Fatigue Failure Patterns And Application Of Detection Technology Of The Anchor Tube Wind Turbine Foundation

As a clean energy,wind energy has inexhaustible and easy-to-use characteristics,making it have broad prospects for development.However,in recent years,with the continuous expansion of the installed scale of inland wind turbines in China,the basic problems of wind turbines,as the main load-bearing components,have gradually emerged.At present,the largest number of installed wind turbines in our country is the foundation of basic ring wind turbines,which has the most problems.The design life of the wind turbine is 20 years.However,in the initial stage of the operation of some wind turbine units,the normal operation of the wind turbine units can‘t be caused by the fatigue damage of the foundation.The serious problems need to be removed and rebuilt,thus causing huge economic losses.Therefore,a series of problems,such as fatigue damage detection method,fatigue damage mechanism and design method of wind turbine foundation in China,need to be further studied and improved.In this paper,the fatigue damage mechanism and detection technology of anchor tube foundation are further studied.Through the damage detection and treatment of a large number of domestic problems,the damage state and formation process of contact concrete around foundation ring are mainly studied.According to the load provided by the wind turbine manufacturer,the bearing capacity of steel bar through foundation ring is under extreme load condition and fatigue.The formation and evolution mechanism of foundation fatigue damage of anchor tube foundation is put forward by checking the labor condition.The main achievements are as follows:(1)Through on-site investigation and field measurement of several problem wind turbine foundations in China in recent years,various kinds of wind-induced fatigue damage commonly existing in anchor tube foundations are studied.The fatigue damage development process of wind turbine foundation can be summarized into three stages:Initial stage: initial cracks are visible to the naked eye between anchor tube and surrounding concrete,and there is no obvious relative displacement between anchor tube and foundation.Development stage: With the continuous operation of the wind turbine,the tower of the wind turbine drives the anchor tube to swing irregularly,and the initial crack extends downward to the flange under the anchor tube.At the same time,because of the stiffnessof the anchor tube,the swing of the anchor tube makes the concrete in the upper triangle area of the lower flange punch repeatedly,and the concrete strength is affected by fatigue,leading to the formation of the fracture surface in the weak area.A small amount of surface concrete is crushed.Ultimate stage: The damaged concrete is ground into powder.Under the action of the water entering the crack,it is brought out along the crack between the ring wall of the foundation and the concrete to form the lower flange cavity.With the increasing of the cavity,the fatigue of the perforated steel bar is brittle and the concrete near the perforated steel bar is loosely damaged.Large area crushing of foundation surface concrete occurs.(2)Combined with a large number of engineering practice and the anchor tube foundation wind-induced fatigue damage characteristics,puts forward the fracture observation,anchor tube levelness measurement method,concrete core pulling strength testing,the flange around the compactness of concrete video out hole and radar detection and so on a series of wind turbine foundation that can be used for fatigue damage detection technology,not only has realized the problem of single wind turbine foundation,accurate assessment of the fatigue damage and can be used in wind farm large wind turbine foundation of rapid evaluation of fatigue damage,implementation issues early discovery and treatment of the wind turbine,for the wind power enterprise to restore the economic loss.