Study On Horizontal Bearing Capacity And Deformation Of Offshore Wind Monopile Foundation

The monopile foundation accounts for more than 65% of the offshore wind farms built at home and abroad because of it's unique advantages.In order to resist wind,wave,tidal and other horizontal loads,the pile foundation must be deep underground the seabed,but if the pile depth exceeds a certain value,it inevitably increase the construction cost and difficulty.That is,we need a reasonable pile depth not only to ensure the normal operation of the wind turbine,but also to facilitate the construction and save the cost.Based on this,we use a combination of indoor model test and numerical calculation to study the bearing and deformation characteristics at different pile depth conditions.The main work is as follows:Firstly,the horizontal static load test of different loading height and depth is carried out to research the variation of pile bending moment,pile deformation,pile-soil reaction force and soil pressure.The results show that the bending moment is basically unaffected by the depth,and the pile deformation gradually decreases to a stable value with the increase of depth.The soil reaction force and pressure gradually decrease as the depth increases.Then,a three-dimensional finite element model of pile-soil is established by using ABAQUS to simulate the pile deformation.Those two results are in good agreement with each other.On this basis,the further study on the critical depth of pile by using ABAQUS is carried out.It is suggested that 8 times of pile diameter can be used as the critical depth of pile foundation.Horizontal dynamic load test was conducted by using a self-made device.The researchs show that the bending moment,soil reaction force,soil pressure and the displacement were all affected by the number of cycles.The displacement accumulation will occur when the number increases,the final displacement value will be much larger than the displacement under static loading.