Discrete-element method modelling of structural clay

Clay structures are mainly formed by cementation between particles, and play an important role in the weakening and failure of foundations when disturbed. Existing constitutive models reflect the failure characteristics of clay from the phenomenological aspect, while the mechanism of clay damage from a microscopic perspective remains unclear. Herein, the discrete-element method is used together with the bond and cohesive contact model (to capture the cohesion and structure of soft clay, respectively) to reproduce the cementation of clay; numerical models of the confined compression test, vane shear test and triaxial test are established, aiming to reveal the influence of a clay's structure on its deformation and failure process. Results show that the deformation and stress-strain development agree well with experimental findings at the macroscopic level. Moreover, the relationship between structural failure and macroscopic mechanical behaviour can be established, which is helpful for revealing the failure mechanism of structural clay. Considering the development of a failure surface at the micro scale, optimised suggestions are proposed for conventional shear stress calculation in the vane shear test. The method used has potential to simulate the mechanical behaviour of structural clay and carries significant implications for improvement of constitutive models and engineering design.