土坡体系可靠度分析方法及在高土石坝工程中的应用

Method of reliability analysis of stability for soil slope and its application in high soil and rockfill dams

针对土坡稳定体系可靠度分析问题,提出了一种分析方法框架,包括采用缩减方差抽样技术生成随机变量样本值、采用全局优化算法搜索边坡最小安全系数、采用Monte-Carlo法计算边坡体系可靠度3个主要部分。在此框架下,建立了一种较为简便实用的高土石坝坝坡稳定体系可靠度分析方法。该方法采用拉丁超立方抽样技术生成随机变量的样本值,再用商业软件STAB搜索相应的坝坡最小安全系数,最后用可靠指标法或Monte-Carlo法计算坝坡体系可靠度。工程算例表明,筑坝材料强度参数的随机不确定性对坝坡临界滑弧的位置影响较大,坝坡稳定体系可靠度小于单一滑动面的坝坡稳定最小可靠度,提出的方法可用于实际工程坝坡稳定体系可靠度分析。

To address the reliability analysis problems of earth slopes system, a framework was developed consisting of three major components： generation of random sample by variance-reduction techniques, minimization of slope safety factors by global optimization algorithms, and determination of system reliability of slope by Monte-Carlo method. A relatively simple method for system reliability analysis of slope stability of high earth and rockfill dams was established within the proposed framework. The sample values for input random variables were produced using the Latin hypercube sampling technique. The minimum safety factors for slip surfaces were gained using the commercial slope stability analysis software STAB. Finally, the system reliability of dam slope was calculated by reliability-index method or Monte-Carlo method. The engineering example demonstrates that variability in shear strength parameters of dam construction materials has significant effect on the location of critical slip surfaces. The system reliability of slope is less than the minimum slope reliability of single slip surface. The proposed approach can be applied to system reliability analysis of actual dam slopes.