Abstract: To investigate soil-water characteristic curve (SWCC) of Huai-an expanded soil, three different suction control or measurement methods are used. These are the pressure plate method for low suction, the filter paper method, and the vapor equilibrium technique for high suction. SWCC shows obvious hysteresis features during drying and wetting circle in the low suction range. When the suction is greater than 100 MPa, the hysteresis effect of SWCC disappears, and the drying and wetting curves are almost the same. Test data of SWCC, obtained using the filter paper method, are between the main drying and wetting
SWCCs. The tendency of SWCC in the high suction by the vapor equilibrium method shows that the water content is almost zero when the suction is close to 1 000 MPa. Based on the result of expanded soils by using filter paper, when SWCC is expressed with degree of saturation and suction relation, SWCC with higher dry density is on the upper side in the relatively low suction range, and the dry density has no effect on SWCC in the relatively high suction range.

Key words: compacted expensive soil, filter paper method, pressure plate method, soil-water characteristic curve (SWCC), vapor equilibrium method