Stress-history impact on yielding, shear and energy dissipation response of earthen dam soil under static and cyclic loading conditions

The present paper evaluates the impact of stress history on yielding, shear and energy dissipation response of earthen dam soil under static and cyclic loading conditions by conducting consolidated undrained (CU) triaxial tests and cyclic simple shear (CSS) tests respectively. The current research has been performed at four different stress histories (over consolidation ratio = 1, 2, 5, 10) on loose, medium and very-dense specimens under static and cyclic loading conditions. The generation of stress history enhanced the soil particle interlocking and stability of the soil structure resulting in substantial improvement in the undrained static and cyclic strength of the soil. Loose and medium-dense specimens’ shear response exhibited metastable structure formation; conversely, the very-dense specimens revealed more stable structural adjustments. The ‘teardrop’ shaped yield surface grew substantially as the density state changed from loose to medium-dense to very-dense. The incremental strain vectors at pre and post-instability states indicated highly compressive behaviour in loose and medium-dense specimens. The undrained static and cyclic shear behaviours were analysed in the context of energy dissipation under different stress histories. All soil specimens (loose to very dense) exhibited liquefaction susceptibility under cyclic loading conditions at all stress histories.