RESEARCH ON SWCC OF UNSATURATED NATURAL RESIDUAL SOIL

The stress-dependent pressure plate extractor system is used to study the residual soil SWCC curve of different vertical stresses, drying and wetting cycles and different types of natural residual cohesive soil and residual sandy clay. Then the laws of SWCC hysteresis loop area with and without volume change and AEV and AexV of residual soils are analyzed and compared. Results show that not only the ability of soil to resist deformation can be overestimated by the traditional method of SWCC curve, but also the underlying cause of SWCC curve changing is due to soil internal structure change constantly; Meanwhile, the higher net stress levels are, the larger size pores are much more influenced by the net stress. Thus the wetting branch is much more affected. The observed unequal change in the shape of drying and wetting branches of SWCC at higher net stress values brings them close to each other, and reduces the SWCC hysteresis as the net stress level increasing. Finally, according the simplicity of model parameters and the goodness-of-fit analysis results of the 3 kinds of improved SWCC models, the improved VG model has been found to be the most suitable model for all SWCC of the natural residual soil in southeast of Fujian. The above research is useful and meaningful as reference for the engineering characteristics and governance of the residual slope.