HDPE土工膜长期性能稳定性的研究进展

Review on Long-term Stability of HDPE Geomembrane

垃圾填埋场底部高密度聚乙烯(HDPE)土工膜会因氧化降解而使防渗性能降低,对环境带来二次污染风险,因此,HDPE膜的长期稳定性是值得关注的问题,但国内相关研究甚少。HDPE膜的降解过程可分为3个阶段,主要受自身性质、温度、接触介质和衬垫结构等因素的影响。文章重点综述了国外研究HDPE膜长期稳定性的试验方法,归纳了相关的数学模型,并根据存在的问题提出了建议。室内试验一般采用老化试验,包括浸泡试验和模拟试验,二者均能加快HDPE膜的老化进程。前者一般将试样完全浸泡于研究介质中试验,试验值较为保守;后者将样品置于模拟的衬垫构造中试验,结果更接近实际。数学模型采用Arrhenius模型,精度和所需参数取决于老化试验,现阶段大部分计算结果较片面,完善试验是后续工作的重点。

Anti-seepage performance of high density polyethylene （HDPE） geomemhrane at the bottom of landfill will downgrade due to oxidative degradation, which would cause risk of secondary pollution to environment. Therefore long-term stability of HDPE geomembrane worths attention while few studies have been done in China so far. Divided into three stages, the degradation process of HDPE geomembrane is affected by properties of geomembrane, temperature, exposure media and structure of liner. Laboratory methods on long-term stability of HDPE geomembrane were reviewed, corresponding mathematical model was summarized. Suggestions were given according to the existing problem. Aging test is widely used as indoor test, which includes both immersion test and simulation test that can accelerate the aging process of HDPE geomembrane. For the former, sample will be immersed completely into the research media with a more conservative result, while the latter, sample will be tested in the experimental liner structure, and results shall be much closer to reality. Arrhenius model is used as mathematical model, with the accuracy and parameters depending on the aging test. Most results calculated are unilateral for now and improvement of the experimental research will still be a key point for subsequent work.