Daganshan hydroelectric power station is situated in the middle reaches of the Dadu River in Shimian county of west part of Sichuan Province. The maximum dam height is 210 meters and the general installed capacity is 2400 MW. The dam site is located in complex geological structural and seism geological environments, having fairly intensive geotechnical movements. The seism intensity is Richter VII. The rockmass surrounding the project area consists mainly of granite, however, several diabase dikes are exposed in the underground power house area, thrusting into the granite and several large faults penetrate through the power house area. The project has a large underground power house complex, including transformer house and tailrace surge chamber etc. The major house measures 72 m high and 27 m wide.