An experimental study on effects of interactions of ambient parameters on permeability of geosynthetic clay liners

Geosynthetic clay liners (GCLs) play a crucial role in landfills, making their hydraulic evaluation essential. This paper focuses on measuring the permeability of GCLs to various permeant liquids, specifically leachates from municipal solid waste landfills (MSWLF), under different ambient conditions. It aims to assess the individual and interactive effects of ambient parameters on GCL permeability. To achieve this goal, a parametric analysis was conducted to evaluate the impact of GCL type, GCL area density, permeant solution, confining pressure, hydraulic head and gradient, and the interaction of these parameters on GCL permeability. The tests were performed on two types of GCLs with varying area density percentages, providing insights into GCL permeability measurements. The findings revealed a direct correlation between hydraulic head and effective stress on the specimen. Under variable hydraulic head conditions, an increase in stress was found to elevate permeability. Conversely, with a constant hydraulic head, there was an inverse correlation between effective stress and permeability. Distilled water exhibited the lowest permeation, while treated MSWLF leachate displayed the highest. Ethanol demonstrated higher permeation than NaCl, and an increase in permeant solution concentration led to a rise in the permeability coefficient.Notably, at hydraulic gradients above a certain level, GCL-II (with a larger area density) exhibited a larger permeability coefficient compared to GCL-I (with a smaller area density).