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现有边坡可靠度分析大多数只考虑土体参数的固有变异性,而忽略了地层变异性的影响。为此,提出了同时考虑地层变异性和土体参数固有变异性的边坡可靠度分析方法,利用耦合马尔可夫链模拟地层分布,采用基于乔列斯基分解的中点法离散土体参数随机场,采用有限元强度折减法计算边坡安全系数,通过蒙特卡洛法模拟进行边坡可靠度分析。利用澳大利亚珀斯市钻孔资料,以边坡可靠度问题为例阐明了同时考虑地层变异性和土体参数固有变异性的重要性,研究了钻孔布置方案对边坡可靠度的影响规律,结果表明:提出的方法能够有效地反映地层变异性和土体参数固有变异性对边坡可靠度的影响。当钻孔数目较少时,模拟的边坡土体类型分布与真实边坡土体类型分布相差较大,此时忽略地层变异性将导致边坡可靠度不精确的估计结果。钻孔布置方案对边坡失效概率和安全系数有明显的影响,钻孔应尽可能多的布置在边坡关键影响区域。边坡失效概率和安全系数统计量与钻孔数目并不呈单调关系,但是随着钻孔数目的增加,边坡失效概率和安全系数统计量逐渐收敛至“精确解”。
Most of the existing slope reliability analysis only consider the inherent variability of soil parameters, while ignoring the influence of formation variability. Therefore, a slope reliability analysis method considering both the formation variability and the inherent variability of soil parameters is proposed. The coupled Markov chain is used to simulate the formation distribution and the mid-point method based on Cholesky decomposition is used to discretize the soil parameters In the random field, the slope safety factor is calculated by finite element strength reduction method, and the slope reliability is analyzed by Monte-Carlo simulation. Based on the borehole data of Perth, Australia, the importance of considering the variation of formation properties and inherent variability of soil parameters is illustrated by taking the slope reliability problem as an example. The influence of drilling layout on slope reliability is studied. The results show that the proposed method can effectively reflect the influence of formation variability and inherent variability of soil parameters on slope reliability. When the number of boreholes is small, the simulated slope soil type distribution is quite different from the actual slope soil type distribution. Ignoring the formation variability will lead to the inaccurate estimation of slope reliability. The layout of borehole has a significant impact on the failure probability and safety factor of the slope, and drilling should be arranged in the key influence area of the slope as much as possible. The slope failure probability and safety factor statistic are not in a monotonic relationship with the number of boreholes. However, as the number of boreholes increases, the slope failure probability and safety factor statistic gradually converge to “exact solution ”.