干湿循环与垃圾渗滤液耦合作用下GCL防渗性能

中国环境科学2020,40(2)：701~707ChinaEnvironmentalScience干湿循环与垃圾渗滤液耦合作用下GCL防渗性能王宝1,2∗,陈彬3,窦桐桐1,葛碧洲1,王楼4(1.西安建筑科技大学环境与市政工程学院,陕西西安710055；2.西安建筑科技大学陕西省岩土与地下空间工程重点实验室,陕西西安710055；3.西安建筑科技大学土木工程学院,陕西西安710055；4.中国城市建设研究院有限公司西安分院,陕西西安710054)摘要：开展膨胀指数和渗透系数测定试验,研究干湿循环与垃圾渗滤液渗透耦合作用下膨润土的膨胀性能和土工合成黏土衬垫(GCL)防渗性能变化规律.结果表明,干湿循环与垃圾渗滤液渗透耦合作用对膨润土的膨胀性能和GCL的防渗性能具有显著负面影响:在7次干湿循环后,垃圾渗滤液饱和的膨润土的膨胀指数从20mL/2g降低至7.5mL/2g,GCL的渗透系数从1.65×10-11m/s增加到1.89×10-7m/s.膨胀指数下降和渗透系数升高的根本原因是膨润土渗透膨胀性能的丧失.单纯的垃圾渗滤液渗透不会改变GCL的渗透系数.将有效应力从20kPa升高至150kPa,可以促使GCL的渗透系数降低4个数量级,满足填埋场防渗要求(<5.0×10-11m/s).关键词：土工合成黏土衬垫；干湿循环；垃圾渗滤液；渗透系数；耦合中图分类号：X705文献标识码：A文章编号：1000-6923(2020)02-0701-07HydraulicperformanceofGCLunderwet-drycyclingconcurrentwithmunicipalsolidwasteleachatepermeation.WANGBao1,2∗,CHENBin3,DOUTong-tong1,GEBi-zhou1,WANGLou4(1.SchoolofEnvironmental&MunicipalEngineering,Xi'anUniversityofArchitectureandTechnology,Xi′an710055,China；2.ShaanxiKeyLaboratoryofGeotechnicalandUndergroundSpaceEngineering,Xi′anUniversityofArchitectureandTechnology,Xi′an710055,China；3.SchoolofCivilEngineering,Xi'anUniversityofArchitectureandTechnology,Xi′an710055,China；4.Xi'anBranchofChinaUrbanConstructionDesign&ResearchInstituteCo.,Ltd.,Xi′an710054,China).ChinaEnvironmentalScience,2020,40(2)：701~707Abstract：Laboratoryfreeswellandhydraulicconductivitytestswereconductedtoassesstheeffectofwet-drycyclingconcurrentwithlandfillleachatepermeationontheswellindexofbentoniteandhydraulicperformanceofageosyntheticclayliner(GCL).Wet-drycyclingconcurrentwithleachatepermeationhadasignificantlydetrimentaleffectontheswellindexofbentoniteandhydraulicperformanceofGCL.Theswellindexofbentonitedecreasedfrom20mL/2gto7.5mL/2gandthehydraulicconductivityofGCLincreasedfrom1.65×10-11m/sto1.89×10-7m/s.ThedecreaseintheswellindexofbentoniteandtheincreaseinhydraulicconductivityofGCLshouldbeattributedtothelossofosmoticswellofbentonite.TheGCLcontinuouslypermeatedwithmunicipalsolidwasteleachatemaintainedalowkduringtheentirestudyduration.Increasingtheeffectivestressfrom20to150kPacausedtheh