Integrated Experimental and DEM Approach to Assess Geotechnical Behavior, Liquefaction Hazard, and Foundation Optimization in Babai and Bansilaghat River Soils

This study presents an integrated experimental and Discrete Element Method (DEM) simulation approach to evaluate the geotechnical behavior, liquefaction hazard, and foundation optimization potential of soils from the Babai and Bansilaghat Rivers in Nepal. Both rivers’ soils were characterized through extensive field sampling, Standard Penetration Tests (SPT), grain size analysis, Unified Soil Classification System (USCS), and direct shear testing, complemented by advanced DEM simulations to assess liquefaction susceptibility under seismic loading conditions. The Babai River soils predominantly consist of finer-grained, sand-dominated materials with significant fines content (silt and clay up to 42%) and moderate SPT N-values, reflecting loose to medium dense conditions. In contrast, Bansilaghat River soils are gravel-dominated, well-graded, and compact, with high SPT N-values and frequent presence of boulders, indicative of dense and strong material conditions. Direct shear tests revealed considerably higher cohesion (12–15 kN/m²) and internal friction angles (34–36°) in Bansilaghat soils compared to Babai soils (cohesion: 0.34–2.36 kN/m², friction angle: 28–29°), confirming superior shear strength and load-bearing capacity of the former. DEM simulations further quantified the liquefaction potential, demonstrating that Babai soils with loose packing, finer grain size, lower density (~1800 kg/m³), and frequent particle rearrangements exhibit high kinetic energy accumulation and significant porosity changes under cyclic loading, resulting in elevated liquefaction susceptibility. Conversely, Bansilaghat soils, characterized by dense packing (~2200 kg/m³), coarse-grained, well-graded particles, and stable force chains, show minimal kinetic energy increase and porosity variation, translating into low liquefaction risk. These findings highlight critical differences in soil behavior and seismic vulnerability between the two river sites, with Babai River soils prone to settlement and liquefaction hazards during earthquakes, whereas Bansilaghat soils provide reliable foundation stability. This integrated experimental-DEM approach offers valuable insights for geotechnical hazard assessment and foundation design optimization in alluvial riverine environments influenced by Himalayan sedimentation dynamics.