MOE Key Laboratory of Soft Soils and Geoenvironmental Engineering, Institute of Geotechnical Engineering, Zhejiang University, Hangzhou 310058, China.
MOE Key Laboratory of Soft Soils and Geoenvironmental Engineering, Institute of Geotechnical Engineering, Zhejiang University, Hangzhou 310058, China.
Waste Manag. 2022 Jan 1;137:39-49. doi: 10.1016/j.wasman.2021.10.030. Epub 2021 Oct 31.
Anisotropy of hydraulic conductivity is an important parameter controlling fluid movement in municipal solid waste (MSW) landfills, while measurements of anisotropy are rare. In this study, a laboratory-scale enhanced reactor was built to create MSW samples with different degrees of degradation. Vertical and horizontal hydraulic conductivities of these samples were measured in a self-designed permeameter to study the effects of compression and degradation on anisotropy of MSW. CT scanning was performed to observe the internal pore-structure of MSW under compression. A prediction model of anisotropy under compression was established. It was found that as degradation time increased from 0 month to 18 months, the dry mass percent of 0D particles increased from 12.3% to 38.8%, while 2D particles content decreased from 78.7% to 47.2%. As vertical stress increased from 50 kPa to 400 kPa, dry unit weight (γ) increased from 3.26 kN/m to 5.51 kN/m, anisotropy (A) increased from 1.26 to 5.17. It was because that the size and continuity of pores decreased and the angle of pore arrangement tended to be horizontal as the vertical stress increased. The relation between anisotropy and vertical stress could be well fitted with the prediction model. When degradation time increased from 0 month to 18 months, A decreased linearly from 5.02 to 2.75 due to the decreasing content of 2D particles. Anisotropy also decreased with the decreasing C/L. Compression has much greater influence on waste anisotropy than that of degradation. Anisotropy of MSW at different depths of landfills could be determined based on the trend lines in this study.
水力传导率各向异性是控制城市固体废物（MSW）填埋场中流体运动的一个重要参数，而各向异性的测量却很少见。本研究中，构建了一个实验室规模的增强型反应器，以制造具有不同降解程度的 MSW 样品。在自行设计的渗透仪中测量这些样品的垂直和水平水力传导率，以研究压缩和降解对 MSW 各向异性的影响。进行 CT 扫描以观察压缩下 MSW 的内部孔隙结构。建立了压缩下各向异性的预测模型。结果发现，随着降解时间从 0 个月增加到 18 个月，0D 颗粒的干质量百分比从 12.3%增加到 38.8%，而 2D 颗粒的含量从 78.7%下降到 47.2%。随着垂直应力从 50 kPa 增加到 400 kPa，干重度（γ）从 3.26 kN/m 增加到 5.51 kN/m，各向异性（A）从 1.26 增加到 5.17。这是因为随着垂直应力的增加，孔隙的大小和连续性减小，并且孔隙排列的角度趋于水平。各向异性与垂直应力之间的关系可以用预测模型很好地拟合。随着降解时间从 0 个月增加到 18 个月，由于 2D 颗粒含量的减少，A 从 5.02 线性下降到 2.75。由于 2D 颗粒含量的减少，各向异性也随着 C/L 的降低而降低。降解对废物各向异性的影响远小于压缩。根据本研究中的趋势线，可以确定填埋场不同深度处的 MSW 各向异性。
