Effect of Shear Rate on the Residual Strength of Clayey Soils

Abstract

The residual strength of soils in the shear zones at different shear rates can correspond to the movement of landslides. However, the rate-dependency of residual strength has not been quantified. A laboratory study on the residual strength of clay soils at shear velocities is present in this paper. The samples were extracted from the shear zone of a deep-seated landslide experiencing reactivation movement. The residual strength of samples at step-up shear rates from 0.5mm/min to 10000mm/min was obtained. Test results indicate that the samples at increasing shear rate tend to exhibit positive rate effect. At 10000mm/min the residual strength shows a gain of 2.21~2.68 times above the slow residual value. A model for predicting the residual strength correlating the shear rate is introduced. The different features in the slow and fast residual strength are attributed to soil fabric modifications within the shear zones. This is of practical significance to the stability and kinematic analysis of landslides.