Simplified Design Method of Laterally Loaded Rigid Monopiles in Cohesionless Soil

Abstract

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.

Keywords

• monopile
• lateral load
• rotation depth
• monotonic design
• cohesionless soil