Research

The cone penetration test (CPT) is one of the most widely used tools for in situ characterization of soils, providing continuous measurements of penetration resistance that are used to infer geotechnical soil properties. However, CPT interpretation becomes significantly less reliable under non-standard conditions such as partial drainage or partial saturation, where existing correlations break down and the assumptions underlying conventional interpretation no longer hold. This project uses coupled lattice Boltzmann method and discrete element method (LBM-DEM) simulations to model CPT at the pore scale, directly resolving the interaction between grain motion and pore fluid during penetration. The goal is to build a mechanistic understanding of how drainage conditions and fluid phases influence penetration resistance and pore pressure response, with implications for more reliable CPT interpretation in complex field conditions.

Most soils in nature exist in an unsaturated state, with both water and air occupying the pore space between grains. The distribution of these fluid phases within the pore space gives rise to capillary forces between grains that affect soil stiffness and shear strength in ways that current engineering models capture only empirically, without a full mechanistic understanding of the underlying pore-scale physics. This project uses coupled multiphase LBM-DEM simulations to directly visualize and quantify how fluid distributions and capillary forces evolve at the grain scale under varying saturation conditions. Resolving the full three-phase interaction between water, air, and soil grains enables systematic investigation of how pore-scale processes influence the mechanical and hydraulic response of unsaturated soils, which can ultimately inform more reliable constitutive models for engineering practice.