Uncertainty Analysis and Risk Management of Underground Cavern Group at Jinping II Hydropower Station

The epistemic uncertainty and aleatory uncertainty caused by the geology condition and construction method make the surrounding rock stability evaluation of underground cavern group difficult. The first may be reduced with more field investigation, tests or monitoring, but the later can not be avoided completely. So the risk analysis method can be used to evaluate the cavern group stability. In this paper, based on the large hydropower underground cavern group database, the risk management stages were divided into two main stages: initial risk management and dynamic and final risk management. For the first stage, the assessment and mitigation methods of overall risk and local risk before the construction of hydropower underground cavern group were suggested. And the dynamic risk was assessed with the fuzzy mathematical method and mitigated during the construction of each layer of cavern according to the revealed geological conditions and actual behaviors of surrounding rock after excavated. Finally, one layer of Jingping II Hydropower Station was analyzed with the proposed method.