• The Journal of Engineering Geology
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• v.18 no.4
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• pp.523-535
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• 2008

A simulated rainfall system was built, and the unsaturated characteristics were examined by execution of simulated rainfall system test and soil water characteristic curve cell test(SWCC Cell Test) under the various rainfall and slope conditions. With the results, the applicability of infiltration behavior under rainfall and soil water characteristic curve models to the unsaturated weathered granite soil was examined. At the results of comparison the volumetric water content and matric suction measured in the wetting process(under rainfall) with those in the drying process(leaving as it was) of the simulated rainfall system, the volumetric water content showed a difference of $2{\sim}5%$ and matric suction of about $3{\sim}10\;kPa$, indicating the occurrence of hysteresis. In addition, the difference was relatively larger in matric suction than in the volumetric water content, and this tells that the hysteresis behavior is larger in matric suction. When the soil water characteristic curve derived from measurements in simulated rainfall system test were compared with those from the soil water characteristic curve cell test, both methods produced soil water characteristic curves close each other in the wetting process and the drying process, but in both, there was a difference between results obtained from in the wetting process and those from in the drying process. Thus, when soil water characteristic curves are rationally applied to the design and stability analysis considering of the properties of unsaturated soil, it is considered desirable to apply the soil water characteristic curve of the wetting process to the wetting process, and that of the drying process to the drying process.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.1C
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• pp.7-16
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• 2012

In this paper, using the principle of Static Measurement Methods suggested by Huang (1998), a new experimental device has been made and used in order to calculate the unsaturated permeability of Nak-dong river sand with silt which is an important basic property in the unsaturated soil. This device was designed to measure changes of the unsaturated permeability according to the increase of matric suction. The value of the unsaturated permeability obtained in testing and that obtained using the empirical permeability functional formula were compared and analyzed. As a result, the value of the unsaturated permeability tends to be decreased according to the increase of relative density, silt content and matric suction. This tendency shows it is very closely related to the change of moisture content and void ratio. The empirical permeability functional formula presented by Frelund & Xing (1995) was regarded as the most appropriate model to represent the unsaturated permeability of Nak-dong River silty sand.