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The three-dimensional topography of the seabed has a significant influence on the wave field and the failure characteristics of the sloping seabed. Nevertheless, previous experimental studies were predominantly limited to two-dimensional wave conditions. In this study, a series of regular wave experiments (including a rigid-slope seabed and a sandy-slope seabed) have been done in a large-scale three-dimensional harbor basin to investigate the three-dimensional wave field in the Zhoushan sea area and the response characteristics of the sloping seabed under the wave actions, respectively. The results of the rigid-seabed tests show that the wave field has obvious three-dimensional characteristics under the influence of three-dimensional topography. During the process of propagation, wave shoaling occurs which leads to wave breaking finally. At the same time, the wave will reflect when it meets the topography, and the reflected wave will affect the wave field in turn. The pore water pressure response and three-dimensional failure modes of sandy sloping seabed under the wave actions are obtained by the sandy-seabed experiment. Three-dimensional seabed topography of typical sea area is established in the harbor basin. The characteristics of the three-dimensional wave field and the response of submarine slope under the three-dimensional wave actions were investigated. The three-dimensional topography of sandy sloping seabed after wave actions was captured. [ABSTRACT FROM AUTHOR]

Suction-bucket-supported jacket foundations are being used increasingly for offshore wind turbines, the advantages being large bearing capacity and efficient installation. For a large-capacity wind turbine, the pullout capacity and displacement of the bucket in the tripod or tetrapod jacket can be critical to the safety of the structure. The loading rate, which is commonly dominated by the offshore environmental conditions, has a significant effect on the ultimate capacity and stiffness of the bucket foundation. In this paper, a numerical model is developed to investigate the response of a bucket foundation under vertical pullout loading at different rates. A bounding-surface model based on critical state soil mechanics is introduced to account for the soil behaviour under different stress states and drainage conditions. The model is modified and calibrated against a comprehensive set of laboratory tests, including both triaxial compression, triaxial extension and direct simple shear tests in drained and undrained conditions. How partial drainage affects the load–displacement response and pore pressure field are thus presented. A parametric study on the selection of soil parameters is also conducted to shed light on practical foundation design. [ABSTRACT FROM AUTHOR]