Abstract：The phenomenon of cracking and uneven settlement is often found in the foundation of the wind turbine tower, when serious, it will cause the tower to collapse. Compared with the uneven settlement, cracking degree is hard to measure directly, especially when the cracks are not on the surface, the influence of cracks is also difficult to accurately assess . In this paper, the vibration test and analysis were carried out on the wind turbine tower with foundation cracks: First, we carried out vibration test on two wind turbine towers of the same type in the same site, one tower had cracks in the concrete foundation another as a reference was intact; Then, the vibration characteristics of two wind turbine towers were analyzed; Finally, by comparing the natural frequency and vibration intensity and other vibration characteristics, we found out that, under the same work conditions, compared to the reference wind turbine tower the FFT amplitude ratio of its third order natural frequency and the first order natural frequency of the tower with cracks in foundation was far greater, although the first three order natural frequency values had little difference; The difference of maximum acceleration value in the breeze was not large, but in the larger wind or under the engine room yawing condition, the maximum acceleration value of the failure wind turbine tower was significantly greater than the reference one. The test results of this paper show that, the vibration strength of the tower is sensitive to the foundation cracks; The natural frequency is not sensitive, but the high order FFT amplitude is sensitive to the concrete foundation cracks. Test results can provide a reference to quickly evaluate the serious degree of foundation cracks and the influence of this type of disease on the safety of wind turbine tower operation, based on vibration characteristics.
