锦屏一级水电站左岸坝肩边坡施工期高效三维可靠度分析

 基于可靠度理论的边坡稳定性分析是一个重要的发展趋势，然而目前国内外关于复杂三维高边坡可靠度方面的研究几乎还是空白。以锦屏一级水电站左岸坝肩边坡为例，研究了施工阶段三维边坡可靠度问题。由于三维边坡稳定性分析有限差分强度折减法计算量较大，并且安全系数没有显式表达式，通过参数敏感性分析减少随机变量数目，提出三维边坡可靠度分析的非侵入式随机有限差分法。探讨了预应力锚索和深层混凝土抗剪洞2种主要加固措施失效对边坡变形、稳定及其可靠度的影响规律。研究了施工阶段边坡横河向位移、安全系数以及失效概率的变化规律。结果表明：参数敏感性分析可以有效地识别敏感性较大的随机变量，从而提高边坡可靠度计算效率。非侵入式随机有限差分法实现了概率分析与通用商业软件如FLAC3D的有机结合，极大地简化了可靠度分析过程，而且能充分利用参数敏感性分析中边坡稳定性计算结果，为解决三维高边坡可靠度问题提供一种有效的工具。此外，锦屏一级水电站左岸坝肩边坡所采取的预应力锚索和深层混凝土抗剪洞联合加固措施能够有效地控制边坡变形和确保边坡稳定性。施工阶段边坡开挖扰动作用对边坡稳定可靠度有着重要的影响。

EFFICIENT THREE-DIMENSIONAL RELIABILITY ANALYSIS OF AN ABUTMENT SLOPE AT THE LEFT BANK OF JINPING I HYDROPOWER STATION DURING CONSTRUCTION

Reliability-based slope stability analysis has great prospect in design but few attempts have been made to study the reliability of rock slopes in three dimensions. In order to evaluate the reliability of 3D rock slopes during the construction period，an abutment slope at the left bank of Jinping I hydropower station was taken as an example. The computational costs for stability analysis of 3D rock slopes are high and the factor of safety can not be explicitly expressed as functions of input parameters when the finite difference based shear strength reduction method is incorporated in slope stability analysis. In this paper，a parametric sensitivity analysis was carried out to reduce the number of random variables and the non-intrusive stochastic finite difference method was proposed for reliability analysis of the 3D rock slope. The effects of the failure of two main reinforcement measures，including the pre-stressed cables and the shear-resistant concrete plugs，on the deformation，stability and reliability of the slope were investigated. The variation of the displacement perpendicular to river flow，the factor of safety and the reliability of the slope during the construction period were also studied. The proposed approach of parametric sensitivity analysis identifies effectively the rank of the sensitivities of different random parameters，which lead to greatly improved efficiency of calculation. The non-intrusive stochastic finite difference method provided an effective way for analyzing the reliability of the practical 3D rock slopes，where a decoupled data interface between a probabilistic analysis module and the software FLAC3D is implemented and the results of the slope stability analysis in the parametric sensitivity analysis are further used in the slope reliability analysis. The jointed measure of stabilization with the pre-stressed cables and the shear-resistant concrete plugs in the left abutment slope at Jinping I is found to be able to effectively control the slope deformation and ensure the slope stability. The disturbances induced by the slope excavation during the construction period are found to have a significant influence on the slope reliability.