UCLA

We assess soil liquefaction effects on ground surface motions as a function of factor of safety against liquefaction triggering (FSliq) The effects of soil liquefaction on ground motions are quantified by the ratio of acceleration response spectra (AFliq) calculated based on one-dimensional effective- and total-stress simulations conducted in a finite-difference code. Three methods for computing FSliq are explored: one from a liquefaction triggering model, including a magnitude scaling factor, and two from cycle counting for ground surface motion or shear stresses at depth. Our results indicate that soil liquefaction leads to a predominant amplification of ground motions in the short- and long-period ranges and de-amplification of ground motions in the intermediate period range, approximately from 0.1 to 0.9 s. We found that FSliq is a promising indicator of the liquefaction effects on ground motions and that ground motions at sites with FSliq higher than 0.9 are only moderately to slightly amplified or de-amplified.