Numerical investigation of plastic strain localization for rock-like materials in the framework of fractional plasticity

The plastic strain localization phenomenon is of critical importance for rock-like materials when undergoing non-homogeneous deformation. This paper presents a fractional plastic framework which is applied to take into account the plastic strain localization of rock-like materials. The novelty of the presented framework lies in the non-coaxial plastic flow that is controlled by the RiemannLiouville (RL) fractional derivative without additional plas-tic potential. The hardening response is described by a function of the generalized plastic shear strain. The capability of the fractional constitutive model to predict the main me-chanical behaviors of rock-like materials is assessed by the conventional triaxial compres-sion test data of Vosges sandstones from the literature. With the help of a MATLAB-based finite element method, several numerical examples (i.e., a plate, a plate with a hole, and a plate with a crack) are implemented, compared and analyzed to demonstrate the effec-tiveness of the proposed framework and the influence of the fractional order on the strain localization. It can be found from the numerical application of the twin-tunnel that the fractional model is promising to flexibly capture the strain localization zone for rock-like materials.(c) 2023 Elsevier Inc. All rights reserved.

Automated summary

This paper presents a fractional plastic framework to consider the plastic strain localization of rock-like materials. The framework utilizes a non-coaxial plastic flow controlled by the Riemann-Liouville (RL) fractional derivative, without the need for additional plastic potential. The ability of the fractional constitutive model to predict the mechanical behaviors of rock-like materials is evaluated using triaxial compression test data. Numerical examples are implemented to demonstrate the effectiveness of the proposed framework and the influence of the fractional order on strain localization.