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1.
As numerical models are increasingly used as a design tool in geotechnical engineering, it is highly desirable if geotechnical reliability analysis can be conducted based on numeral models. Currently, the practical use of geotechnical reliability analysis-based numerical models is still quite limited. In this study, an easy to access method is derived to conduct geotechnical reliability analysis based on numerical models. To facilitate its application, a procedure is outlined to implement the suggested method such that geotechnical reliability analysis can be automated using existing geotechnical numerical packages. The procedure is illustrated in detail with an example, and the source codes provided can be easily adapted to analyze other similar problems. The method described in this paper is used to study the reliability of a deteriorating reinforced concrete drainage culvert in Shanghai, China. The suggested method provides a convenient means for reliability analysis of complex geotechnical problems. 相似文献
2.
In application to numerical analysis of geotechnical problems, the limit-state surface is usually not known in any closed form. The probability of failure can be assessed via the so-called reliability index. A minimization problem can naturally be formed with an implicit equality constraint defined as the limit-state function and optimization methods can be used for such problems. In this paper, a genetic algorithm is proposed and incorporated into a displacement finite element method to find the Hasofer–Lind reliability index. The probabilistic finite element method is then used to analyse the reliability of classical geotechnical systems. The performance of the genetic algorithm (GA) is compared with simpler probability methods such as the first-order-second-moment Taylor series method. The comparison shows that the GA can produce the results fairly quickly and is applicable to evaluation of the failure performance of geotechnical problems involving a large number of decision variables. 相似文献
3.
In this study, a new reliability analysis method was developed based on the adaptive high-dimensional model representation (HDMR) and applied to geotechnical engineering problems. For practical problems requiring finite element (FE) analysis or other numerical methods to evaluate system responses such as stresses and deformations, an efficient and accurate metamodeling technique is needed because it is not efficient or straightforward to directly adopt the conventional sampling-based or gradient-based reliability analysis approaches. In this work, an adaptive metamodeling approach was created and studied based on the HDMR framework and augmented radial basis functions (ARBFs). In this adaptive ARBF-HDMR technique, a simple and inexpensive first-order ARBF-HDMR metamodel was first constructed to explicitly express a performance function, and an alternate first-order reliability method (FORM) was applied to locate the design point and compute the reliability index. A local window was then defined such that additional sample points were generated and a higher-order HDMR component function was created using ARBF and added to the existing ARBF-HDMR metamodel. The accuracy of the ARBF-HDMR metamodel was improved through this adaptive process, especially in the region surrounding the design point. One mathematical and four geotechnical engineering problems were studied and solved using the proposed adaptive ARBF-HDMR approach. The proposed method was found to be capable of obtaining accurate reliability indices within a few iterations in all test problems. 相似文献
4.
J. Michael Duncan 《Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards》2017,11(1):70-74
ABSTRACTA core principle of geotechnical engineering practice is the need to exercise judgement in evaluating soil and site conditions and in performing analyses. The requirement for considering judgement applies equally to performing deterministic or probabilistic analyses. In addition, for probabilistic analyses, choices must be made among the possible methods of analysis and the method of characterising variables. Consequently, geotechnical reliability studies inevitably involve significant uncertainties, and judgement is needed to perform reliability analyses and to evaluate the results. Two case histories, briefly described here, show that judgement and experience are essential prerequisites for meaningful assessment of geotechnical reliability. 相似文献
5.
相关型岩土参数分析和选用 总被引：2，自引：0，他引：2
岩土参数与应力环境、沉积条件、风化程度和埋藏条件等因素相关,其统计值具有空间变异性和相关性,采用非相关型岩土统计参数进行岩土工程设计具有不经济性。通过分析岩土参数的变化规律及与其相关的主要因素,说明岩土参数可用深度或参数与地层顶面或底面的距离作为相关参数进行相关型判别,论述相关型参数的判定标准和相关型标准值的计算方法,采用图解法分析相关型参数多种取值方法的可靠性。以华南某核电厂常规岛地基和某变电站边坡为例,介绍了相关型岩土参数标准值经验公式在岩土设计优化中的应用。分析表明：具有规律性变化的岩土参数宜选择恰当的相关参数划分为相关型,相关参数可取参数与地层顶面或底面的距离,相关型岩土参数标准值可使岩土设计方案更具合理性和经济性。 相似文献
6.
基于均质路堤边坡Monte Carlo法的稳定可靠度计算,分析了临界滑面搜索策略和稳定分析方法两类模型不确定性对边坡可靠度的影响特性,讨论了边坡失效概率随土工参数变异性的变化规律。研究表明,选用不同的临界滑面搜索策略所得可靠度结果差异不大,参数滑面法（overall slope）的失效概率略大于均值滑面法（global minimum）,但差别对边坡稳定性分析没有实质性影响;土性参数变异水平是影响边坡可靠度的最重要因素,边坡在相同设计参数安全系数下的可靠度指标随参数变异性增大而急剧降低;不同稳定性分析方法对应的安全系数概率密度函数曲线形态基本一致,但失效概率差异明显,因此目标可靠度指标取值应与稳定性分析方法相适应。提出的考虑土工参数变异水平的安全系数取值修正原则,对改进确定性设计的边坡稳定分析技术有积极意义。 相似文献
7.
岩土工程可靠度分析中,功能函数往往呈隐式且具有强非线性性质,而目前最为实用的矩方法,如JC法、二次二阶矩法,主要适用于显式功能函数情形。为此,将高效的统计矩估计方法和可靠度分析的高阶矩法相结合,提出了一种岩土工程可靠度分析的改进四阶矩方法。首先,通过引入变量的独立化变换和线性变换将功能函数转换为参考变量的函数,并结合多变量函数的单变量降维近似方法和参考变量计算节点与权系数的确定方法,建立了功能函数前四阶矩的高效点估计法。然后,将上述统计矩与立方正态变换假设相结合,提出了易于实现的岩土工程可靠度分析的改进四阶矩方法。最后,由数学算例验证了统计矩估计方法的效率和精度,并通过经典的岩土工程算例验证了建议的改进四阶矩方法具有高效率、高精度且操作简单等特点。 相似文献
8.
9.
Structural optimization methods are used for a wide range of engineering problems. In geotechnical engineering however, only
limited experience exists with these methods. The difficulties in applying such methods to geotechnical problems are discussed
in this paper, and the adaption of the commonly known SIMP-method to geotechnical problems is introduced for a special case.
An application example is used to present the potential of topology optimization methods, and the application to geotechnical
engineering is evaluated. 相似文献
10.
High-steep slopes in open pit mines are much more likely to collapse due to mining operations. Challenges such as data acquisition, precise numerical models and adaptable methodologies have impeded more reliable results of slope stability analysis based on the current methods. Within this context, this paper proposes a combined methodology using light detection and ranging technology to capture high-resolution slope geometry, three-dimensional geological and geotechnical modeling technologies for creating high-quality numerical simulation models and finite-element slope stability analyses combined with a new automatic strength reduction technique to analyze complex geotechnical problems. At the end, the methodology introduces a time series analysis to improve the reliability of the calculated factor of safety. A case study in the deepest open pit mine in Hambach, Germany, was conducted to test and demonstrate the effectiveness and applicability of the proposed methodology. 相似文献
11.
岩土力学数值分析方法研究 总被引：3，自引：0，他引：3
随着岩土工程领域的不断扩展与延伸,岩土力学数值分析方法得到了迅速发展,出现了各种各样的数值分析方法。将岩土力学常用的数值分析方法分为连续变形分析方法与非连续变形分析方法两大类,对各种方法的研究现状和最新进展进行了评述,着重介绍了各种方法的优缺点,并提出了解决问题的思路、方法和建议。 相似文献
12.
传统有限元强度折减法在边坡稳定性数值分析中取得了一定的成功,但由于未考虑岩土体材料参数的变异性等不确定性因素,尚不能直接应用于边坡稳定性特别是动力稳定性可靠性分析问题。为此提出了基于有限元强度折减法的地震边坡动力稳定性可靠性分析方法。将有限元极限分析法、动力分析法和可靠性分析法三者耦合,分析求解边坡在地震作用下的动力稳定性可靠性问题,并将这一过程在数值计算程序中得以实现。在计算分析过程中,克服了原方法需不断人工试算才能得到边坡安全系数而无法量化处理问题,并对边坡动力失效准则进行了适用于程序化的改进,使其计算过程完全实现自主运行。结合典型算例分析结果表明,该方法显著的特点是能较全面地反映岩土体的动力特性和边坡岩土体材料强度参数的变异性及相关性,所得结果相对更加合理且更符合工程实际。该方法既是对有限元强度折减法的应用范围的有益推广,也为边坡动力稳定性可靠性问题研究提供了一条新的有效途径。 相似文献
13.
公路工程建设呈现的岩土工程问题主要有地基稳定问题、边坡稳定问题、围岩稳定问题和渗透稳定问题。这些问题对工程的影响体现在变形和强度两个方面,根据工程的功能和性质,应考虑按变形控制或强度控制来确定工程安全标准和评价工程稳定性。基于岩土工程问题的产生条件,提出了在工程实践中应注重的内容及研究方向,如：路基岩土的强度与变形特性研究、地基处理技术及工程特性研究、深基础与地基相互作用研究、边坡稳定性评价方法研究、边坡治理技术及可靠性研究、围岩与结构应力变形研究、地下水对各种岩土体的作用研究等等。 相似文献
14.
15.
相关情况下Hasofer_Lind可靠度指标的求解 总被引：15，自引：0，他引：15
岩土工程的可靠度计算中, 基本变量之间往往存在着较强的相关性。 阐述了相关情况下 Hasofer-Lind 可靠度指标计算的几种方法: 正交变换法; 改进的验算点一次二阶矩法; Monte-Carlo 模拟法; 优化求解法。 在用优化方法求解可靠度指标 β 时, 利用 Microsoft Excel 中的规划求解器来进行优化求解, 避免了相关变量的独立变换以及求极限状态函数对基本变量的偏导数这两个问题。 实例比较了不同方法的求解结果。 相似文献
16.
针对统一强度理论（UST）拟合非线性强度的局限和岩土材料强度特点,提出拟合岩土非线性强度特征的脆性剪切分析方法,建立了过渡式双线性强度分解公式。以脆断、剪切双重破坏机制,解释Hoek-Brown准则的非线性特征机制,并推导出体现岩石、岩体类材料非线性强度特征的脆剪强度公式。Mine-by隧道和北山花岗岩强度数据分析显示,在岩体折减强度、试验数据直接拟合实例分析中,脆剪强度与Hoek-Brown强度相关性系数均在0.98以上,在该基础上建立岩体非线性强度脆剪分析的双线性过渡式,并提出对应的统一强度理论形式,实现统一强度理论在拟合岩土非线性强度准则中的扩展。 相似文献
17.
This study focuses on the geotechnical engineering structures with implicit or unknown expressions of performance functions. A one-dimensional integral approach (ODIA) consisting of sampling, evaluation of statistical moments for multivariable functions, probability density function fitting, and simple integration of failure probability was developed through system integration. A convergence study of an illustrative example was conducted, and the error analysis revealed that the accuracy of ODIA is equivalent to that of the second-order reliability method. Applications of ODIA to a slope and surrounding rock of an excavation were presented to further confirm the accuracy, efficiency, and practicability of the approach. 相似文献
18.
在重要的岩土工程中,确定大样本岩土参数的概率分布对岩土工程稳定性和可靠性分析有着极其重要的意义。为此,基于积分均方误差最小计算得到的最优窗宽,提出了推断大样本岩土参数概率密度函数的正态信息扩散法。该方法基于信息扩散原理,从试验样本和信息论的角度出发,充分利用样本提供的数据信息,而不是先假定成经典的概率分布曲线拟合检验,数学意义和物理意义更加充分和严密。以推断压缩指数Cc的概率密度函数为例,分析了窗宽对信息扩散估计结果的影响规律,说明了该方法在大样本岩土参数概率密度函数推断方面的合理性。用该方法推断了大样本岩土抗剪强度参数的概率密度函数,通过K-S检验,验证了该方法的正确性和实用性。 相似文献
19.
Classification of slopes and prediction of factor of safety using differential evolution neural networks 总被引：6，自引：4，他引：2
Sarat Kumar Das Rajani Kanta Biswal N. Sivakugan Bitanjaya Das 《Environmental Earth Sciences》2011,64(1):201-210
Slope stability analysis is one of the most important problems in geotechnical engineering. The development in slope stability
analysis has followed the development in computational geotechnical engineering. This paper discusses the application of different
recently developed artificial neural network models to slope stability analysis based on the actual slope failure database
available in the literature. Different ANN models are developed to classify the slope as stable or unstable (failed) and to
predict the factor of safety. The developed ANN model is found to be efficient compared with other methods like support vector
machine and genetic programming available in literature. Prediction models are presented based on the developed ANN model
parameters. Different sensitivity analyses are made to identify the important input parameters. 相似文献
20.
现行的抗滑桩滑坡推力以及抗滑桩内力计算方法本质上属于定值方法,由于该方法未考虑边坡岩土体材料参数的变异性等不确定性因素,存在着抗滑桩支护不足或过度支护等问题,因此提出基于有限元强度折减法(SRFEM)的抗滑桩滑坡推力及抗滑桩内力可靠性分析方法。将极限分析法、有限元方法和可靠性分析法三者耦合,用2结点梁单元模拟抗滑桩受力状态,采用拉丁超立方抽样法(LHS)进行可靠度计算,分析求解边坡抗滑桩可靠性问题,并将该过程在数值计算程序中得以实现。对抗滑桩滑坡推力以及抗滑桩内力进行概率统计,得出函数分布关系,并根据已给定的失效概率控制值,反算出滑坡推力以及抗滑桩内力设计值。结合典型算例分析结果表明该法显著区别于一般方法,能较全面地反映出边坡整体现状特征和岩土体材料强度参数的变异性,相对更加合理,且更符合工程实际。 相似文献