Yielding of overconsolidated sensitive clays due to unloading

Paper in proceeding, 2026

Natural slopes composed of overconsolidated sensitive clays are susceptible to large retrogressive flow slides that can occur rapidly once the soil structure is disturbed. Such disturbances may result from unloading processes. This study presents a series of anisotropically consolidated drained triaxial stress probing tests performed on intact samples of natural sensitive clay to investigate its yield response. Yield points are identified from multiple stress-strain plots to account for changes in anisotropy. Based on these results, the initial shape and size of the yield surface for the investigated material are determined. However, the portion of the yield surface on the dry side of the compression critical state requires further investigation, as sensitive clays exhibit a rapid increase in creep rate when approaching the Critical State Line (CSL). The experimental findings will be used to refine an existing constitutive model for sensitive clays, enhancing its capability to simulate the stress strain behaviour of sensitive clays during unloading.