Analytical Solution for Contaminant Transport through a Soil-Bentonite (SB)/Geosynthetic Clay Liner (GCL)/Soil-Bentonite (SB) Composite Cutoff Wall and an Aquifer

被引:0
作者
Peng, Ming-Qing [1 ]
Qiu, Zhi-Chao [1 ]
Chen, Zhang-Long [2 ]
Xu, Hui [1 ]
Shen, Si-Liang [1 ]
Zhou, Jia-Jie [1 ]
机构
[1] Zhejiang Sci Tech Univ, Sch Civil Engn & Architecture, Hangzhou 310018, Peoples R China
[2] Tsinghua Univ, Dept Hydraul Engn, State Key Lab Hydrosci & Hydraul Engn, Beijing 100084, Peoples R China
基金
中国国家自然科学基金;
关键词
composite cutoff wall (CCW); analytical solution; advection; GCL; contaminant transport; TRANSIENT ANALYTICAL SOLUTION; HYDRAULIC CONDUCTIVITY; ANALYTICAL-MODEL; DIFFUSION; BARRIER; LIQUID;
D O I
10.3390/pr12071486
中图分类号
TQ [化学工业];
学科分类号
0817 ;
摘要
This study develops a one-dimensional analytical solution for contaminant advection, diffusion and adsorption through a soil-bentonite (SB)/geosynthetic clay liner (GCL)/SB-aquifer composite cutoff wall (CCW) system. The solution agrees well with an existing double-layer model. Adopting toluene as a representative contaminant, using the present solution, the analysis systematically investigates the impact of hydraulic gradient (i) and the hydraulic conductivities of GCL (kgcl) and SB (ksb). The results show the following: (1) Increasing i from 0.1 to 1 reduces the concentration breakthrough time (tcb) from 20 to 11 years and mass flux breakthrough time (tfb) from infinite to 11 years, indicating lower i significantly extend both tcb and tfb, which is crucial for optimizing CCW barrier performance; (2) lowering kgcl from 5.0 x 10-11 m/s to 1 x 10-12 m/s and reducing ksb from 1.0 x 10-9 m/s to 1.0 x 10-11 m/s, would increase the tcb by 36% and 100%, respectively. It demonstrates that reducing kgcl and ksb could enhance barrier performance. (3) To achieve equivalent barrier performance, soil-bentonite cutoff wall (SBCW) requires greater thickness compared to SB/GCL/SB CCW, indicating that GCL reduces the required amount of bentonite; and (4) CCWs can use SB with lower adsorption capacity to achieve equivalent performance, further reducing bentonite requirements. The present solution can aid in the design and optimization of GCL-enhanced CCWs.
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页数:16
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