Large-Scale Model Experiments on Multi-field interactions in Landfills of Municipal Solid Waste

摘要

The experiments are conducted in a large-scale model facility with three testing cells, each cell is 5m in length, 5m in width and 7.5m in depth, to a better understand of the multi-field interactions in MSWs with high food waste content. Operations done in the first cell in the past 4.5 months are as follows: Filling of 91.3 tons crude MSWs, vertical loading of 33kPa on the top, water level drawdown and refilling tests. The cumulative volume of effluent leachate increased to nearly 27.3m~3 in the 4.5 months, and the leachate production rate (mass ratio of leachate quantity over burial waste) achieved to 0.30. The leachate level built up to nearly 87% of initial burial thickness of the waste layer after waste filling, then developed to over 100% after vertical loading, demonstrating a rapid build-up of high leachate level. The coefficient of earth pressure at rest K_0 was measured in the range of 0.13～0.25, and the unit weight of MSW was obtained as 7.5～12.5kN/m~3. The cumulative settlement increased to over 2.0 m, and the modified primary compression index C(?)_c was obtained as 0.24, while the modified secondary compression index C(?)_a ranged from 0.03 to 0.035. The results of selected TDR probes are reliable to the variation of volumetric moisture content caused by the rise and fall of leachate level, but a deviation may come out when compared to the results based on weight-volume calculations. Temporal trends of pH, COD in leachate and LFG compositions indicated that the waste has experienced initial adjustment phase, transition phase and acid formation phase in the past 4.5 months.