考虑地层变异的边坡稳定不确定性分析

发布时间：2018-03-08 01:11

本文选题：耦合马尔可夫链(CMC)　切入点：地层变异　出处：《岩土力学》2017年05期 　论文类型：期刊论文

【摘要】：目前涉及岩土体不均匀性的岩土问题可靠度分析大多只考虑岩土体的固有变异,即岩土体特性参数的不均匀性,未考虑涉及不同岩土体材料的地层变异。地层变异在实际滑坡中广泛存在,其表现为不同类型岩土材料(如黏土、粉土、砂土)的互相嵌套,或一种类型岩土体在另一种较均质岩土体中的随机分布。为此,提出了利用钻孔资料评估考虑地层变异时边坡稳定不确定性的分析方法。根据已有钻孔资料设计了不同的钻孔布置方案,建立了表征地层变异的马尔可夫链模型,采用有限元强度折减法进行边坡稳定性分析,探讨了钻孔布置方案对评估边坡稳定安全系数和失效概率不确定性的影响。以澳大利亚珀斯市钻孔资料为例,分析了所提方法的有效性。结果表明,钻孔布置方案对边坡稳定安全系数和失效概率的不确定性评估有重要影响。考虑地层变异时,边坡稳定安全系数可以用Johnson分布来描述;边坡稳定安全系数统计量和失效概率不一定随钻孔数量增加而单调变化,边坡影响区域以内钻孔对评估边坡稳定安全系数的不确定性最为有效;当钻孔数目逐渐增加时,边坡安全系数均值逐渐收敛至精确值。
[Abstract]:At present, the reliability analysis of rock and soil problems involving the heterogeneity of rock and soil only considers the inherent variation of rock and soil, that is, the heterogeneity of characteristic parameters of rock and soil. Stratigraphic variation involving different rock and soil materials is not taken into account. Stratigraphic variation exists widely in actual landslides, which is manifested by the nesting of different types of rock and soil materials (such as clay, silt, sand). Or the random distribution of one type of rock and soil in another more homogeneous soil mass. This paper presents an analytical method for evaluating slope stability uncertainty when formation variation is considered by using borehole data. According to existing borehole data, different drilling arrangement schemes are designed, and Markov chain model is established to characterize formation variation. Finite element strength reduction method is used to analyze slope stability, and the influence of drilling arrangement on the uncertainty of slope stability safety factor and failure probability is discussed. The drilling data in Perth, Australia, are taken as an example. The effectiveness of the proposed method is analyzed. The results show that the borehole layout scheme has an important effect on the uncertainty assessment of the slope stability safety factor and failure probability. Considering the formation variation, the slope stability safety factor can be described by Johnson distribution. The statistics of slope stability safety factor and failure probability do not necessarily change monotonously with the increase of the number of boreholes, the boreholes in the affected area of slope are the most effective in evaluating the uncertainty of slope stability safety factor, and when the number of boreholes increases gradually, The mean value of slope safety factor gradually converges to the exact value.
【作者单位】：武汉大学水资源与水电工程科学国家重点实验室;武汉大学水工岩石力学教育部重点实验室;
【基金】：国家杰出青年科学基金项目(No.51225903) 国家自然科学基金项目(No.51329901,No.51528901,No.51579190)~~
【分类号】：TU43

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