2D and 3D continuum static and dynamic modeling of a large span powerhouse cavern in Italy

Following geological and geomechanical investigations with laboratory and in-situ tests, as well as the selection of the seismic input based on past earthquake records, stability analyses of the Venaus powerhouse cavern in Italy have been performed with both static and dynamic modeling studies. 2D and 3D design analyses have been carried out in static conditions by accounting for the excavation-construction sequence, including the simulation of the reinforcement system installed. Close attention has been given to the analysis of the disturbed zone around the cavern as well as to the reinforcement system used to insure the cavern stability. Performance monitoring data of crown displacements have been taken into account for appropriate validation of the analyses performed. Performance analyses have also been carried out under seismic conditions and for selected design ground motions. The dynamic response of the surrounding rock mass and of the reinforcement system has been investigated. The results obtained are of interest in relation to future stability analyses to be performed for large underground caverns constructed in the past, based on seismic design analyses and input data derived from updated post earthquake records recently made available in Italy.