Rigid monopiles with small slenderness ratios (i.e., ratio of monopile embedded length to outer diameter) are widely used as foundations to resist lateral load and moment transferred from superstructures, e.g., large diameter steel pipes used by offshore wind turbines and piers in electric utility industry or sound barriers. A design model for laterally loaded rigid monopiles in cohesive soil is presented in this paper. The proposed design model assumes a constant depth of rotation point as well as a trilinear distribution model of soil lateral reaction along the embedded length of the monopile, and introduces a mobilization coefficient of soil reaction to quantify the magnitude of soil reaction mobilized under a certain load applied at the monopile head. The relationship between the mobilization coefficient and monopile head rotation is established by back-analyzing test results measured from series of laterally loaded pile tests, and then a general design procedure for a laterally loaded rigid monopile in cohesive soil is recommended. The feasibility and reliability of the proposed design model is validated against three cases of numerical simulations on laterally loaded piles in cohesive soils. It shows that this study’s proposed design model produces a relatively satisfactory prediction of the nonlinear load-deformation response, and can be used for laterally loaded monopile design in the sites with undrained shear strength being uniform or increasing linearly with depth.

The bearing capacity of an open caisson under lateral loads is a key factor affecting the normal operation of an open caisson. It will inevitably have a disturbing effect on the surrounding soil layers during the sinking process of the caisson; that is, a disturbance ring will develop around the caisson. Based on the Jurong Yangtze River water supply project, the lateral bearing characteristics of the open caisson are analyzed by the numerical method with due consideration to soil disturbance, and the reinforcement scheme is optimized. The numerical results show that when the thickness of the disturbance ring is less than 0.5 m the disturbance ring has little effect on the lateral bearing capacity of the open caisson. An arc-shaped cement–soil reinforcement at the loading area can effectively improve the lateral bearing performance of the caisson. The optimized reinforcement thickness is 2 times that of the disturbance ring, and the reinforcement angle is approximately 60°.

This paper presents a simplified design method for laterally loaded rigid monopiles in cohesionless soil. The proposed design method is based on a constant depth of the rotation point and a bi-linear distribution of soil lateral reaction along the embedded length of the monopile. Furthermore, a mobilization coefficient of soil resistance is introduced to quantify the magnitude of the soil reaction mobilized under a certain load level applied at the pile head. The mobilization coefficient is found to be directly related to the pile head rotation by back-analyzing test results measured from 13 laterally loaded piles in the published literature. The feasibility and reliability of the proposed design method are evaluated with another 23 laterally loaded piles, which are compiled in a database. The results show that the proposed design method yields relatively satisfactory predictions of the nonlinear load-deformation responses of these piles. Furthermore, comparison of soil lateral reaction profiles between those measured and calculated with the proposed method proves the validity of the assumed soil reaction profiles. As the mobilization coefficient is back-analyzed from piles mostly embedded in uniform ground and the pile bending and translational deformations are neglected in this study, the proposed method is suitable for monopile designs in uniform sites with medium~medium-dense sand, in which the pile bending and translational deformations can be ignored.