Model tests on interaction between soil and geosynthetics subjected to localized subsidence in landfills

• Published in: Journal of Zhejiang University. A. Science 2012-06, Vol.13 (6), p.433-444
• Main Authors: Zhu, Bin, Gao, Deng, Li, Jun-chao, Chen, Yun-min
• Format: Article
• Language: English
• Subjects: Civil Engineering; Classical and Continuum Physics; Deflection; Engineering; Geosynthetics; Industrial Chemistry/Chemical Engineering; Landfills; Liners; Mechanical Engineering; PVC膜; Reinforcement; Soil (material); Strain; Subsidence; 土工合成材料; 垃圾填埋场; 局部塌陷; 模型试验; 沉降区; 沙质土壤; 相互作用
• ISSN: 1673-565X; 1862-1775
• DOI: 10.1631/jzus.A1100315

In a landfill, excessive tensile strains or failure of the liner system due to localized subsidence underneath the geosynthetic liner, is a concern in design and operation of the landfill. The localized subsidence can be commonly withstood by reinforcements such as geogrids. A total of nine model tests were carried out to study the influence of soil arching in overburden sandy soil on the geosynthetics and the interaction between the soil and the geosynthetics. The localized subsidence was modeled by a strip trapdoor under the geosynthetic reinforcements. The reinforcement includes several layers of polyvinylchlorid （PVC） membrane or both PVC membrane and a compacted clay layer. Test results show that the vertical soil pressure acting on the geosynthetics within the subsidence zone is strongly related to the deflection of the geosynthefics. The soil pressure acting on the deflected geosynthetics will decrease to a minimum value with respect to its deflection if the final deflection is large enough, and this minimum value is almost independent of the overburden height. Otherwise, the deflection of geosynthetics cannot result in a full degree of soil arching, and the soil pressure within the subsidence zone increases with the increase of overburden height. Deflections and strains of the geosynthetics obviously decrease with the increase of their tensile stiffness. The presence of a compacted clay layer buffer can therefore reduce both deflections and strains of the geosynthetics. Finally, a composite liner structure is recommended for landfills to withstand the localized subsidences.