Safe geotechnics by observation. Leaning tower of Pisa.

+ I believe we should habitually ‘back-analyse’ the behaviour of our man-made structures to assess whether the input parameters could have been more accurate. Ultimately this will lead to safer and more sustainable assets.

In geotechnics more than in other engineering disciplines much can be learnt from the behaviour of finished structures regardless of where they are located in the world. This is certainly true for major collapses such as the Nicoll Highway or the centuries of mitigation attempted on the still-leaning tower of Pisa. 

But we do not need to rely on catastrophes or mistakes to enhance our understanding of soil behaviour and of how man-made structures interact with it. By monitoring the behaviour of structures during and after construction we have the opportunity to compare the predictions made at design stage with their real behaviour. 

Beyond a validation of the design, I believe we should habitually ‘back-analyse’ the behaviour to assess whether the input parameters could have been more accurate. In this way we can generate deeper insights into the geotechnics of a given project or location, arriving at valuable conclusions that we can share with our peers.

The monitoring industry is ever evolving thanks to advancements in instrumentation, such as the use of fibre-optics and post-processing tools which now also include those used for big data. This then creates data that can be shared in the cloud and made available in real-time and shared with users via web portals such as the Global Analyser

But industry codes and regulations do not typically prescribe back-analyses, which means that if they take place at all, they’re left to the initiative of the designers for whom they’re not a priority and who may not have access to the monitoring data. I firmly believe that whenever there is this sort of disconnection between a project’s design and construction activities the construction industry misses a golden opportunity to improve. 

As a geotechnical engineer I always look for precedents when a new project starts. Published case histories in the project area or with comparable features are particularly valuable to designers as they can contain a wealth of information on what went well but also on what might have been problematic in previous construction projects. The International Society for Soil Mechanics and Geotechnical Engineering publishes a journal on this topic for example and encourages academics and practitioners to contribute to it. 

Looking forward, we have the opportunity to bring together all this data into a single, shared computer model for the behaviour of say Copenhagen till, Milan gravels, London clay, San Francisco Bay mud and so on. 

I believe the time is right for legislators to consider adding back-analyses as a requirement to the virtuous circle of design > construction > observed behaviour > improved design. Ultimately this will lead to safer and more sustainable assets.