• A coupled numerical model integrating COMSOL electrical breakdown and 4D-LSM mechanical analysis accurately simulates HVEP-induced rock fragmentation.
• The model reveals the full fragmentation process under varying electrical parameters, highlighting the importance of plasma channel temperature in driving mechanical failure.
• Confining pressure and mineral grain size significantly influence fragmentation efficiency and fracture patterns.
• Optimization of electrode spacing is critical for achieving energy-efficient rock fragmentation, as demonstrated by parametric simulations across 25 combinations.