Analysis Of Flexural Performance Of New Grouted Connection In Offshore Wind Power Foundation

Offshore wind power is a hotspot of wind power development in recent years.The design of offshore wind turbine infrastructure is one of the keys to the construction of offshore wind farms,and the transition between the connection foundation and the upper fan tower is the key to ensure the normal operation of the wind turbine.At present,the commonly used grouted connecting section for setting the shear key has a severe stress concentration in the area near the welding shear key,which severely reduces the fatigue life of the connecting part.Concerning the problem of stress concentration in the grouted connecting section at the shear key,the research team proposed a new type of grouted connecting section that has a wavy groove in the outer wall of the outer steel tube and the outer wall of the inner steel tube.This article has completed the following aspects of the proposed bending performance of the new grouting connection:(1)The force mechanism of the grouting connecting section under the bending moment was analyzed.The new grouting connecting section mainly depends on the contact pressure between the steel pipe and the grouting material,the horizontal and vertical friction forces,and the friction between the wave groove and the grouting material on the steel pipe to transfer the moment load.Compared with the grouting connecting section where the shear key is provided,its ability to transfer the bending moment has not been significantly improved.With the increase of the grouting length,the carrying capacity of the connecting section gradually decreases.(2)The stress distribution on the grouting material of the new grouting connection section and shear connection grouting connecting section is compared and analyzed.The first and third principal stresses on the grouting material near the wave groove are respectively 1/3 and 1/2 of the first and third principal stresses on the grouting material near the shear key,which better relieves the area near the shear key.There is a problem of stress concentration.(3)Taking a 5.0MW wind turbine as an example,the fatigue analysis software nCode was used to compare and analyze the fatigue performance of the new grouting connecting section and the grouting connecting section with shear keys.Comparing with the life of the fatigue life calculation formula in the DNV-GL specification,the two are in good agreement.The fatigue life of the new grouted connecting section is 109 orders,which is much higher than that of setting the shear strength of the grouted joint section 107.It can meet the requirements of the current design life of 108 orders,and has obvious advantages.(4)Using ANSYS Workbench to optimize the details of the structure that affects the bending performance of the new grouted connecting section,including the length of the grouting,the thickness of the grouting,the depth of the grooving groove,the spacing of the groove,the way of grooving,and the layout range,etc.factor.The analysis found that the optimum range of grouting thickness is 90～100mm;the grouting length is too large to reduce the overall mechanical performance of the connecting section,and the length of steel piles should be 1.5 times the length;the appropriate size of the undulating groove is the depth of the groove.h=8mm,spacing s=500mm;The first wave-shaped groove on the steel pile is used as a groove,and the first wave-shaped groove on the sleeve is a convex groove.The arrangement of the groove peak on the groove is arranged in the middle part of the grout.