Experimental study of the hydrodynamic force on a pipeline subjected to vertical seabed movement

Abstract

Using an underwater shaking table, model tests of a free-spanning flexible submarine pipe subjected to vertical seabed movement were carried out. The fluid field adjacent to the pipe and the hydrodynamic force exerted on the pipe were measured. Based on Morison's equation, the hydrodynamic force coefficients related to earthquake, such as the drag coefficient CD and the added mass coefficient CA, were obtained by the least squares method. The effects of the Reynolds number Re, the Keulegan–Carpenter number Kc, the water depth d, and the span height e on the hydrodynamic coefficients were analyzed. The experimental results illustrate that Re and Kc have a strong effect on the hydrodynamic forces imposed on the pipeline under vertical earthquakes. The variation of the hydrodynamic coefficients with Re and Kc is fitted by a regression analysis. The calculated results from the hydrodynamic force model suitable for vertical earthquakes are in good agreement with the measured data.