Abstract: Safety monitoring is an important technical approach of safeguarding the stability of surrounding rockmass in large underground powerhouse during construction and operation, and can also be adopted in feedback design and construction guidance. Based on safety monitoring data of Bailianhe underground powerhouse during construction and operation, the authors analyzed the variation and the regularity of mutual impact of rock deformation, anchor bar stress, anchor force, steel-bar stress in the surrounding rockmass and evaluated its stability. Results showed that the maximum surface deformation of the underground powerhouse reached 15.79mm, the maximum anchor bar stress 150.5MPa, the maximum steel-bar tensile stress 63.76MPa and the maximum steel-bar compressive stress 75.56MPa. All of them were stabilized. It's concluded that the surrounding rockmass has tended to be stable in the subsequence of rapid deformation and creep deformation caused by construction.

Key words: underground powerhouse,  , surrounding rockmass,  , deformation,  , stability,  , Bailianhe pumped storage power station