FOCUS: Intelligent Fibre Optic Monitoring to Inform the Construction of Underground Services

Lead Research Organisation: University of Oxford
Department Name: Engineering Science

Abstract

UK construction is a multi-billion pound industry. While it is the most vital cog in the UK economy for creating physical assets, it is widely regarded as slow to innovate. High risks and the significant cost of mistakes promotes a level of conservatism which is much greater compared to other industries. Change therefore tends to be iterative and cautious. Supported by the UK Government through the implementation of various construction initiatives, such as 'Construction 2025' and 'Transforming Construction', the industry is beginning to embrace technology in a transformative way. The technological revolution is already under way for 'above-ground' construction activities, with modular construction and building information modelling being primary examples. One of the biggest obstacles to underground construction making similar gains is uncertainty surrounding how structures interact with soils during construction operations i.e. 'soil-structure interaction' (SSI). Soil-structure interaction plays a critical role in underground construction operations yet the tools that are used to predict them remain remarkably over-conservative. This is because predictive models for SSI are non-existent, over-simplified or are calibrated against measured data obtained from model-scale replicas of the process in the laboratory, essentially representing an 'ideal' soil-structure interface.

The work described in this proposal will develop the underpinning engineering science for SSI design applied to underground construction. Laboratory testing and numerical modelling will be used to elucidate the mechanics of soil-structure interface behaviour such as the role of strain level, stress level and time on the development of soil-structure contact stresses and pore water pressures. Intelligent monitoring systems will be developed to measure and monitor soil-structure contact stresses on live construction projects to provide (i) field data for rigorous validation of developed design methods and (ii) real-time, automated feedback to site engineers to inform construction processes and provide 'early warning' of adverse responses. Recent advances in fibre optic sensing will be exploited to develop novel multi-directional contact stress sensors. The new sensors will alleviate limitations associated with traditional transducers such as excessive sensor flexibility (which actually influences the soil stress field the sensors are intended to measure) and immunity to electromagnetic noise and water damage. A multi-directional interface shear apparatus will be developed to validate the contact stress sensors and provide additional insight into the behaviour of an 'ideal' soil-structure interface in the laboratory. The monitoring system will employ machine learning algorithms in the form of Bayesian non-parametrics such that prior data from previous construction projects may be synthesised with newly-acquired data to provide a robust data-driven decision-making process. The monitoring system will be deployed on live construction projects in the UK alongside industry partners. A suite of new design methods tailored specifically for underground construction operations will be developed, informed by the field monitoring, laboratory testing and numerical modelling. Embracing the innovation and technology developed in this project will allow the construction industry to obtain and utilise intelligent and actionable data that can save time and money, and improve construction safety. This will contribute to the UK becoming a global hub for the rapidly growing market for construction-related services throughout the world.

Planned Impact

The potential to translate research outcomes into economical, societal, and environmental benefits are very substantial. The construction industry would benefit significantly from the proposed SSI design methods and monitoring systems. These methods and systems will reduce the uncertainty associated with soil-structure interaction during underground construction, leading to improved project outcomes. For example a build-up of soil-structure interface friction will be identified early on in projects, thereby allowing preventative action to be taken, avoiding work stoppages and project delays. The development of an underground construction research group at Oxford will also produce the next generation of construction professionals to revitalise the industry.
The public sector will benefit from this research because a reduction in underground construction risks are associated with lower construction costs as a result of reduced contingency in project budgets and more reliable project timelines. Construction activity is one of the cornerstones of the UK's economy and contributes significantly to economic growth. It reflects dynamic growth in other industries and is itself a core provider of jobs. Beyond the construction activity itself, construction also drives demand for various building materials. Often perceived as being behind the curve, it is critical that the construction industry embraces innovative technology to guarantee UK prosperity.
The PI will also personally benefit as the research leader of FOCUS by further developing his skills and expanding his research team. The research team will benefit from the valuable training in state-of-the-art facilities offered by the industry partners. They will also benefit from a number of career development opportunities including outreach events and a very wide range of courses run by the Mathematics and Physical Life Sciences Division at Oxford. In the long-term, the PI intends to integrate 'Construction Engineering' into the undergraduate curriculum which is, perhaps surprisingly, not currently taught at Oxford. The Oxford engineering undergraduates will therefore also benefit from both a new course and the inclusion of cutting-edge research being conducted by the PI's group.
The construction industry is the single largest global consumer of resources and raw materials, so even a 1% reduction in construction costs would save society huge sums globally. Value therefore lies in improving construction practice, leading to efficiency gains and reduced consumption of materials. Society as a whole will experience a major benefit from significant reductions in CO2 emissions on planned construction projects. Driving down both the economic and environmental costs of construction will boost the resilience of the UK infrastructure sector.
The construction industry is generally perceived by the public as an old-fashioned, wasteful and male-dominated industry which has, in part, contributed to a major skills shortage in the UK construction sector. Attracting young engineers and tradespeople into construction has become increasingly challenging. Inevitable retirements of experienced UK construction personnel means the UK skills shortage is likely to worsen. The public engagement / outreach activities outlined in 'Pathways to Impact' will increase public awareness of modern underground construction practice. They will also highlight the huge variety of construction related careers. For the industry to begin appealing to those who currently view it as very static, it is crucial that young people are made of aware of these opportunities and developments.

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