Abstract: In order to evaluate the in-situ stress field and surrounding rock stability of Kariba Hydropower Plant’s underground powerhouse, we employed multi-factor regression analysis method based on three-dimensional finite element simulation in the regression fitting of measured data so as to obtain the distribution of stress field. The calculated values could well fit the measured values, so the regression results were good. According to regression results, the stress field of underground powerhouse was mainly influenced by horizontal structural stress field and in low stress level due to the effect of topography and geomorphology, formation lithology and fault structure. The direction of maximum horizontal principal stress approximately paralleled to the long axis of the powerhouse, beneficial to the stability of surrounding rock.

Key words: underground powerhouse, stress field, regression analysis, finite element, stability of surrounding rock