A modified constitutive model is proposed in the current study for analyzing plastic concrete in cut-off walls using a Finite Difference Modeling (FDM) approach by making modifications to the friction, dilation, and cohesion mobilization functions of the current constitutive models. The new proposed model is capable of simulating the hardening-softening behavior and the volumetric-axial strain of plastic concrete, and using the simulated experimental results of triaxial plastic concrete, a hardening function for the mobilized friction and a modified function for the mobilized cohesion are proposed. The robustness of the proposed model was compared with the experimental results of triaxial tests of cylindrical plastic concrete specimens used in the cut-off wall of two embankment dams. The comparison proves that the proposed model is capable of simulating the elastic, hardening, softening, and volumetric behavior of a plastic concrete with favorable accuracy. The results also indicate the influence of the plastic concrete constitutive model on the interaction of the plastic concrete wall with its adjacent materials. The outputs of this study will help researchers better understand the non-linear behavior of plastic concrete and lead to a more realistic design of plastic concrete cut-off walls.

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