Performance of nonlinear 2D numerical models for the seismic response of a natural slope

Within the framework of the Spoke 5 “Environment and Natural Disasters” of the National Research Centre in High Performance Computing, Big Data and Quantum Computing, aimed at developing advanced numerical tools for the real-time simulation of natural disaster-inducing phenomena, such as earthquakes and landslides, for reducing the associated risks, the present work illustrates the results of a preliminary numerical investigation conducted to assess the performance of nonlinear 2D finite element (FE) analyses in the evaluation of the seismic response of an ideal natural slope inspired to a real case study. The simulations are performed with the FE code OpenSees and its pre/post processor STKO, taking advantage of the National Research Centre HPC resources to improve their efficiency. The cyclic response of the slope soils is described by the Pressure Independent Multi Yield model, a nonlinear elasto-plastic constitutive law accounting for both isotropic and kinematic hardening. The slope model developed in OpenSees adopts quadrilateral elements implementing the u-p formulation for the solid-fluid interaction during fully coupled dynamic analyses. As benchmark, the same slope is modelled in Plaxis 2D, using the nonlinear elasto-plastic constitutive model HSsmall and a mesh composed by 15-noded triangles. The comparison between the two FE models allows to validate the predictions of OpenSees against a well-established FE software and, more generally, to identify the advantages and limitations of adopting different numerical tools for the assessment of the seismic response of a typical geotechnical boundary value problem.