A coupled thermo-hydrologic-mechanical damage model and associated application in a stability analysis on a rock pillar

A numerical model of coupled thermo-hydrologic-mechanical damage (THMD) in the failure process of rock is proposed using elastic damage mechanics, thermal-elastic theory and seepage mechanics. In the proposed model, the mechanical deformation of rock subjected to thermo-hydrologic-mechanical loading is considered. The model includes the accumulation of damage applied to individual elements, which modifies the modulus, strength, permeability and thermal properties with the severity of the damage. This concept is introduced as a practical method to simulate progressive failure in heterogeneous and brittle rocks, obviating the need to explicitly identify crack tips and their interactions. The model is validated through comparisons of the simulated results with known analytical solutions. The proposed THMD model is implemented in the Rock Failure Process Analysis code (RFPA), and RFPA-THM is developed. Using RFPA-THM, numerical simulation is performed to investigate the stability of a hard rock pillar in the Äspö Pillar Stability Experiment (APSE). The numerically obtained stress field, failure pattern of the rock pillar and the associated Acoustic Emission (AE) events are all in agreement with the in situ experiment conducted at the Äspö Hard Rock Laboratory (HRL) and the phenomenological observations reported in previous studies.

► A model of coupled thermal-hydrologic-mechanical damage (THMD) is proposed.
► The outlines and numerical implementation of the THMD model are presented.
► Numerical simulation is performed to investigate the stability of the Äspö pillar.