Correlation between drained shear strength and plasticity index of undisturbed overconsolidated clays

A number of triaxial compression tests have been performed by The Danish Geotechnical Institute over the past decades on undisturbed overconsolidated Danish clays; ranging from clay till of low plasticity to extremely high plasticity marine Tertiary clays. The test results confirm that the drained peak angle of shearing resistance can be related to the plasticity index, though a large scatter is generally seen. Based on the results and a review of published data a conservative relationship between drained peak angle of shearing resistance and plasticity index for undisturbed overconsolidated clays is proposed. The proposed relationship and the interrelation to the effective cohesion are discussed.