Seismic damage response of anchor cage wind turbine foundations under different incidence angles

Considering the randomness of seismic waves and their significant impact on the seismic performance of structures are considered. Using a wind farm in Xinjiang as an example, the focus of this study is on the vibration characteristics and damage assessment of anchor cage wind power foundations under different incident angles of P and SV waves. First, using the equivalent node method, viscoelastic boundary simulation of the subsoil boundary spring-damper was performed and verified by a numerical example. In addition, a three-dimensional numerical simulation model of the subsoil, foundation and anchor cage was established; based on the concrete CDP constitutive model, vibration response analysis and damage evaluation of the anchor cage wind power foundation under different incident angles of P and SV waves were carried out. The results show that under a near-field pulse seismic load, the anchor bolt inside the anchor cage is subjected to greater stress under the oblique incident seismic waves, which have a significant influence on the safety of the wind power foundation. At different incidence angles, the damage effects of the P and SV waves on the anchor cage wind power foundation differ. The damage caused by the oblique incidence of the P wave increases with increasing angle, whereas the degree of damage caused by the SV wave shows a nonmonotonic change, and the minimum damage occurs at an incidence angle of 15°.The damage is mainly concentrated in the contact area between the foundation, anchor bolt and cushion, especially at the junction and longitudinal joint of heterogeneous materials; additionally and the damage expands with time, and is positively correlated with the incidence angle. The stress concentration near the anchor hole of the anchor plate is significant, and the stress caused by the SV wave exceeds that caused by the P wave.