左岸深部裂缝的地质特征及成因分析

Geological features and genesis analysis of deep fissures at left bank of Jinping I Hydropower Station

锦屏一级水电站普斯罗沟坝址左岸发育的深部裂缝,由于其分布深度大,张开破裂形态多样,且超出过去工程经验认识范围。因此,自勘探揭示以来其成因问题一直受到高度重视。在对其空间分布规律、地质特征进行了充分揭示的基础上,对其成因从地震地质、河谷演化、构造学、数值模拟等多方面开展了多次专题研究。认为普斯罗沟坝址左岸深部裂缝是在特定的高边坡地形、地质构造、高地应力环境和岩性组合条件下,伴随河谷的快速下切过程,边坡高应力发生强烈释放、分异、重分布,在原有构造结构面基础上卸荷张裂形成一套边坡深卸荷裂隙体系。

The deep fissures develop at left bank of the Pusiluogou dam site of Jinping I Hydropower Station.They have been the focus since the beginning of the geological survey due to their deep distribution and various fracturing shapes,which are not encountered in previous engineering practices.By using the methods of seismic geology,valley evolution analysis,tectonic and numerical simulation,the genesis of the deep fissures have been studied on the basis of full investigation about their spatial distribution rules and geological features.The results show that the deep fissures at left bank are a serious of deep unloading ones,which are formed on the basis of original tectonic structure planes,accompanied with the process of valley incising quickly,intensive stress release and stress redistribution of high slope at the dam site.The above formation process is under a multiplex condition combining the factors such as high slope terrain,geological structure,high ground stress environment and lithology.