Shear Rate Effect on Strength Characteristics of Sandy Soils

In this study, the effects of different shear rates during direct shear tests on variations in the strength characteristics were investigated for the sand samples of various particle size distribution. Direct shear tests were carried out at nine different shear rates ranging from 0.05 to 5 mm/min under normal stresses of 54.5, 109, and 218 kPa. Both sample groups were tested under a condition of defined water content and in a water-filled condition. Results show that with increasing shear rate, the internal friction angle and peak shear strength values increased. The increase in the internal friction angles and peak shear strengths were particularly evident for shear rates higher than 1 mm/min. Even though the effect of grain size on the variation in strength parameters due to shear rate is limited for the soils examined in this study, the effect should be considered.