Evaluating seismic forces and soil liquefaction potential during the development of offshore wind farms in Taiwan is crucial. Wang et al. (2016) conducted a seismic hazard analysis and proposed a design earthquake response spectrum for the bedrock at the Changbin offshore wind farm. In this study, the recommended acceleration response spectrum was used to generate two design earthquakes (BH01_EW and BH01_NS) at the bedrock level that were compatible to the seismic characteristics of the Changbin offshore wind farm. The original soil data of borehole BH01(TORI) at the site were used to conduct a ground motion analysis and obtain design seismic surface forces. In engineering practice, simplified engineering soil profiles are commonly used to design foundations. The simplification of soil profiles causes uncertainties in the ground motion analyses. To determine the effects of soil profile simplification on design seismic loading, we established two engineering soil profiles for borehole BH01(TORI) and compared the ground motion analyses results. One of the simplified engineering soil profiles comprised a simplified profile of shear wave velocity distributed along the depth, whereas the other involved a simplified profile of soil unit weight along the depth. The soil profile with a simplified distribution of shear wave velocity engendered a significant underestimation of the maximum design seismic load at the seabed surface. The acceleration responses at the seabed level obtained from the ground motion analyses were used to evaluate the soil liquefaction potential at BH01(TORI) by employing the New Japan Road Association simplified empirical method. The results indicated a high potential of soil liquefaction in the seabed at the Changbin offshore wind farm, Taiwan. We observed more than 10-m-long liquefiable soil layers. A risk assessment of foundation stability loss due to soil liquefaction should be considered in offshore wind turbine foundation design.
Kuo, Yu-Shu; Lin, Chi-Sheng; Chai, Juin-Fu; Chang, Yu-Wen; and Tseng, Yu-Hsiu
"Case Study for the Ground Motion Analyses and Seabed Soil Liquefaction Potential of Chang-Bin Offshore Wind Farm,"
Journal of Marine Science and Technology: Vol. 27:
5, Article 7.
Available at: https://jmstt.ntou.edu.tw/journal/vol27/iss5/7