中文摘要：

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。

英文摘要：

Most reliability analyses of geotechnical structures considering soil heterogeneity mainly focus on inherent variability, namely the heterogeneity in soil parameters. Another type of soil heterogeneity, i.e. geological uncertainty, is not well studied. The geological uncertainty is very common in reality. It appears in the form of one soil layer embedded in another or the inclusion of pockets of different soil types within a more uniform soil mass. Hence, a borehole-based method is proposed to evaluate the uncertainty in probability of failure（Pf） and statistics of factor of safety（FS） for a slope when geological uncertainty is considered. Firstly, different borehole layout schemes are designed using available borehole data. A coupled Markov chain model is constructed to simulate the geological uncertainty. Secondly, slope stability analyses are conducted using a finite element – strength reduction method. Finally, the effect of borehole layout scheme on the uncertainty in FS and Pf of a slope is analyzed. The borehole data in Perth, Australia are adopted to illustrate the effectiveness of the proposed method. The results show that the borehole layout scheme has a significant influence on the uncertainty of FS and Pf of the slope. The FS of the slope in the presence of the geological uncertainty can be described by a Johnson distribution. The Pf and statistics of FS do not necessarily vary with the number of boreholes monotonously. The boreholes within the influence zone of slope are the most effective in evaluating the uncertainty in the FS. The mean of the FS converges to an accurate value as the borehole number increases.