Influence of leachate pollution on mechanical properties of compacted clay: A case study on behaviors and mechanisms

The environmental safety and engineering stability of landfills are always a concern of the public in view of its potential impact on public health. This study investigates the effect of leachate corrosion on the mechanical properties of a compacted clay. Batch tests were conducted to measure the permeability as well as the compressibility and the shear strength of the compacted clay that was polluted by landfill leachate under different concentrations. The influence mechanisms of leachate on the mechanical properties of compacted clay were investigated through microscopic experiments. The results showed that the hydraulic conductivity of compacted clay decreased because of the reduction in effective porosity resulting from the infiltration of leachate. Moreover, hydraulic conductivity decreased with the increase in leachate concentration and penetration time. The increase in leachate concentration respectively led to a decrease in the cohesion (C) and an increase in the internal friction angle (φ) of leachate-polluted compacted clay. The content of quartz and clay minerals in compacted clay decreased while albite increased after pollution. The compressibility of the compacted clay rises with pollution. An increase in compressibility and compressive deformation as well as a reduction in the compression modulus occurred as the leachate concentration increased. The maximum decline of void ratio was 9.7%.