Effect of thickness and deformation of sand–bentonite liner system on permeability

Compacted clay is often used as liner material in landfills due to its excellent impermeability. However, its poor crack resistance can lead to cracking under deformation conditions, which further impacts the impermeability of the liner. To investigate the variation in permeability performance of a liner system under deformation conditions, a model test apparatus was designed to simulate the deformation and permeability of a sand–bentonite liner system. Particle image velocimetry was used to analyse the deformation characteristics of the liner system. The experimental results showed that changes in the deformation and thickness of the liner significantly affected the permeability performance of the liner system. For the same liner thickness, an increase in the liner deformation increased the number and width of cracks in the system, leading to more seepage channels and reduced impermeability under deformation conditions. Conversely, for the same deformation, an increase in liner thickness enhanced the effective thickness of the liner, thereby improving its impermeability under deformation conditions.