基于渗流–压缩耦合作用的填埋场渗沥液导排量分析

Calculation of leachate drainage volume of landfills based on seepage-compression coupling action

目前,渗滤液的导排量分析通常采取水文分析方法或经验公式获得,不考虑由于填埋体的压缩引起的排出,从而低估渗滤液导排量或难以估计封场后渗沥液的产生情况。采用有限元软件模拟填埋体压缩及饱和–非饱和渗流过程,考虑了填埋体渗透系数由于压缩发生的改变而变化,分析了各堆填阶段的渗沥液导排量。研究了初始含水率、压缩性、降雨强度等对渗滤液导排量的影响,并和现场实测数据进行了对比验证。结果表明:垃圾初始含水率、压缩性、降雨强度是决定渗沥液导排量的主要因素,垃圾初始压缩指数Cc为1.31时的渗沥液导排量比不考虑压缩堆填期间的渗沥液导排量提高了26.0%;分区填埋作业时,渗沥液导排较小,且随时间波动较小。

At present the hydrological analysis method or empirical formula is usually used in leachate drainage volume analysis.The leachate drainage volume is underestimated since the leachate generation induced by the compression of MSW is not taken into account in these methods.Also,the leachate generation after field sealing cannot be obtained or it may be underestimated.By means of FEM,the compression of MSW and the seepage of leachate in landfill are simulated,and a numerical analysis method is proposed to calculate the leachate drainage volume for each filling stage with time.The variation of saturated hydraulic conductivity of MSW with compression is taken into consideration in the analysis procedure.The influences of the initial moisture content,compressibility and precipitation on the leachate drainage volume are studied and verified by use of the field measured data.The results show that the initial moisture content of waste,compressibility and precipitation are the main factors to determine the leachate drainage volume.The leachate drainage volume of MSW whose initial compression index is 1.31 is increased by 26.0% than that of MSW whose compression index is 0 in the landfill period.The leachate generation is smaller and has an easy curve when the zoning landfilling is taken.