Abstract: Based on the key technology research of the application of the cylindrical foundation in offshore wind power engineering projects and the requirements of the foundation design, this paper analyzes the cylindrical samples collected from more than 20 meters deep and shallow water area of an offshore wind turbine project site in Guangdong Province, explores the basic physical and mechanical properties of the seabed surface soil in this area, and obtains the parameters and indexes of the seabed surface soil in this area. The results show that the surface soil is classified as clay or silty clay, and the physical and mechanical properties of the surface soil vary in different stations and depths, which is significantly different from the sediment properties in other offshore areas; the natural water content and AtterbergLimits are low, the void ratio is small, and the water retention capacity of the surface soil in this area is poor; the particle gradation curve of surface soil is continuous and the gradation difference in the surface soil is not significant. The direct shear strength of the soil samples at different stations is different, but there is regularity and unity along the depth. The full flow penetration Tbar test suitable for low strength soil is used to measure the strength of undisturbed and remolded soil samples. The undrained shear strength of soil increases with the increase of depth, and the sensitivity is basically in the middle sensitivity range. Through a series of analysis and research, the physical and mechanical properties of the surface soil on the seabed of the site are obtained, which not only provides the key geological survey and design data for design and construction projects in the area, but also provides an important reference for the future study of the mechanical properties of the sediment in the offshore soils.

Key words: Offshore Wind Turbine, Seabed Soil, T-bar Test, AtterbergLimits, Shear Strength, Sensitivity