As mining depth increases

the large deformation of soft rock

such as roof fall

floor heave and two-side movement of the tunnel

poses a severe challenge to safe mining. Currently

continuous-discontinuous methods

combining advantages of both continuous and discontinuous methods

are rapidly developing. However

creep has not yet been introduced into these methods. Based on the experimental phenomenon that rock creep failure strain occurs in the post-peak region of the triaxial compression stress-strain curve

the viscoelasticity of the element is considered. A creep shear cracking model is developed to account for the viscoplasticity of the interface

and a criterion of creep shear cracking is introduced into the combined Lagrangian-discrete element method (a kind of continuous-discontinuous method) to simulate the creep shear cracking. The calculated creep curve under uniaxial compression aligns closely with experimental results. Once creep shear cracking begins

the specimen enters the accelerated creep stage. The proposed method has the potential to simulate accelerated creep. Results of the soft rock tunnel indicate that discrete blocks move into the tunnel due to the pushing of deep rock

sharply reducing tunnel size. Macroscopically

the tunnel exhibits a large deformation. The tunnel’s vertical shrinkage rate can reach 58.8%. The mechanisms of large deformation in the soft rock tunnel

attributed to the viscoelasticity of the element and the viscoplasticity of the interface (fictitious crack surface)

result from a combination of small viscoelastic deformation of the medium

large block displacement

and viscoplastic deformation of the interface. It is unnecessary to describe the tunnel’s macroscopic large deformation using complex large deformation theories.