Thermal damage evolution of granite under different thermal conditions based on two-scale tessellation via discrete element method

Abstract

This paper presents a numerical modeling method that integrates a grain-growth model and Voronoi polygon configuration to investigate the thermal damage characteristics and fracture mechanism of granite under three distinct thermal conditions: rapid heating, slow heating, and cycle heating. The proposed method accurately simulates the intra-grain damage modes of mineral particles and the mechanical responses of granite. Through the simulation, it was observed that slow heating induces more significant deterioration compared to rapid heating, while cycle heating leads to wider crack openings and apparent brittle damage during the cooling phase. Furthermore, the peak strength and elastic modulus of granite demonstrate a significant decrease with increasing temperature under all three heating conditions. Notably, slow heating exhibits ductility characteristics in its post-peak residual strength. This study also analyzes the effects of different thermal conditions on the damage evolution pattern and cracking mechanism of rocks. It is found that slow heating generates a higher number of cracks with a broader distribution and intra-grain damage, whereas cycle heating results in severe cracks and fractures. The findings of this study have practical implications for preventing and controlling thermal disasters in deep rock engineering.