Discrete element study of method for installation forces of screw piles in sand under different advancement ratios

The installation of a screw pile, as a potential offshore wind power foundation form, is the key to its successful application in offshore wind power engineering. Based on the discrete element method, the installation forces of the screw pile installed under different advancement ratios in sand and the interaction between the screw pile and the surrounding soil are simulated with PFC^3D. On the macro-level, the effects of the installation advancement ratio on the installation forces acting on the shaft, base and upper and lower surfaces of the helix of the screw pile are studied. Microscopically, the changes in porosity, coordination number and stresses in the surrounding soil during the installation of the screw pile are analyzed. The research shows that with the reduction of the advancement ratio, both the vertical force and the torque acting on the screw pile decrease, and the disturbance caused by installation of the screw pile to the surrounding soil also reduces. The mechanisms of installation of the screw pile are different for advancement ratios equal to or below 1. The research results provide some insights into the conditions required for the installation of screw piles under different advancement ratios.