黏土-膨润土屏障中氯离子对流扩散规律研究
Advection and dispersion of Cl- in clay-bentonite barriers
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摘要: 摘 要：黏土与一定量膨润土混合,构成阻滞垃圾填埋场污染物迁移的黏土-膨润土屏障。试验研究了不同膨润土含量的黏土-膨润土混合物中
迁移扩散规律,使用经验公式和解析方法对试验结果进行拟合,获得
在土-膨润土混合物中的有效扩散系数,通过数值分析探讨了天然堆场或简易填埋场使用土-膨润土屏障进行污染防治的可行性。试验结果表明,加入膨润土后黏土渗透系数和有效扩散系数显著降低,在试验涉及的膨润土含量范围内,渗透系数和扩散系数的对数值与膨润土含量之间呈线性关系；所使用的解析方法能综合考虑对流和扩散作用,得出的有效扩散系数比通常采用的经验公式更为准确；取场底渗滤液水头为30 cm和3 m进行对流-扩散分析,表明天然垃圾堆场或简易填埋场较易对周边造成污染,黏土-膨润土屏障可有效避免或降低污染。
Abstract: Abstract: Clay-bentonite barriers composed of clay and bentonite mixtures are proposed to delay contaminant migration from landfills. Diffusions ofin the clay-bentonite mixtures with different contents of bentonite are analyzed by means of laboratory tests. The test results are fitted by an empirical formulation and an analytic solution respectively to get the effective diffusion coefficient. The feasibility of using the clay-bentonite barriers to prevent pollution by the contaminant in non-sanitary landfills is discussed. The test results show that the hydraulic conductivity and the effective diffusion coefficient of the clay-bentonite mixture decrease greatly as the content of bentonite increases. According to the tests, the logarithmic values of the hydraulic conductivity and the effective diffusion coefficient show a linear relationship with the bentonite content. The effective diffusion coefficient obtained from the analytical method is more accurate than that obtained from the empirical formulation because both effects of the diffusion and the advection on migration of
are considered in the analytical method. Advection-diffusion analysis is carried out considering leachate heads of 30 cm and 3 m on the bottom of a landfill. The results show that the surroundings are prone to being polluted by non-sanitary landfills and that the pollution can be effectively avoided or delayed by the clay-bentonite barriers.
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