Undrained deformation behavior of saturated soft clay under long-term cyclic loading

This paper reviews foundations for offshore wind energy convertors considering the significant growth of offshore wind energy since the early 2000s. The characteristics of various foundation types (i.e., gravity, pile, suction caisson, and float type) and the current status of field application are discussed. Moreover, the mechanical characteristics of soil are described in the sense that these characteristics including modulus, strength, damping, and modulus degradation of soil play critical roles for the design of offshore foundations. By using these mechanical properties of soil, theoretical studies to consider structure-soil interaction are classified (into equivalent spring models, distributed spring models, and continuous element models) and explained. Field and laboratory experiments on the response of structure embedded in soil to static and dynamic loads are discussed. Based on the review of previous studies, directions for future research and study on offshore wind turbine are suggested.

A review of foundations of offshore wind energy convertors: Current status and future perspectives

Soil degradation is studied from the point of view of cyclic axial strain through stress-controlled triaxial tests on Hangzhou normally consolidated clay. Different influence factors on strain, suc...

Strain degradation of saturated clay under cyclic loading

Undrained behavior of natural marine clay under cyclic loading

Stiffness degradation of natural fine grained soils during cyclic loading

https://www.jstage.jst.go.jp/article/sandf1972/22/3/22_3_77/_pdf

Cyclic strength and deformation of normally consolidated clay

https://www.jstage.jst.go.jp/article/sandf1972/32/1/32_1_100/_pdf

Effects of cyclic loading on undrained strength and compressibility of clay.

Results are presented from a series of one-way cyclic undrained triaxial tests on Ariake Clay, a highly plastic, normally consolidated marine clay from Kyushu in southwest Japan. Considering first pore water pressures developed during cyclic loading, it is shown that the build up of pore water pressure is a time-dependent phenomenon, independent of frequency. The rate of pore pressure accumulation decreases exponentially with elapsed time of cyclic loading and at any given time it is a function of the applied cyclic stress. A similar creep type of relationship also exists for the accumulation of plastic strain with time, and from this a relationship is developed between pore pressure and strain. Effective stress paths for samples taken to failure suggest that the projection of the critical state line may be taken as a failure criterion under cyclic loading. Combining the exponential relationship for pore pressure against time with this failure criterion, related stability criteria are developed for pore pressure and strains at different cyclic stress levels.

Stability Criteria for Marine Clay Under One-Way Cyclic Loading

https://www.jstage.jst.go.jp/article/sandf1972/32/4/32_4_117/_pdf

Kazutoshi Hirao

Papers

Cyclic strength and deformation of normally consolidated clay

Effects of cyclic loading on undrained strength and compressibility of clay.

Stability Criteria for Marine Clay Under One-Way Cyclic Loading

Prediction of clay behaviour in undrained and partially drained cyclic triaxial tests

Approximate Prediction of Soil Deformation Under Drained-Repeated Loading