Crack analysis of the foundation gallery within an asphalt concrete core dam based on 3D SBFEM-PFM

• A novel 3D SBFEM-PFM coupling algorithm is proposed to interpolate phase-field within polyhedral element. • A unified and parallelized computational framework is established that couple 3D SBFEM-PFM with geomaterial elastoplasticity and nonlinear contact. • The proposed approach enables the first 3D phase-field simulation of a large-scale rockfill dam, capturing crack initiation, propagation, and optimization measures in the world’s highest asphalt concrete core dam on the overburden. Fracture analysis of anti-seepage systems in earth-rock dams involves pronounced material nonlinearity, frictional contact behavior, and convergence difficulties, which remain long-standing challenges in geotechnical engineering. In this study, A nonlinear 3D SBFEM–PFM formulation was created by embedding the phase-field model (PFM) into the scaled boundary finite element method (SBFEM) and implementing an intra-element phase-field interpolation scheme. Base on independently developed GEODYNA, a unified and parallelized framework was established through various coupling schemes, including FEM-SBFEM, phase-field, and nonlinear contact algorithm. The method is validated against a classical benchmark and subsequently applied to the world’s highest asphalt concrete core rockfill dam (ACCRD) on the overburden to simulate full-process cracking of gallery. Cracks were identified along the inner surface of the gallery and on the outer surfaces of both banks, with reservoir impoundment exhibiting opposing effects on crack width. Additionally, the severity of structural damage was significantly influenced by the interface characteristics between the gallery and surrounding geomaterial. This study signifies the inaugural implementation of PFM to achieve a full-process simulation of stress accumulation, crack initiation, and progressive propagation within dam anti-seepage systems. High risk zones were precisely identified, and the practical optimization measure was suggested, providing an innovative and effective approach for structural analysis in related geotechnical engineering applications.