金川水电站坝区主要断裂断层泥中石英碎砾表面SEM特征及断裂活动性

SEM characteristics of quartz grains in fault clay and fault activity in Jinchuan hydroelectric power station dam area

断层泥中石英碎砾表面形貌在水溶液的作用下会不断地发生变化,显然这种变化与溶蚀作用时间的长短及物化条件有关。因此,断层泥中石英碎砾表面显微溶蚀结构就反映了断层形成后至今所经历时间的相对长短。而断层活动时期是坝区活动性评价重要指标。在大型的地质工程中,查明断层的活动性对于工程稳定性评价尤为重要。对大渡河金川水电站坝区的断层泥中石英碎砾SEM结构特征研究分析表明,该区断层最新活动时期主要集中在新近纪末期,中-晚更新世有过微弱活动,晚更新世以来已无活动性。因此,该区未来地震地质灾害频度相对较低,比较适合大型工程的建设。

The surface texture of quartz grain fault clay varies gradually under the effect of water solution. It is obvious that this variation is related to the dissolving time and physical and chemical conditions. Therefore, the surface texture of quartz grain can reflect the forming time of the fault. The epoch of fault activity is the most important index for the activity in the dam region. It is very important to find out the fault activity for evaluating the stability of a large geology project. The study on SEM characteristics of quartz grains in the fault clay shows that the newest fault activity in Jinchuan hydroelectric power station dam area, Dadu River mainly occurred in Late Neogene, reduced in Middle and Lower Pleistocene, disappeared in Lower Pleistocene. Therefore, these areas are low in seismogeological disaster frequency and suitable for the construction of a large project.