Simulation Study Of Local Scour And Anti-scouring Device For Supporting Offshore Wind Turbine Pile Foundation

Offshore wind power is an important development direction to promote the adjustment of energy structure of all countries in the world.The South China Sea is an important sea area for my country’s current offshore wind power energy development.In view of the vast area of the South China Sea,the marine hydrology,topography and geology of different sea areas are complex and changeable,so we must choose the basic form which is compatible with the environmental conditions of the site can ensure that the wind farm can give full play to the social and economic benefits.The inclined pile-bearing wind power foundation has a series of advantages such as good adaptability to foundation conditions,better structural stability and mature construction technology.It has been widely used in the construction of offshore wind farms in China,but the problem of local scour on the seabed is causing the phenomenon of instability and local strength failure of the lower pier column,and even has a huge impact on the overall stability of the wind power foundation.Therefore,the foundation scour problem is especially the scouring problem of single-inclined piles with different inclination angles and the scour of combined pile groups of multi-inclined piles.The problem is getting more and more attention from academia and industry.For this reason,this article will conduct a numerical simulation study of hydrodynamics for these two important basic scour problems.At the same time,it is based on the circular pipeline on the horizontal seabed surface in the downstream direction of waves and currents whicn will produce the characteristics of sedimentation.This paper proposes a new method of active protection of pile foundation scour,that is,laying horizontal pipelines can make up for the sediment loss caused by the back pile foundation scour.The research on the scour simulation and active protection method of the inclined pile-bearing offshore wind power foundation in this paper will have important practical significance for the construction and maintenance of the South our country Sea wind farm in China.First of all,in order to obtain the surrounding environmental conditions of the real offshore wind farm,this paper combines the project of the team to collect environmental conditions such as marine hydrology and other environmental conditions in the sea area of the site,and analyzes the measured data to obtain the characteristics of waves and ocean currents.This paper adopts the combination of effective wave height and effective period which is the largest probability of distribution as the reference condition,and the maximum possible bottom velocity of the year is used as the water flow condition.Those environmental conditions are prepared for the research and analysis of the basic scour later.Secondly,this paper uses the inclined pile-bearing concrete foundation proposed by the Xuwen offshore wind farm design department in the South China Sea for the super typhoon in the sea as a reference form.Based on the experimental verification,the turbulence module and the sediment in the FLOW-3D hydrodynamic software are used.The scour module performs a numerical simulation of local scour on single piles with different inclination angles relative to the direction of the incoming flow,and obtains the quantitative morphological changes of the scour pits under different incoming flow conditions and different inclination angles.Based on these regular studies,this paper research on the scour problem of two different arrangement forms of group pile foundation.Finally,according to the characteristics of the circular pipeline on the surface of the flat seabed that sedimentation will occur behind the action of waves and currents,this paper proposes a new type of anti-scouring device for offshore wind power foundations that uses siltation to compensate for the erosion.Through the physical model test and the numerical simulation jointly verify the damping effect of the device,and the final result shows the effectiveness of the device.This paper studies the scour rules of single piles and pile groups of the inclined pile-bearing offshore wind power foundation,and gives engineering suggestions on the relative positions of the inclined single piles in the arrangement of the pile groups.Based on the characteristics of the circular pipeline on the surface of the flat seabed that sedimentation will occur behind the action of waves and currents,a new type of anti-scouring device with good effect is proposed,which can obtain 60% effect under proper layout.