Abstract:

Guanyinyan hydropower station on the Jinsha River is a double fold mixed dam. Its concrete gravity dam foundation is located in the red beds of central Yunnan Province and mainly contains conglomerate and sandstone of J₂s stratum, in which dissolution affects the stability of foundation rock mass. According to the distribution of red beds in China, we analysed the deposition and distribution features of red beds in Yunnan and systematically researched the features of karst in red beds of clastic rock as well as some small caves, dissolution holes and cracks. We also conducted tests on the physical and mechanical properties of karstic rock mass in red beds. The results show that the distribution characteristics and mechanical parameters of karstic rock mass could reach the quality of Ⅲa, Ⅲb classes, and meet the dam foundation requirement when appropriately treated. The research achievements provide basis for selecting dam foundation and treating geological defects of karstic rock mass.

Key words: red beds in central Yunnan, solution, physical and mechanical properties of foundation, Guanyinyan hydropower station