The static and dynamic characteristic of undisturbed residual soils under drying-wetting cycle's repetition

In tropical volcanic countries such as Indonesia, residual soil covers most of the islands; as the weathering process of igneous, sedimentary and metamorphic rocks is still actively undergone due to the tropical climate. The presented objective of this paper is the effect of drying-wetting cycle's repetition on the static and dynamic properties of three natural residual soils. The laboratory and field test results from three residual soils show that the low void ratio and high soil cohesion occured due to the increasing of clay fraction. Drying-wetting cycle's repetition reduces the void ratio, negative pore-water pressure, cohesion and internal friction angle of soils. The cohesion of three natural residual soils after the sixth cycle reduces 8, 70%, 9, 09% and 1, 5% respectively. On the other hand, the unit weight of soil and shear modulus (GUBE) increase with the number of cycles. Shear modulus (GUBE) after the sixth cycle for all residual soils increases 25, 46%, 24, 15% and 11, 25% respectively. As the soil densities and void ratio were increase, the soil cohesion were decrease.