The Geotechnical Particle Finite Element Method for the modelling of soil-structure interaction under large deformation conditions

The possibilities of the Particle Finite Element Method (PFEM) for modelling geotechnical problems are increasingly evident. PFEM is a numerical approach to solve large-displacement and large strain continuum problems that are beyond the capabilities of classical FEM. In PFEM the computational domain is reconfigured for optimal solution by frequent remeshing and boundary updating. PFEM inherits many concepts, such as a Lagrangian description of continuum, from classic geomechanical FEM. This familiarity with more popular numerical methods facilitates learning and application. This work focuses on G-PFEM, a code specifically developed for the use of PFEM in geotechnical problems. The article has two purposes. The first is to give the reader an overview of the capabilities and main features of the current version of the G-PFEM and the second is to illustrate some of the newer developments of the code. G-PFEM can solve coupled hydro-mechanical static and dynamic problems involving the interaction of solid and/or deformable bodies. Realistic constitutive models for geomaterials are available, including features, such as structure and destructuration, that result in brittle response. The solutions are robust, solidly underpinned by numerical technology including mixed-field formulations, robust and mesh-independent integration of elasto-plastic constitutive models and a rigorous and flexible treatment of contact interactions. The novel features presented in this work include the contact domain technique, a natural way to capture contact interactions and impose contact constraints between different continuum bodies, as well as a new simplified formulation for dynamic impact problems. The code performance is showcased by the simulation of several soil-structure interaction problems selected to highlight the novel code features: a rigid footing insertion in soft rock, pipeline insertion and subsequent lateral displacement on over consolidated clay, screw-pile pull-out and the dynamic impact of a free-falling spherical penetrometer into clay.