Coupled Thermal, Hydraulic And Mechanical (THM) Model For Excavation Damaged Zone In Rockmass

The creation of an excavation damaged zone (EDZ) is expected around all man-made openings in geologic formations. The formation and its subsequent spatial and temporal evolution of EDZ, being considered as a coupled process among thermal, hydraulic mechanical, and damage fields, which is a significant issue for evaluating the engineering stability and safety, and for optimizing the supporting parameters. Recently, aiming to the study of the strategic energy storage and the radioactive waste disposal, a signficant development in EDZ characterization and coupled thermal-hydraulic-mechanical (THM) modelling has been achievend.A coupled THM model during the rock failure is proposed when the damage is considered as a key factor that controls the THM coupling. The model is solved using numerical method by programming on the base of COMSOL Multiphysics, a powerful PDE-based multiphysics modelling environment using finite element method. The proposed THM model is firstly utilized to simulate the THM response of the elastic medium and it is validated by comparing the numerical results with the analytical solutions. Secondly the proposed THM model with damage evoluation incorporated is validated by comparing the numerical results with the experimental obseravation of the failure process around circular openings under uniaxial compression.At last, the model is employed to predict EDZ under HM conditions and the numerical results indicate that, the damage zone is dominantly controlled by in-situ stess conditions, and the hydraulic pressure also has an important influence on the initiation and evolution of EDZ. At last the EDZ development of fracuted rockmass under TM conditions has been numerically simulated and the numerical results denote that both the existing fractures and the thermal effects play a important role on the initiation and evolution of EDZ.