Research On Horizontal Bearing Characteristics Of Offshore Wind Turbine Screw Pile Foundation In Sand

Screw pile foundation is a new type of pile foundation.Because it has the advantages of no piling installation,simple construction,friendly to the environment,short construction period,high bearing capacity and easy recovery,it has attracted the attention of researchers in the field of offshore wind power.If screw pile is used as offshore wind power foundation,screw pile will bear large horizontal load.However,the screw pile has been used as anti pull anchor pile before,which leads to the sufficient research on the vertical bearing characteristics of screw pile,while the relevant research on the horizontal bearing characteristics of screw pile is relatively scarce.Based on the above problems,this paper deeply studies the horizontal bearing characteristics of screw pile through small-scale model test,and analyzes the optimization scheme to improve the horizontal bearing capacity of screw pile,which has guiding significance for the application of screw pile in offshore wind power foundation.The main contents of this paper are as follows:The horizontal bearing characteristics of screw pile and ordinary pile are analyzed by the combination of model test and numerical simulation.It is found that the bearing characteristics of screw pile are much larger than ordinary pile,the greater the loading speed is,the larger difference between the horizontal ultimate bearing values of the two piles is.Under the displacement load of 2 mm/s,the horizontal bearing energy of screw pile can be increased by 80% compared with ordinary pile.Based on the above research contents,the influence of vertical load on the horizontal bearing characteristics of screw pile and ordinary pile is further explored.The experimental results show that the effect of vertical load on the horizontal bearing capacity of ordinary pile is obvious,and it has little effect on the horizontal bearing capacity of screw pile.The horizontal bearing capacity of ordinary pile will be improved whether it is subjected to vertical ballast or vertical tensile load;The horizontal bearing capacity of screw pile will decrease under the action of vertical ballast,and increase under the action of vertical tension.Finally,the optimization of horizontal bearing characteristics of screw pile is tested and analyzed,and the effects of screw pitch,blade outer diameter,blade buried depth,blade number and blade spacing on the bearing capacity of screw pile are explored.The results show that the horizontal bearing capacity of screw pile is better when the outer diameter of blade is D=1～3d,the pitch p=0.6 ～1.2d,the buried depth of blade is 7～9 times the diameter of pile body,and the number of blades n is less than 3.