Vertical barrier technique is an ideal candidate for site contamination control. In practical application, the characteristic of vertical cut-off wall is heterogeneous with permeability decreases with depth due to the increasing geostatic stress. In this study, a numerical model was established considering the coupling effect of groundwater flow and contaminant transport considering depth dependent permeability. The results showed that a heterogeneous barrier with variable permeability can reduce the breakthrough time by 63.7% compared to a fixed permeability barrier. The contaminant concentration inside the wall was up to 10 times higher than outside. Shallow leakage occurs where the horizontal migration is dominated by advection. The distribution of pore-water pressure in the system after the installation of high-density polyethylene (HDPE) membranes significantly reduced the shallow convective effect by reducing up to 90% pore-water pressure. Reinforcing the vertical barrier wall using HDPE membrane can effectively prevent the shallow leakage caused by the heterogeneity.

中文翻译：

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异质垂直屏障中污染物传输的建模

垂直屏障技术是现场污染控制的理想选择。在实际应用中，垂直防渗墙的特性是不均匀的，由于地静应力的增加，渗透率随着深度的增加而减小。在本研究中，建立了考虑地下水流和污染物迁移耦合效应并考虑深度相关渗透率的数值模型。结果表明，与固定渗透率屏障相比，具有可变渗透率的异质屏障可以减少63.7%的突破时间。墙内的污染物浓度比墙外高出10倍之多。浅层泄漏发生在水平迁移以平流为主的地方。安装高密度聚乙烯 (HDPE) 膜后系统中孔隙水压力的分布显着减少了浅对流效应，孔隙水压力降低了 90%。采用HDPE膜加固垂直屏障墙可以有效防止因不均匀性引起的浅层渗漏。