Geoelectrical Real-time Ground Prediction 

The Bore-Tunnelling Electrical Ahead Monitoring - BEAM® -, developed and patented by Kaus et. al., managing director of GET, is a geophysical ground prediction technique especially designed for the underground construction industry.

Supplied on a rental basis, it is increasingly ordered since the year 2000 to serve at more than 80 international TBM projects, thereof 74 TBM projects with a total length of more than 300 km

Beside the standard TBM operations, special applications has been performed for drill & blast drives and also perimeter investigations for cavity detection in karst formation around existing tunnels.

BEAM SCAN mode at Highway tunnel Galleria
SPARVO in Italy, 2011-2012: EPB Ø 15.55m



Real-time Ahead Monitoring for TBM Drives

BEAM is a non-intrusive focused-electrical induced polarisation ground prediction technique, permanently operating while TBM tunneling.

It is a robust and reliable long-term operating geophysical probing technique fulfilling the practical demands under the rough conditions of tunnelling work in hard rock as well as in soft ground.

Main components of the survey system are the measuring instrument placed in the TBM operator cabin and special adapted excavation tools which are used as electrodes. The unit is connected to the guidance system and receives the boring signal which allows fully automatic data acquisition and visualisation in real-time on an integrated monitor. Communication facilities transfer the forecast results to every accredited computer world wide simultaneously.

Based on the measuring data the percentage frequency effect PFE and the resistivity R, an advanced evaluation software is established for geoelectrical-geological/ hydrogeological classification and interpretation.

Early warning information of significant ground changes while tunnelling is advantageous to reduce hazardous risks, in particular during excavation with tunnel boring machines. Accidents or complications and hence expensive standstills can be prevented by planning precautionary and logistical measures.

 On the condition that TBM operations and lining works should not be obstructed by data acquisition, a probing and documentation without predrillings is one major demand. On the other hand knowledge of non-critical ground conditions ahead of the face allows rapid excavation resulting in high production rates and contributes to shield staff and equipment.

BEAM Multi Channel Unit

Early warning information for critical ground while TBM boring reduces hazardous geo risks like enhanced water-inflow




l2 The TBM based BEAM system allows a fully automatically and permanent driving accompanying exploration of ground conditions about 3 times the tunnel diameter.




l2 BEAM combines the well established principles of focusing-electrode logging and frequency-domain induced polarisation  (IP) measurements.



l2 e.g lateral distribution view of PFE values: Indication of a cavity zone (red anomaly) within pyroclastics on the left top side ahead of the TBM.