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Kok-Kwang Phoon 《Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards》2019,13(2):101-130
The calculated response from a numerical model will deviate from the measured one given the presence of modelling idealizations and real world construction effects. This deviation can be directly captured by a ratio between the measured and the calculated quantity. The ratio is also called a model factor in many design guides. The probabilistic distribution of the model factor is arguably the most common and simplest complete representation of model uncertainty. The characterisation of model uncertainty is identified as one of the critical elements in a geotechnical reliability-based design process in Annex D of ISO 2394:2015 “General Principles on Reliability of Structures”. This Spotlight paper reviews the databases for various geo-structures and determines their associated model statistics. Foundation load test databases are the most prevalent. A recent effort to compile a large generic database (PILE/2739) that contains 2739 field load tests conducted on various piles and installed in different soils and countries, is highlighted. This systematic compilation of load test data is part of a broader research agenda to digitalise foundation design for “precision construction”, which is targeted at characterising “site-specific” model factors and soil parameters based on both site-specific and generic data for further customisation of design to a particular site. The mean and COV of the model factor for a range of geo-structures, geomaterials, and limit states (both ultimate and serviceability) are summarized in a form suitable for adoption in design and codes of practice. Based on this summary, it is proposed that a model factor for a design model can be classified as: (1) moderately conservative (1?≤?mean?相似文献
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岩土工程随机参数统计特征的不确定性,使得岩土工程可靠度设计存在一定风险。岩土工程稳健性设计能够充分考虑随机参数的不确定性结合结构安全性、稳健性和经济性实现最优设计。针对随机参数统计特征的不确定性对柱下独立基础设计的影响,基于可靠度理论和岩土工程稳健性设计方法,考虑岩土参数、混凝土和钢筋材料力学参数统计特征不确定性的影响,以独立基础几何尺寸作为可控设计参数进行设计分析。将独立基础地基承载力、地基变形、基础结构冲切破坏和基础弯曲破坏4种失效模式视为串联系统,进行多失效模式下的结构体系稳健性设计,分析了多失效模式下结构几何参数与结构体系可靠度的关系。结合稳健性和经济性,进行了独立基础多目标优化设计,确定柱下独立基础设计的最优解。 相似文献
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井下超声波成像提取岩层节理产状信息 总被引：2，自引：1，他引：1
井下超声波电视能够提取工程勘察中岩层产状信息并完成井眼岩层3维（3D）信息图。在某地下石油储备库的工程勘察中,完成7口井的超声波电视成像测井,以其中的钻孔ZK10为例,研究并分析了井下超声波电视成像所获取的结构面倾角和倾向、岩体完整性、结构面线密度、3D岩心图和井壁图以及节理极坐标图、节理方位频率图。统计分析结果表明：井下超声波电视技术可以对钻孔所揭露的岩体质量进行初级定量化分析,为区域稳定分析、工程岩体质量分级及工程设计提供有价值的基础数据,对提高工程勘察质量具有重要意义。 相似文献
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论述了岩土工程极限状态设计的基本思想,包括极限状态的概念、土工参数设计值的确定过程和方法、构造物的重要度和场地地基复杂程度的划分、岩土工程类别、作用载荷组合、分项安全系数和极限状态设计等;给出了土工参数的实测值、导出值、标准值和设计值的确定原则或方法;指出在极限状态设计中,可通过增大设计作用效应或降低设计抗力的方法来进行岩土工程的可靠性设计. 相似文献
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建筑工程勘察、设计和施工一体化模式,逐渐成为国内大型勘察设计企业新的核心竞争力,亦是国际国内经济一体化和市场经济发展的必然趋势。本文结合目前国内主要从事岩土工程的勘察、设计或施工企业对项目的运作情况,提出了岩土工程勘察、设计和施工一体化运作模式。通过对目前国内岩土工程勘察、设计和施工独立运作模式和一体化模式的对比研究和分析,结合典型的工程实例,总结和分析了采用一体化或近似一体化模式运作项目的优劣和经验。针对目前国内大型勘察设计企业实施岩土工程勘察、设计和施工一体化模式的困难进行了探讨并提出相关建议,供相关部门或同行参考。 相似文献
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Geotechnical modeling at the city scale using statistical and geostatistical tools: The Pessac case (France) 总被引：3，自引：0，他引：3
In the context of the RIVIERA project, the building of a 3D geotechnical model at the city scale (Pessac, France) has been undertaken, from several hundreds of boreholes and geotechnical tests. It is first shown how the combination of the lithological information and of geotechnical results can improve thanks to Bayesian statistics the knowledge of mechanical characteristics in the various alluvial terraces which can be encountered in this area. Secondly the upper and lower limits of the 3D model at the city scale are computed by improving an initial digital elevation model for the upper limit and by kriging under inequality constraints for the lower limit. These limits border Quaternary formations which are of interest for geotechnical applications. In a third stage, it is focused on the spatial modelling of the pressuremeter modulus. The sequential indicator simulation method enables to obtain the spatial probability of occurrence of a given pressiometer modulus class. Coupled with other information, the analysis of these statistical and geostatistical models makes possible to develop decision support tools such as to localise, for instance, areas more prone to the clay shrinkage–swelling hazard. 相似文献
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Application of Three-Dimensional Laser Scanning and Surveying in Geological Investigation of High Rock Slope 总被引：4，自引：0，他引：4
The appearance of 3D laser scanning technology is one of the most important technology revolutions in surveying and mapping field. It can be widely used in many interrelated fields, such as engineering constructions and 3D measurements, owing to its prominent characteristics of the high efficiency and high precision. At present its application is still in the initial state, and it is quite rarely used in China, especially in geotechnical engineering and geological engineering fields. Starting with a general introduction of 3D laser scanning technology, this article studies how to apply the technology to high rock slope investigations. By way of a case study, principles and methods of quick slope documentation and occurrence measurement of discontinuities are discussed and analyzed. Analysis results show that the application of 3D laser scanning technology to geotechnical and geological engineering has a great prospect and value. 相似文献
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地下环境信息系统是运用岩土工程、地理学、计算机图形学、计算数学等多学科理论和方法，以GIS技术为基础，结合数据库处理、C 语言编程、OpenGL编程技术、三维图像处理技术建立的对地下环境信息进行数据综合管理和分析的大型信息管理系统。结合笔者开发的广东省东深供水改造工程地下环境信息系统特点，阐述了重大工程地下环境信息系统的功能特征：探讨了GIS二次开发的主要技术，包括：SQL Server数据库处理技术、OpenGL三维图形编程技术、C Builder面向对象编程技术、MAPGIS二次开发技术等；建立了地层三维模型，并提出了映射变换和插值技术相结合的地层切剖原理，以及在地层三维显示和分析中实用的径向基函数插值、滑动最小二乘插值、分片Lagrange插值等方法；开发了数字制图与分析、地基基础设计计算与稳定性分析、三维空间分析的主要功能；提出了地面结构景观和地下空间一体化分析的研究方向，并初步实现其分析功能。最后，在东深供水改造工程中进行了成功应用。 相似文献
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Spatial estimation of geotechnical parameters for numerical tunneling simulations and TBM performance models 总被引：1，自引：1，他引：0
In this paper, we further elaborate on a methodology dedicated to the modeling of geotechnical data to be used as input in numerical simulation and TBM performance codes. The expression “geotechnical data” refers collectively to the spatial variability and uncertainty exhibited by the boundaries and the mechanical or other parameters of each geological formation filling a prescribed 3D domain. Apart from commercial design and visualization software such as AutoCAD Land Desktop® software and 3D solid modelling and meshing pre-processors, the new tools that are employed in this methodology include relational databases of soil and rock test data, Kriging estimation and simulation methods, and a fast algorithm for forward or backward analysis of TBM logged data. The latter refers to the continuous upgrade of the soil or rock mass geotechnical model during underground construction based on feedback from excavation machines for a continuous reduction of the uncertainty of predictions in unsampled areas. The approach presented here is non-intrusive since it may be used in conjunction with a commercial or any other available numerical tunneling simulation code. The application of these tools is demonstrated in Mas-Blau section of L9 tunnel in Barcelona. 相似文献
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Explicit dynamic relaxation is an efficient tool that has been used to solve problems involving highly non-linear differential equations. The key feature of this method is the ability to use explicit dynamic algorithms in solving static problems. Few attempts have been made to date to apply this technique in conventional geotechnical engineering. In this study, an algorithm that incorporates the application of a stiffness dependent time step scheme is proposed. The algorithm has been successfully used to solve 2D and 3D non-linear geotechnical engineering problems. To calibrate the developed algorithm, numerical simulations have been conducted for a strip and square footings supported by Mohr–Coulomb material. Performance of four different types of brick elements used in collapse load calculation is examined in terms of convergence speed and accuracy. In addition, the role of employing adaptive time steps in reducing the number of iterations needed for convergence is also evaluated. 相似文献
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In many geotechnical engineering cases, the factor of safety may be defined as the ratio of the capacity, of the geotechnical structure or its support elements, to the pertinent demand. By representing the capacity and the demand as independent piecewise linear random variables, an analytic solution is obtained for the probability density and cumulative distribution functions of the factor of safety. Thus, solutions for the calculation of the mean value, the standard deviation and the minimum and maximum values of the factor of safety, are provided. Application of the developed analytical solutions, to the probabilistic analysis of a published case of rock spalling in a deposition tunnel complex, follows. The methodology allows for the parametric evaluation of the effect of specific design variables to the distribution of the safety factor and to the probability of failure. The closed form solution may be programmed as a computer code that may run easily on a tablet or netbook or even on a smartphone. It proves useful for the probabilistic design of a variety of geotechnical applications, such as foundations, tunneling, mining, underground roof reinforcement, and earth retaining structures, and permits decisions to be taken in terms of risk and reliability. 相似文献
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将基于统一强度理论的岩土材料参数c、φ值引入到锚杆的抗拔力及规范推荐的粘性土广义库伦土压力中,以此建立锚杆挡土墙的功能函数。考虑岩土参数全部为正态分布与对数正态分布的两种情况,分别采用设计验算点法和JC法对一工程实例编制了考虑中主应力影响的可靠度计算程序。计算结果表明:锚杆挡土墙的可靠指标随中主应力影响系数b的增大而增大,且参数变异系数越小,增量越大;参数为对数正态分布的可靠指标比参数为正态分布时大,且两者的差量随b的增大而增大。 相似文献
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This paper aims to develop an efficient geotechnical reliability-based design (RBD) approach using Monte Carlo simulation (MCS). The proposed approach combines a recently developed MCS-based RBD approach, namely expanded RBD approach, with an advanced MCS method called “Subset Simulation (SS)” to improve the computation efficiency at small probability levels that are often concerned in geotechnical design practice. To facilitate the integration of SS and expanded RBD, a generalized surrogate response f is proposed to define the driving variable, which is a key parameter in SS, for expanded RBD of geotechnical structures (e.g., soil retaining structures and foundations). With the aid of the proposed surrogate response, failure probabilities of all the possible designs in a prescribed design space are calculated from a single run of SS. Equations are derived for integration of the surrogate response-aided SS and expanded RBD, and are illustrated using an embedded sheet pile wall design example and two drilled shaft design examples. Results show that the proposed approach provides reasonable estimates of failure probabilities of different designs using a single run of the surrogate response-aided SS, and significantly improves the computational efficiency at small probabilities levels in comparison with direct MCS-based expanded RBD. The surrogate response-aided SS is able to, simultaneously, approach the failure domains of all the possible designs in the design space by a single run of simulation and to generate more complete design information, which subsequently yields feasible designs with a wide range of combinations of design parameters. This is mainly attributed to the strong correlation between the surrogate response and target response (e.g., factor of safety) of different designs concerned in geotechnical RBD. 相似文献
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Sara Khoshnevisan Lei Wang C. Hsein Juang 《Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards》2017,11(1):90-102
ABSTRACTThe robust geotechnical design (RGD) approach which involves optimization to obtain a design that is safe, cost-efficient, and robust in the face of uncertainties, can be computationally challenging for complex geotechnical structures. In this study, the RGD approach has become practical by introducing a response surface as a surrogate to finite element- or finite difference-based computer code that is used for analyzing the system, and developing a fast algorithm for the optimization process. For demonstration purposes, a real-world supported excavation project is designed using this modified RGD approach and it is compared with the one designed by a local expert. 相似文献