Investigation of the effect of the relative density and shear strain on liquefaction of sands

Abstract

Liquefaction potential of non-cohesive soils is determined by field tests such as SPT, CPT, which use the stress approach, and laboratory tests such as three-dimensional dynamic shear, torsional shear, resonant column, and bender element tests. Recently, the approach of energy has been used to estimate the liquefaction potential of sands. The main parameters used in this approach are relative density and effective stress of the ground. In this study, Cyclic Simple Shear Test arrangement is used. In this study, the effect of shear strain and relative density on the liquefaction energy of the sands were investigated. In the study, clean fine marine sands were used. In this study, 3 different relative densities for a sand sample (Dr= 40%, 55% and 70%); 4 different stresses (av= 50, 100, 200 ve 300 kPa), and pore water pressure (u= 25, 50, 75 ye 150 kPa). Totally of 36 experiments were performed in and 3 different deformation rates (y= 2%, 3.5%, and 5%). The harmonic loading was applied to the experimental samples at a frequency (I) of 0.1 Hz. The effect of relative density, deformation rate and vertical stress conditions on the liquefaction energy of sands has been demonstrated for a type of fine-grained clean sea sand. The increase in the shear strain rate reduces the liquefaction potential by about 3%. The increase in relative density, increases the shear resistance of the sand. This delay liquefaction and causes an increase in the number of cycles.