Aging effects on liquefaction resistance of sand estimated from laboratory investigation

Abstract

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 Gsec), 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, Gsec, and the laboratory penetration resistance. In the case of Toyoura sand of Dr = 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. Gsec started to degrade at greater shear strain in the long-term consolidated specimens. An increase in the CRR, evaluated from the Gsec of 0.01% shear strain, had a much better agreement with that obtained from the cyclic undrained triaxial tests.