An exponential model for strain softening behavior of sensitive clays

Abstract

Abstract Strain softening in sensitive clays is a major cause of retrogressive landslides. The assessment of post failure movements like retrogression or run out in such landslides requires detailed data regarding the post peak parameters, especially in terms of stress and strain at remoulded state. The limitations concerning experimental studies in this regard is well known which has often led to the use of mathematical and analytical models in assessing strain softening. Here, an exponential model to predict strain softening is proposed by making use of triaxial testing data. The model is developed through a series of triaxial testing results collected from ten different sites in Eastern Canada. The developed softening equation is governed by the peak undrained shear strength, sensitivity of the clay, ease of strength reduction from the peak to the remoulded state and the strain at remoulded strength. The main advantage is that a quick and reasonable evaluation of the softening behaviour of the sensitive clay maybe carried out through experimental studies. The prediction of strain at remoulded state is an important outcome of this study and is consistent with field data. Keeping in mind the effect of geological and topographical factors in the estimation of post failure movements in retrogressive landslides, an attempt has been made to conduct a preliminary assessment of the retrogression distance through the strain at remoulded state.