土工膜衬垫对不同龄期垃圾填埋体稳定性的影响

城市垃圾填埋场在填埋和运营过程中，垃圾土的抗剪强度会随着龄期的增长而变化，作为中间衬垫的土工膜规格和参数也将直接影响垃圾填埋场的稳定性。针对柱点、喷着和光面3种不同规格的HDPE土工膜衬垫，结合室内土-膜界面剪切实验和数值模拟手段，分析HDPE土工膜作为中间衬垫对垃圾填埋体稳定性的影响。结果表明，随着填埋龄期的增加，生物降解持续，垃圾土纤维物含量降低，废渣颗粒含量增加，导致土-膜界面粘聚力呈下降趋势，内摩擦角呈现上升趋势；相较于粘土覆盖，HDPE土工膜能有效抑制填埋体底部位移。结合工程实例，垃圾填埋体底部位移绝对值由粘土覆盖的0.084 m减小到土工膜覆盖的0.073 m；整体稳定安全系数较粘土覆盖分别增大 28% (柱点) 、30% (喷着) 和18.5% (光面) 。HDPE土工膜能明显延缓垃圾填埋体滑移面向填埋体中部和深部的发展，阻断滑裂带的形成。本研究结果可为垃圾填埋场设计和现场工程的安全性评价提供参考。

The influence of geomembrane liner on the stability of landfill at different ages

During the landfilling and operation of MSW landfills, the shear strength of waste soil will change with age. The specifications and parameters of geomembrane as the intermediate liner will also directly affect landfill stability. Aiming at three different specifications of HDPE geomembrane liners, such as salient point, textured and smooth, combined with indoor soil-geomembrane interface shear test and numerical simulation, the influence of HDPE geomembrane as an intermediate liner on the stability of landfill was analyzed. The results showed that with the increase in landfill age, the biodegradation continued, the fiber content of waste soil decreased, and the particle content of waste residue increased, resulting in the decrease of soil-film interface cohesion and the increase of internal friction angle. Compared with clay cover, HDPE geomembrane can effectively restrain the bottom displacement of landfill. Combining with the engineering example, the absolute value of the bottom displacement of the waste landfill decreases from 0.084 m of the clay coating cover to 0.073 m of the geomembrane coating cover. Compared with clay cover, the overall stability safety factor increases by 28% (salient point), 30% (textured) and 18.5% (smooth), respectively. HDPE geomembrane can delay the penetration of landfill slip towards the middle and deep of landfill and block the formation of slip zone. The results of this study provide a reference for landfill design and site engineering safety evaluation.