Research on Water Retention Characteristics and Pore Size Distribution of Landfilled Municipal Solid Waste
Soil-water characteristic curve (SWCC) is used to describe the relation between water content and matric suction in porous media, and reflects to some extent the pore size distribution. However, a complete SWCC of municipal solid waste (MSW) is difficult to achieve by direct measurement because of the existence of macropores. For this reason, SWCCs of the matrix region in MSW were measured by a pressure plate extractor, and SWCCs of the macropore region were determined from water breakthrough tests in this paper. Water retention characteristics and pore size distribution of MSW were analyzed based on the complete SWCC. The results show that the residual water contents of municipal solid waste were high. Field capacity of shallow, middle and deep waste were 38.5%, 42.2% and 46.8%, respectively, corresponding to a matric suction range of 3–8 kPa. As the depth and age increase, the effective water content interval and specific yield decrease. Taking 1-kPa matric suction as a limit, pores in MSW can be divided into macropores and micropores. The probability density function of pore radius is bimodal. As the depth increase, the amount of macropores and their radius decrease, and the amount of micropores increases with the average pore size becomes smaller.
KeywordsLandfilled municipal solid waste Water retention characteristics Dual-porosity Macropore Soil-water characteristic curve
This research was supported by National Natural Science Foundation of China (Nos. 51478256 and 41772300).
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