Predicted performance of clay-barrier landfill covers in arid and semi-arid environments.
Predicted performance of clay-barrier landfill covers in arid and semi-arid environments.
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DOI：
10.1016/j.wasman.2006.06.008
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发表时间：
2007
期刊：
影响因子：
8.1
通讯作者：
Salah Sadek;S. Ghanimeh;Mutasem El-Fadel
中科院分区：
文献类型：
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作者：
Salah Sadek;S. Ghanimeh;Mutasem El-Fadel
用于城市固体废物的常规填埋场覆盖系统包括低渗透性压实粘土屏障，以最大限度地减少对填埋废物的渗透。这些层在干旱至半干旱条件占主导地位的气候中是脆弱的，因此粘土覆盖层倾向于干燥和破裂，导致显著更高的渗透，即，覆盖效率低。迄今为止，在实地观察中报告的这一现象尚未得到充分评估。在本文中，覆盖系统的性能完全依赖于一个粘土屏障进行了模拟，使用数值有限元公式捕捉粘土层的变化和相应的修改水力特性。覆盖系统遵循美国环保局副标题D的最低要求，由保护性植被土壤下的粘土层组成。粘土屏障和植被土壤覆盖层的固有特性，包括其饱和水力传导率和土壤-水特征曲线，根据需要进行变化，以模拟完整或“破裂”的条件，通过拟议方法中的数值分析确定。结果表明，通过受损或破裂的覆盖层的渗透水平比完整覆盖层的渗透水平高出两倍，从10 - 5cm/s的完整粘土水力传导率开始。
Conventional landfill cover systems for municipal solid waste include low-permeability compacted clay barriers to minimize infiltration into the landfilled waste. Such layers are vulnerable in climates where arid to semi-arid conditions prevail, whereby the clay cover tends to desiccate and crack, resulting in drastically higher infiltration, i.e., lower cover efficiency. To date, this phenomenon, which has been reported in field observations, has not been adequately assessed. In this paper, the performance of a cover system solely relying on a clay barrier was simulated using a numerical finite element formulation to capture changes in the clay layer and the corresponding modified hydraulic characteristics. The cover system was guided by USEPA Subtitle-D minimum requirements and consisted of a clay layer underlying a protective vegetated soil. The intrinsic characteristics of the clay barrier and vegetative soil cover, including their saturated hydraulic conductivities and their soil-water characteristic curves, were varied as warranted to simulate intact or “cracked” conditions as determined through the numerical analyses within the proposed methodology. The results indicate that the levels of percolation through the compromised or cracked cover were up to two times greater than those obtained for intact covers, starting with an intact clay hydraulic conductivity of 10−5cm/s.