<p>This study examines the factors influencing internal erosion and hydraulic conductivity in sand-clay mixtures used in earth structures. Internal erosion, defined as the dislodgement and transport of particles within the soil due to internal water movement, encompasses processes such as suffusion, backward erosion, and concentrated leak erosion. It is a major cause of failures in hydraulic geo-structures. Utilizing a modified triaxial apparatus, this research investigates the effects of gap ratio, fines content, clay-sized particle types, confining stress, and hydraulic loading conditions on soil erosion mechanisms. The findings highlighted the critical role of soil fabric in erosion behavior. Higher confining pressures (σ') generally reduce erosion ratios. However, excessive fines content can increase erosion under high stress due to the detachment of force-chain particles and subsequent erosion. Soils with higher fines content exhibit reduced pore connectivity, creating more tortuous paths and increased clogging, which can lower erosion rates compared to soils with lower fines content. The gap ratio affects erosion dynamics: smaller ratios lead to clogging and partial filtration, while larger ratios facilitate particle migration but may also cause collapse and arch formation, particularly in low-plasticity soils. Increased clay content enhances erodibility, resulting in more defined erosion paths and greater susceptibility to suffusion. The type of hydraulic loading also impacts erosion rates and channel formation. Incremental loading results in slower development of erosion pipes compared to linear loading, which forms more distinct erosion channels rapidly.</p>