Summary
This Case Study covers the construction of twin-bore tunnels for a 6.8km metro rail extension passing beneath a densely developed urban area. The tunnel alignment ran within 8 metres of three heritage-listed buildings, beneath Victorian-era cast-iron water mains, and through unstable, poorly characterized ground. OctaSense deployed a real-time Construction Risk Assessment (CRA) engine that correlated TBM (Tunnel Boring Machine) operational data with live ground and structural responses, allowing engineers to proactively adjust face pressure and advance rates before any settlement thresholds were breached.
Background & Context
Tunnel boring machine (TBM) construction in urban environments requires the most exacting monitoring of any civil engineering activity. As a TBM advances through the subsurface, the removal of ground creates a stress redistribution and volume loss that can cause surface settlement, building damage, and — in the worst cases — sudden collapse of the surface or adjacent structures. In densely built urban settings, even 10mm of differential settlement can cause structural damage to nearby buildings and serviceability problems for utilities.
This case study covers the construction of twin bores for a 6.8-kilometre metro rail extension passing beneath a densely developed urban area. The tunnel alignment passed within 8 metres of the foundations of three heritage-listed buildings, beneath a section of cast-iron Victorian water mains, and through a zone of heterogeneous made ground with poorly characterized geotechnical properties. The construction team and city authorities required real-time monitoring of ground and structural response throughout the TBM advance.
Sensor Deployment
Key Outcomes & Results
Real-time monitoring eliminated the need for costly precautionary underpinning works, saving approximately $3.2M
6.8 km
Tunnel length
Deployment Snapshot
Language
Sydney, Australia