一、工程概况白山水电站地下式厂房有三条尾水洞,其出口高程为279米,而江面平水期水位为290～292米。1976年施工初期,为了形成工作面,在尾水洞的出口浇筑了长300余米的混凝土纵向围堰(共19个分块),作为施工挡水设施。围堰内用四道混凝土支撑墙加固。之后,在围堰内开挖了斜坡道,完成了三条尾水洞的开挖 First, the project profile Baishan Hydropower Station underground plant has three tail water hole, the exit elevation of 279 meters, while the river level water level of 290 to 292 meters. In 1976, in the early stage of construction, in order to form a working face, a concrete longitudinal cofferdam (totaling 19 blocks) with a length of 300 meters was poured at the outlet of Tailrace Cave as a water retaining facility for construction. Cofferdam reinforced with four concrete walls. Afterwards, ramps were excavated in the cofferdam to complete excavation of three tailrace tunnels