration of fluorine ions in the soil is faster and faster;the third stage,when the permeability coefficient is gradually stable,the migration of fluorine ions is mainly affected by the change of the head and the seepage velocity as the water head in the variable head pipe becomes lower and lower,and the migration of fluorine ions gradually slows down;(5)The lower the initial head height,the longer the permeability coefficient tends to be stable,the slower the soil permeability tends to be stable,and the slower the migration of fluorine ions in the soil is.