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Title: Monitoring ground movements and infrastructure in London, UK, using Permanent Scatterer Interferometry
Author: Bischoff, Christine Anna
ISNI:       0000 0004 8499 569X
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 2019
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Satellite-based surface deformation monitoring across London reveals fascinating patterns of mainly anthropogenic origin, associated with various civil engineering projects. Geological anomalies-e.g. faults, buried hollows, etc.-affect groundwater flow and so become visible in the surface deformation patterns associated with dewatering. The unique ability of Permanent Scatterer Interferometry (PSI) to detect these millimetre-scale movements over a wide area opens up the possibility for construction monitoring and safer aquifer management, while also providing a tool for detecting subsurface anomalies. This research explores the capabilities of InSAR data, from several sensors, processed using the SqueeSAR® algorithm, and explores how these data can be utilised and interpreted for an urban environment. The comparison between high-resolution TerraSAR-X data and medium-resolution Sentinel-1 data shows that regional phenomena are detected in both datasets but local deformation is significantly better resolved in TerraSAR-X data. Crossrail Ltd terrestrial monitoring data are used to validate the ground deformations observed in TerraSAR-X data, and show very good agreement. The observed Crossrail settlement trough is highly variable in extent, mainly resulting from the size and different tunnelling techniques used for stations and crossovers, but not all the variability is explicable. Further investigation of anomalous deformation patterns reveals a seasonal pattern of rise and fall of the roof of Blackfriars Bridge, superimposed on long-term settlement, and differential settlement across the O2 Arena caused by dewatering north of the Thames. Subsurface piezometer readings taken in London's Chalk and Thanet Sands aquifer are strongly correlated with PSI surface displacement, confirming that dewatering is detected in TerraSAR-X data, and anomalies in the deformation patterns reveal the locations of groundwater-sealing faults. Surface deformation associated with dewatering for the Northern Line Extension in South London show distinctive patterns related to buried hollows. These observations all demonstrate the unique capability for PSI data for ground monitoring and its potential value to geoscientists and civil engineers.
Supervisor: Mason, Philippa ; Ghail, Richard ; Ferretti, Alessandro Sponsor: Engineering and Physical Sciences Research Council
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral