Infiltration study on compacted clay liners subjected to wet-dry cycles

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Compacted clay barriers used as liners and covers in landfills are subjected to alternate wet-dry cycles. During the drying cycles, the compacted clay loses the moisture content, which results in shrinkage and the formation of desiccation cracks in them. These desiccation cracks act as preferential flow paths, through which fluids percolate and reduce the efficiency of the clay barrier. The cracks formed during the drying cycle may heal during the subsequent wetting cycles when the clay absorbs moisture and swells. However, the swelling process is not instantaneous, and the healing of the cracks takes time, during which the leachate can infiltrate into the underlying ground. The healing capacity of the clay may also be hampered as the soil is subjected to repeated cycles of wetting and drying. Hence, in addition to studying the hydraulic conductivity of the compacted clays, infiltration studies must be carried out on compacted clay to understand its hydraulic behaviour. The present study is conducted on a compacted red soil-bentonite mixture to understand the effect of wet-dry cycles on its infiltration behaviour. The tests were carried out using an in-house fabricated oedometric-infiltrometer test apparatus, using distilled water as the percolating fluid. The inflow and the outflow of DW through the specimens were measured at specific time intervals until the inflow and outflow reached equilibrium. The study showed a variation in the flow patterns through the soil specimens with the increase in the wet-dry cycles, indicating that the wet-dry cycles influence the infiltration behaviour of the compacted soil.

9th International Congress on Environmental Geotechnics (ICEG2023)

Engineered Barriers