论文部分内容阅读
为了研究孔隙结构和水动力对悬浮颗粒在饱和多孔介质中沉积和迁移特性的影响,对天然硅粉(悬浮颗粒)和荧光素钠(示踪剂)在饱和多孔介质中的渗流迁移特性进行土柱试验,分别得到了5种不同渗流速度(0.033、0.066、0.132、0.199、0.265 cm/s)、两种不同多孔介质(石英砂和玻璃球)的悬浮颗粒和示踪剂全组合下的20条穿透曲线。根据试验结果,研究孔隙结构、渗流速度对饱和多孔介质中颗粒迁移和沉积过程中水动力作用机制、弥散效应、加速效应的影响。研究表明,悬浮颗粒的穿透曲线可以用一阶沉积动力学对流弥散方程的解析解来描述。随着渗流速度的增大,水动力学作用对颗粒出流浓度的影响越来越大,而孔隙结构的影响则相对减弱。同时,存在一个临界渗流速度值。当渗流速度超出该值时,悬浮颗粒迁移要快于示踪剂,而且临界渗流速度对于玻璃球和石英砂两种多孔介质是不同的;其次,在两种介质中,随渗流速度增大,弥散度增加,回收率和回收悬浮颗粒粒径增大,沉积系数先增大后减小。此外,在孔隙比相近的情况下,悬浮颗粒在玻璃球介质中的回收率要大于其在石英砂中的。可见,孔隙结构和渗流速度是影响饱和多孔介质中颗粒输运的重要因素,渗流速度越大,孔隙结构的作用越明显。
In order to study the effect of pore structure and hydrodynamic force on the sedimentation and migration of suspended particles in saturated porous media, the effects of porous silica (suspended particles) and sodium fluorescein (tracer) on seepage migration in saturated porous media Column test, respectively, obtained five different seepage velocity (0.033,0.066,0.132,0.199,0.265 cm / s), two different porous media (quartz sand and glass beads) suspended particles and tracers under the full combination of 20 Article through the curve. According to the experimental results, the influence of pore structure and seepage velocity on the hydrodynamic mechanism, dispersion effect and acceleration effect during the migration and deposition of particles in saturated porous media was studied. The results show that the breakthrough curve of suspended particles can be described by the analytic solution of the first-order sedimentation kinetics convection-dispersion equation. With the increase of seepage velocity, the influence of hydrodynamics on the particle outflow concentration is more and more obvious, while the influence of pore structure is relatively weakened. At the same time, there is a critical seepage velocity value. When the seepage velocity exceeds this value, the suspended particles migrate faster than the tracer, and the critical seepage velocity is different for both glass and quartz sand porous media. Second, in both media, with the increase of seepage velocity, With the increase of dispersion, the recovery and recovery of suspended particles increased, and the deposition coefficient increased first and then decreased. In addition, in the case of similar void ratio, the recovery rate of suspended particles in glass ball media is greater than that in quartz sand. It can be seen that the pore structure and seepage velocity are the important factors affecting the particle transport in saturated porous media. The larger the seepage velocity, the more obvious the role of pore structure.