Seboong Oh

Relationship between the Soil-Water Characteristic Curve and the Suction Stress Characteristic Curve: Experimental Evidence from Residual Soils

The part of effective stress resulting from soil moisture or soil suction variation can be defined by the suction stress characteristic curve (SSCC). For a given soil, the SSCC can be experimentally determined from shear-strength tests. Recent work shows that the SSCC can be uniquely linked to the soil-water characteristic curve (SWCC). The uniqueness of the SSCC determined from both shear strength and soil moisture retention tests is examined for several residual soils in Korea. The validity of the effective stress principle is demonstrated by showing that effective stress-based on the SSCC describes the same unique failure criterion as that for the saturated failure criterion. The measured SSCCs are also shown to predict the soil-water retention curves within a few percentage. The SWCCs of these residual soils, determined directly from soil moisture retention tests, also accord well with the SSCCs determined directly from triaxial shear-strength tests with the difference within several tens of kPa. Therefore, we show that the suction stress characteristic curve or soil-water retention curve alone can be used to describe both the effective stress and soil-water retention characteristics of variably saturated soils. DOI: 10.1061/ (ASCE)GT.1943-5606.0000564.

Experimental Validation of Suction Stress Characteristic Curve from Nonfailure Triaxial K0 Consolidation Tests

AbstractIn recent years, the suction stress characteristic curve (SSCC) has been shown to represent a key constitutive relationship for defining effective stress in variably saturated soils. The SSCC can be deduced either from shear strength tests under variably saturated conditions or from soil water retention tests. This paper provides an alternative way to obtain the SSCC by conducting nonfailure K0 consolidation tests. Multiple remolded specimens from two different granitic residual soils, a silty sand (SM) and a clayey sand (SC), were evaluated in suction-controlled triaxial tests under K0 conditions. The results from these tests show that the stress paths for remolded specimens with different initial suction values differ during K0 consolidation when plotted in terms of the net normal stress, but follow a single path when plotted in terms of the effective stress defined using the SSCC. This observation confirms the validity of the effective stress principle before failure. Further, the results of th...

Design Methodology on Steel-type Breakwater II. Pile Design Procedure

In this paper, the design procedure of substructure of the steel-type breakwater was described and the actual foundation design was performed for the test bed. The site investigation was executed at the Osan-port area, in Uljin, Gyeongbuk, where the steeltype detached breakwater is constructed. The foundation mainly depends on the lateral load and uplift force due to the wave force. Since the superstructure is stuck out about 9.0m from the ocean bed, the foundation must resist on the lateral force and bending moment. After considering various factors, the foundation type of this structure was determined by the steel pipe pile(). On the stability of pile foundation, the safety factors of the pile on the compressive, lateral and uplift forces were grater than the minimum factor of safety. The displacements of pile under the working load were evaluated as the values below the permissible ones. Based on the subgrade reaction method, we evaluated the relationship of subgrade reaction and displacement for the lateral and the vertical directions in the layers. The structural analyses along with the foundation were perfomed and the effect of pile foundations were compared quantitatively.