Profile Monitoring System for Tunnel Concrete Segments

Geonor, Inc - Precision Instrumentation


The RST Profile Monitoring System for Tunnel Concrete Segments is a series of tilt meters, fixed to the tunnel wall on each of the precast concrete segments erected in place as tunnel lining by a Tunnel Boring Machine (TBM). The system is based on the assumption that each concrete segment is a rigid body and that the complete ring deforms by rotation of the individual segments one relative to the other, and the rotation points are the contact surfaces between adjacent segments. This assumption is very often considered as acceptable by tunnel designers and reasonably close to reality, although spot checks using traditional convergence measurements or surveying methods should be conducted to confirm its validity for each individual tunneling circumstances. This Profile Monitoring System using tiltmeters is a simplified version of the Tunnel Profile Monitoring System (see separate data sheet) and its main advantage is that it can be deployed in the tight space available around the TBM, whereas the Tunnel Profile Monitoring System would be much more difficult to install in the same situation to monitor deformation. A data logging system and Geoviewer software (see separate data sheet) are available to provide near real time displacement and generate a graphical representation of the tunnel convergence.


  • Very low profile design, suitable for installation in the tight space available around TBMs.
  • No tunnel traffic interference.
  • High system accuracy.
  • Tiltmeters can easily be redeployed periodically to follow tunnel face progression.
  • Built in connectors for manual tape extensometer connection to verify operation, and aid in initial installation and commissioning.
  • Integral transient lightning protection.
  • Immune to the air density related problems inherent in optical systems.
  • On board electronics to minimize electrical noise problems, and permit tilt sensor calibration independent of cable length effects. Cable length may be changed without affecting sensor calibration.
  • GeoViewer near-real time software with full graphic and alarm capability.
  • Digital Bussed System: single, interconnected cable from one tiltmeter to the next, to simplify installation and reduce cost.


  • Monitor the convergence of precast concrete segments in TBM-driven tunnels during construction for control and safety.
  • Monitor tunnel deformation due to nearby construction activities.
  • Monitoring long term deformation and performance of existing tunnels.


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