Abstract: In order to solve the problem of soft rock deformation in the construction stage of a deep buried watercarrying tunnel of NJ Hydropower Station in Pakistan, a combined approach consisting of indoor rheological test, field monitoring and rheological parameter inversion was used to evaluate the tunnel supporting strength parameters of the TBM construction section (NJTBM) in NJ Hydropower Station. And the existing supporting systems at different depths of NJTBM in different types of surrounding rock were optimized by the numerical simulation and capacity checking. It is proposed to increase the thickness of concrete in Type Q5 surrounding rock mass and fault extrusion section to improve the safety and stability in the construction of NJTBM tunnel. This measure also provided as reliable technical basis for the construction of the project.

Key words: Rheology, Soft Rock, Inversion, Supporting Strength Parameters, Optimization