Study Of Water Vapor Transfer And Coupled Calculation Of Vapor And Liquid Water In Unsaturated Soil

Usually there is two forms of water transfer which is water vapor transfer and liquid water transfer in unsaturated soil. The thesis studies the theories of water vapor transfer in unsaturated soil, and gets the water contents equations of water vapor transfer in unsaturated soils. Then this paper devises experiments to research on the laws of water vapor transfer in unsaturated soil, studies the amount of water vapor transfer under different water contents, different water content gradients, different densities, different transfer time and the difference between loess and sands, studies the ratio of water vapor transfer contrasting with admixture transfer, and which can make us judge the importance of water vapor transfer in unsaturated soils by intuition.The experiments reveals that : the amount of water vapor transfer is affected by both water content gradient and the value of water contents, when the water content of one end is approximate, the water content gradient increases, then the amount of water vapor transfer increases; when the water content gradients are approximate, the amounts of water vapor transfer can get great differences if the water contents are different, under this condition when the water content of the dry soil is very little, the amount of water vapor transfer is much greater; the differences of density havn't great effects on water vapor transfer, but have some effects on the admixture transfer, when the density is smaller, the amount of admixture transfer is greater. The water vapor transfer finishes more quickly and need less time, and the liquid water finishes more slowly and need less time. When the experiment time prolongs, the amount of water vapor transfer increases a little, but the amount of admixture transfer increases obviously, so the increase amount of admixture transfer mostly come from liquid water transfer.The ratio of water vapor transfer contrasting with admixture transfer reveals that usuallywater vapor transfer can not be neglected. The amount ratio of water vapor transfer contrasting with admixture transfer is related to the value of water content, the water content gradients and the soil category. As to the same soil, when the water source doesn't have much free water and the water contents gradient is relatively greater, the ratio of water vapor transfer is much greater; otherwise, when the experiment time prolongs, the ratio of water vapor transfer has a trend to decrease.With the equation for water vapor transfer in unsaturated soil the thesis deduces the equation for liquid water transfer, and then puts forward the coupled calculation method for water vapor and liquid water transfer together, and then build the difference calculation program to realize the coupled calculation under the one-dimension and constant-temperature condition, and put the program into practice with the experiment conditions, the calculation result tallies well with the experiment data , the facts proves the reliabilities of theory deduction and the feasibility of coupled calculation method.At another aspect the thesis discusses the calculation method of gravity potential in unsaturated soils, and then puts forward that the calculation of gravity potential is related to the water content (saturation), it should be expressed as mgh . Because the determination of the expression needs a large amount of experiments, so the thesis hasn't got some concrete outcomes. The thesis just makes some correlative discussion.