EVALUATION OF UNDRAINED CYCLIC STRENGTH OF
GRAVELLY SOIL BY SHEAR MODULUS
YUKIHISA TANAKA
ABSTRACT: The possibility of evaluating
undrained cyclic strength of natural gravelly deposits using
shear moduli was investigated. Through this study, the following
conclusions were drawn.
1) It was found that cyclic shear moduli at relatively large
strain amplitude were closely related with undrained cyclic
strengths, irrespective of the effective confining
pressure, grain size distributions and whether or not the samples
are intact, whereas there seems to be no unique relationship
between initial shear moduli and undrained cyclic strengths.
2) It was found that the G/G0-grelation
of an intact sample can be approximated by that of the reconstituted
sample depending on the initial shear modulus of the intact
sample. Based on this fact and the relationship mentioned in
1), a simplified method to evaluate undrained cyclic strength
of gravelly soil by shear modulus of the ground, which was calculated
using both initial shear modulus of the ground and the G/G0-g
relation of the disturbed sample, was proposed.
3) It was revealed that reduction in shear modulus with an increase
in shear strain is closely related to void ratio. Based on this
fact and the relationship mentioned in 1), a more simplified
method to evaluate undrained cyclic strength of gravelly soil
by initial shear modulus and void ratio of the ground was proposed.
Key words: earthquake, gravel,
liquefaction, shear modulus, site investigation,
(undrained cyclic strength) (IGC: D7)
