污染物在二层非饱和土中运移过程综合分析

摘要

The landfill site was idealized as three-layer stratum composed of a compacted clay liner（CCL）,a underlying layer and a layer of aquifer below the landfill.Based on Richards equation,the analytical solutions of volumetric water content in both CCL and underlying layer were obtained under steady-state seepage.According to the contaminant migration mechanism in the porous media,the one-dimensional computing model was established for contaminant migration in the three-layer strata including two unsaturated soil layers.The model considered nonlinear sorption of CCL and bio-degradation of contaminant migration process and bio-degradation of waste.The established mathematical model was used for carrying on the concrete computation on some hypothesis landfill sites.The studies on the calculation and analysis of variable parameters were conducted to examine the effect of all the related factors on the contaminant migration.The calculated results show that the sorption and bio-degradation of unsaturated soil have remarkable effect on the contaminant migration process,especially when the sorption and degradation of CCL are important controlling factors for contaminant migration process.When volumetric water content of unsaturated soil is large,the variation of volumetric water content has negligible influence on contaminant migration.%假设填埋场下部为具有压实黏土衬里（CCL）、下卧土层及含水层的三层结构体系,基于Richards方程,在稳态渗流下,得到了CCL与下卧土层体积含水率的解析解.依据污染物在多孔介质中运移机制,建立了污染物在包含两层非饱和土层的三层结构体系中运移的一维计算模型.在计算模型中分别考虑了CCL的非线性吸附特性、污染物运移过程中的生物降解特性、垃圾的生物降解特性等.采用所建立的数学模型,对某一假想填埋场进行了具体计算,通过变动参数计算与分析,探讨了各种因素对污染物运移的影响.计算结果表明,非饱和土层的吸附与生物降解