A Research On Composite Clay Of Landfill Impermeable Liner In The Loess Region

With the economic and technological development, the amount of waste grows day by day. People have paid more attention on waste disposal. The use of sanitary landfills is the ultimately treatment, which is used widely in waste disposal.However, in the process of landfill, a large number of leachate will be produced, because of its deep color, odor heavy and complex components, the high concentration of pollutants, once we take the improper protective measures,it will pollute groundwater, surface water and Soil.The bottom liner system is the essential measure of antipollution.To stop the leachate polluting the environment, the latest national standard divided the liner system into natural impermeable clay lining, double layer of synthetic materials and synthetic materials. Under the single-layer lining and the he second synthetic materials, there must be not less than 75cm thick layer of natural clay, its compacted saturated hydraulic conductivity K value equal to the natural clay liners are Should be less than 1.0×10-7cm/s. Accordingly, the nature clay,K value of less than 1.0×10-7cm/s, is necessary and important in the liner systemThe text base on actual project, using compact and permeability experiment to determine permeability of loess of the maximum dry density. The study analyzed the feasibility of loess, weathered red soil and loess soil mixed with weathered red soil act as the liner of landfill.Through the compaction and permeability tests of loess, either natural or compacted loess can not meet the requirements of the impervious clay setted by the "Landfill Pollution Control Standards".while The compacted weathered red soil layer of the third Ji,widely distributing under the loess, has low permeability, its permeability coefficient is less than 1×10-7cm/s. therefore, in the loess area, on the one hand,landfill can be built on the place where has a lot of the third Ji weathered red soil layer, on the other hand, we should consider to modify the loess, in this study, using 50% of the loess soil mixed with 50% of weathered red soil to get a kind of composite soil. through the text,the composite soil meet the national standards, its permeability coefficient is 6.2×10-8 cm/s. When the composite soil clay content up to 21%, the permeability coefficients were generally able to meet the requirements.Composite clay can make the impervious material of landfill to be localization and low-cost.The permeability coefficient is affected by clay content, mineral composition, microstructure and permeability of soil and the interaction between the liquid and many other factors.