The paper describes two new developments in the PLAXIS geotechnical finite element software. The first part involves some new developments related to the Material Point Method. Here, attention is given to user requirements, with special focus·on the di­vision of the geometry into different MPM and FEM domains, and on contact boundaries. The second part involves the development of a reliability analysis (or probabilistic analy­sis) module to deal with uncertainties in geo-engineering applications. In contrast to the use of (partial) safety factors on loads and materials, a reliability analysis determines the chance that an undesired event occurs (probability of failure). The paper gives some backgrounds of the calculation methods, and user input features and results are highlight­ed. @en

Following up on previous research on Automated Parameter Determination (APD), in which the soil stratification and numerical model parameters are automatically derived from individual CPTs, this article describes ongoing research in which the geotechnical modelling workflow is further automated in a BIM / Digital Twin environment. Especially in a preliminary project phase, when limited soil data are available, a workflow in which CPT data are used to automatically create a 3D geological model from which 2D or 3D numerical models can be extracted, may be very helpful in exploring different design alternatives. For existing (infrastructural) projects, such an automated system in a Digital Twin environment could also help responsible authorities to check the infrastructure’s safety under changing conditions. In addition to the description of technical solutions used for automatic layer detection and clustering (based on Machine Learning) across different CPTs, the article touches upon the discussion on transparency and accessibility of the automated system in view of the expertise and responsibilities of the operating geotechnical engineer.@en

To simulate the behaviour of saturated sands under cyclic loading, the PM4Sand constitutive model (version 3.1) formulated by Boulanger & Ziotopoulou [1], is used. The model can realistically reproduce the pore pressure build-up, accumulation of strain as well as triggering of liquefaction. The effect of dif-ferent relative densities on liquefaction resistance is evaluated by comparing the results of a site response analysis performed on a soil column character-ized by a saturated sand layer and subjected to given earthquake signals. The analyses are performed using the finite element code PLAXIS.@en

When saturated soils are subjected to an earthquake, the excess pore pressuresincrease, and, in the case of sands, this may cause liquefaction. To simulate the behaviour of saturated sands under cyclic loading, the PM4Sand constitutive model (version 3.1) formulated by Boulanger & Ziotopoulou (2017), is used. The PM4Sand model represents an improvement of the elasto-plastic, stress ratio controlled, bounding surface plasticity model formulated by Dafalias & Manzari (2004). The model can realistically reproduce the pore pressure build-up, accumulation of strain as well as triggering of liquefaction. In this paper, the effect of different relative densities on liquefaction resistance is evaluated by comparing the results of a site response analysis performed on a soil column characterized by a saturated sand layer and subjected to given earthquake signals. The analyses are performed using the finite element code PLAXIS.@en

In this paper the man-induced earthquakes in Groningen (the Netherlands) are studied in terms of site response analyses and liquefaction evaluation. A particular soil profile in Loppersum is employed and soil properties are determined based on available geotechnical data. Clayey soil layers are modelled by means of the Generalised Hardening Soil (GHS) model. Sandy soil layers are modelled either with the GHS model or with the UBC3D-PLM model, depending on the purpose of the analysis. The UBC3D-PLM model is used to assess the liquefaction potential. Numerical results are verified against analytical formulations. The non-linear site response of the relatively soft soil deposit is captured well by PLAXIS. Special focus is given to a practical application, considering the response of a shallow-founded masonry structure under seismic excitation. The masonry is simulated by means of the Jointed Rock (JR) model, which constitutes an anisotropic elastic perfectly plastic constitutive model. Two orthogonal slide planes are used in correspondence with the horizontal and the vertical joints of the masonry. A Coulomb criterion is used to simulate failure in each individual plane. Failure mechanisms, such as vertical, horizontal or shear cracking, developed in the body of the superstructure, are identified.@en

The Creep-SCLAY1S model is capable of simulating the anisotropic and rate-dependent behaviour of soft soils. The mathematical formulation also includes the possibility to model bonding and destructuration. Many constitutive models have been proposed in literature to describe the behaviour of structured natural clays. Most of the rate-dependent models were developed based on the Perzyna' (Perzyna (1963) and Perzyna (1966)) overstress theory (e.g. Hinchberger & Rowe (2005) and Zhou, Yin, Zhu & Cheng (2005)), with the disadvantage of a difficult parameter calibration process (Karstunen & Yin (2010)). Another approach consists in using empirical formulations, as for example the Soft Soil Creep model available in the PLAXIS standard library. The Creep-SCLAY1S can be considered a special kind of extended overstress model derived from an empirical equation (Sivasithamparam, Karstunen & Bonnier (2015)). @en