【作者】 吴振君；

【导师】 葛修润；

【作者基本信息】 中国科学院研究生院（武汉岩土力学研究所） ， 工程力学， 2009， 博士

【摘要】 土体参数变异性是土坡可靠度问题中最基本的不确定性因素，而其空间变异性是不能忽略的，本文着重于土体参数空间变异性模拟方法和土坡可靠度分析方法的应用研究，主要研究内容如下：1)可靠度方法的改进和应用。提出了边坡可靠度分析的LHS—BP神经网络方法。将LHS方法、改进的FORM约束优化方法、Harr改进概率矩点估计法用于边坡可靠度分析。2)阐述并分析了目前边坡可靠度研究中的一些问题，如边坡的体系可靠度、临界滑面、评价指标、中心点法和验算点法存在的问题等。3)由于土体参数空间变异性的存在，在边坡可靠度分析中采用随机变量模型是有条件的，随机场理论和地质统计学的区域化变量理论可较好地描述这种空间变异性。波动范围是随机场理论的重要指标之一，其大小与土体成因关系密切，在资料有限的情况下可由土体成因根据统计资料估算。首次在边坡可靠度分析中引入了约束随机场的概念，将随机场理论和地质统计理论的Kriging方法结合起来，尽可能地利用已有的勘查、试验数据，考虑土性参数的空间分布构建约束随机场。4)考虑土体参数空间变异性的边坡可靠度分析方法土体参数的空间变异性与其成因密切相关，将土体地质成因纳入可靠度分析框架。文中采用随机场模型来模拟土体参数的空间变异性。提出了考虑土体参数空间变异性的边坡可靠度分析的框架及具体的实现方法，包括验算点优化求解法和LHS抽样MC模拟方法。提出了随机场模型下的边坡可靠度因素敏感性分析方法，其结果对于边坡设计、加固具有重要的指导意义。首次较为系统地研究了土体参数空间变异性及其模拟方法对边坡可靠度的影响，如波动范围、相关函数、等效各向同性、随机场离散尺度等，也对比了土体参数空间变异性模拟方法如方差折减方法、不同的随机场离散方法的边坡可靠度分析结果，得到的结论对实际应用有一定参考价值。采用随机有限元方法介绍了约束随机场模拟的应用，算例结果表明对于土体参数变异性较大的边坡，忽略其空间位置信息，用完全随机场模拟实际上高估了土体的空间变异性。5)矢量和安全系数是一种新的安全系数定义，采用极限平衡方法求解矢量和安全系数，通过实例介绍了该方法在边坡可靠度分析中的具体应用。更多还原

【Abstract】 The variability of soil properties is the fundamental uncertainty in reliability study of soil slopes, and the spatial variability of soil properties can not be ignored. The research presented in this thesis focuses on the simulation of spatial variability of soil properties, its effects on slope reliability and practical reliability analysis methods of soil slopes considering spatial variability. The emphases are as follows:A new slope reliability analysis method - LHS-BP neural network is proposed. LHS method, improved constraint optimization method for FORM and Harr’s PEM are applied to slope reliability analysis.Some common problems in slope reliability study are presented and discussed, such as systematic reliability, critical slip surface, reliability evaluation index and problems related to FOSM and FORM and etc.The most widely-used random variable model is only applicable to particular circumstances in slope reliability analysis. The techniques of random field theory and geostatistics can be used to quantify and model the spatial variability of soil properties.The constraint random field (CRF) is first introduced in slope reliability analysis and implemented utilizing random field theory and regionalized variable theory of geostatistics to ensure that the random field realizations match the parameters at the sample locations exactly.The spatial variability of soil properties is mainly dominated by its geological genesis, thus geological genesis of soil can be incorporated in reliability analysis method. The random field model is employed to simulate spatial variability of soil properties and slope reliability methods considering spatial variability is proposed such as FORM by optimization approach and Monte-Carlo simulation with LHS technique.Sensitivity analysis method for slope reliability under random field model is proposed. The sensitivity analysis results can play an important role in slope design and reinforcement.The influence of spatial variability of soil properties and simulation methods on slope reliability is first thoroughly studied such as scale of fluctuation, correlation function, equivalent isotropic correlation structure, discretization scale of random field and etc. Simplified variance reduction method and random field discretization methods in slope reliability analysis are compared, and results are quite valuable for practice.The application of CRF is introduced through Monte-Carlo random finite element method. The results show that the CRF can significantly reduce variance of the random field simulation and get lower probability of failure when high variability of soil properties exists.Vector sum factor of safety is a new definition for slope factor of safety. A simple method for solving vector sum factor of safety is proposed under equilibrium framework and then applied to slope reliability analysis.更多还原