Abstract: The left bank excavation slope of Jinping first stage hydropower station is remarkable of its height, scale and bad stability condition. The tension-displaced rock mass is comprised of several structural tectonic structural planes and is critical to the stability of the whole excavation slope. The safety monitoring for the tension-displaced rock mass is introduced. Overall analysis on the time evolution and spatial distribution of the tension-displaced rock mass is conducted by using correlation, factors analysis, and eigenvalues statistics according to geological conditions and construction information. The monitoring data of surface, shallow and deep deformation suggest that the tension-displaced mass is consistent with the overall slope deformation characteristics after excavation and support, and after six years of tests, it has gradually stabilized.

Key words: tension-displaced rock mass, monitoring during construction, influence factors, comparative analysis, deformation features