An enhanced understanding of the lateral response of large-diameter monopile: Development of a new P-y curve

The present design practices of laterally loaded monopiles tends to discretize the pile into a series of beam elements and connect each element to uncoupled non-linear springs, or P-y curves, to represent soil reactions. The prevailing design codes tend to support the use of a universal P-y curve irrespective of pile configuration, flexural rigidity, and soil rigidity index. However, accumulating evidence suggests otherwise, underscoring the imperative to revise formulas, especially for large diameter rigid monopiles. This study conducts a thorough examination of load transfer and failure mechanisms in large diameter monopiles subjected to monotonic lateral loading in clayey soil. A refined formula is proposed to estimate ultimate net soil resistance, rectifying deficiencies in prevailing design codes prone to underestimation. Findings reveal significant influence of soil rigidity index on the P-y curve of rigid monopiles. Consequently, endeavours are undertaken to develop a new P-y formulation integrating the pivotal role of soil rigidity index. The newly devised P-y curve is anticipated to propel advancements in the design of large diameter monopiles, pivotal in offshore renewable energy exploitation.