Numerical analysis of interaction between seabed and mono-pile subjected to dynamic wave loadings considering the pile rocking effect

Abstract

Pile rocking is the motion of a mono-pile foundation as a result of cyclic loads caused by wind and wave, and the effect of upper structures such as offshore wind turbines. The rocking effect further complicates the interaction between a mono-pile and the seabed and results in instability of offshore structures. In this research, a three-dimensional integrated numerical model, combining the effect of wave loads with the seabed and mono-pile, is adopted to investigate wave-structure-seabed interaction (WSSI) considering the pile rocking effect. The present model is validated by available laboratory experiment data and analytical results. In addition, a detailed comparison with a non-rocking single pile is conducted to examine the effect of pile rocking on soil response more clearly. Finally, the momentary liquefaction depth is investigated and a parametric study on pore pressure response has been carried out. Results indicate that local pressure enlargement occurs near the mudline and the rate of pore pressure decrease in depth is slowed down due to pile rocking, leading to a relatively high pore pressure in the upper soil range. Furthermore, the pile rocking effect has a significant influence on the liquefaction distribution and enlarges the liquefaction zone in the vicinity of mono-pile foundation.