The Fractal Characteristics of Rough‐Fractured Rock Masses Based on THM Multi‐Field Coupling

ABSTRACT

Degradation of the self‐similarity of fracture systems in high‐temperature and high‐stress environments can lead to inaccurate predictions of underground rock mass structures, restricting the reliability of geothermal reservoir development and deep rock mass stability assessment. To address this issue, this study constructs an intelligent Thermo‐Hydro‐Mechanical (THM) multi‐field coupling model for rough fractured rock masses. Taking granite and sandstone as typical cases, the model analyzes the evolutionary behavior of fracture fractal characteristics under the coupled action of THM fields. Results show that temperature and stress ratio exert significant nonlinear effects on fracture fractal structure. The fracture fractal dimension exhibits a continuous downward trend under high‐temperature and high‐stress conditions; fracture morphology evolves from a branched complex structure to a trunk‐dominated structure. Under the hydraulic‐mechanical coupling effect, the connectivity of fracture networks is remarkably enhanced, and the hydraulic capacity has a cross‐scale transition; this indicates that the fracture system has undergone a structural reconstruction process from local connectivity to overall connectivity under the shear‐slip‐dominated mechanism. The innovation of the intelligent THM model lies in the integration of deep reinforcement learning and the adaptive fractal grid method; this realizes the dynamic modeling of multi‐field coupling processes and multi‐scale representation of fracture structure under physical constraints. The model results show that this method can stably describe the evolution trend of fracture fractal characteristics; it also effectively reflects the response relationship between fracture structure and hydraulic behavior under multi‐field coupling. Hence, these results provide a reference for fracture geometric evolution modeling in geothermal energy exploitation and stability assessment of rock masses in deep engineering projects.