Abstract
In Hokkaido, Japan, over 40% area has been covered by volcanic coarse-grained soils. Due to the extreme weather in Hokkaido, snowfall always reaches several meters. After winter, a large amount of snow melts into water simultaneously, and at the same time permeated into ground rapidly and continuously. Fine particles contained in soil, therefore, will be carried out of soil structure by water. Changes in soil structure should be expected. The main purpose of this paper is to examine influences of fine particles run off on the shear behavior and Soil-Water Characteristic Curve, SWCC, which plays a very important role in the determination of unsaturated soil property function, of the volcanic coarse-grained soil under unsaturated condition. A series of triaxial compression tests and soil-water characteristic test were performed for volcanic coarse-grained soil from which fine particles were removed by water flow previously. The experimental results show that the shear strength of volcanic coarse-grained soil decreases a lot under both saturated condition and unsaturated condition when fine content was removed. Fine particles run off also gives a strong influence to soil-water characteristic curve. It causes a right shift in soil-water characteristic curve.
