Analytical non-linear "m-θ" curves for monopiles in clay

Dependable predictions of monopile foundation response to lateral loads is crucial to the efficient design of offshore wind turbine foundations. For squat monopile foundations, it is important to incorporate the distributed non-linear moment-rotation response with depth, known as “m-θ” curves, in addition to traditional “p-y” curves and lumped force-displacement curves at the pile base. Recognising the limited number of “m-θ” curves available in the literature, this paper develops new theoretical “m-θ” curves using a rational two-dimensional horizontal pile/soil “slice” model to obtain improved representations of the stress and displacement fields in the soil around the pile. Firstly, this model undergoes validation through comparisons with available linear-elastic solutions. Subsequently, it is employed in conjunction with a numerical discretisation of the pile circumference to obtain non-linear “m-θ” curves accounting for both soil yielding and slippage between pile and soil. The resulting curves are compar