基于极限平衡法和有限元法的边坡协同式可靠度分析

极限平衡法和有限元法是两种常用的边坡稳定分析方法。基于极限平衡法的边坡可靠度分析计算效率较高,但需要假定失效模式,从而导致计算结果不准;与之相反,基于有限元法的边坡可靠度分析更为严格,但计算效率较低。为此,提出了一种新的基于随机模拟的边坡可靠度分析方法——边坡协同式可靠度分析方法。该方法包括初步可靠度分析和精细可靠度分析两步,可以同时利用极限平衡法和有限元法的优势,实现既高效又准确的边坡可靠度分析。通过一个考虑空间变异性的两层土坡算例验证了该方法的有效性,结果表明:协同式可靠度分析方法与基于有限元法的蒙特卡洛模拟或子集模拟相比,不仅具有一致的可靠度分析结果,而且显著提高了小概率水平下的计算效率,促进了基于有限元法的边坡可靠度分析在实际工程中的应用。该方法可以将基于极限平衡法的边坡可靠度分析成果合理纳入到基于有限元法的边坡可靠度分析中,从而获得大量的失效样本,以制定合理的边坡防治措施。该方法非常适用于高维可靠度问题,如考虑空间变异性的边坡可靠度问题。

Auxiliary slope reliability analysis using limit equilibrium method and finite element method

The limit equilibrium method (LEM) and the finite element method (FEM) are two commonly-used slope stability analysis methods. The LEM-based slope reliability analysis is computationally efficient based on the prescribed slip surfaces, while the FEM-based one tends to give more realistic reliability estimates. A new simulation-based reliability method, namely auxiliary slope reliability analysis method, is developed, which includes two major steps (preliminary and target reliability analyses) and makes use of advantages of both LEM and FEM to achieve efficient and consistent slope reliability analysis. A two-layered slope example considering spatial variability is illustrated using the proposed method. The results indicate that the proposed method gives reliability estimates consistent with those obtained by the Monte Carlo simulation or subset simulation based on FEM, and it also significantly reduces the computational efforts at small probability levels. This enhances the application of FEM-based reliability analysis in slope engineering practice. The information generated in the LEM-based reliability analysis can be properly incorporated into the FEM-based reliability analysis, through which a large amount of failure samples can be obtained and used for making slope remedy measures. In addition, the proposed method is very practicable for high-dimensional reliability problems, such as slope reliability problem considering spatial variability.