Abstract：Owing to the composition diversity of MSW and the compacted nature in landfills, the leachate transport in landfills is found to be dominated by the preferential flow and shows significant anisotropy (i.e., horizontal permeability higher than vertical one). The vertical well pumping and leachate level recovery tests are conducted at Chengdu landfill. Meanwhile, the leachate distribution and transportation characteristics are examined quantitatively and qualitatively using electrical resistivity tomography (ERT). Through the vertical well pumping and leachate level recovery tests, it is found that the leachate transport in landfills is highly heterogeneous. The performance of vertical wells at different regions of this landfill shows great difference, and the hydraulic conductivity of the surrounding waste ranges from 2.35×10-5 to 3.90×10-4 cm/s. The leachate levels in the surrounding monitoring wells change unusually under pumping of vertical wells. It is mainly due to the existence of preferential flow in the leachate transportation process. In addition, the monitoring results on changes of waste resistivity in the process of leachate pumping and recirculation by ERT further reveal that there are significant anisotropy and preferential flow characteristics in leachate transportation. And the angle between leachate seepage path and horizontal direction is found to be 0~30°.
柯瀚, 胡杰, 吴小雯, 孟猛. 竖井抽水下垃圾填埋场渗滤液运移规律研究[J]. 岩土工程学报, 2018, 40(5): 786-793.
KE Han, HU Jie, WU Xiao-wen, MENG Meng. Investigation into leachate transport in MSW landfills under pumping of vertical wells. Chinese J. Geot. Eng., 2018, 40(5): 786-793.
 陈云敏, 兰吉武, 李育超, 等. 垃圾填埋场渗滤液水位雍高及工程控制[J]. 岩石力学与工程学报, 2014, 33(1): 154-163. (CHEN Yun-min, LAN Ji-wu, LI Yu-chao, et al. Development and control of leachate mound in MSW landfills[J]. Chinese Journal of Rock Mechanics and Engineering, 2014, 33(1): 154-163. (in Chinese))  ZHAN T L T, XU X B, CHEN Y M, et al. Dependence of gas collection efficiency on leachate level at wet landfills of municipal solid wastes and its improvement methods in China[J]. Journal of Geotechnical and Geoenvironmental Engineering, 2015, 141(4): 1-11.  KOERNER R M, SOONG T Y. Leachate in landfills: the stability issues[J]. Geotextiles and Geomembranes, 2000, 18(5): 293-309.  张文杰, 陈云敏. 垃圾填埋场抽水试验及降水方案设计[J]. 岩土力学, 2010, 31(1): 210-215. (ZHANG Wen-jie, CHEN Yun-min. Pumping tests and leachate drawdown design in a municipal solid waste landfill[J]. Rock and Soil Mechanics, 2010, 31(1): 210-215. (in Chinese))  詹良通, 徐 辉, 兰吉武, 等. 填埋垃圾渗透特性室内外测试研究[J]. 浙江大学学报(工学版), 2014, 48(3): 478-486. (ZHAN Lang-tong, XU Hui, LAN Ji-wu, et al. Field and laboratory study on hydraulic conductivity of MSW[J]. Journal of Zhejiang University (Engineering Science), 2014, 48(3): 478-486. (in Chinese))  BURROWS M R. Landfill hydrogeology and the hydraulic properties of in situ landfilled material[D]. London: University of London, 1998.  ROSQVIST N H, DOLLAR L H, FOURIE A B. Preferential flow in municipal solid waste and implications for long-term leachate quality: valuation of laboratory-scale experiments[J]. Waste Management & Research, 2005, 23(4): 367-380.  WOODMAN N D. Modelling of transport in highly heterogeneous porous media, with application to the flushing of waste[D]. London: University College London, 2007.  柯 瀚, 吴小雯, 张 俊, 等. 基于优势流及各向异性随上覆压力变化的填埋体饱和渗流模型[J]. 岩土工程学报, 2016, 38(11): 1957-1964. (KE Han, WU Xiao-wen, ZHANG Jun, et al. Modeling saturated permeability of municipal solid waste basing on the compression changes of its preferential flow and anisotropy[J]. Chinese Journal of Geotechnical Engineering, 2016, 38(11): 1957-1964. (in Chinese))  LANDVA A O, PELKEY S G, VALSANGKAR A J. Coefficient of permeability of municipal refuse[C]// Proceedings of the 3rd International Congress on Environmental Geotechnics. Lisbon, 1998: 63-68.  HUDSON A P. Evaluation of the vertical and horizontal hydraulic conductivities of household wastes[D]. Southampton: University of Southampton, 2007.  SINGH K, KADAMBALA R, JAIN P, et al. Anisotropy estimation of compacted municipal solid waste using pressurized vertical well liquids injection[J]. Waste Management & Research, 2014, 32(6): 482-491.  CJJ 176—2012 生活垃圾卫生填埋场岩土工程技术规范[S]. 2012. (CJJ 176—2012 Technical code for geotechnical engineering of municipal solid waste sanitary landfill[S]. 2012. (in Chinese))  GB/T 50123—1999 土工试验方法标准[S]. 1999. (GB/T 50123—1999 Standard for soil test method[S]. 1999. (in Chinese))  陈崇希, 林 敏. 地下水动力学[M]. 武汉: 中国地质大学出版社, 1999. (CHEN Chong-xi, LIN Min. Groundwater dynamics [M]. Wuhan: China University of Geosciences Press, 1999. (in Chinese))  SL320—2005 水利水电工程钻孔抽水试验规程[S]. 2005. (SL320—2005 Borehole pumping test procedures for water resources and hydropower engineering[S]. 2005. (in Chinese))  CLÉMENT R, OXARANGO L, DESCLOITRES M. Contribution of 3-D time-lapse ERT to the study of leachate recirculation in a landfill[J]. Waste Management, 2011, 31(3): 457-467.  ROSQUIST H, LEROUX V, DAHLIN T, et al. Mapping landfill gas migration using resistivity monitoring[J]. Waste and Resource Management, 2011, 164(1): 3-15.  LING C, ZHOU Q, XUE Y, et al. Application of electrical resistivity tomography to evaluate the variation in moisture content of waste during 2 months of degradation[J]. Environmental Earth Sciences, 2013, 68(1): 57-67.  蒋小明. 高密度电阻率法用于垃圾填埋体液气分布探测的试验研究[D]. 杭州: 浙江大学, 2016. (JIANG Xiao-ming. An experimental study on detection of leachate and gas distribution in municipal solid waste landfill using electrical resistivity tomography[D]. Hangzhou: Zhejiang University, 2016. (in Chinese))  GRELLIER S, REDDY K R, GANGATHULASI J, et al. Correlation between electrical resistivity and moisture content of municipal solid waste in bioreactor landfill[J]. Geoenvironmental Engineering, 2007, 226: 1-14.