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An experimental study was carried out to evaluate the influence of silt content on cone penetration measurements and its implication for soil classification. The investigation includes twenty-seven peizocone tests in saturated salty sand samples, which had been prepared in a big rigid thick walled steel cylinder-testing chamber. The samples were prepared with several different silt contents ranging from 0 to 50 percent and were consolidated at three-overburden effective stresses including 100, 200 and 300 kPa. This study showed that, the amount of silt content in sand is an important parameter affecting CPT results. As the silt content increases, the cone tip resistance decreases. The recorded excess pore water pressure during sounding was increased with increasing silt content. It is also concluded that friction ratio, in general, increases with increasing silt content. The method presented by Robertson and Wride [25] and Olsen [17] to evaluate soil classification are also verified.

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An experimental study was carried out to evaluate the liquefaction resistance of silty sand utilizing laboratory techniques. In this study, liquefaction potential of silty sand by using cyclic triaxial tests on frozen samples retrieved from calibration chamber and constructed samples by dry pouring method were investigated. Correlation between cone penetration resistance and cyclic strength of undisturbed silty sand samples are also examined using CPT calibration chamber and cyclic triaxial tests. The cone penetration tests were performed on silty sand samples with fine contents ranging from 0% to 50% and overburden stresses in the range of 100-300 kPa. Then the soil sample in calibration chamber, in the same way that soil samples were prepared during CPT sounding, was frozen and undisturbed soil specimen retrieved from frozen soil sample were tested using cyclic triaxial tests. Analysis of results indicates that the quality of frozen samples is affected by fine content and overburden pressures. Also, using data obtained in this research, the relationship between cone tip resistance and cyclic resistance ratio (CRR) for silty sand soils will be presented. These correlations are in relatively good agreement with field case history data. Also increasing confining pressure in silty sand material increases the cone tip resistance and generally, cyclic resistance ratio increases by increasing silt content.