某简易垃圾填埋场渗滤液在场底天然土层迁移模拟与长期预测

为了解我国早期建设的简易填埋堆场底部天然土层中污染物迁移状况,作者以安徽某填埋场为例,在前期现场勘查、取样和室内测试工作基础上建立了三维有限元分析模型,对宏量有机污染物COD在土层中的迁移状况进行了模拟分析.通过拟合求参获得COD在该场底土层中扩散系数、机械弥散系数和阻滞因子等运移参数的合理取值,在此基础上开展了污染物...

Numerical simulation and prediction of migration of leachate into natural soil strata under a simple MSW dump

In order to investigate soil contamination under a simple dump of MSWs in Anhui of china, 3D finite element models were set up to simulate the migration of the pollutant of COD into the natural soil strata under the waste dump. The simulation was carried out on the basis of the previous field and laboratory studies. The model parameters of COD, including retard factor, diffusion and dispersion coefficients, were obtained by the back analyses of field investigation results. Long-term simulation was carried out to predict the migration of COD into the soil strata. The simulation results show that advection is the predominant mechanism controlling the migration of COD into the soil strata under this dump with a high leachate head level, the effect of retard factor can not be neglected, and the role of dispersion is relatively insignificant. For the central part of the dump with 8 m of leachate head, the migration depth of COD is 5.4 m after a duration of 100 years, reaching 1.4 m deep into the relatively impermeable clay layer. For the sloping part of the dump, the hydraulic gradient in the soil strata is relatively large, and the migration depth of COD after 100 years, being 7.0 m, is 1.6 m greater than that for the central part. In the horizontal direction, the migration distance of COD in the shallow relatively permeable soil layer reaches 48.5m, being greater than that in the deep relatively impermeable clay layer (i.e., 18.1m). The long-term simulation results indicate that the deep relatively impermeable clay layer is an effective barrier for hindering the migration of contaminant.