Widely-graded soil is a good anti-seepage filling material for core of earth dams and embankment

and its impermeability is determined by its hydraulic properties. For the same soil

compaction is the primary factor that controls its hydraulic properties. In this study

the effect of compaction on hydraulic properties of a widely-graded soil is studied by laboratory tests

and through data analysis

the hydraulic property model is established

which is based on the effect of compaction. The results demonstrate that the higher the degree of compaction

the less macropores between particles of the soil

the higher the air-entry-value of the soil

the lower the saturated permeability coefficient. A prediction model of osmotic suction is proposed and it can accurately describe the changing principle of osmotic suction for unsaturated soil upon drying. The air-entry-value of the soil has linear relationship with the relative compaction on semi-log coordinate

and saturated permeability coefficient has linear relationship with the dry density on semi-log coordinate. An experiential model among air-entry-value

saturated permeability coefficient

unsaturated permeability coefficient and relative compaction is established

also an experiential calculation formula for soil-water characteristic curve (SWCC) of widely-graded soil is established

which has general applicability.