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UrbanWaves Report Summary

Project ID: 336084
Funded under: FP7-IDEAS-ERC
Country: United Kingdom

Mid-Term Report Summary - URBANWAVES (Urban Waves: evaluating structure vulnerability to tsunami and earthquakes)

Since the 2004 Boxing Day tsunami in the Indian Ocean (December 2004), and more so since the Tohoku tsunami (March 2011), governments have shown substantially greater awareness of the threat of coastal flooding and/or erosion by tsunami, and particularly the need for more robust strategies and structures to evacuate and/or protect populations. Essential to those processes are better improved understanding of tsunamis from near-shore (where conventional Shallow-water Wave Equation models may give reasonable predictions of behaviour) to onshore where data are very sparse and model reliabilities are highly uncertain.
Tsunamis generally have quite small wave heights in deep water (<1m), but will shoal substantially as they approach the shore (to circa 5-8m). At present, there is considerable difference of academic opinion on the processes that influence tsunami behaviour from near-shore to onshore. The URBAN WAVES project arose from the conviction that none of the historical attempts to reproduce tsunamis in the laboratory had been realistic. There had to be a better way! URBAN WAVES brings together expertise at UCL EPICentre and HR Wallingford to try to find that way. Its aim has been to fill the knowledge gap in engineering design and assessment of seawalls and buildings subjected to tsunamis. The collaboration has led to the development and application of 3 generations of a unique laboratory device, the Tsunami Simulator (TS). This device can recreate stable depression-led and elevated waves that that provide realistic representations of tsunamis.
Within URBAN WAVES 2 phases of experiments are being carried out using this novel tsunami generator to measure tsunami impact on coastal defences, forces on single buildings and arrays of structures, and for the first time, scour around simple structures from tsunami inundation. The project is supporting the large scale experiments in the tsunami facility with smaller scale experiments at UCL, and is developing a suite of different numerical analysis tools to help engineers and scientists implement the new science being discovered on tsunami inunundation interaction with coastal infrastructure.
The first phase of tsunami test was completed in December 2015. It focussed mainly on an investigation of the impact of tsunami on coastal defence structures and single buildings. These data are informing development of simplified relationships for tsunami forces / pressures suitable for inclusion in codes of practice. In parallel, advanced finite element models of buildings subjected to tsunami time-histories are being used to develop guidance on how to apply tsunami loads to buildings and assess their response and damage level. These findings are being extended to develop simplified structural analysis methods that are more suitable for the development of fragility functions for the estimation of damage to populations of buildings (N.B. these are used extensively in the calculation of tsunami risk to coastal populations).
Phase 2 testing within URBANWAVES is currently underway and will end in October 2016. It looks to measure how tsunami interact with multiple buildings, and integrates the coastal defence and buildings research to investigate what happens to buildings that are fully or partially protected by sea defences. These tests are taking place in the new Fast Flow Facility at HR Wallingford; a 70m long by 4m wide wave flume, that due to its width will allow 3D effects to also be investigated, and will for the first time allow the investigation of tsunami scour around buildings.
Scientifically, experiments carried out with the tsunami generator have demonstrated that tsunami (i.e. very long waves) show different run-up characteristics than the longest waves generated previously (n.b. run-up is a measure of how far inland the tsunami inundates). New run-up relationships have been derived and the current experiments looking at forces on buildings and on coastal defence structures are being developed into new semi-empirical equations for the estimation of tsunami forces from knowledge of the inundation flow characteristics. Preliminary relationships have been published and are being further developed. These have the potential to change guidance in current tsunami design codes for vertical evacuation structures, sea walls and critical infrastructure. Novel simple numerical codes are being written that are calibrated to the experiments and which can be used to predict tsunami forces on single and clusters of buildings. The aim is to make these codes freely available, as they can be used to assess coastal urban areas and estimate the level of physical damage and resulting economic and life loss to be expected in future tsunami events. Such a tool will therefore contribute to our capacity to prepare and plan for tsunami.
Further information is available at the following website: https://www.ucl.ac.uk/epicentre/research/engineering-for-natural-disasters/Urban_Waves

Contact

Giles Machell, (European Contracts Executive)
Tel.: +44 20 3108 3020
Fax: +44 20 7813 2849
E-mail
Record Number: 191632 / Last updated on: 2016-11-21
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