Influence of soil and pile properties on the critical length of laterally loaded piles

Piles could undergo various deformation and failure modes which were depended on their classification. Previous research primarily utilized the equation proposed by Poulos and Hull to classify the pile. While the Poulos and Hull method offers advantages in terms of its simplicity, it is not entirely suitable for contemporary applications involving large-diameter piles and complex soil profiles. In this study, a three-dimensional pile-soil coupling finite element model is proposed using the hypoplastic constitutive model. The main goal of this paper was to present extensive three-dimensional finite element analyses to examine the lateral response of a monopile embedded in sand. This research reevaluates five existing methods for determining the critical length of laterally loaded piles. The evaluation considers both directly assigned and indirectly calculated methods for determining the soil's elastic modulus. The findings reveal that Dobry's equation offers superior prediction for the critical length across various soil conditions. However, for low relative density soils, the Poulos and Hull method demonstrates better suitability. The numerical results presented in this study are expected to provide design references for further practical applications of the monopiles.