Scouring effects on lateral cyclic responses of piles in sand

The wind turbine has become an efficient way for clean energy. For offshore wind turbine in a sandy area, the monopile is a widely used foundation type under proper water depths. During the life time, monopiles are subjected to millions of cyclic loads from winds and waves and scouring around the pile is a common phenomenon, both of which can influence the operation safety of the offshore turbine. To study the coupled effects of cyclic loading and scouring on the horizontally loaded pile, a series of horizontal monotonic and cyclic loading tests on model piles were carried out in sandy soil. The influence of pile diameter, cyclic loading amplitude, and scour depth on the long-term residual accumulated displacements of a monopile is investigated. The test results show that the deformation mode of pile and the dilatancy of sand result in different static responses of the pile. A quantised work is presented to estimate the accumulated residual displacements of the pile, in which the effects of the three factors can be expressed in a united expression. Since the lateral capacity is a crucial parameter for the normalisation in regression analysis, the confirmation of a lateral capacity should be related to the corresponding concern in practical projects.