<p>It is crucial for the safety and stability of landfill operations to maintain resistant to clogging drainage layers. In this study, through the utilization of indoor physical simulation experiments, the clogging characteristics inherent in both single granularity structure and coarse particle sandwich structures within drainage layers were analyzed and compared. The influences of leachate percolation on the mechanisms of drainage layer clogging were revealed. The results showed that the clogging of landfill drainage layers involved three primary mechanisms: the precipitation of carbonates, the formation of biofilms, and the accumulation of solid suspended particles. A significant enhancement in the permeability coefficient was achieved by replacing the middle section of a single granularity structure with larger sand particles. Superior anti-clogging performance was exhibited by the coarse particle sandwich structure compared to the single granularity structure, thereby enhancing the long-term stability of the landfill drainage layer’s function. The findings provide valuable insights on the efficient design of landfills.</p>