Study on the influence of seabed scour on monopile stability of offshore wind power by discrete element method

At present, the construction technology of offshore wind power of Taiwan is mostly based on foreign case experience and related design standards. However, the long-term scour effect of the Taiwan current will take away the soil around the pile foundation with the current, thus reducing the embedding depth of the foundation and reducing the stability of the foundation. In addition to being affected by loads such as wind and waves, the offshore wind power foundation is also the key to the overall design of the interaction between the seabed soil and the offshore wind power foundation. Therefore, this study adopts the method of discrete element method coupled with fluid mechanics to deeply explore the pore water pressure and stress changes inside the seabed soil during the seabed scour process around the offshore wind power foundation, and also explores the seabed under different scour mechanism scenarios for offshore wind power foundations. The results of this study show that the sand density of the seabed has a significant impact on the development of the scouring pit. The greater the sand density, the smaller the scouring depth, and the horizontal and vertical development of the scouring pit will also be reduced. the higher the sand density of the seabed, the smaller the lateral displacement of the single pile foundation affected by the erosion effect, which means the higher the lateral bearing capacity that the seabed sand can provide to the monopile foundation.

Key words: scour effect, the offshore wind power foundation, discrete element method, scour process; monopile.