The term blinding is used to describe the thin layer of unreinforced over-site concrete which is used to protect the base of excavations. Blinding is not generally seen or exploited as a beneficial structural element even though it clearly provides some temporary lateral support to the walls of cut and cover works until the base slab is constructed. This proposal stems from Powderham's pioneering work at Mott MacDonald, which shows that blinding struts can eliminate the need for temporary steel propping in cut and cover excavations. Mott MacDonald has used blinding struts in the construction of the Channel Tunnel cut and cover works, the Limehouse Link and the Heathrow Express cofferdam. The hallmark of these projects was the elimination of temporary steel propping from a series of deep excavations which paved the way for further time and cost saving schemes. It is important to note that in all these applications, the actual capacity of the blinding struts and the loads they were carrying were unknown. Therefore, a very conservative approach was adopted for the blinding struts which resulted in the struts being thicker than necessary with consequent cost and environmental implications. Research is required since many clients are unwilling to sanction the use of blinding struts because their performance has not been definitively established.The research will develop a numerical method for predicting the response of blinding struts in cut and cover excavations that is calibrated with data from laboratory tests and field data where possible. Predicting the failure loads of blinding struts is complex since the buckling load depends on factors including cracking, creep, shrinkage and the rates at which the lateral and transverse loadings are introduced into the slab relative to the development of concrete strength. This problem will be solved by carrying out a coupled analysis using both geotechnical and structural finite element programs. A simplified model for the structural response of the blinding strut will be used in the geotechnical analysis. This will enable strut loadings to be determined which will then be used in a refined structural analysis of the strut itself. The overall process will involve iteration, with the structural analysis refining the simplified strut model used in the geotechnical analysis, which in turn will provide improved estimates of the strut loading. This process, combined with the results from the laboratory testing, will lead to a proposed model for the non-linear behaviour of the blinding strut that can be adopted by others in their geotechnical analyses accounting for the specific site and construction conditions.The numerical analysis of the blinding strut will be carried out using the nonlinear structural analysis program ADAPTIC, developed by Izzuddin, which already provides all the necessary elements and material models for assessing the timedependent response of the blinding strut. The geotechnical analysis will be performed using the finite element program ICFEP developed by Potts. This program has been written specifically for geotechnical engineering and has been applied to a wide variety of soil-structure interaction problems. The geotechnical analysis will investigate the behaviour of an embedded cantilever wall with and without a single prop near its top. In both cases, a temporary blinding strut will be modelled at final excavation level. The construction sequence will be based on the procedures adopted at the Limehouse Link, Heathrow Express Cofferdam and Airside Road Tunnel constructions. Soil conditions will also be based on these sites with analyses conducted for excavations in predominantly London Clay and in the Lambeth Group. A series of 20 laboratory tests will be carried out on scale models of blinding slabs with variations in material properties, end conditions and lateral imperfections. The test results will be used to validate and refine the numerical analysis.

Many large buildings in cities around the world, including transport hubs such as major underground stations, have significant basement structures constructed within an overconsolidated clay formation. A key uncertainty in the design of the basement structures is the earth pressures that build up underneath the lowest ground-contacting floor slab due to the tendency for long-term swelling of the clay. As soil is excavated to form the basement, unloading of the clay beneath the basement results in an initially undrained soil response, in which the reduction in total stress is transferred to the soil pore water as a tension as the clay tries to heave. Initial heave of the clay beneath the excavation occurs on unloading due to shear, and from swelling as rain or ground-water infiltrates into the soil. In the longer term, swelling of the clay takes place as the non-equilibrium pore pressures and suctions generated during excavation continue to equilibrate to a long-term steady state condition. In low permeability clays, this can take decades, and much of the swelling may take place long after the basement structure is complete. Basement slabs are often designed to be ground contacting, to avoid the difficulty in creating a void into which swelling can occur. Long-term clay heave and pore water pressures (if no drainage beneath or through the slab is allowed) then load the base of the concrete slab directly. It is therefore necessary to design large basement structures to accommodate the long-term heave of the clay. The flexural stiffness of the basement slab dictates the pressures that build up underneath it, with more flexible slabs allowing some soil swelling to take place that likely reduces the build up of pressure. Stiffer slabs will reduce heave, but at the cost of greater effective earth pressures. The final swelling pressure is dependant on the soil stiffness and movement, which can be difficult to determine. The tendency is to be conservative, although this results in deep slabs, which create a stiffer structure that then has the potential to attract more load from the swelling soil. The difficulty in determining the final swelling pressure is primarily in estimating the stiffness of the clay to determine the soil strain and movement that will occur. The high stiffness of the soil at small strain is important, and models that match stiffness to the likely strain level in the soil tend to produce better estimates of heave. The stiffness of soils at very low stresses can also be difficult to determine, and relationships obtained from laboratory testing may give unrealistically high void ratios at very low soil stresses. Field measurements have proved an important means of benchmarking models for clay soils, however, there have been few, if any, attempts to measure the heave pressure and associated structural reactions within the base slab, or to take long-term measurements of continued change long after construction has finished. Basement structures in cities such as London are becoming ever deeper (recent cases are up to 35 m deep), with the result that estimated swelling pressures and design slab depths are increasingly large. A better understanding of how swelling takes place, and the pressures that build up beneath ground-contacting slabs will to produce significant efficiencies in design and cost. This project proposes to investigate the relationship between swelling heave and base slab pressures, initially in the short-term, through instrumentation of a large excavation in London Clay being constructed as part of the Victoria Station upgrade. Instrumentation will be installed to measure soil displacements, changes in pore water pressures and base slab loading; and to monitor them during and shortly after construction. A further application will be made to EPSRC to continue to monitor and investigate long-term changes.

Field monitoring has provided many important insights into the real behaviour of geotechnical transport infrastructure such as embankments, tunnels and retained or battered cuts, resolving uncertainties for research, design, construction control or economic purposes. Where such monitoring is carried out, it is usually over a relatively short period of time for example during construction or in connection with a specific maintenance or remediation requirement. Professor Robert Mair's March 2006 Rankine lecture demonstrated the value of longer term field measurements, which may indicate unexpected and unforeseen continuing changes in the behaviour and condition of the infrastructure and the state of the surrounding ground. As the owners and custodians of our transport infrastructure seek to extend its economical life through sometimes extensive in-service maintenance and refurbishment, an understanding of the factors governing its long-term behaviour and state will become increasingly important.In recent years, the Geomechanics Research Group at the University of Southampton has installed loggable instrumentation in connection with a number of research projects to investigate the performance during and for a short period after construction of geotechnical structures such as slopes and retaining walls for transport infrastructure. In some cases, this instrumentation is still in place and working, offering a unique opportunity to continue monitoring to gain an insight into the long-term performance of the structures as equilibrium conditions are gradually reached, perhaps in response to new or unforeseen boundary conditions such as changing climate patterns and groundwater conditions or further construction nearby. The proposed research offers the opportunity to answer some questions concerning the long-term performance of geotechnical transportation infrastructure whose answers have remained elusive for decades. These are the potential for the re-establishment of in situ lateral stresses on retaining structures in overconsolidated deposits; the interpretation of strain gauge readings in underground concrete structures as the concrete ages; the impact of cyclic seasonal variations on the stability of unreinforced and remediated cutting and embankment slopes; and the interactions between buried structures and the groundwater regime. All of these will have major benefits in terms of the design of new infrastructure and predicting the service life and impacts of climate change on existing structures.

There are a variety of aerodynamic effects associated with train design and operation - the determination of aerodynamic drag, the effect of cross winds on train stability, pressure transient loading on trackside structures, the physiological effect of tunnel pressure transients, the effect of train slipstreams and wakes on waiting passengers and trackside workers etc. The magnitude of these effects broadly increases as the square of the vehicle speed and thus with the continued development of high speed train lines aerodynamic effects will become more significant in terms of design and operation. Now it can be hypothesised that the techniques that have been used to predict aerodynamic effects in the past (wind tunnel and CFD methods) are likely to determine magnitudes of pressures, velocities, forces etc. that are higher than those observed in practice, where other effects - such as track roughness, variability in meteorological conditions etc. are likely to usually obscure aerodynamic effects to some extent and, because of this, some of the current design methodologies are unnecessarily restrictive and/or conservative. Thus the aim of the current project is to investigate and measure a range of aerodynamic phenomena observed in real train operation, both relative to the train and relative to a fixed point at the trackside, and to compare how such effects match model scale measurements and various types of CFD calculation, and thus to test the validity, or otherwise, of the above hypothesis. This will be achieved through the instrumentation of the Network Rail High Speed Measuring Train to measure aerodynamic effects, as the train carries out its normal duty cycle around the UK rail network. Also trackside instrumentation will be installed at a suitable site that will allow off-train phenomena to be measured. Calibration wind tunnel, CFD and moving model tests will be carried out in the conventional way for comparison with data measured at full scale. The full scale, model scale and computational trials will be carried out by experienced RFs and will provide data for two doctoral studies, one of which will investigate how the train based measurements of cross wind forces, pressure transients etc compare with those predicted by conventional methodologies, and one of which will investigate how the track side measurements compare with conventional test results. The investigators will synthesise the results and make recommendations for future aerodynamic test methods.

Central to the UK's ambition to achieve Net Zero is the increasing transition to renewable wind energy. To achieve this goal, the UK has set out a Ten Point Plan for a Green Industrial Revolution which places offshore wind at Point One in its energy strategy. Already a global leader, the UK aims to generate 50% of its electricity using wind power by 2030, nearly doubling its current output. However, the UK is facing a compelling challenge of dealing with massive amount of waste blades while benefitting from wind power. The lifetime of wind blades is 25 years. It is estimated that around 5,200 blades of ~34,400 tons will be decommissioned in the next 5 years in the UK and this number will increase by 10 times by 2050. By then, Europe will have 325,000 waste blades. It is estimated that 43 million tons of waste blades will be decommissioned globally by 2050, making it a pressing national and international issue. The wind turbine blades are predominantly made of fibre glass composites comprising glass fibres embedded in a polymer resin (e.g. epoxy). These composites are engineered to be very tough, making them extremely difficult to decompose in the natural environment. Unfortunately, the current recycling methods are either energy intensive or too expensive, leaving the waste blades to be landfilled or incinerated creating serious environmental problems. Some European countries have banned landfilling waste blades through legislation and the UK is expected to follow this trend. Construction industry is also facing a critical environmental issue because the production of cement (as the key constituent of concrete) is an energy intensive process with huge CO2 emissions. Generally, producing one ton of cement releases about one ton of CO2 in the air, making cement production account for 8% of global greenhouse gas emissions. The UK construction industry consumed 15,218,000 tons of cement in 2020, and it is in an urgent need of technologies for reducing cement consumption to achieve the Net Zero goal by 2050. My fellowship aims to develop a completely new and feasible technology to recycle waste wind turbine blades for making low-carbon concrete (WINDCRETE). This is underpinned by my pioneering research which shows that the silica-rich recycled powder from grinding the waste blades is chemically reactive in alkaline solution (pozzolanic reactivity), so that it can replace cement for making concrete. I will develop WINDCRETE into a new construction material through a series of fundamental research in (a) glass and polymer separation, (b) hydration and molecular modelling, (b) pozzolanic reactivity maximisation, (c) strength/durability optimisation and (d) life cycle analysis (LCA). I have engaged with 9 industrial partners across broad sectors including wind blade manufacturer, cement and concrete producer, construction and designer, waste management, composites trade association and innovator. In close collaboration with industries, I will bring WINDCRETE from the lab to the real world through a startup which is underpinned by two patents developed from this research and successful demonstrations on the partners' construction sites. WINDCRETE brings an exciting opportunity to address two global issues in both wind energy and construction industries, establishing a new paradigm in recycling waste blades while decarbonising concrete. More importantly, I will generalise WINDCRETE to extend its impact to wider industries like aviation, automobile, marine and electronics, which are using massive fibre glass composites but facing the same challenge of recycling the waste.