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The strength and deformation properties of tailing materials are strongly affected by their hydromechanical history including the cycles of desiccation and re‐saturation they undergo due to the often layered deposition process. The current study reviews the fundamental characteristics of some of the commonly used constitutive models for partially saturated soils, namely Barcelona Basic Model (BBM), Glasgow Coupled Model (GCM), and a dilatancy‐based model by Buscarnera and Nova Model (BNM) in predicting the hydromechanical response of tailing materials. In particular, we investigate the strength and shortcomings of each model and compare their capability of capturing the salient trends during drying/wetting cycles, as well as during shearing. Based on comparison with experimental data, modifications are suggested for the models, specifically related to a realistic formulation of the water retention curve and its hysteresis. The results point to a potential trade‐off in the accuracy of the constitutive models in capturing the volumetric responses during the drying/wetting cycles on one hand, and the stiffness and strength characteristics during the shearing phase on the other. [ABSTRACT FROM AUTHOR]

A mass-conservative formulation of one-dimensional (1D) coupled large-strain consolidation and unsaturated flow using a piecewise-linear formulation is developed. The volume and water-content changes in the unsaturated zone are described using threedimensional (3D) constitutive surfaces of void ratio and gravimetric water content as functions of net stress and matric suction, whereas the volume change in the saturated zone is described using a two-dimensional (2D) curve relating void ratio to Terzaghi effective stress. The hydraulic conductivity varies with both void ratio and suction in the unsaturated zone, and with void ratio only in the saturated zone. The associated nonlinearities are addressed by solving the flow-continuity equation for water mass conservation through a finite-difference scheme in a piecewise-linear manner. The unknowns are calculated from variables in the previous time step without requiring iteration. A novel algorithm is developed to smoothly model transition between the saturated and unsaturated zones. Four types of top boundary conditions are formulated to account for complex soil-atmosphere hydraulic interactions. The developed program is also capable of performing a quasi-unsaturated analysis, which uses the saturated soil's constitutive relationships in the unsaturated zone, similar to the approach of several models currently used in practice. The theoretical and numerical development of the model is described in this paper, and is followed by verifications of the program's implementation using a numerical example of saturated large-strain consolidation and an analytical solution to unsaturated flow. Validation of the quasi-unsaturated and unsaturated formulations is presented in the companion paper, using comparisons with numerical cases as well as laboratory and field data. [ABSTRACT FROM AUTHOR]

The authors (Lloret-Cabot et al. in Acta Geotech 1-23, 2017) applied the glasgow coupled model (GCM), originally proposed by Wheeler et al. (Géotechnique 53(1):41-54, 2003), to the simulation of several experimental tests that involve transition between saturated and unsaturated states. The authors show qualitatively, but not quantitatively, predictions of GCM for shrinkage during air drying of normally consolidated samples (Fig. 13) under low mechanical stress conditions, without presenting the material parameters. The discussers, who have worked with GCM to model multilayer deposition of tailings/soft soils (Qi in Numerical investigation for slope stability of expansive soils and large strain consolidation of soft soils. Doctoral dissertation, University of Ottawa, 2017; Qi et al. in J Geotech Geoenviron Eng 143(7):04017018, 2017, Qi et al. J Geotech Geoenviron Eng 143(7):04017019, 2017), have made quantitative predictions of similar cases. Satisfactory simulations of such cases using GCM are sensitive to the selection of the coupling parameters k1 and k2. By considering an alternative analytical form of GCM, an analytical procedure can be derived for calibrating the coupling parameters for problems involving virgin drying. [ABSTRACT FROM AUTHOR]