Relationship among suction, void ratio and water content of expansive soils during wetting process

By means of soil water characteristic tests and wetting tests under different initial void ratios, the relationship between the initial void ratio and the fitting parameters of soil water characteristic curve and volume change curve are discussed. Surface fitting is carried out to establish the relationships among void ratio-gravimetric water content-initial void ratio, void ratio-suction-initial void ratio, gravimetric water content-suction-initial void ratio and volumetric water content-suction-initial void ratio. The test results show that in the gravimetric water content (or suction) -initial void ratio-void ratio coordinate, the volume change surface contains saturation and unsaturation parts. In the wetting process, the gravimetric water content at turning point between saturation and unsaturation parts increases with the initial void ratio, while the suction at this point decreases on the contrary. In the suction-initial void ratio-gravimetric water content (or volumetric water content) coordinate, the soil water characteristic curves that correspond to the specific initial void ratios are plane curves with constant vertical coordinates. However, in the suction-void ratio-gravimetric water content (or volumetric water content) coordinate, the soil water characteristic curves that correspond to the specific initial void ratios are space curves with variable vertical coordinates, which can reflect the influences of both the initial void ratio and the variation of the void ratio during test process.