Phase field fracture modeling of cohesive-frictional materials like concrete and rock using the scaled boundary finite element method

Abstract

Understanding and predicting the mechanisms and behaviors of crack propagations in engineering structures made of rock and concrete is important when producing reliable designs. This study proposes a phase field crack model suitable for cohesive-frictional materials such as rock and concrete. Novelty lies in introducing and coupling the multiaxial strength criterion for cohesive-frictional materials and the micro-damage evolution law within the fracture process zone within the basic phase field method. Another novel feature is the decomposition of volumetric and deviatoric components of the stiffness matrices in the precomputation phase of the scaled boundary finite element method. The combination of this numerical technique with the proposed constitutive model enables the effective and efficient simulation of compression-shear cracks. Novelty also lies in integrating the proposed model with scaling theory. This keeps the computational cost for large-scale problems within an acceptable range. The technique we adopt to achieve this advancement involves making the simulation results insensitive to the characteristic length. This improvement allows the characteristic length for large-scale problems to be uniquely determined and larger than the value used at the laboratory scale. This enables the use of coarser meshes, reducing the computational resources needed for simulating large-scale problems.