多层地基土坡的随机有限元模型不同参数比较分析(英文)  

Comparative study on different parameters of random finite element models for an embankment supported by multilayered foundations

作　　者：李亚军[1,2] 刘斯宏[1] 傅中志[3] 李卓[3] 

机构地区：[1]河海大学水利水电学院,江苏南京210098 [2]代尔夫特理工大学 [3]南京水利科学研究院,江苏南京210024

出　　处：《岩土工程学报》2014年第1期162-169,共8页Chinese Journal of Geotechnical Engineering

基　　金：The National Natural Science Foundation of China(51209141)

摘　　要：对JamesBay堤坝进行了基于随机有限元方法的蒙特卡罗模拟。该法可以给出边坡可靠度（或破坏概率）而不是更加传统的安全系数作为边坡安全评估的度量准则。不同土层的不同的土性参数由随机场产生并且投影到有限元网格的高斯积分点上。研究了非均质各向同性和各向异性的不同的一维和二维随机场模型参数对结果的影响。通过对其结果的比较分析，展示了5种随机场相关结构对边坡可靠度的影响，并强调了选择一个适合模型及其参数的重要性。根据统计分析结果，提出了基于可靠度的土强度特征设计参数，结果显示只有10％-40％（取决于不同的随机有限元模型）的土坡可以达到所期望的确定性分析中的平均结构反应。这是由于随机有限元方法可以更加严格地考虑空间相关性，使得边坡破坏可以更加自然地沿着最小阻力（即最弱材料强度）的路径发展。结果证明水平方向的相关距离在该堤坝的分析中起主导作用，并且指出随机有限元模型中若采用简单公式（不考虑破坏面几何形状）得出的等效各向同性的相关距离，可能导致错误的可靠度评估。The Monte Carlo simulations based on the random finite element method （RFEM） are conducted to assess the reliability of the James Bay dike. The RFEM method leads to predictions of reliability （or probability of failure） as opposed to the more traditional ＂factor of safety＂ measures of slope safety. Different independent random fields are generated for different soil properties and different soil layers and mapped onto the Gaussian points in the finite elements. Both the isotropic and the anisotropic spatial variabilities are considered, and the influences of various model parameters used in 1D and 2D random fields are investigated and compared. Five different models are used to show the effect of correlation structure on slope reliability, and the importance of selection of a proper model as well as its parameters is highlighted. A reliability-based characteristic design factor is defined based on the statistical analysis results. It is shown that only 10%~40% of the slopes, depending on the RFEM model, can reach the expected mean performance as one would expect in a deterministic analysis. It is thought to be due to RFEM taking into account the spatial correlation in a rigorous way, allowing slope failure to occur naturally along the path of the least resistance or the weakest points. The results show that the horizontal scale of fluctuation （SOF） has a dominant effect in the present case and that a model using an equivalent isotropic SOF, based on a simple equation without considering the geometry of the failure surfaces, may possibly result in an erroneous assessment of reliability.

关 键 词：有限元 蒙特卡罗模拟 随机场 边坡稳定性 空间变异性 

分 类 号：TU470[建筑科学—结构工程]