A unified soil reaction model for laterally loaded monopiles in soft and stiff clays

To develop a unified soil reaction model suitable for laterally loaded monopiles in soft and stiff clays, this paper employs an experimentally validated numerical method to analyze the influence of diameter, embedded length (L), and clay types (soft or stiff) on the soil reaction model, proposing a unified model based on hyperbolic soil reaction curve. This model fully considers the contributions of distributed lateral load, base moment, base shear force, and distributed moment to the lateral resistance. The results of the analysis indicate that the ultimate normalized lateral soil resistance (${\overline{p}}_u$) of soft and stiff clays in the wedge flow zone increases with depth, reaching a peak in the full flow zone with the peak points located around 0.5 L. The maximum of ${\overline{p}}_u$ between soft and stiff clays is positively correlated with the ratio of effective vertical stress to undrained shear strength (${\sigma }_{\text{v}}^{\prime }/s_u$) at the current depth. The ultimate base shear force and base moment for monopiles in soft and stiff clays can also be represented by ${\sigma }_{\text{v}}^{\prime }/s_u$ at the base. Through rigorous validation with centrifuge and field tests, the unified soil reaction model proposed in this paper can accurately predict the response of monopiles in soft and stiff clays.