Numerical analysis of lateral bearing capacity of monopiles in clay, part 1: single uniform and isotropic soil layer with strength profile su = su1 × z

Global energy consumption is becoming a serious issue, and improving the energy structure and transition to renewable energy has become a worldwide priority. Large-diameter monopile foundations are commonly used for offshore wind turbine foundations, and their design usually adopts the p–y curve method. However, a simple and practical design method is still lacking. Therefore, this paper details a numerical investigation of the monotonic lateral behavior of large-diameter monopiles in uniform clay with linear strength growth based on the NGI-ADP constitutive model, considering a wide range of pile geometric dimensions and soil properties. Based on the numerical results, equations to calculate the critical burial depth L_crit and critical ultimate bearing capacity F_u, a criterion for a monopile in clay with linearly increasing strength was established, and a calculation method for the load–deformation curve (at the mudline) of a large-diameter pile suitable for a wide range of pile geometric parameters and soil strength distributions was proposed. After the effectiveness of the proposed method is verified through measured test results, the influence mechanism of different pile or soil parameters on the lateral load characteristics of monopile foundations in clay is systematically analyzed via the proposed method.