金沙江下游白鹤滩水电站岩体结构的建造特征

拟建的白鹤滩水电站的坝基为峨眉山玄武岩。峨眉山玄武岩由火山熔岩类、火山碎屑熔岩类、火山碎屑岩类和沉积火山碎屑岩类所组成。火山熔岩又可划分为斜斑玄武岩、块状玄武岩和杏仁状玄武岩;火山碎屑岩包括集块岩、火山角砾岩以及凝灰岩;而沉积火山碎屑岩类则由沉火山角砾岩和沉凝灰岩所组成。不同类型岩石的结构构造、矿物成分和形成环境不同,导致它们的岩石力学性质和工程性能也不相同。块状玄武岩、斜斑玄武岩和沉积火山碎屑熔岩的抗压强度和抗风化能力都比较大,因而具有很好的工程地质稳定性;杏仁状玄武岩、火山碎屑熔岩的抗压强度稍低,但抗风化能力很好,因此也具有较好的工程地质稳定性;而火山碎屑岩包括火山角砾岩、凝灰岩的抗压强度和抗风化能力都很低,往往形成岩体中的软弱夹层,工程地质稳定性较差。

CHARACTERISTICS OF BASALT OF BAIHETAN HYDROPOWER PLANT, JINSHA-RIVER, SOUTHWEST CHINA

The basement of Baihetan Hydropower Plant is the Emei Mountain Basalt. It is discovered that the Emei Mountain Basalt is consisted of basalt lava (including massive basalt, porphyritic basalt, and amygdaloidal basalt), pyroclastic-lava, volcanic breccia, and tuff. The authors describe the petrological properties of the rocks and find out that all of these kinds of rocks formed in different conditions and are of different mineral composition, texture, and structure. As a result, they have different physical and engineering properties. The compressive strength and elastic modulus of massive basalt, porphyritic basalt, amygdaloidal basalt, and pyroclasfic-lava are 156.4MPa, 62.4GPa; 122.4MPa, 37.6GPa; 156.4MPa,62.4GPa; and 108.9MPa,30.0GPa respectively. In addition, weathered degree of the rocks is different. From basalt lava to tuff the weathered degree is reduced gradually. The basalt lava is very strong , but the tuff is weak and easily to weathered.