Numerical investigation of wave run-up and impact forces on large offshore jacket platforms

Abstract

This paper focuses on wave interactions with large deep-sea jacket platforms. A numerical wave tank is designed and developed to simulate the wave-structure interactions, and the accuracy and precision of this numerical wave tank are verified by the theoretical values and LWI experimental tests. Then the processes of wave run-up along with the legs and impact the lower deck of a large deep-sea jacket platform located at the South China Sea are simulated, analyzed, and discussed. The results show that the greater the wave steepness, the stronger the wave run-up ability. The wave run-up processes are mainly concentrated within a radius R around the legs, and the maximum wave run-up ratio reaches 1.56 on the front side of leg 1 when the wave steepness is 0.03. Due to the interference, reflection, and superposition effects, all the legs show different wave run-up characteristics, and additional high-frequency side wave peaks are observed around the legs, which are mainly focused on 0–0.6 Hz in the frequency domain. With the increase of wave steepness λ, the wave drag forces increase significantly during the wave run-up processes. Especially, when the waves impact the lower deck under case 3, it will cause huge vertical wave impact loads, and the maximum value reaches 46.59 MPa, which will cause further attenuation to the vertical and lateral resistance of the jacket platform.