滇中红层坝基溶蚀岩体及物理力学特性研究

Karstic Rock Mass of Dam Foundation and Its Physical and Mechanical Properties in the Red Beds of Central Yunnan Province

金沙江观音岩水电站双折混合坝中混凝土重力坝部分坝基位于中生代侏罗系中统蛇店组J2s砾岩、砂岩为主的滇中红层地层上,而岩石胶结物溶蚀现象不利于坝基岩体稳定。为此,在我国红层分布特点基础上,分析了滇中红层沉积、分布特征,系统地研究了红层坝基碎屑岩因胶结物溶蚀而出现的喀斯特现象以及岩体出现小的溶洞、溶孔、溶蚀裂隙及岩体解体、砂化、结构变坏等特征,并进行了红层坝基溶蚀岩体物理力学性质试验研究。结果表明:溶蚀岩体分布特征及其岩体质量力学参数指标达到Ⅲa和Ⅲb类岩体质量要求,坝基适当处理可满足建基面要求。研究成果为坝基建基面确定、溶蚀岩体地质缺陷处理提供了依据。

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 Ⅲ a,Ⅲ b 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.