The 1995 Hyogoken Nannbu (Great Hanshin) earthquake, boiled sand composed of the so-called Masado (weathered granite) was observed widely on the ground surface at the coastal areas along the Osaka bay. Ground condition indicates that the liquefaction was caused by the earthquake at considerably large areas of reclaimed land. After the earthquake, field soil survey and laboratory test were performed to investigate the physical properties and the liquefaction characteristics of reclaimed lands in Kobe Port, such as Port Island and Rokko Island, which were mainly composed of Masado, and damagged during the earthquake. Soil data before the earthquake were also corrected for comparison with this investigation. The followings are the results of this study;
(1)The grain size distribution curves of frozen undisturbed samples are almost the same as those of block samples. However, the grain size distribution curves obtained from the SPT (Standard Penetration Test) samples shift the points nearly 10% to 20% upwards on the figure representing the relationship between the grain size and percentage finer by weight.
(2)The average SPT N-values of the reclaimed land with Masado are relatively small indicating nearly 10 blow counts at the shallower depths of -10m to -15m below the ground surface. Although the average SPT N-values tend to have slightly increased after the earthquake. the amount of increase is not considered to be large when the wide variations and scatters in the SPT N-values at different depths are taken into account.
(3)The density of reclaimed land with Masado is larger than that with usual clean sand with uniform grain size, because Masado is classified as well-graded soil. The relationship between the density and SPT N-values was found to be poor, but the density tends to increase as the SPT N-value increases.
(4)The comparison of shear wave velocity and shear modulus with the SPT N-values showed certain correlations. The velocity of dilation wave was found to be constant independent of the SPT N-values.
(5)The shear modulus, Go, at very small shear strain amplitudes measured with frozen samples using the cyclic triaxial tests is fairly consistent with that measured in the field using the PS logging.
(6)The G/Go versus γ curves measured with frozen samples showed very good agreement with those presented as standard curves for sandy soils in the Technical Standards for Port and Harbour Facilities in Japan. The measured damping ratios, however, became smaller as a whole and the h versus γ curces shifted downwards compared to the standard curves for sandy soils.
(7)The liquefaction resistance of reclaimed land behind the quaywalls tends t61o be slightly higher than that of replaced layers with Masado beneath the caissons. The relationship between the liquefaction resistance of the ground measured from frozen samples and the corrected SPT N-values is well represented by the curve proposed by Yoshimi (1994).