考虑地层变异性和土体参数空间变异性的边坡可靠度全概率设计方法

目前边坡稳定设计研究中大多数考虑了土体参数的空间变异性,但忽略了地层变异性的影响。为此,提出了一种同时考虑这两类变异性的边坡可靠度全概率设计方法。在全概率设计框架内,将广义耦合马尔可夫链模型与随机场模型相耦合用于同时表征地层变异性和土体参数空间变异性,给出了所提方法的计算流程。利用澳大利亚珀斯市钻孔资料,以某边坡为例进行可靠度设计,为说明在边坡可靠度设计中同时考虑地层变异性和土体参数空间变异性的重要性,分析了仅考虑土体参数空间变异的情况,进一步分析了同时考虑两类变异性的情况,并对二者进行了比较。结果表明:所提出的边坡可靠度设计方法能够有效地考虑边坡中存在的地层变异性和土体参数空间变异性。当仅考虑土体参数空间变异性时,边坡可靠度设计结果很大程度上取决于所采用地层的分布情况,特别是地层分布中抗剪强度较强土体类型占比高于真实情况时,将导致得到的最优设计方案偏于危险。反之,若地层分布中抗剪强度较弱的土体类型占比高于真实情况,得到的最优设计方案偏于保守。因此,为准确地得到最优设计方案,在边坡可靠度设计中应同时考虑地层变异性和土体参数空间变异性的影响。

Full probabilistic design method for slopes considering geological uncertainty and spatial variability of soil parameters

The geological uncertainty is often ignored in slope reliability-based design, even though the spatial variability of soil parameters is considered. A full probabilistic design method is proposed for the slopes considering the geological uncertainty and spatial variability of soil parameters. In the full probabilistic design framework, a generalized coupled Markov chain model is combined with a random field model to simultaneously characterize the geological uncertainty and spatial variability of soil parameters. The procedure for this method is presented. A slope is taken as an example for the reliability-based design using the borehole data in Perth, Australia. In order to illustrate the importance of considering the geological uncertainty and spatial variability of soil parameters in the slope reliability-based design, the reliability design results associated with two cases, i. e. only considering the spatial variability of soil parameters and considering both types of uncertainties, are compared. The results indicate that the proposed method can effectively conduct the slope reliability-based design considering these two types of uncertainties. If only the spatial variability of soil parameters is considered, the reliability design results mainly depend on the used geological profiles. If the geotechnical practitioners infer a geological profile with a higher proportion of strong soil materials than the reality, the resulting optimal design scheme will lead to dangerous slope. In the opposite case, the resulting