多孔介质中悬浮颗粒渗透迁移特性的试验研究

通过室内土柱试验, 研究硅微粉和聚苯乙烯微球两种不同的悬浮颗粒的迁移特性, 考虑pH、温度和渗流速度对悬浮颗粒迁移的影响, 结合理论解对试验数据进行拟合, 并确定迁移参 数, 进而讨论pH对迁移参数的影响. 结果表明 pH是影响多孔介质中悬浮颗粒迁移的重要因素, 当温度为5℃时, 两种悬浮颗粒质量浓度峰值随着pH值的增大而提高; 当温度增大至30℃和58.3℃时, 悬浮颗粒的迁移特性发生了变化, 温度升高导致颗粒表面电荷发生改变, 随着pH值的增大质量浓度峰值呈现先增后减的趋势; 当温度和渗流速度一定时, 两种悬浮颗粒的相对速度随着pH值的增大而略微增大, 在流速较高时表现尤为显著, 表明悬浮颗粒在多孔介质中存在加速效应; 随着孔隙水流速的增大, 水动力影响增强, 悬浮颗粒受pH的影响相对减弱, 不同pH时质量浓度峰值变化减小; 两种悬浮颗粒的弥散度都表现为随着pH值的增大而降低, 且硅微粉的弥散度整体比聚苯乙烯微球大.

Experimental study on permeation and transport behavior of suspended particles in porous media

Soil column experiments were carried out considering two different suspended particles (i.e., silicon powder and polystyrene microspheres), and different pHs, temperatures and flow rates were considered to obtain a series of migration curves. The analytical solution was used to fit the experimental data and the migration parameters were then determined. The effect of pH on migration parameters was discussed. Studies have shown that pH is an important factor affecting the transport of suspended particles in porous media. When the temperature is 5℃, the peak concentrations of the two suspended particles increase with the increasing of pH. When the temperature increases over 30℃, the breakthrough curves of suspended particles change. The surface charges of suspended particles have changed with increasing temperature, and as the pH increases, the concentration peak first increases and then decreases. When the temperature and percolation velocity are constant, the relative velocity of the two suspended particles increases slightly with increasing pH, especially at higher flow rates, indicating the acceleration effect of suspended particles in porous media. As the permeation velocity becomes greater, the effect of hydrodynamic force also gets more obvious, and the effect of pH on migration of suspended particles becomes smaller, with peak concentration being of little change at the same time. The dispersion of both suspended particles decreases with increasing pH, and the dispersion of silicon micro powder is larger than that of polystyrene microspheres.