A modified numerical model for moisture-salt transport in unsaturated sandy soil under evaporation

摘要

Soil salinization,caused by salt migration and accumulation underneath the soil surface,will corrode structures.To analyze the moisture-salt migration and salt precipitation in soil under evaporation conditions,a mathematical model consisting of a series of theoretical equations is briefly presented.The filling effect of precipitated salts on tortuosity factor and evaporation rate are taken into account in relevant equations.Besides,a transition equation to link the solute transport equation before and after salt precipitation is proposed.Meanwhile,a new relative humidity equation deduced from Pitzer ions model is used to modify the vapor transport flux equation.The results show that the calculated values are in good agreement with the published experimental data,especially for the simulation of volume water content and evaporation rate of Toyoura sand,which confirm the reliability and applicability of the proposed model.