College of Environment and Civil Engineering, Chengdu University of Technology, Chengdu 610059, China; School of Engineering, Sun Yat-sen University, Guangzhou 510275, China.
School of Earth Science and Engineering, Hohai University, Nanjing 210098, China.
J Contam Hydrol. 2019 Feb;221:118-126. doi: 10.1016/j.jconhyd.2019.02.002. Epub 2019 Feb 11.
This paper employed a one-dimensional large-deformation model in consideration of the coupling of mechanical consolidation and solute transport, to study the transport of contaminants in a largely-deformed aquitard. An analytical solution has been derived to describe the drawdown variation in a largely-deformed aquitard which is subjected to abrupt hydraulic head decline in adjacent confined aquifers. The pore water flux and void ratio variation were obtained on the basis of the analytical solution. The equation for transient contaminant flux was solved by the finite difference method. A hypothetical case study was done to explore the effect of consolidation on the contaminant transport in a largely-deformed aquitard. The transit time of contaminant transport in the aquitard is mainly determined by the hydraulic conductivity, thickness, partitioning coefficient, void ratio and effective diffusion coefficients of aquitard, as well as the drawdown in the adjacent confined aquifer. The impact of delayed drainage on the contaminant transport in the largely-deformed aquitard is mainly controlled by two factors: the transient water flow and the decrease of aquitard thickness, in the process of aquitard consolidation. The former increases the breakthrough time of contaminant transport in the aquitard, and the latter gives rise to an opposite case with its effect decreasing with increasing contaminant partitioning coefficient for soil particles sorption. A larger deformation, which may be induced by a larger thickness, higher specific storativity of aquitard or a larger drawdown of the adjacent confined aquifer, and a lower hydraulic conductivity of aquitard cause a more significant impact of delayed drainage on the contaminant transport in an aquitard.
本文采用一维大变形模型，考虑了力学固结与溶质运移的耦合作用，研究了在大变形含水层中污染物的运移。推导了一个解析解来描述在相邻承压含水层中水力水头突然下降时大变形含水层中的水位降变化。根据解析解得到了孔隙水通量和空隙比的变化。通过有限差分法求解了瞬态污染物通量方程。通过一个假设的案例研究，探讨了固结对大变形含水层中污染物运移的影响。污染物在含水层中的传输时间主要由含水层的水力传导率、厚度、分配系数、空隙比和有效扩散系数以及相邻承压含水层中的水位降决定。延迟排水对大变形含水层中污染物运移的影响主要由两个因素控制：含水层固结过程中的瞬态水流和含水层厚度的减小。前者增加了污染物在含水层中的穿透时间，而后者则相反，随着土壤颗粒吸附的污染物分配系数的增加，其影响减小。更大的变形，可能由更大的厚度、更高的含水层比储容系数或更大的相邻承压含水层的水位降引起，以及更低的含水层水力传导率，会对含水层中的污染物运移产生更显著的延迟排水影响。
