Aging effects on liquefaction resistance of sand estimated from laboratory investigation

Liquefaction resistance is known to increase concomitantly with the increase in time after construction or sedimentation. Nevertheless, the mechanisms of its aging effect on liquefaction have not been completely elucidated. To clarify the mechanisms of aging in sandy soils, the liquefaction resistance (CRR), initial and secant shear moduli (G₀ and G_sec), and laboratory penetration resistance of long-term consolidated sand specimens were examined using cyclic undrained triaxial tests, local small strain (LSS) tests equipped with bender elements (BEs), and penetration index tests, respectively. Based on the existing reports, the CRR was inferred from G₀, G_sec, and the laboratory penetration resistance. In the case of Toyoura sand of D_r = 40%, the CRR increased by about 14% with a 360-day consolidated specimen in the cyclic undrained triaxial tests. However, increases in the CRR evaluated from G₀ and the laboratory penetration resistance were nothing and only 2%, respectively. G_sec started to degrade at greater shear strain in the long-term consolidated specimens. An increase in the CRR, evaluated from the G_sec of 0.01% shear strain, had a much better agreement with that obtained from the cyclic undrained triaxial tests.