某水电站左坝肩上方堆积体成因机制分析及稳定性评价

Analysis on formation mechanism and stability of deposits slope located above left dam abutment

针对国内西南水电工程建设中经常遇到的堆积体边坡问题,结合现场调查在地表看到的地质现象,以及钻孔岩芯资料,在分析区域地质环境、降雨等条件的基础上,对堆积体边坡的稳定性进行了宏观定性评价。在地质分析的基础上,指出该堆积体具有多期次复合成因的特征,是怒江峡谷岸坡演化的典型模式之一,并进一步提出了该堆积体成因机制的内外动力耦合作用模式。由于该堆积体边坡特殊的空间结构特征和其处于重要工程部位的特点,采用有限差分强度折减法对边坡在天然状态、暴雨、地震等工况下的稳定性进行了分析评价,为工程建设的顺利进行和暴雨等工况下可能的局部加固处理提供合理的依据,并为流域内类似成因和结构的堆积体边坡稳定性评价提供参考。

The problem of deposits slope is often encountered in constructions of hydropower projects in Southwest China.The study combines geology phenomena and drill core data,based on areal geology survey,rainfall data,and so on.The thought of engineering geology qualitative analysis is applied to study on the slope stability.On the basis of geological analysis,the deposits body has the feature of multi-stages and composite formation mechanism,and it is one of typical evolution models of the bank slope of Nujiang Great Canyon.The coupling effect mechanism of endogenic and exogenic geological processes of the deposits body is proposed.Aiming at spatial structure features and special location of deposits slope,the finite-difference and strength-reduction method is adopted to compute its stability factors under natural,rainstorm,seismic conditions.The above discussions offer reasonable evidence to constructions of the project and partial reinforcements of the slope and provide reference for stability analysis of similar deposits slopes in the river basins.