The huge Three Gorges Project is technically complex. Quite a lot of technical breakthroughs have been made on the issues such as river closure of the Grand Channel and concrete construction of the cutoff wall, prompt concrete construction of dam, high slope construction of permanent shiplock, large-scale steel-lined reinforced concrete penstocks of power station and temperature and pressure maintaining of the spiral case, asphalt concrete core wall, metal works of the shiplock, turbine generating units, and so on.