A viscoplastic-fatigue peridynamic model and the GPU-accelerated simulation of creep-fatigue failure in geomaterials

A three-dimensional viscoplastic-fatigue micropolar peridynamic model is proposed for creep-fatigue failure of geomaterials, in which Perzyna viscoplasticity and fatigue degradation evolve within a unified bond-level framework. A directed-bond GPU implementation is developed to improve the computational efficiency of three-dimensional peridynamic simulations. The proposed model and the GPU acceleration implementation are validated by a cyclic compression simulation of rock salt. Results show that the proposed model can reproduce the progressive inclined damage pattern observed in the physical tests, capturing the three-stage creep-fatigue damage evolution, and obtaining fatigue lives that reasonably agree with the experimental results. Besides, the overall speedup becomes faster with material-point discretization refinement, reaching 21.19 for the finest model with 31,250 material points. An engineering-scale salt-cavern simulation is conducted, which captures the progressive development of cavern-wall damage under cyclic internal pressure, and the results indicate that the cavern-wall damage is creep-dominated. The simulations show that the proposed model can successfully simulate creep-fatigue damage in geomaterials.