1 Influence of K0 Consolidation on Yield Undrained Shear Strength in Triaxial Compression Yashay Narainsamy*, Schalk Willem Jacobsz University of Pretoria, South Africa ABSTRACT Recent global tailings dam failures have placed a renewed interest in the design and safety evaluation of tailings dams. With the introduction of the Global Industry Standard on Tailings Management it is becoming more common to evaluate the stability of tailings dams considering undrained shear strengths. In practice, this is typically done by performing undrained triaxial compression tests on tailings samples and measuring their yield undrained shear strength. A stability analysis is then conducted where the measured yield undrained shear strength is assigned to the soil using an undrained shear strength ratio. Due to the difficulty in obtaining undisturbed samples from tailings dams, triaxial specimens are usually prepared from disturbed bulk samples and the in situ stress conditions are recreated by consolidating the specimens. Since it is known that the stress conditions in tailings dams are not isotropic, it is becoming more common to anisotropically consolidate the specimen to recreate this effect. The effect of the stress conditions during consolidation on the yield undrained shear strength was investigated by reviewing published triaxial data on three sandy soils: iron ore tailings, gold tailings and Hostun sand. For each soil, specimens were consolidated anisotropically and isotropically and then sheared undrained in triaxial compression. The yield undrained shear strengths were interpreted and expressed in terms of undrained shear strength ratios. It was found that the samples that were anisotropically consolidated exhibited a more brittle material response compared to the isotropically consolidated samples. It was also found that the yield undrained shear strength ratios were consistently larger for the samples that were anisotropically consolidated compared to the samples that were isotropically consolidated. This indicates that the stress conditions during consolidation need to be carefully considered as they play a key role in the magnitude of the yield undrained shear strength of sandy soils, including tailings.