A timestep-based mass-scaling NCDDAM for efficient thermal–mechanical fracture modelling in rock masses

Rock masses in deep underground engineering are commonly subjected to complex thermal–mechanical interactions induced by geological conditions and engineering disturbances. However, an explicit thermal–mechanical coupled analysis is usually restricted by the smallest stable timestep, which is often determined by the mechanical field rather than the thermal field, resulting in excessive computational costs for long-duration simulations. To overcome this limitation, this study proposes an enhanced nodal-based continuous-discontinuous deformation analysis method (NCDDAM) incorporating a timestep-based mass scaling technique. By scaling the mechanically controlled stable timestep to be consistent with that of the thermal field, the proposed numerical model substantially reduces the total number of computational steps and provides an efficient and practical tool for long-term thermal–mechanical damage and stability analysis of deep rock masses.