Applications of the Particle Finite Element Method (P-FEM) to faulting in the brittle crust

Accurately modeling faulting in the so-called brittle crust remains a challenge due to limitations in numerical algorithms and problems in choosing realistic constitutive models. These challenges are reflected in difficulties linking observations across scales: from laboratory to outcrop and up to regional geology.

Here we present the Geotechnical Particle Finite Element Method (P-FEM), a large-deformation numerical tool developed to capture detailed progressive failure and fracturing using a non-local formulation.

A key advantage of P-FEM is its ability to simulate localized shear bands (fault zones with finite thickness) that naturally emerge independent of mesh discretization, both in thickness and orientation. Continuous remeshing further enables the modeling of large deformations within a Lagrangian framework, and techniques used to minimize numerical diffusion help producing realistic localized shear/fault zone patterns. Additionally, P-FEM benefits from its foundation in standard finite elements, allowing to use efficient and accurate solvers (tested through years by a large community of users) and a wide library of constitutive models to simulate various geo-materials, including non-cohesive soils and fault gouges, weak porous rocks (that could develop deformation/compaction bands), and “standard” brittle-frictional-plastic materials. Multiphysics implementations including fluid and heat flow are also available but will not be specifically discussed here.

These capabilities make P-FEM particularly suited for investigating fundamental tectonic processes such as (i) fault nucleation and growth in mechanically layered materials, (ii) the interplay between faulting and folding in thrust belts, and (iii) the development of fault damage and/or process zones in materials with heterogeneous mechanical properties. Our contribution will outline the P-FEM method and discuss its application to these tectonic problems.