Failure Behaviors and Rock Deformation During Excavation of Underground Cavern Group for Jinping I Hydropower Station

Numerical simulation and field monitoring are conducted in this study to investigate rock deformation and failure behaviors during excavation of underground cavern group under high in situ stresses in Jinping I Hydropower Station. According to the numerical simulation, large deformation and damage in the surrounding rock mass result in anchorage cable overlimit. The traditional elastoplastic model only considers plastic yielding in rock mass and does not consider the evolution of damage in rock mass, i.e., initiation, propagation and coalescence of cracks. It is found from the numerical results that the damage behaviors of rock masses subjected to high in situ stresses are characterized by the formation of multi-fractured zones, i.e., the zonal disintegration. Theoretical basis, general rules and reinforcement method for zonal disintegration of the surrounding rock masses under high in situ stresses are proposed. The proposed methods are applied to strengthen support measures for construction of Jinping I Hydropower Station.