Da Chao Shan hydroelectric scheme.

The adoption of wet-sprayed shotcrete technology and alternative engineering solutions has allowed significant savings of time in the tight construction schedule for the huge underground hydroelectric powerhouse complex, in a remote area of China's Yunnan province. The three main structures are the powerhouse, 26.4 m wide and 67 m high, the transformer chamber, 16.2 m long and 17.9 m high, and the surge chamber, 22 m long and 73.6 m high. They are being excavated in a series of benches in basalt which is generally of good condition but features areas of fractured rock, jointing and faults. Primary support is by wet-sprayed shotcrete combined with extensive rock bolting and prestressed anchors. The concrete is treated with additives to promote high bonding strength between layers, high strength and durability. A secondary concrete lining will be cast in place in the main powerhouse areas, but the wide span of the powerhouse roof arch is supported by steel rib beams over a 45 m section in poor rock.
The adoption of wet-sprayed shotcrete technology and alternative engineering solutions has allowed significant savings of time in the tight construction schedule for the huge underground hydroelectric powerhouse complex, in a remote area of China's Yunnan province. The three main structures are the powerhouse, 26.4 m wide and 67 m high, the transformer chamber, 16.2 m long and 17.9 m high, and the surge chamber, 22 m long and 73.6 m high. They are being excavated in a series of benches in basalt which is generally of good condition but features areas of fractured rock, jointing and faults. Primary support is by wet-sprayed shotcrete combined with extensive rock bolting and prestressed anchors. The concrete is treated with additives to promote high bonding strength between layers, high strength and durability. A secondary concrete lining will be cast in place in the main powerhouse areas, but the wide span of the powerhouse roof arch is supported by steel rib beams over a 45 m section in poor rock.