American Society of Civil Engineers


Estimation of Maximum Liquid Depth in Layered Drainage Blankets over Landfill Barriers


by Han Ke, (Assoc. Prof., MOE Key Lab. of Soft Soils and Geoenvironmental Engrg., Zhejiang Univ., Hangzhou 310027, China. E-mail: k87952267@yahoo.com.cn), Yunmin Chen, (corresponding author), (Prof. and Dir., MOE Key Lab. of Soft Soils and Geoenvironmental Engrg., Zhejiang Univ., Hangzhou 310027, China E-mail: cym@civil.zju.edu.cn), and Chuangbing Huang, (Grad. Student, MOE Key Lab. of Soft Soils and Geoenvironmental Engrg., Zhejiang Univ., Hangzhou)

Journal of Environmental Engineering, Vol. 134, No. 1, January 2008, pp. 67-76, (doi:  http://dx.doi.org/10.1061/(ASCE)0733-9372(2008)134:1(67))

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Document type: Technical Note
Abstract: Based on an extended form of the Dupuit assumption, this technical note proposes a computational solution for calculating the maximum liquid depth (Dmax) in layered porous media (e.g., geosynthetic and/or soil drainage blankets of landfills) under free discharge condition. The liquid profile and the location of Dmax for either homogeneous media or layered media can be provided from the approach presented in this technical note. In comparison with the results obtained by application of other methods, the presented approach is verified. Most approaches other than the presented method may lead to considerable error, especially when applied to the drainage system, which consists of a drainage geocomposite overlain by a sand layer with low hydraulic conductivity. The variations of Dmax in two-layered drainage media with varying geometrical parameters and varying hydraulic properties are studied by a parametric analysis. The results demonstrate for a medium consisting of two sand layers, if the hydraulic conductivity of the upper layer is smaller than that of the lower layer and the maximum liquid thickness above the barrier exceeds the thickness of the lower layer, Dmax is very sensitive to the hydraulic conductivity of the upper layer. For a medium consisting of a drainage geocomposite overlain by a sand layer, Dmax is significantly influenced by inflow rate, transmissivity of the geocomposite, and the hydraulic conductivity of the sand when they are not extraordinarily low, and Dmax is much more sensitive to the slope of the drainage layer compared with the system consisting of two sand layers. It is of great advantage to increase the inclination when geocomposites are applied as drainage material.


ASCE Subject Headings:
Landfills
Drainage
Layered systems
Geosynthetics
Hydraulic conductivity
Slopes
Barriers