Abstract
It is necessary for investigation of soil hydraulic characteristic to examine the stability of slope and bank caused by torrential rain. This study examines accuracy improvement method and effectiveness of measuring method of the field saturated hydraulic conductivity which is measured by using bore-hole in unsaturated ground from ground surface to about 10 m depth. The following conclusions were obtained.(1)It is clarified that the change of initial soil saturation degree influences the value of hydraulic conductivity.(2)It is clarified that nearly identical hydraulic conductivity could be obtained by injecting CO2 gas for a certain amount of time before conducting the permeability test.(3)The evidence that hydraulic conductivity can be measured small than primary one of soil when bore-hole wall is stained by drilling the bore-hole is proved with comparison between permeability test before and after cleaning bore hole wall.
