Study On The Force Characteristics Of Foundation Ring Type Wind Turbine Foundation Considering Soil-structure Interaction

At present,the foundation ring wind turbine foundation,as one of the main foundation forms of inland wind turbines in China,has the most frequent problems.The levelness,as the main parameter to measure the foundation damage and tower tilt,is greatly affected by the uneven settlement of the foundation.Most of the previous studies did not consider the influence of the uneven settlement of the foundation caused by longterm upper load on the level of the foundation ring,but directly the rigid connection at the bottom of the foundation to analyze its force and damage degree.In order to make an accurate judgment of the foundation damage condition,this paper analyzes the force characteristics of foundation ring type wind turbine foundation under consideration of soil-structure interaction,and the main research contents are as follows.In this paper,all aspects of flexible and previously rigidly connected foundation ring type fan foundations are compared and analyzed by ABAQUS to derive the force characteristics and foundation ring level deviations of fan foundations in the actual environment.The effects of four damage conditions on the force and displacement of the wind turbine foundation are studied,and the degree of damage to the foundation is evaluated using the levelness determination criterion,and the corresponding corrections are proposed.Finally,the mechanical parameters of the foundation were changed and the force performance of the wind turbine foundation under different soil conditions was simulated to provide theoretical reference for foundation site selection and excavation and backfill.Research shows that:(1)the two boundary conditions of the fan foundation force and displacement differences are obvious,flexible connection is more in line with the actual situation.The stress concentration area at the foundation flange is wider and extends to the bottom of the foundation when the flexible connection is made,while the stress concentration at the foundation of the rigid connection only appears in the concrete around the flange.Flexible connection takes into account the influence of foundation tilt on the level of the foundation ring,and its level is much greater than the level of the foundation ring of rigid connection.(2)Under the condition of friction between the foundation ring and the foundation concrete,the uneven settlement of the foundation and the level of the foundation ring and the concrete stress are increasing with the increase of the load,while the increase of the friction coefficient of the contact surface is negatively correlated.Under the condition of crack and cavity expansion,as the crack expands to the lower flange,the maximum stress of concrete on both sides of the lower flange increases linearly,and the level of the foundation ring reaches the 5mm limit required for normal use.When both sides of the cavity expand at the same time,the level of the foundation ring increases linearly,and it is necessary to correct the deflection of the foundation ring and reinforce the foundation.(3)With the increase of the modulus of elasticity of the foundation and the backfill weight,the stress concentration of the foundation concrete is obviously relieved,the uneven settlement of the foundation is reduced,and the level of the foundation ring is linearly reduced.This indicates that when selecting the site for the wind turbine and excavating and backfilling,the selection of harder bearing layer and backfill with higher capacity is more conducive to the normal operation of the wind turbine.