| Summary: | The physical and engineering mechanical behaviors between coral sand and terrigenous sandy soils are considerably
different. To study these behaviours, a series of undrained multistage strain-controlled cyclic triaxial tests were conducted on
saturated coral sand from Nansha Islands, South China Sea. The influence of effective confining pressure 0 p and relative density Dr
on the dynamic shear modulus and damping ratio of coral sand was studied. Compared with the test results of coral sand and
terrigenous sandy soil and gravel, significant differences were found in the maximum shear modulus Gmax, the shapes and the upper
and lower boundaries of shear modulus ratio G/Gmax curves, reference shear strains 0 , the shapes and the upper and lower
boundaries of damping ratio curves. The maximum shear modulus Gmax of coral sand is higher than that of terrigenous sandy soil
and gravel, and the Gmax of coral sand predicted by empirical equations of terrigenous sandy soil is underestimated by 30%. The
nonlinearity of coral sand is slightly weaker than that of terrigenous sandy soil and gravel. The empirical formulas for predicting
G/Gmax and of terrigenous sandy soil and gravel are not applicable for Nansha coral sand. The empirical formulas for predicting
G/Gmax and of coral sand are proposed.
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