Numerical model of water transport in partially-immersed unsaturated cement-based materials using Comsol Multiphysics
Saline soils are widely distributed in the desert regions of western China,where road base deformation due to soluble sulfate poses a significant issue.Using multiphase flow theory,this study conducts a numerical simulation of water transport in unsaturated cement-based mixtures under infiltration conditions with Comsol Multiphysics software.The model considers capillary pressure as the driving force for water phase transport and saturated vapor pressure as the driver for both water and gas phase transport.Dynamic and evaporation governing equations for the water and wet air phases in unsaturated porous media are derived,forming the basis of a water transport model for partially-immersed unsaturated mixtures that accounts for water and wet air evaporation.Capillary absorption characteristics of three types of cement-stabilized materials are obtained through water transport testing,and model accuracy is verified against experimental results.Findings show that the capillary absorption coefficient is the highest for XM(0.09 g/cm2),followed by GK(0.085 g/cm2),and lowest for GM.In unsaturated porous media,fluid movement in pores is mainly driven by capillary water transport in the early stages,with later stages dominated by convective effects due to vapor pressure differences.These results highlight the critical influence of water capillary and evaporation on soluble salt transport in partially-immersed unsaturated cement-based mixtures.This research advances understanding of water transport in unsaturated media and provides a foundation for exploring water-salt transport in such materials and establishing numerical models.
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