Numerical modeling and failure analysis of caisson foundations subjected to the monotonic lateral loads

The caisson foundation has evolved into a suitable alternative foundation for offshore structures, specifically for offshore wind turbines (OWT). The OWT caisson foundations are exposed to a combination of lateral, vertical, and overturning moments. A precise assessment of horizontal load response is necessary to ensure the normal functioning of these foundations for a proper design. This paper presents the results of three-dimensional finite element analyses of the lateral load-bearing behavior of the caisson foundation used for offshore wind turbines. The numerical model was validated and cross-checked by experimental data from the literature. The caisson’s behavior and the soil response supporting the caisson foundation subjected to static horizontal loads were examined. The effect of the slenderness of the caisson foundation was examined by changing the diameter and the depth of the caisson. It was observed that the depth of a caisson has a more profound effect on the lateral load-bearing capacity of the foundation. The caisson’s rotation center or inflection point was found to be at a distance of approximately 0.8 times the caisson depth, and it shifted downward with the increase in caisson diameter. Soil upheaval in the loading direction was observed as a precursor to the pullout failure, which increased with loading eccentricity and decreased with the caisson depth. •The effect of aspect ratio and the pullout behavior of caisson were analyzed.•The inflection point of rotation of caisson and soil heave around it were analyzed.•Parametric studies were conducted on the caisson’s thickness, diameter, and depth.•Parametric studies were also conducted on load eccentricity and caisson lid diameter.