楞古水电站碎裂岩质边坡变形破坏模式研究

DEFORMATION FAILURE MODE OF FRACTURED ROCK MASS SLOPE IN LENGGU HYDROPOWER STATION

碎裂结构岩质边坡是地质工程中遇到的一种最不稳定边坡,其原岩松弛,结构面普遍张开,围岩自稳能力差,碎裂结构岩体出露不连续,空间分布存在差异,导致边坡破坏边界不明显,变形破坏机制很难确定。本文以雅砻江楞古水电站碎裂结构岩质边坡为例,在地质环境调查和平硐勘测的基础上,系统研究了碎裂岩体结构特征,分析了控制边坡变形破坏的边界条件和变形破坏模式,并运用UDEC离散元程序模拟验证。研究结果表明:碎裂岩质边坡的变形破坏主要受自身结构及内部相对长大结构面控制,变形演化过程依循应力调整、时效变形和局部失稳3个阶段,变形破坏模式分为断层主控底滑型和裂隙切割破坏型。目前针对碎裂结构岩质边坡研究相对较少,缺乏大型工程实例支撑,该研究成果为水利工程中这类边坡的研究提供了参考。

Fractured rock mass slope is one of the most unstable slopes in geological engineering. It has flabby original rock structures,generally open structural planes and poor stability surrounding rocks. The fractured rock mass is exposed discontinuity and the spatial distribution is different. These characteristics lead to the boundary of slope failure is not obvious. It causes deformation and failure mechanism difficult to be determined. As an example of the fractured rock slope of the Lenggu Hydropower Station in the Yalong River,based on geological environment investigation and survey of adit,this paper systematically studies the fractured rock mass structure characteristics,analyzes the boundary conditions which controls the slope deformation and failure,and summarizes the slope deformation and failure modes. Moreover,the UDEC discrete element simulation is used to verify the modes. The results show that the deformation and failure of the rock slope is mainly controlled by rock slope structures andinternal relative large structures. The deformation evolution process is divided into three stages: stress adjustment,aging deformation and local instability. The deformation failure modes include fault controlled bottom slip mode and fracture cutting failure mode. At present,there are few relatively studies on the fractured rock slope,lack of largescale engineering case support. The research results provide reference for the study of this kind of slope in water conservancy project.