中文摘要：

国内湖泊疏浚污染底泥堆场一般以较厚的黏土层作为主要防渗层,由于在上覆底泥作用下黏土层会发生较大的固结变形,因此,在研究黏土防渗层中的污染物运移和转化规律时,应该考虑土体变形的影响。基于Gibson一维大变形固结理论和饱和多孔介质中的污染物对流扩散方程,建立了二者耦合的可变形多孔介质中污染物的运移和转化模型,其中首次考虑了土体自重和生物降解作用的影响。利用所建立模型的数值解,研究了在可变形黏土防渗层中的污染物运移和转化规律,同时分析了模型中不同项和主要参数的作用和影响。研究结果表明,土体大变形对黏土防渗层中污染物的运移有着较复杂的影响,一方面土体变形会加速污染物的运移;另一方面土体固结带来的渗透性减小会增加污染物的穿透时间,二者的不同作用取决于众多的影响因素,如土层厚度和吸附作用等。研究结果对于评估天然黏土防渗层对污染物的阻隔作用有重要的指导意义。

英文摘要：

By constructing the confined disposal facilities for contaminated dredged sediments from lakes in China the thick clay layer is usually chosen as a natural barrier.Because the clay layer will undergo a large-deformation consolidation due to the overburden of dredged material,the soil deformation should be considered by investigating the transport and transformation of contaminant in clay barrier.Based on the Gibson＇s one-dimensional consolidation theory and the dispersion-advection equation of contaminant in saturated porous media,a theoretical model for coupled large strain consolidation and solute transport is herein presented,in which soil weight and biodegradation effect are first taken into account.Using numerical solutions of the derived model the transport and transformation of contaminant in a deforming soil layer are first studied thoroughly;the effects of different parts and parameters of the model are then analyzed respectively.It is shown that the large deformation of soil has complex effects on the transport of contaminants in clay layer.On one hand,soil deformation can accelerate the transport speed of contaminant,and on the other hand,decrease of coefficient of permeability due to soil consolidation is able to increase the breakthrough time of contaminant.These two different effects rely on many factors,such as the thickness of soil layer,adsorption ability of soil,etc.The obtained results from this study are meaningful by assessing the separating capacity of natural clay barrier for contaminant transportation.