Excavation and Construction of Extra Large Caverns at Longtoushi Hydropower Station

At Longtoushi hydropower station,diversion tunnel and spillway tunnel are extra large caverns with difficult geological conditions.Because short construction period,severe interferences in different construction positions and with different construction procedures,proper construction organization on site is critical factor to achieve successful work.The tunnels are excavated from upper half to lower half cavern.The upper half cavern is excavated from left half to right half cavern.Excavation and construction technology of extra large caverns at Longtoushi hydropower station are summarized and expected to provide references to future similar projects.