Research Talk - Dr Xiaomin Xu, Title - Fibre optic instrumented geogrid for ground movement detection

Abstract: The serviceability of civil engineering assets can be negatively impacted by ground movements occurring after construction. Various factors contribute to such movements, including dissolution features, differential movements at transitions between earthwork and structures, as well as movements associated with mining legacy voids. These issues are further exacerbated by the increasing frequency of extreme weather events, which affect ground conditions and heighten the risk to earthwork assets. Unfortunately, there is a limited number of methods available for monitoring large areas effectively and providing early warning of ground movement development. To address this challenge, the incorporation of distributed fibre optic sensing (DFOS) systems into earthworks can offer crucial insights into ground movements in near-real-time, aiding critical infrastructure situated in high-risk areas. This seminar will introduce a newly developed sensing solution called the Sensorgrid, which is a DFOS instrumented geogrid designed for detecting ground movements. The effectiveness of this solution was evaluated through controlled laboratory tests and small-scale field experiments, which assessed its measurement sensitivity, strain profile characteristics, and overall robustness. Building upon the positive results from these trials, a large-scale field deployment of the Sensorgrid has been installed over a 100 m-long and 10 m-wide section of the mainline alignment on the HS2 site at Tilehouse Lane Cutting (TLC). This deployment enables continuous monitoring, near real-time data processing, and visualization, allowing for the detection of potential ground movements beneath the temporary haul road surface, over which eventually the high-speed line will run. By utilizing DFOS technology in critical infrastructure construction, early identification of ground movement becomes possible, offering opportunities for timely remedial actions to prevent catastrophic failures.