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在大家的大力支持下，我们已成功举办了九届“孙 钧讲座”。今年，“孙 钧讲座基金”理事会将于2015年3月23日，在同济大学举办第十届“孙 钧讲座”学术报告会（第一讲），届时将特邀新加坡工程院院士、新加坡岩土工程协会原主席、新加坡国立大学土木与环境工程系主任Kok-Kwang Phoon教授作“Reliability of Geotechnical Structures”学术报告。讲座内容及讲座人简介附后。
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时间：2015年3月23日下午2:00~4:00
地点：同济大学逸夫楼二楼演讲厅
主 办：“孙钧讲座基金”理事会
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“孙 钧讲座基金”理事会
2015年3月13日
Sun Jun Lecture (23 Mar 2015, 2-4 pm, Yifu Hall, Tongji University)
Reliability of Geotechnical Structures
Professor Kok-Kwang Phoon
A new fourth edition of ISO2394:2015 (General Principles on Reliability of Structures) has been scheduled for publication in 2015. ISO2394 is meant to be used as a basis for national/international code committees to draft codes of practice where the principles of risk and reliability are utilized for design and assessment of structures over the entire service life.
One important difference between the current ISO2394, 2nd edition (1998) and the forthcoming ISO2394, 3rd edition (2015) is the inclusion of a new Annex D on “Reliability of Geotechnical Structures”. The presenter is the chair of the task group responsible for drafting Annex D. The need to achieve consistency between geotechnical and structural reliability-based design is explicitly recognized for the first time in ISO2394 with the inclusion of Annex D. The emphasis in Annex D is to identify and characterize critical elements of the geotechnical reliability-based design process that are distinctive from the general principles presented in main text.
These distinctive elements are:
1. Coefficients of variation (COVs) of geotechnical design parameters can be potentially large, because geomaterials are naturally occurring and in-situ variability cannot be reduced (in contrast, most structural materials are manufactured with quality control).
2. COVs for geotechnical design parameters are not unique and can vary over a wide range, depending on the procedure in which they are derived.
3. Because geotechnical design parameter characteristics are different from one site to another, it is common to conduct a site investigation at each site. For this reason, statistical uncertainty must be handled with much care.
4. It is common to conduct both laboratory and field tests in a site investigation. A geotechnical design parameter is typically correlated with more than one laboratory and/or field test indices. It is important to consider this multivariate correlation structure where possible, because the COV of the design parameter reduces when consistent information increases.
5. Spatial variability of geotechnical design parameters cannot be readily dismissed, because the volume of geomaterial interacting with the structure is related to some multiple of the characteristic length of the structure and this characteristic length (e.g., height of slope, diameter of tunnel, depth of excavation) is typically larger than the scale of fluctuation of the design parameter, particularly in the vertical direction.
6. There are usually many different geotechnical calculation models for the same design problem. Hence model calibration based on local field tests and local experience is important. The proliferation of model factors, possibly site-specific, is to be expected, because of the number of models and the number of calibration databases.
7. A geotechnical system, such as a pile group and a slope, is a system reliability problem containing multiple correlated failure modes. Some of these problems are further complicated by the fact that the failure surfaces are coupled to the spatial variability of the soil medium.
The above list was developed to emphasize the need to avoid over-simplification of ground truths and the need to respect the diversity of geotechnical engineering practice (for example, different calculation models for the same problem). It is not surprising that many of the elements listed above are related to the characterization of geotechnical variability and model errors. The purpose of this presentation is to explain practical methods developed over the past two decades that are suitable for statistical characterization of geotechnical data, both soil and foundation load test data.
The Speaker
Kok-Kwang Phoon is Distinguished Professor and Head of the Department of Civil and Environmental Engineering, National University of Singapore. He is a Professional Engineer in Singapore, an ASEAN Chartered Professional Engineer, and past President of the Geotechnical Society of Singapore. His main research interests include statistical characterization of geotechnical parameters and reliability-based design in geotechnical engineering. He is the editor of 2 books: Reliability-Based Design in Geotechnical Engineering (Spon Press, 2008) and Risk and Reliability in Geotechnical Engineering (CRC Press, 2015). He has delivered more than 100 presentations in 24 countries 71 cities around the world, including the inaugural S.L. Lee Lecture in Singapore and 11th J.E. Jennings Memorial Lecture in South Africa.
He is the recipient of numerous research awards; the notable ones include the ASCE Norman Medal in 2005, the ASTM Hogentogler Award in 2007, the National University of Singapore’s Outstanding Researcher Award in 2010, and the IACMAG John Booker Medal in 2014. He has served as the Editor of Georisk and Chair of ASCE Geo-Institute Risk Assessment and Management Committee. He is currently serving as the Chair of TC304 (Engineering practice of risk assessment and management) in the International Society for Soil Mechanics and Geotechnical Engineering (ISSMGE). He is Fellow of ASCE, Fellow of the Academy of Engineering Singapore, and Kwang-Hua (光华) Chair Professor of Tongji University.
