Evaluation of Mechanical Properties of Fine-Grained Soil Contaminated with Solid Waste Landfill Leachate

One of the most significant environmental consequences of municipal solid waste is the generation of leachate at landfills. Leachate is a very hazardous liquid leading many difficulties including contamination of surface, groundwater, and soil. The mechanical parameters of the soil can be affected in contact with leachate and its changes depend upon the type of leachate and soil. The reactions between the soil system and the leachate cause changes in landfill soil mechanical properties that may affect the structural stability of the landfill structures. So that, the present study investigate the effects of natural leachate of Aq Qala landfill on silty-clay soil. For this purpose, the natural leachate samples and the untoched soil samples with leachate were collected from the Aq Qala landfill. Unconsolidated no drained (UU) triaxial test was performed on soil specimens containing 0, 5 and 15% leachate at three curing times; 7, 14, 28 days. In order to analyze the obtained results, the stress-strain curve was investigated in terms of leachate amount, curing period and cell pressure as the variables applied to the samples. The results indicate that the contamination of soil by leachate reduces the maximum deviator stress and the friction angle, while it increases the soil adhesion. In addition, the influence of leachate increases by leachate concentration in the soil and curing period.