Research On The Influence Of Wall Deformation On The Penetration Resistance In Sand Of Bucket Foundation

The large-scale suction composite bucket foundation is a new type of foundation for offshore wind turbines.It begins to receive attention from engineering field for the feature of convenient transportation and construction recently.However,a relative higher pressure difference will lead to the bending deformation of the bucket wall and even the buckling failure during the penetration.In addition,the leveling process of foundations is complicated.The bucket is more likely to tilt,thus leading to the variation of force patterns between the bucket walls and surrounding soil and the increasing risk of analogous deformation of bucket walls,which will be detrimental to the installation process.In this paper,two kinds of bending deformation analyses were conducted;and three types of models were made,the standard straight bucket,the inverted cone bucket and the positive cone bucket.Bucket penetration tests in sand were conducted and the penetration resistance was analyzed.Meanwhile,effects of bending deformation at different penetration stages were observed.Finally,two kinds of anti-resisatance measures,the resistance reduction ring and the press-pull loading,were proposed.In conclusion,the penetration resistance of the deformed models was much higher than that of the standard bucket model with the same penetration depth.Particularly,the biggest penetration resistance occurred in the inverted cone bucket model.Moreove,the impact of resistance reduction ring varies with different forms of bucket foundations.An obvious resistance reduction presented in the inverted cone bucket test results.In addition,the resistance reduction effects of press-pull loading tests can be applied to all models with different degrees,but it can be weakened by the resistance reduction ring.The conclusions above can be valuable when it comes to the site installation.By changing the geometry form of the reduction ring and adjusting the application mode of the press-pull measure,it will be of great significance to the penetration resisitance reduction of bucket foundations during the installation.