Design and Modeling of Impact and Vibratory Installation of Piles in a 1g Laboratory Scale Test

Abstract

The widespread deployment of offshore wind turbines requires the use of fast, low-cost, and reliable installation methods. While impact pile driving is predominantly used for offshore monopile foundations, vibratory pile driving provides an interesting alternative. The selection of a suitable installation technique is based on cost, marine environment, noise pollution, and soil conditions. To study installation effects, this research aims to develop 1g laboratory scale tests of both impact and vibratory pile driving in a sand filled and saturated container. Numerical models are employed to study the dynamic behavior of the 1g scale test, and are used to design (and optimize) the test setup. Particular attention is related to the reflection of waves at the boundary of the container and the frequency content of the vibratory and impact driving force, as to get the best correspondence with the full-scale pile installation in situ. The numerical model includes (1) a multi-body dynamic models to compute the impact or vibratory loads on the pile head, and (2) a finite element model of the sand box – pile system. This allows us to study the dynamic interaction between the pile and the soil, wave propagation in the sand box, and estimate the soil’s response. The comparison of both scales is then used to optimize the test setup, achieving a good correspondence to a full–scale test, both statically and dynamically.