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Half-day mini-symposium on the observational method

Event organised by The British Geotechnical Association

06 February 2024

This event has now ended

You can catch-up on details or any broadcast and downloads here.


The observational method (OM) in ground engineering is a continuous, managed, integrated process of design, construction control, monitoring and review that enables previously defined modifications to be incorporated during or after construction as appropriate (CIRIA R185, 1999). The OM has also been recognised by recent codes e.g. Eurocode.

The OM process was introduced by Peck (1969) in his Rankine Lecture (Géotechnique, 19, No 2, 171 -187). The objective is to achieve greater overall economy without compromising safety. The method can be adopted from the inception of a project, or later if benefits are identified.

TC206 and TC220 are the Technical Committees of the International Society of Soil Mechanics and Geotechnical Engineering (ISSMGE) dedicated to the Observational Method and Field Monitoring in Geomechanics respectively.

This mini-symposium will present three areas that the technical committees are currently collaborating on:

  • Conditions that enable use of OM, professor Tony O’Brien, Mott MacDonald
  • Real-time back analysis, Dr Ying Chen, Typsa
  • Field monitoring to support the use of the OM, Daniele Fornelli, Geotechnical Observations

A further objective of the mini-symposium is to allow those that have used the OM to share their experiences.

Expressions of interest to do so, should be emailed to [email protected] by 31 December 2023. Please include a title and a 200 word summary of what you will talk about. Those chosen to speak at the symposium will be informed by 12 January 2024.

Photographs may be taken at the event and used for BGA promotional purposes; if you have any objections, please contact the BGA at [email protected] 

You can find the full script here: Events | BGA Half-day Mini-Symposium on The Observational Method (

Image credit: Daniel Imade, Arup

Organised by

The British Geotechnical Association

The British Geotechnical Association

The BGA is the principal association for geotechnical engineers in the United Kingdom and organises a number of high profile events each year.


14:00 - 14:10

Introduction to OM and TC206, Duncan Nicholson

14:10 - 14:35

Contractual arrangements for OM, Tony O'Brien

14:35 - 15:00

Real-time back analysis, Ying Chen

15:00 - 15:25

Monitoring to support OM, Daniele Fornelli

15:25 - 15:45

Questions and discussion

15:45 - 16:15

Coffee break

16:15 - 17:45

Presentations and discussions (these will be from people attending the conference who have registered their interest in speaking)


Tony O’Brien

Tony O’Brien

Mott Macdonald

global practice leader, geotechnics

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Tony O’Brien

Tony O’Brien is a Fellow of the Royal Academy of Engineering and a Fellow of the Institution of Civil Engineering. He is the Global Practice Leader for Geotechnics at Mott MacDonald Ltd and a Visiting Professor at the University of Southampton. He has provided technical leadership on several major projects across Europe, North America and the Asia-Pacific region. Within MM he leads several initiatives to support the development of modern digital tools for data analysis, management and visualisation.

Tony has contributed to best practice guidance, including CIRIA guide (C791) on advanced numerical modelling and recently published a book “The Observational Method in Civil Engineering”. He also works on several international committees and currently chairs a sub-group of TC206 (Interactive Design) developing guidance on contract conditions to facilitate wider use of the Observational Method.

Dr Ying Chen

Dr Ying Chen

TYPSA UK & Ireland Ltd

associate geotechnical engineer

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Dr Ying Chen

Dr. Ying Chen is a chartered geotechnical engineer and researcher with over 17 years of experience in a wide range of geotechnical design and construction activities for railway infrastructure, urban area basements, and high-rise building foundations.

Major infrastructure project experience includes HS2 /Crossrail in the UK, Metro project in Hong Kong, Shenzhen China, and Doha. She is now leading the C2C3 Geotechnical design for Earthworks at Aylesbury Area as an Associate Geotechnical Engineer with TYPSA UK & Ireland Ltd.

After her Ph.D. at the University of Cambridge, on the “Application of the New Observational Method on deep excavation retaining wall design in London Clay”, she was nominated as a member of ISSMGE Technical Committee (TC) 206 – Observational Method, continuing her research work on the Machine Learning back analysis.

The collaboration with SAALG Geomechanics successfully trialled the innovative ‘DAARWIN’ tool on the HS2 project, proving the 'real-time' back analysis in a real construction environment. The success of this trial led to the Observational Method modification proposal on tunnel portal construction at the HS2 project, to optimise the construction program and achieve time and cost savings.

Daniele Fornelli

Daniele Fornelli

Geotechnical Observations Limited

associate technical director

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Daniele Fornelli

Daniele is an associate technical director for Geotechnical Observations Ltd., responsible for the technical aspects (including data validation, analysis and interpretation) of monitoring schemes across the UK.

He is a chartered civil engineer, with more than 10 years experience in Instrumentation and Monitoring. He has been involved, as a contractor and consultant, in a number of complex schemes both in the UK and overseas, including: tunnelling in urban areas, ground treatments, deep excavations and large scale trials.

As a geotechnical engineer, his passion for analytical and numerical modelling has complemented his deep interest for I&M, allowing him to keep a scientific and data-driven approach to complex data interpretation and back-analysis problems.

For more information please contact:

Shelly-Ann Russell

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