Aging effects of liquefied ground for over a decade estimated from in-situ sounding tests and geophysical exploration

Ground liquefaction has been observed often in reclaimed ground during earthquakes. The extents of liquefaction damage have differed according to the reclaimed ground age since construction. However, the aging effect mechanism has not been elucidated adequately. Therefore, the Swedish weight sounding (SWS) test, portable dynamic cone penetration (PDCP) test, and multichannel analysis of surface waves (MASW) surveys were conducted multiple times in this study over about a decade for liquefied ground. The data indicate that liquefaction resistance increased 30% in the repeated liquefied area, but it increased less than 10% in single liquefied areas during the observation period. Findings indicate that the aging effects of liquefaction resistance estimated from cyclic undrained triaxial testing were much greater than those estimated using other methods. Therefore, in-situ tests evaluating liquefaction resistance indirectly might underestimate the actual ground aging effects related to liquefaction resistance.