Roller Compacted Concrete arch dam of Northwest Cold Area in China ― Longshou arch dam

摘要

The thin Longshou double curvature arch dam is located in Gansu Province in the northwest of China, which is featured by the extreme conditions of a typical mainland climate: extremely cold winter and extremely hot summer with an annual temperature range of 70℃, high aridness and heavy evaporation. The seismic intensity scale of this area is 8. The dam of the Longshou Hydropower Station is characterized by relatively great height, thin thickness, and complicated composition. The dam is consisted of three parts: a double curvature arch dam, a gravity dam and a thrust pier. In the thin double curvature arch dam there are three outlets at the middle height and two surface orifices for flood discharge and sand sluicing in combination with a scour bottom outlet. The dam is made from RCC. It is the only anti-seepage element and has to be resistant to freezing. In the mix design, a amount of magnesium oxide and expansion agent is added for higher cracking resistance. In the material study, different types of concrete for different purposes such as anti-freezing, anti-seepage or anti-abrasion were made utilizing the natural sand and stone of the local gobi desert. And concrete of different scales for the respective use of the arch dam, gravity dam and thrust pier was made accordingly. River water was used directly as the major and simple measure for temperature control of the dam body to reduce the cost. The Longshou Dam was completed within only 14 months in 2001. It is 80 m in height and is recorded as the highest, thinnest RCC arch dam with the shortest construction duration in the world.