坪头水电站岩溶砂化细晶白云岩的特性及围岩分类

摘要

The hydrological and karstification conditions at the Pingtou Hydropower Station were investigated aiming to identify the classification of the fine-crystalline dolomite of the wall rocks at the end of the diversion tunnel and hydraulic structure chamber for geological basis of the geological engineering design. Furthermore, the mechanism of the sanded fine-crystalline dolomite due to the intense karstification and corrosion effect was obtained. Based on a large quantity of rocks sections experiments for identification and physical property, material composition, physical and mechanical properties of the wall rocks of different karst corrosion extent were fully surveyed. In accordance with the national standards, combined with experimental results and actual conditions in the excavation process of cave chambers, engineering geological classifications and categories of the wall rocks were determined byⅢ,ⅣandⅤ, which could serve as focused engineering measurements on the different categories, respectively, to maintain the stability and safe functioning of wall rock of the hydraulic structures.%为了能及时准确地对坪头水电站引水隧洞后段及厂址区内各水工建筑物洞室开挖揭示的围岩细晶白云岩进行围岩类别的确定，为工程设计提供科学合理的地质依据，在充分调查该区水文地质条件及岩溶发育特征和认识细晶白云岩岩溶砂化现象形成机制的基础上，通过大量的岩石磨片鉴定试验和物理力学性质试验，全面细致地查明了围岩细晶白云岩的物质组成及其在不同岩溶砂化情况下的物理力学特性。依据国家相关规程规范，结合各洞室实际开挖揭示情况和试验结果，对该区内岩体进行了围岩工程地质分类，总结出不同岩溶砂化细晶白云岩的围岩类别的特征及其综合评分情况，并对该区确定的Ⅲ类、Ⅳ类和Ⅴ类不同类别的围岩，有针对性地采取相应的工程处理措施，从而确保了各水工建筑物洞室的围岩稳定和安全运行。