Dr. David Igoe

Geotechnical infrastructure fundamentally underpins the transport, energy and utility networks of our society. The design of this infrastructure faces increasing challenges related to construction in harsher or more complex environments and stricter operating conditions. Modern design approaches recognise that the strength and stiffness of ground, and therefore the safety and resilience of our infrastructure, changes through time under the exposure to in-service loading - whether from trains, traffic, waves, currents, seasonal moisture cycles, redevelopment of built structures or nearby construction in congested urban areas. However, advances in geotechnical analysis methods have not been matched by better tools to probe and test the ground in situ, in a way that represents realistic real-world loading conditions. This research will improve current geotechnical site investigation practice by developing ROBOCONE - a new site investigation tool for intelligent ground characterisation - and its interpretative theoretical framework - from data to design. ROBOCONE will combine modern technologies in robotic control and sensor miniaturisation with new theoretical analyses of soil-structure interaction. Breaking free from the kinematic constraints of conventional site investigation tools, ROBOCONE will feature three modular sections which can be remotely actuated and controlled to impose horizontal, vertical and torsional kinematic mechanisms in the ground closely mimicking loading and deformation histories experienced during the entire lifespan of a geotechnical infrastructure. The device development will be supported by new theoretical approaches to interpret ROBOCONE's data to provide objective and reliable geotechnical parameters, ready for use in the modern "whole-life" design of infrastructure. This research will provide a paradigm shift in equipment for in situ ground characterisation. ROBOCONE will enable the cost-effective and reliable characterisation of advanced soil properties and their changes with time directly in-situ, minimising the need for costly and time-consuming laboratory investigations, which are invariably affected by sampling and testing limitations. Geotechnical in-situ characterisation will be brought into step with modern, resilient and optimised geotechnical design approaches.

In order to achieve the greenhouse gas emissions targets set out in the Paris agreement, Ireland will need to significantly decarbonise its energy supply. Due to reducing costs, offshore wind now offers the most viable means for large scale decarbonisation of Irelands electricity supply by 2030. It is predicted that the offshore wind installation rate in Europe will increase 400% resulting in an industry worth more than €20 Billion per year in Europe alone [1]. In Ireland, it is estimated that 1.8GW of offshore wind capacity at an estimated cost of ~€4.5 billion, will be installed by 2030 [1]. One of the key challenges in the engineering design of an Offshore Wind Turbine (OWT) relates to choosing appropriate values for damping of the OWT structure. Choosing more realistic values of damping in design can lead to significant reductions in the calculated loads acting on the structure, and also large reductions in fatigue damage, which can lead to savings of up to 10% in steel weight across the structure [2]. In the Irish context this would equate to potential cost savings of ~€230m by 2030 (assuming 1.8GW of offshore wind is developed) and in excess of €1 billion per year across Europe. The primary goal of this project is to advance the scientific knowledge of OWT damping and provide accurate and realistic damping values for use in the design of Irish offshore wind farms, specific to soil types and conditions relevant for potential offshore wind development zones around Ireland.

The European Union (EU) has established ambitious renewable energy targets in order to de-carbonise the energy sector. In Ireland, it is estimated that 2.3GW of offshore wind capacity will be installed by 2030 at an estimated cost of €6 billion. The foundations for offshore wind turbines (OWTs) can represent up to 30% of the overall cost of development. Among all components of an OWT structure, the foundations offer the greatest scope for optimisation. Monopile foundations, which are large diameter (typically 4 - 8m) steel tubes driven into the ground, represent around 80% of all offshore wind turbine foundations installed to date and will continue to the be the most common foundation solution for offshore wind for at least the next 15 years [1]. As larger wind turbines are being developed, XL monopiles from 8 - 12m in diameter are needed to be support these. These larger diameter piles typically have a lower slenderness (ratio of length to diameter) than standard monopiles and are therefore significantly more susceptible to the effects of cyclic loading. Because of inadequate understanding of the effects of cyclic loading, XL monopiles are currently over-designed, causing excessive manufacturing, transportation and installation costs. This project aims to improve design methods for cyclic loading effects on XL monopiles through state of the art numerical modelling and calibration against new field test data, and will lead to significant advances in scientific knowledge and improvements in the design efficiency of OWTs. Specifically this will build upon recent advances in the state of the art in numerical modelling of monopiles and a will be validated against recent monopile field test data. The ultimate goal is to reduce cost and improve the viability of the offshore energy, leading to a more rapid reduction in carbon emissions and reliance on fossil fuels.

In order to achieve the greenhouse gas emissions targets set out in the Paris agreement, Ireland will need to significantly decarbonise its energy supply. Due to reducing costs, offshore wind now offers the most viable means for large scale decarbonisation of Irelands electricity supply by 2030. The new program for government 2020 has targeted 5GW of offshore wind capacity to be installed by 2030 at an estimated cost of more than €10 billion. At the end of 2019 there was 22 GW of offshore wind installed in Europe, mainly in areas near shore with favourable shallow water conditions. The foundations of an offshore wind turbine can represent up to 25% of the overall cost of development and more than 90% of offshore wind turbines installed to date are fixed to the seabed using steel piled foundations. This project aims to investigate pile ageing effects, one of the key challenges facing offshore foundation designers. This will be achieved through a combination of novel field and laboratory testing, and will lead to significant advances in scientific knowledge in Geotechnical Engineering and improvements in the design efficiency of Offshore Renewables.

The impact of flooding in Europe has increased over the past 50 years, which is directly attributed to climate change. Due to its geographical position and features, Ireland is especially vulnerable to extreme flooding caused by global warming. The probability of occurrence of these extreme events is increasing and climate disruption will add to the magnitude of such events. Across Britain and Ireland, the magnitudes have been increasing at a rate of approximately five per cent per decade since the 1960s. Flood defence infrastructure built during the 1960s in Ireland is no longer sufficiently resilient to withstand the magnitude of flooding now predicted for vulnerable areas. As a result, there is an urgent need for identifying upgrades for existing flood defence infrastructure in addition to the development of new infrastructure. Typically flood defence infrastructure consist of primarily earth embankments, cuttings, dams, dykes and retaining walls, which are underpinned by Geotechnical Engineering (the branch of civil engineering concerned with the engineering behaviour of earth materials, i.e. soils and rock). Increases in the intensity of rainfall events in recent years have led to a rise in the number of slope failures, and many areas benefitting from flood defence infrastructure are at risk from climate change induced flooding. It is therefore essential to efficiently indentify and allocate resources to the infrastructure which are at highest risk of failure. The proposed research aims to back-analyse industry geotechnical data to better understand the design efficiency, safety and resilience of our flood defence infrastructure in the face of climate change. In order to determine the appropriate risk-reduction measures and cost-effectiveness, the project aims to develop a risk framework to quantify the costs of climate change impact and will include the development of a decision support tool for upgrading and maintenance of Ireland's flood defence infrastructure.