The future may well be digital, but most of our underpinning infrastructure is still dependent on large-scale physical assets with no embedded real-time performance monitoring; Alister Smith is developing novel asset health monitoring technologies that ‘listen’ to buried infrastructure systems
Infrastructure is vital for society – for economic growth and quality of life. Existing infrastructure assets are rapidly deteriorating, the rate of which is accelerating with increasing pressures from climate change and population growth (e.g. increasing flood levels and weight and frequency of trains) and new-builds are being designed and constructed to withstand largely unknown future conditions. Society urgently needs to be better prepared to face these grand challenges by exploiting technology to increase understanding of asset deterioration and improve decision making and asset management.
Infrastructure networks cover vast geographical areas to transport people and products (e.g. water, oil and gas) and hence are critical lifelines upon which society heavily relies. These assets rest on or are buried inside soil, which exposes them to potential damage from ground movements. Deterioration can have catastrophic economic, environmental and societal consequences and the service of entire networks can be terminated.
Proportions of the energy dissipated during deformation of particulate materials (i.e. soil) are converted to heat and sound. The high-frequency (>10kHz) component of this sound energy is called acoustic emission (AE). AE monitoring offers the potential to sense particle-scale behaviours that lead to macro-scale responses of granular materials.
AE is widely used in many industries for non-destructive testing and evaluation of materials and systems; however, it is seldom used in geotechnical engineering, despite evidence of the benefits, because AE generated by particulate materials is highly complex and difficult to measure and interpret.
AE is generated in soil bodies and soil/structure systems through a suite of mechanisms including: inter-particle friction; particle contact network rearrangement (e.g. release of contact stress and stress redistribution as interlock is overcome and regained); degradation of particle asperities; particle crushing; and friction at the interface between the soil and structural element.
The above illustration shows a monitoring concept applied to a buried pipeline. My goal is to develop continuous, remote, real-time AE monitoring systems that can be distributed across geotechnical infrastructure assets (e.g. buried pipelines, foundations, retaining structures, tunnels) to sense soil and soil/structure interaction behaviour, and provide early warning that will enable targeted and timely interventions.
My Philip Leverhulme Prize research programme will use a combination of numerical simulations, laboratory experiments and field tests with particulate materials and soil/structure systems to develop methodologies, such as artificial intelligence analytics, to interpret the AE generated by geotechnical infrastructure assets, enabling implementation in autonomous monitoring systems. If we can listen to geotechnical assets with intelligent sensors - analogous to a stethoscope being used to listen to a patient’s heartbeat – we will be able to provide information on the condition of infrastructure and early warning of deterioration in real-time.