Immediate minimisation of impact from tunnelling on neighbouring structures 1=Engineering 2=Ground Engineering

Lead Research Organisation: University of Warwick
Department Name: Sch of Engineering

Abstract

Underground construction of tunnels, shafts and basements results in ground movements. In many cases these movements can cause damage to the existing built environment and measures must be taken to mitigate the severity of these impacts. For around 30 years a technique known as compensation grouting has been performed to provide this protection. This method requires cementitious grouts and mortars to be injected into the ground under very high pressures. The technique requires large scale construction equipment which is not only expensive but also requires large worksites. On recent projects in London alone (e.g. Crossrail) it is estimated that over £500m has been expended on compensation grouting schemes.

With increasing urbanization, utilisation of underground space is only going to grow, and new and innovative techniques to protect the built environment are needed which are capable of being implemented at a smaller scale and lower cost. It is therefore proposed to investigate the use of expansive geo-polymer injection into the ground, as an alternative to compensation grouting. Expansive geo-polymers are conventionally used for ground improvement of weakened soils and for localised building underpinning at shallow depth, and have the advantage that much lower injection pressures and more compact plant is required compared to other grouting methods. Their combination with real-time monitoring and modelling, in competent ground conditions at greater depth, could enable immediate and efficient reactions to ground behaviour, preventing interruptions of the construction process and ensuring the integrity and functionality of all assets around the construction area.

The response of the ground to expansive geo-polymer injection and the physical processes involved in the expansion in competent ground conditions will be investigated at the laboratory scale and at full-scale, in a field case study. This knowledge will be applied in the development and verificaton of a numerical model suitable for application in prediction of settlement mitigation effects and design of a monitoring and mitigation scheme using expansive geo-polymers with tunneling . This should lead, probably in a future project, to development of a real-time monitoring, modeling and ground movement control system for the geo-polymer injection, utilising appropriate feedback numerical procedures.

Publications

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Studentship Projects

Project Reference Relationship Related To Start End Student Name
EP/R512229/1 01/10/2017 30/09/2021
1935527 Studentship EP/R512229/1 02/10/2017 30/09/2021 Luke Richard Evans