Preliminary determination and inversion of rock mass parameters of underground cavern of Kaluma hydropower station

Abstract

The dam site of Kaluma Hydropower Station is located on the Nile River in northern Uganda. It is a diversion power station with a total installed capacity of 600MW. The surrounding rock deformation and block instability in the plant area of the hydropower station are the key factors affecting the stability of the underground cavern. Determining the mechanical parameters of rock mass is the primary task of the cavern stability evaluation and calculation. Based on the actual geological conditions revealed by the Kaluma Hydropower Station on-site, and on the basis of mastering the deformation and stress of the surrounding rock of the underground cavern group and the stress characteristics of the supporting structure, this paper systematically analyzes the on-site monitoring data, adopts the appropriate feedback analysis method to modify the three-dimensional numerical calculation model, simulates the complex geological conditions on site, and carries out the inverse analysis of the relevant parameters of rock mechanics and in-situ stress. The results show that the calculated response characteristics of surrounding rock excavation of underground powerhouse caverns are consistent with the displacement and stability characteristics of surrounding rock revealed by the monitoring data. The rock mass parameters obtained by inversion are also close to the empirical estimation results, indicating that the empirical prediction is consistent with the actual excavation exposure.