Crack propagation, failure and ultimate load capacity of the grout layer in the prestressed anchor bolt foundation of wind turbine tower

Abstract

The finite element (FE) analyses based on linear elastic fracture mechanics (LEFM) for the crack propagation and failure of the grout layer in the wind turbine foundation with pre-stressed anchor bolts are presented. Firstly, one half-symmetric planar numerical model is developed. According to the linear elastic analytical results, one initial crack is set to be the zone of the maximum tensile streess and its direction is perpendicular to the direction of the maximum principle tensile stress. The crack will propagate in the direction of the zero mode-II stress intensity factor during the failure of the grout layer. The numerical simulations with different prarmeters are performed. The histories of mode-I stress intensity factor are analyzed and design formulas predicting the failure and ultimate load capacity of the grout layer are proposed based on parametric studies. The increasing width or the decreasing depth of the grout layer can significantly mitigate the failure. One case study of the grout layer with the typical size and the corresponding fatigue analyses are carried out. The numerical results show that the proposed equation can agree well with the cracking status and failure of the grout layer in practical engineering and help predict the fatigue life of the grout layer under the certain intial crack length.