The Soil Water Retention Curve (SWRC) is a key constitutive relationship describing the behavior of variably saturated soils. The objective of this research is to assess the performance of a hydro-mechanical model, developed by coupling the lattice Boltzmann method (LBM) with the discrete element method (DEM), for micromechanical simulation of the SWRC. The DEM-LBM model is used to examine the effects of wave propagation on fluid-solid interaction. A multi-phase LBM is then employed within a static particle array generated by the DEM to examine the effects of initial fluid density distribution. The SWRCs are generated by recording the liquid pore pressure and the degree of saturation within a porous medium subjected to imbibition for two cases: randomized fluid density simulation (non-unified wetting front) and droplet simulation (unified wetting front). The coupled DEM-multiphase LBM model is shown to be a promising tool to characterize capillary regime in partially saturated porous media.