Unveiling rock heterogeneity-driven multiphysics field coupling mechanisms under microwave radiation by 3D numerical study

Microwave-assisted hard rock breakage technique can promote the excavation efficiency in a sustainable way. While beneficial, its complex and unclear multiphysics coupling mechanism limits its application and precise control. We qualitatively and quantitively analyse the involving Electromagnetic(E)-Thermal(T)-Mechanical(M) coupling mechanism from macro to meso -perspectives via a novel 3D high-fidelity heterogeneous rock numerical study. The results show that rock heterogeneity has a significant disturbing effect on the multiphysics field, with the maximum disturbance degree reaching 345.92 % in electromagnetic loss density, 12.48 % in temperature, and 104.96 % in first principal strain. Furthermore, microwave power intensity can amplify the disturbance effect of rock heterogeneity, as quantified by the Disturbance Amplification Factor (DAF), which under high intensity 6 kW microwave radiation for 1 min amplified the effect 6 times of electromagnetic field, 3.22 ∼ 4.44 times of thermal field, 1.98 ∼ 2.31 times of mechanical field, compared with the 1 kW for 6 min condition. This amplification effect decays along the ETM pathway, where microwave power nonlinearly intensifies multifield disturbances initially driven by mineral dielectric disparity. The multifield presents a 3D high core area coupling relation from the macroscopic level, and the spatio-temporal anchoring effect of mineral components under microwave radiation was dissected through time evolution analysis from the mesoscopic level. This approach reveals the multifield coupling laws and highlights the rock heterogeneity effects, which provide a foundation for target control strategies for future microwave rock breakage.