Main and auxiliary power houses and installation rooms, bus tunnel, main transformer switch room, outgoing shaft, ventilation system, drainage system, access tunnel and exploratory tunnel backfill, fault treatment backfill, construction adit backfill, over excavation backfill caused by unforeseen geological reasons, etc. The main and auxiliary power houses are 311.75m long, the maximum excavation width is 30m, and the maximum height is 74.84m; Length of main transformer switch room 23