颗粒迁移和离子吸附对粗粒土渗透性的影响试验研究

为了研究颗粒迁移和氨氮离子吸附对粗粒土渗透性的影响，利用渗透仪对3种不同细粒含量的花岗岩全风化粗粒土进行渗透试验.研究3种土样分别在蒸馏水和硫酸铵溶液环境中的渗透系数变化规律.结果表明，在蒸馏水渗透环境中，随着土样中细颗粒含量的增加，颗粒迁移对土样渗透性的影响将有所减弱；在氨氮溶液环境中，氨氮吸附对细颗粒含量更高土样的渗透性影响更为明显；随着渗透时间延长，不同溶液环境中土样的渗透系数趋于一致，表明细颗粒迁移对土样渗透性的影响较氨氮离子吸附更强，但离子吸附对渗透系数降低具有一定的延迟效应.在此基础上，讨论土样在渗透过程中渗透性的演变机理，表明颗粒迁移造成土样下游孔隙堵塞，以及氨氮离子吸附造成颗粒表面水化膜厚度的变化，均是引起土样渗透性变化的主要原因. 

An experimental study on the effects of particle migration and ion adsorption on the permeability of coarse grained soil

In order to study the effects of particle migration and ammonia ion adsorption on the permeability of coarse grained soil, the permeability test of three kinds of granite weathered coarse grained soil was carried out by a penetration apparatus. The variation law of permeability coefficient of these soil samples in the distilled water and the ammonium sulfate solution were studied. The results show that the influence of particle migration on the permeability of the soil samples decreases with the increase of fine particles in the soil, and the effect of ammonia nitrogen adsorption on the permeability of the soil sample is more obvious in the ammonia nitrogen solution environment. With the extension of the infiltration time, the permeability coefficient in different solution environments tends to be consistent, showing that the migration of fine particles have a stronger effect than nitrogen ion adsorption on the sample soil permeability. However, the ion adsorption has a certain delay effect on the reduction of permeability coefficient. On the basis of this, the evolution mechanism of the permeability coefficient of the soil samples in permeation process was discussed. The results show that the migration of particles caused by the pore blockage of the soil samples, and the changes of the thickness of the hydration film on the surface of the particles caused by the adsorption of ammonia nitrogen ions are the main reasons for the changes of the permeability of the soil samples.