基于正态分布概率模型的渗滤液回灌影响分析

渗滤液回灌能有效加速填埋场的稳定并处理多余的渗滤液, 而预测回灌过程中渗滤液的运移规律对于合理设置回灌井的间距和数量具有重要的意义. 考虑了垃圾体的非均质性, 建立了垃圾体的渗透系数随空间正态分布变化的概率模型. 利用 COMSOL Multiphysics^® 软件, 首先对单孔隙度的横纵向均质模型和正态分布模型的 渗透系数以及压力水头进行了比较, 其次研究了在横纵向渗透系数比值、回灌速率和回灌时间等不同 影响因素下, 均质模型和正态分布模型的含水率以及横向影响范围的变化规律. 结果表明, 随着横纵向渗透系数比值的增加, 最终在 100 d 时: 均质模型的含水率由 0.609 增加到 0.68, 横向影响范围从4.842 m 增加到 6.79 m; 正态分布模型的含水率由 0.573 增加到 0.610, 横向影响范围从4.097 m 变为 4.04 m. 这说明横纵向渗透系数比值对正态分布模型的含水 率和渗滤液横向影响范围的影响明显高于均质模型. 而当回灌速率和回灌时间相同时, 正态分布模型渗滤液的渗流速度更快, 易于优先达到饱和含水率, 并在短暂的峰值后迅速下降, 且随着回灌速率和回灌时间的增加, 达到饱和含水率和峰值的时间也逐渐增加.

Numerical analysis of leachate recirculation based on a normal distribution probability model

Leachate recirculation can enhance landfill stability and solve the issue of excess leachate. Predicting the migration characteristics of leachate during the recirculation process is important for determining a reasonable number of recharge wells, and their separation distances. In this study, considering the heterogeneity of municipal solid waste, a probability model was developed for hydraulic conductive changes in space. Using COMSOL Multiphysics^® software, the hydraulic conductivity and head pressure of a transverse-longitudinal homogeneous model were compared with those for a normal, single porosity distribution model. The influence of the transverse-longitudinal hydraulic conductive ratio ($a$), recirculation rate ($q$), and recirculation duration ($t$) on the moisture content and horizontal radius of the two models were investigated. The results showed that after 100 d, the moisture content and horizontal influence range increased from 0.609 to 0.68, and from 4.842 to 6.79 m, respectively, under homogeneous conditions. However, in the case of the normal distribution, the moisture content and horizontal influence range increased from 0.573 to 0.610, and from 4.097 to 4.04 m, respectively. The results indicated that the influence of $a$ on leachate moisture content and horizontal migration range under conditions of a normal distribution was significantly higher than that under conditions of a homogeneous distribution. At the same $q$ and $t$, the leachate recirculation ratio under normal distribution conditions reached saturated moisture content quickly. This was only maintained for a short time, before rapidly decreasing. In contrast, with increasing $q$ and $t$, the time required to reach saturation moisture content and peak value increased gradually.