Field monitoring and numerical simulation reveals low ground volume loss during twin mechanised excavation, indicating calibrated 3D models accurately predict urban tunnelling impacts.
Key Points
To evaluate ground displacement induced by twin mechanized tunnel boring and validate a predictive three-dimensional numerical model.
Monitored surface and subsurface ground response using extensive field instrumentation at a greenfield test site during twin-tunnel excavation using earth-pressure balance tunnel boring machines.
Performed 3D numerical analyses simulating progressive face advancement using constitutive soil models calibrated with laboratory and in situ geotechnical data.
Observed ground volume loss was 0.3% for the first tunnel drive and 0.45% for the second tunnel drive.
Prior excavation generated plastic strains that resulted in non-symmetrical settlement troughs and cumulative horizontal subsurface displacements directed toward the second tunnel.
The 3D numerical simulation accurately replicated the observed surface and subsurface displacement fields, resolving field measurement uncertainties.