三峡大坝深层抗滑稳定研究

三峡左岸厂房1～5号机组坝段存在高陡边坡沿缓（中）倾角结构面的深层滑动稳定问题，对坝基和高陡边坡稳定十分不利。根据实测的长大缓倾角结构面的分布，概化出各坝段的确定性滑移模式，并提出了两种假定的、极端的滑移模型。从工程结构措施、稳定分析方法以及监测资料分析等几个方面，探究了工程稳定性问题，校核和验证了大坝的稳定安全。分析方法主要采用刚体极限平衡法，同时辅以有限元数值分析与地质力学模型试验。左厂1～5号坝段按刚体极限平衡法求得的K′c值满足稳定安全的判据的要求，用其它分析方法：有限元法分析的K′c在3.0～4.5以上，地质力学模型试验，超载系数为3.5～4.2，表明左厂1～5号坝段在采取了各种工程结构措施后大坝及其岩基的抗滑稳定已有保证。

Stability against sliding in intake dam section of Yangtze River Three Gorges Project

Lots of long and large fissures with slight slope and few with medium slope towards the downstream in the bedrock of the foundation of No.1-5 dam units of the left powerhouse of the Yangtze Three Gorges Project constitute the problems of the deep layer slide and stability by the joints of the high slope. The modes of sliding of various monoliths are generalized based on the distribution of the measured long and large gentle inclination structural faces. In addition, two kinds of hypothetical and extreme sliding models were proposed. This paper researches the slide and stability of the No.1-5 units dam from the aspects of engineering structural measures, analysis of deep stability against sliding, analysis for observed data. The rigid limit equilibrium is used for analysis of deep stability against sliding in the No.1-5 monoliths of the left intake dam section, which is accompanied by FEM numerical analyses and geo-mechanical model tests. The results above show that the Kc′ values derived from the rigid limit equilibrium of the No.1-5 monoliths of the left bank intake dam section meet the requirements for stability safety. The values by other analysis methods are: 3.0－4.5 or above for FEM analysis, 3.5－4.2 for geo-mechanical model test. The stability analysis of the sliding modes dominated by rigid limit equilibrium and supplemented by various other analysis methods indicates that after engineering structural measures taken for the No.1-5 monoliths of the left bank intake dam section, guarantee has been provided for the stability against sliding of the dam and its foundation rocks. Analysis of observations shows that for the foundations of No.1-5 monoliths of the left bank intake dam section, horizontal deformation is little; vertical deformation is undersized; asymmetric settlement does not appear. The dam foundation is stable.