ABSTRACT
Reduction or decline of soil strength as the result of liquefaction phenomenon occurring in loose and saturated sands is one of the important discussions of seismic geotechnics. Regarding the existence of sand deposits at the coasts of Caspian Sea, it seems necessary to identify the strength parameters of this type of sand. Unstability in these soils occurs when the shear stresses created in soil mass is more than its shear strength; then until meeting the conditions in which shear stress is not more than shear strength, soil is deformed. In such conditions the soil undrained shear strength is called steady state strength (SUS). In this research it was tried that the strength of Anzali sand steady state to be studied in different conditions (change in multi-lateral stress, percent of fine-grained and percent of relative condensation) and in various sites performing undrained-consistent static three-dimensional tests. In continuation, the strength of steady state obtained from three-dimensional tests was compared with the amounts obtained from relations based on standard penetration test and the accuracy of these relations was evaluated. In the end considering the experimental tests obtained from three-dimensional ones and the amounts of standard penetration test obtained from field studies, a new relation was suggested.
