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Lang, R.; Liu, R.; Lian, J., and Ding, H., 2015. Study on load-bearing characteristics of different types of pile group foundations for an offshore wind turbine.Elevated pile-cap foundation is one of the most popular foundation types for offshore wind turbines. Form selection and design are the keys in the construction of offshore wind farms. Because offshore wind turbines are high-rise structures, a reasonable and applicable foundation can ensure the normal operation of wind turbines. Meanwhile, it can decrease the size of foundation and reduce the cost of construction effectively. Four types of pile group foundations named BPG-type, SPG-type, VPG-type, and CPG-type are developed. Combined with laboratory model experiments, a numerical simulation method is established and verified in this paper. The vertical bearing capacity, horizontal bearing capacity and bending bearing capacity are studied comparatively with the numerical simulation method. Combined with practical engineering, the applicability of the foundations is evaluated. The results indicate that BPG-type and SPG-type have the stronger vertical bearing capacity, horizontal bearing capacity and bending bearing capacity than VPG-type and CPG-type in the same amount of steel. In addition, batter piles can effectively increase the bearing capacity of pile foundations. The VPG-type needs to increase the size of foundation to meet the requirements of wind turbine operation. In practical engineering, the combination of vertical piles and batter piles can increase the bearing capacity of pile group foundations and decrease the cost of construction. ADDITIONAL INDEX WORDS:Elevated cap, pile group foundation, vertical bearing capacity, horizontal bearing capacity, bending bearing capacity.

Because offshore wind turbines are high-rise structures, they transfer large horizontal loads and moments to their foundations. One of the keys to designing a foundation is determining the sensitivities and laws affecting its load-bearing capacity. In this study, this procedure was carried out for a new high-rise cap pile group foundation adapted to the loading characteristics of offshore wind turbines. The sensitivities of influential factors affecting the bearing properties were determined using an orthogonal test. Through a combination of numerical simulations and model tests, the effects of the inclination angle, length, diameter, and number of side piles on the vertical bearing capacity, horizontal bearing capacity, and bending bearing capacity were determined. The results indicate that an increase in the inclination angle of the side piles will increase the vertical bearing capacity, horizontal bearing capacity, and bending bearing capacity. An increase in the length of the side piles will increase the vertical bearing capacity and bending bearing capacity. When the length of the side piles is close to the central pile, the increase is more apparent. Finally, increasing the number of piles will increase the horizontal bearing capacity; however, the growth rate is small because of the pile group effect.