Study on horizontal bearing characteristics of single-blade rigid screw pile for offshore wind power in clay

Screw piles have advantages of fast installation speed and superior bearing performance, and as the foundation of offshore wind power, they can effectively reduce construction costs and promote large-scale development of offshore wind power. During service of wind turbines, screw piles are subjected to huge horizontal loads. However, most of current research on screw piles focuses on vertical bearing performance, and it is urgent to study horizontal bearing performance of screw piles. In this paper, finite element numerical analysis method is used to analyze influence of blade size and blade position on the horizontal ultimate bearing capacity of a single-blade rigid spiral pile from perspectives of the rotation center of the screw pile and influence range of the soil around the pile, and the failure mode of the soil around the pile under horizontal loading is obtained. A prediction formula of the horizontal ultimate bearing capacity of the single-blade rigid screw pile in clay is proposed. The results show that horizontal ultimate bearing capacity of the screw pile increases with the increase of the blade diameter, and shows a trend of first increasing and then decreasing and then increasing with the downward movement of the blade position. When the blade is located at the bottom of the screw pile, the horizontal ultimate bearing capacity reaches the peak, and it is recommended to set the blade at 0.3~0.5 times the embedded depth of the pile or the bottom of the screw pile when the screw pile mainly bears horizontal load. When the blade is located above the center of rotation, the soil around the pile presents a rigid rotational failure accompanied by an inverted wedge. When the blade is located below the center of rotation, the soil around the pile presents a rigid rotational failure without inverted wedge.