Analytical approach to influencing mechanism of cement-soil reinforcement on horizontal dynamic response of single piles

Abstract

This study centers on the horizontal dynamic response of cement-soil composite (CSC) piles, which are of vital importance for stabilizing offshore structures like bridges and wind turbines against the dynamic loads of wind, waves, and rotational forces from wind turbine blades. Despite their practical significance, theoretical research on the horizontal dynamics of CSC piles trails behind their engineering applications. A sophisticated mathematical model has been developed to delineate the coupled vibration behavior of CSC piles and the adjacent soil under horizontal dynamic loads. Through meticulous theoretical derivation, the analytical expressions for the dynamic impedance at pile head related to horizontal, rocking, and horizontal-rocking motions were acquired. Subsequently, elaborate numerical computations and parametric analyses were executed to explore the influence of cement-soil parameters on these dynamic impedance. The results demonstrate that augmenting the cement-soil radius elevates the dynamic impedance at pile head in all three kinds, yet exerts a negative influence on the horizontal dynamic impedance under high-frequency vibrations. The research also determines an optimum depth for cement-soil reinforcement (about 0.4 times the length of the concrete pile), beyond which the advantages recede. Furthermore, it is manifested that increasing the cement-soil elastic modulus prominently enhances the dynamic impedance, which is propitious to enhancing the horizontal vibration resistance of CSC piles. This conclusion significantly contributes to a profound comprehension of CSC pile behavior and provides highly valuable guidance for their design and application in offshore engineering.