重力坝两种滑移失稳机理及安全度评价方法

结构面对坝体抗滑稳定极为不利，尤其是当坝基存在多组结构面，其深度、范围、厚度等因素均对坝体稳定具有较大影响。本文针对工程实际中两种常见的滑移模式，即缓倾角结构面产状平缓的水平滑移模式和结构面倾角较大的倾斜滑移模式，采用弹塑性有限元强度储备系数法模拟重力坝渐进破坏过程，应用各向异性节理材料模拟坝基中的岩层、泥化夹层、断层等地质缺陷，探讨了重力坝深层滑动的失稳机理、破坏模式及极限承载力。两个典型工程实例的研究分析表明，两种滑移模式的重力坝失稳机理均表现为首先沿结构面滑动，直至尾岩抗力体压碎或者隆起失效时坝体达到其极限承载力。最后根据重力坝深层滑动失稳机理及其破坏模式，建议了与其配套的安全度评价方法。

Mechanism of two sliding failure modes in gravity dam and method for safety evaluation

The structural plane is disadvantage to the sliding resistance of dams. Its depth, thickness, range may greatly affect the stability of dam. In this paper, two types of sliding mode, including the horizontal sliding due to structural plane with gentle dip angle and incline sliding owing to the structural plane with larger dip angle, are investigated. The strength reserve coefficient method based on elastoplasticity FEM is used to simulate the progressive collapse process of dams and the anisotrpie material is used to simulate the geological faults. On this basis, the mechanism of sliding failure, collapse mode and ultimate bearing capacity are investigated. The analysis of two typical gravity dams show that both mechanisms of buckling collapse are the same. At first the sliding occurs along the structural plane and then the dam reaches the ultimate capacity as the tail rock crushed. According to the analysis results, the method for evaluating safety of dams is proposed.