The projections of sea level rise show that UK sea level will continue to rise well beyond 2100, even under scenarios where future temperature rise is stopped. Extreme sea level events are also expected to become more frequent in the future and occurring about 20 to 30 times more frequently by the year 2050, according to Intergovernmental Panel on Climate Change (IPCC). Sea level rise poses a distinctive and severe adaptation challenge as it implies dealing with slow onset changes and increased frequency and magnitude of extreme sea level events which will escalate in the coming decades. According to IPCC, unavoidable sea level rise will bring cascading and compounding impacts resulting in flooding and damages to coastal infrastructure that cascade into risks to livelihoods, settlements, health, well-being, food, and water security in the near to long-term.

Vertical or near vertical seawalls, or dykes/embankments with wave walls are example defences as adaptation measures to sea level rise. In the UK 3,200 km of coastline is defended, particularly in seaside towns and cities. Yet, they have the risk of increased exposure to climate risks in the long-term. The extent to which the seawalls can be integrated as a part of the long-term climate change adaptation plans will depend substantially on their response to future sea level rise and extreme sea level events. To adapt the seawall design accordingly, the impact of wave overtopping on the overall stability of seawalls need to be evaluated in terms of modified backfill soil-seawall interaction due to wetting-drying cycles.

The purpose of this PhD research is to administer a thorough knowledge on the response of backfill soil – seawall interaction subjected to wetting-drying cycles. The project will achieve it through performing element-scale, backfill soil – seawall shear interface tests to investigate the impact of (i) wave overtopping regime (frequency, amount, length), (ii) soil properties and (iii) wall interface properties on the interface response. The successful candidate will work within the framework of the Project “PIONEER: An adaptation approach for resilient coastal infrastructure against sea level rise”, a collaboration between the University of Edinburgh and Virginia Tech, funded by Engineering and Physical Sciences Research Council (EPSRC). Therefore, the project will not only forge an experimental framework in understanding the fundamental mechanics of backfill soil – seawall interaction but will also serve opportunities of upscaling from element-scale to full-scale.