<![CDATA[Seismic-induced soil liquefaction poses significant risks to infrastructure in regions characterized by loose, saturated coastal deposits and moderate seismic activity. This study aims to evaluate the liquefaction susceptibility of tropical soils using laboratory-based shear strength characterization as a preliminary assessment framework. Soil samples were collected from two coastal locations and subjected to comprehensive index property testing, including grain size distribution, Atterberg limits, moisture content, specific gravity, and pH analysis. Static strength behavior was evaluated using Unconsolidated Undrained (UU) triaxial compression tests under confining pressures of 25, 50, 100, and 200 kPa. Results reveal distinct mechanical responses between the two soil origins. Soils with lower plasticity indices (PI = 12–19) exhibited moderate susceptibility characterized by limited strain-softening behavior at low confinement, while higher-plasticity soils (PI = 23–25) demonstrated confinement-dependent responses with pronounced post-peak softening under low effective stress conditions. Peak undrained shear strength increased significantly with increasing confining pressure, indicating stress-dependent liquefaction resistance. The findings highlight the critical influence of plasticity, confinement level, and soil structure on undrained stability. This research contributes baseline laboratory evidence for tropical coastal soils and establishes a region-specific framework for preliminary liquefaction screening in seismic-prone environments.]]>
