Abstract: It is hot and difficult point that research on thermo-hydro-mechanical (THM) coupling for fractured rock mass at present. Firstly, the research status of mechanism, models, numerical simulation methods and contents for multifield coupling of fractured rock mass are summarized. Meanwhile, the significant effect on THM coupling of fractures is analyzed. As a result, the critical problem considering the fracture network propagation and its simulation during the THM coupling is proposed. Furthermore, 3 critical points are pointed out: (1) building the THM coupling model which can consider the fracture network propagation; (2) selecting numerical simulation method of simulating fracture propagation; (3) proposing the simulation algorithm for THM coupling and the whole process of rock mass from deformation to collapse. Then, the numerical methods for simulating coupling and fracture propagation are classified and compared; therefore, the various numerical methods, including finite element method, element-free method, partition of unity method, discrete element method, rock fracture process analysis method and numerical manifold method, are discussed thoroughly and particularly, from the advantages and disadvantages. Following, the numerical manifold method (NMM) is recommended for solving the critical problem. Finally, some ways and difficulties of the work are discussed preliminarily.

Key words: fractured rock mass, multifield coupling, fracture propagation, numerical simulation, numerical manifold method (NMM)