关键词: 饱和多孔介质, 悬浮颗粒, 孔隙结构, 穿透曲线, 土柱试验

Abstract: To investigate the effects of pore structure and hydrodynamic forces on the particle transport and deposition, the penetration processes of a typical silica powder (suspended particles) and fluorescein (as the dissolved tracer) in saturated porous media is studied through a series of column tests. Two kinds of porous media (i.e.,quartz sand and glass beads) and 5 seepage velocities (i.e., 0.033, 0.066, 0.132, 0.199, 0.265 cm/s) are considered, and twenty breakthrough curves are obtained. Based on the experimental results, the influence of pore structure and seepage velocity on the hydrodynamic mechanism, dispersion effects and accelerated effects are analyzed during deposition and migration processes of suspended particles in saturated porous media. It is shown that, the breakthrough curves (BTCs) are well described by an analytical solution of the advective-dispersive equation with a first-order deposition kinetics. In contrast with the effect of pore structure, the effect of hydrodynamics processes on particle transport increases significantly with the increase of seepage velocity. There exists a critical seepage velocity, beyond which suspended particles travel faster than the dissolved tracer, and the critical velocity is different for glass beads and quartz. In addition, the mean diameter of the recovered particles, the longitudinal dispersivity and recovery rate increase with the seepage velocity, and a decrease of the deposition rate of particles beyond the critical seepage velocity is also observed in two porous media. Furthermore, the recovery rate of suspended particles is higher in the glass beads even if the porosities are similar. Overall, the study highlights the effect of pore structure and seepage velocity on the transport of particles in saturated porous media, and the pore structure even plays a greater role in high seepage velocity conditions.

Key words: saturated porous media, suspended particles, pore structure, breakthrough curves, column test