Research On Anchoring Performance Of Base Ring Of Onshore Wind Turbine

A large number of wind turbines are distributed in the vast inland area of our country.The basic structure of these wind turbines often adopts the metal ring type expansion foundation.The thin-walled ring structure with flange is the core component connecting the upper tower and transmitting load in the extended foundation.Its anchoring performance is one of the main factors to ensure the safety and stability of wind turbine.In the actual project,the construction quality often does not meet the requirements,which leads to the quality problems of the concrete around the foundation ring in the fan foundation,and then affects the safe operation of the wind turbine.In view of the above problems,this paper based on the theoretical analysis,test and numerical simulation research to explore the anchoring mechanism of the metal ring puts forward the optimization design idea of increasing the anchoring redundancy of the metal ring.The main research contents are as follows:(1)Through theoretical analysis,it is found that the anchoring behavior of the metal ring is mainly realized by "bonding function","punching function" and "local pressure bearing function".The construction quality has a direct weakening effect on the above three functions.At the same time,through the analysis,it is found that under the action of wind load,the large bending moment is the most unfavorable load,which makes the foundation structure affected by the tensile stress on one side in the horizontal plane and the compressive stress on the other side.Therefore,when the construction quality problem occurs on the tension side of the foundation,the anchorage performance of the metal ring is more likely to fail.(2)Select the local area of the foundation column of the extended fan,make three test models of normal void free,low concrete strength void free and normal void free to carry out the pull-out failure test.It is found that the main failure modes of the specimens are punching failure and axial tension failure,and the steel of the metal ring is still in the elastic stage.Low concrete strength and voids affect the punching and tensile capacity of the concrete cone,which makes the specimen early damaged.Therefore,the main factors affecting the anchoring performance of the metal ring are the strength of the structure around the metal ring.(3)The finite element model is established for numerical simulation analysis,and the gradient of concrete strength and cavity size is increased based on the agreement between numerical simulation and experimental results.It is found that the lower the concrete strength or the larger the void defect,the higher the risk of concrete collapse.(4)On the basis of the above research,through the optimization design of "increasing the buried depth","increasing the reinforcement" and "setting the perforated reinforcement",the strength of the structure in the surrounding area of the metal ring is strengthened,so as toachieve the purpose of strengthening the anchoring capacity of the metal ring.It is found that the method of "increasing the depth of embedment" and "setting the perforated reinforcement" has limited effect,and the method of "adding the reinforcement" strengthens the punching and tensile resistance of the concrete structure,and the construction is convenient,which is more conducive to the improvement of the anchoring performance of the metal ring.