Study of a testing method for permeability of unsaturated soil with applied air pressure

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Testing method for permeability through unsaturated sands were examined in consideration of three measuring ways of saturation. On the other hand, behaviors of pore air/water in soil were analyzed by the use of FDM program for the multi-phase flow. It was found that the degree of saturation under confined air pressure was inclined to be uniquely distributed within sand column, which was also confirmed in experiment.Considering this properties of the mix fluids and reforming the permeability test apparatus in the applying air pressure type, for example,combining the two burette to measure seepage quantity, we performed permeability tests of unsaturated sand and silt in this last fiscal year, and obtained some concrete testing guides as follows.(1) As for the necessary filter abjacent to soils, the effect of correction of its resistance against seepage on permeability is evaluated with selection of its material.(2) Unique distribution of water content in soil and appropriate applied hydrauric gradient of 1.0-3.0 is recognized in the experiments.(3) High quality of measuring system of seepage quantity by two burette results in the continuous measuring way of the relation between permeabilty and degree of saturation, in comparison with the previously proposed methods for estimating permeability of unsaturated soils.