Analysis of Liquefaction Triggering in the Nakdong-river Delta Sediments Based on Broadband Hybrid Ground Motion Simulation and Microtremor Array Method

Abstract

We present a case study of liquefaction triggering analysis performed in the Nakdong-river delta region, based on the shear wave velocities obtained by the Microtremor Array Method and the ground motions generated by the broadband hybrid ground motion simulation. Assuming a M_w6.2 earthquake occuring at the Dongrae fault, the ground motions at the studied sites exceeded the design spectra provided by the Korean Design Standard and many of the studied sites exhibited low factors of safety against liquefaction triggering. We found that the Idriss and Boulanger (2008) method yields larger Cyclic Stress Ratios (CSR), compared with the site response analysis based method. Cyclic Resistance Ratios (CRR) estimated from the shear wave velocity were sensitive to small changes in the velocity, which suggests that high accuracy and depth resolution are desired when the shear wave velocity is used to estimate the CRR.