Tailings dam failures are one of the most destructive phenomena, both in terms of number of victims and of generated environmental impact. Over the years, different causes have been identified, with flow liquefaction being a prominent factor to consider when assessing the stability of tailings deposits. Due to the complexity of these events, numerical models are crucial for the analysis and design phases, where appropriate advanced soil constitutive models must be selected to reproduce the relevant features of the soil behaviour. In this paper, the Clay And Sand Model (CASM), originally proposed by Yu (1998) and later modified by Arroyo and Gens (2021) and Manica et al. (2021), has been adopted for the simulation of flow liquefaction of tailings deposits. The model incorporates the state parameter concept (Been and Jefferies, 1985) and has been implemented as a User-Defined Soil Model (UDSM) into the finite element code PLAXIS; thereby, it becomes generally applicable to a wide range of geotechnical applications. Due to its versatile yield surface and plastic potential formulations, CASM can be used to model the behaviour of a wide range of soils, from fine-grained (e.g., clays) to coarser-grained soils (e.g., silts and sands). This paper shows the capability of the model, as well as the robustness of the finite element formulation, to reproduce the soil flow liquefaction observed in boundary value problems.@en

The use of soil data is essential in geotechnical design, but in a preliminary project phase such data are usually limited to that inferred from field tests, like CPT, SPT or DMT. In previous publications by the authors and co-workers, it was shown how such data can be automatically processed into soil profiles and parameter sets for geotechnical finite element analysis. Another publication demonstrated the automated processing and creation of geological models as an intermediate step to more advanced 3D geotechnical modelling in a BIM / Digital Twin environment, which facilitates the link with other disciplines and stakeholders in a project. The major challenge of connecting layers across multiple 1D boreholes to form 3D soil layers is overcome by using a Machine Learning clustering algorithm. As a next step, the previously introduced Automated Parameter Determination (APD) method (connecting correlations using Graph theory) is applied based on averaged CPT parameters from all contributing layer sections. The result is an automated system that creates a complete 2D or 3D finite element model, including constitutive model parameters, for geotechnical analysis purposes. An automated system may be very efficient when exploring different design alternatives in an early stage of a project. However, it is important to emphasize the role and responsibilities of the geotechnical engineer in the design process, which requires the system to be transparent, verifiable, and adaptable. This paper describes the state-of-the-art of this ongoing research project. @en

This paper presents the implementation, validation, and application of the PM4Sand model (version 3) formulated by Boulanger and Ziotopoulou (2015) in the PLAXIS finite element code. The model can be used for modelling geotechnical earthquake engineering applications, especially in the case liquefaction is likely to occur. The PM4Sand model represents an improvement of the elasto-plastic, stress ratio controlled, bounding surface plasticity model for sands formulated by Dafalias and Manzari (2004). The two-dimensional version has been implemented in PLAXIS and compared to the original implementation by Boulanger and Ziotopoulou (2015). The original implementation has been used in explicit finite difference simulations which can be sensitive to the size of the returned stress increment, based on the chosen time step size and loading rate. Therefore, the user needs to evaluate the sensitivity of the solution with respect to the chosen time step sizes. On the contrary, in the finite element method used here, the default time step together with the sub-stepping used at the constitutive model level provide a robust solution independent of the size of the returned stress increment.

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In this paper, a constitutive model for masonry structures is presented. It is based on the Jointed Rock (JR) model with overall Mohr-Coulomb (MC) failure criterion, and it is implemented as a user-defined soil model in the finite element
code PLAXIS. The Masonry model is a linear elastic-perfectly plastic model capable of simulating the macroscopic, anisotropic response of masonry structures, by making use of different potential sliding planes (directions) with
different strength properties. A Coulomb criterion is used to simulate failure in each plane, whereas an overall Mohr-Coulomb criterion is used to represent failure of the masonry as a whole. The model is verified against analytical
formulations and validated against experimental data. Particular focus is given to its practical application, considering the response of a masonry structure located in Groningen (the Netherlands) under seismic excitation. A soil profile at a specific location between Loppersum and Huizinge is employed, and soil properties are determined based on available geotechnical data. Clayey soil layers are modelled using the Generalised Hardening Soil (GHS) model. Sandy soil
layers are modelled with the PM4Sand model. The liquefaction potential is also assessed under certain seismic conditions. The masonry, assumed to be shallow-founded, is subjected to an induced strong ground motion, and its response is studied via the proposed constitutive model.@en