Analysis of site-specific ground amplification in Saemangeum Reclaimed Area, South Korea

This research investigates the seismic amplification characteristics of soft ground profiles in the Saemangeum reclaimed land area of South Korea. The study employs probabilistic seismic hazard analysis utilizing Peak Ground Acceleration (PGA) maps from the MOLIT (Korean design standard (KDS 1710 00:2018), 2018) at three different annual return periods (ARP)—1000, 2400, and 4800 years—to define the level of seismic shaking for a target bedrock uniform hazard spectrum (UHS) and the selection of earthquake scenarios. Ten (10) recorded input time histories are selected and spectrally matched with the target UHS. Three (03) representative soil profiles are then chosen for simulating one-dimensional (1D) nonlinear ground response analysis using the DEEPSOIL program. The study presents seismic ground response characteristics including PGAs, maximum shear strain, surface response spectrum, and amplification factors for each return period. Results indicate that soft reclaimed layers dampen seismic response, resulting in de-amplification, particularly at higher shaking levels. Notably, MOLIT (2018) overestimates amplification at short periods: Fa is overestimated by 23%, 26%, and 29%, and Fv by 14%, 9%, and 4% for the 1000, 2400, and 4800 ARPs, respectively. Modified amplification factors are therefore proposed to refine the code-based design spectrum in line with observed site response behaviour.