Pre-Symposium Webinar Series and Sunday On-Site Sessions
The organizing committee of the 4th ISFOG has proposed a series of six webinars on topics of relevance to the offshore geotechnical engineering community. These webinars will emphasize theoretical engineering aspects and will be offered free-of-charge monthly from January 2022 to June 2022. They will consist of 45-min live online presentations, followed by 15 min Q&A. They will be recorded and posted on YouTube. The webinars will take place according to the following schedule:
January 18, 2022
Data Science 101
Organizer: Bruno Stuyts, Visiting Professor Offshore Geotechnics, Ghent University
Moderator: Rodolfo Sancio
Offshore geotechnical engineering is a data-intensive discipline which utilises geo-data from different sources (geological, geophysical, geotechnical investigation and in-situ monitoring data). Recently, an acceleration in the field of data science has put tools at the disposal of practicing engineers to process this data more efficiently and use it as the basis for creating predictive models.
This online presentation provides an essential introduction to data science for offshore geotechnical engineering applications. Based on two practical applications (soil type classification and pile driving blowcount predictions), participants will be introduced to the principles of building a data analysis pipeline. The essential tools for manipulating large datasets and building predictive machine learning models will be introduced.
February 22, 2022
New Proposed ISO/API P-Y Curves for Piles in Clays
Organizer: Philippe Jeanjean, Senior Advisor, Geotechnics, BP America
Moderator: Bob Gilbert
The International Organization for Standardization, ISO, will soon update its recommendation ISO 19901-4 Petroleum and natural gas industries — Specific requirements for offshore structures — Part 4: Geotechnical design consideration. One of the important changes relates to the analysis of laterally loaded piles in clays and the generation of the lateral soil springs, the so-called p-y curves.
The current ISO/API recommendations include the long-standing curves recommended by Matlock in 1970 and introduced in the API RP2A code in 1972 for monotonic and cyclic load conditions. The new ISO framework updates and replaces these monotonic and cyclic curves and adds recommendations for an additional limit state: the fatigue limit state. Generally speaking, these new curves provide increased strength and stiffness, as compared to existing recommendations.
The webinar will present these new curves, as codified in the upcoming ISO standard, and the philosophy and thought process behind their development. The talk will also address their intended use and limitations.
March 15, 2022
New Proposed ISO/API Unified CPT-based Method for Axial Pile Capacity in Sand
Organizer: Farrokh Nadim, Technical director, Norwegian Geotechnical Institute
Speaker: Barry Lehane, Professor, University of Western Australia
Moderator: Arash Zakeri
Until about a decade ago, the axial capacity of tubular steel piles for offshore installations was primarily based on the American Petroleum Institute (API) Recommended Practice. This talk will discuss the theoretical basis of the new Unified CPT-based method developed through a Joint-Industry Project (JIP) by NGI and UWA to estimate the axial capacity of piles in sand.
This new Unified CPT-based method will be implemented in the main text of the upcoming update to the design code ISO 19901-4 and was calibrated with the unified database of pile load tests recently developed by Lehane et al. (2017). It incorporates key factors known to influence pile capacity, including a) the degree of soil displacement (plugging) during installation, b) friction fatigue, c) sand-pile interface friction angle, d) changes in radial stress during loading and e) the influence of loading direction.
The new method provides more reliable predictions of the capacities of the pile load tests in the Unified database than any of the existing axial pile capacity design methods in the current API and ISO guidelines.
April 28, 2022
Fundamentals of Cyclic Loading in Offshore Geotechnics
Organizer: Phil Watson, Professor, University of Western Australia
Speakers: Mike Rattley, Director, Geowynd Limited, and Carl Erbrich, Technical Director, Fugro
Moderator: Phil Watson
This webinar will focus on two central considerations:
- Soils respond to cyclic loading:
The cyclic loading response of real soils in the offshore environment will be presented, focusing on the undrained condition, and using examples from tests performed on offshore soil samples. The discussion will highlight several key behavioural aspects which influence idealisations for foundation analysis: cyclic stress-strain response, pore pressure accumulation, and post-cyclic behaviour. The talk will also address the importance of considering the design application during test specification to ensure production of a fit for purpose site-specific laboratory dataset.
- Impact of soil response on foundation behaviour:
The incorporation of site-specific cyclic soil properties into the design process for offshore foundations will be presented. The benefits of appropriate site-specific cyclic design rather than defaulting to standard design methods that exclude or minimise cyclic effects will be presented. Performance-based approaches that focus on foundation displacement rather than ‘capacities’ will be presented. These points will be highlighted through several examples including storm loading of laterally loaded piles and seismic loading of shallow foundations.
May 19, 2022
New Integrated Design Models for Offshore Wind Turbines Foundations (REDWIN JIP)
Organizer: Ana Page, Head of Section - Advanced Modelling, Norwegian Geotechnical Institute, Oslo
Moderator: Zack Westgate
Recent improvements have been achieved in the methods and tools used in the design of offshore wind turbines (OWT) foundations through the projects REDWIN and REDWIN 2.
The REDWIN project (2015-2018) improved the modelling of the foundation response in integrated dynamic time-domain analyses of OWT by developing simple macro-element models for typical OWT foundations. These models exhibit characteristic foundation behaviour such as nonlinearity, coupled response from different load components and hysteretic load-dependent damping. They have been so far implemented in more than seven integrated analyses tools employed in the design of OWTs.
The REDWIN 2 project (2019-2022) focused on advancing and merging foundation engineering tools and methods, enabling foundation designers to apply recent research and development results in design practice. It has developed a streamlined design process and a foundation optimization routine incorporating all geotechnical and structural design limit states.
This workshop will present the main outcomes of these two projects, highlighting some of the limitations and suggesting possible directions for future improvements.
June 23, 2022
New Design Tools for Laterally Loaded Wind Turbine Monopiles (PISA JIP)
Organizer: Byron Byrne, Professor, University of Oxford
Moderator: Proserpine Peralta
Offshore wind turbines in shallow coastal waters are typically supported on monopile foundations. The webinar describes a new 1D design model for monopile foundations which was developed through the Pile Soil Analysis (PISA) JIP, which ran between 2014 and 2018. The model is specifically formulated for offshore wind turbine applications, although the general approach could be adopted for other applications. The model draws on the conventional p–y approach, but extends it to include additional components of soil reaction that act on the pile. The 1D model is calibrated using a set of bespoke 3D finite-element analyses of monopile performance, for pile characteristics and loading conditions that span a predefined design space. The calibrated 1D model provides results that match those obtained from the 3D finite-element calibration analysis, but at a fraction of the computational cost.
This 1D modelling approach will be demonstrated for monopiles installed in a stiff, over-consolidated glacial clay till with a typical North Sea strength and stiffness profile. The general approach can be applied to other foundation and soil–structure interaction problems, in which bespoke calibration of a simplified model can lead to more efficient design.
As a follow-up to the above webinars, pre-conference workshops will address practical, hands-on applications to illustrate the use of the methods presented in the webinars and will be offered on Sunday August 28, 2022.