Tunnels and Underground Workings

Instrumentation

In the context of this domain, drilling parameter data recorded by the FORALIM 4G are used both for reconnaisance boreholes and those drilled during the excavation itself. By providing vital information on the geomechanical properties of the formations, drilling parameters make an important contribution to the security and efficiency of tunnelling operations and other underground operations.

In respect of tunnelling operations, the way the drilling parameters are measured depends on the method being used:

Les forages de reconnaissance avec enregistrement des paramètres de forage sont utilisés lors de percements de galeries ou tunnels :

when excavating using explosives, the FORALIM 4G instrument is installed directly on the jumbo drilling the blasting holes. By analysing the parameters recorded during the drilling of these holes, it is possible to detect potential geological accidents such as faults, fractures and cavities and adapt the blasting methodology accordingly.

in the case where a tunnel boring machine (TBM) is used, the FORALIM 4G is installed on the machine that drills an exploratory pilot hole from the tunnel face. In this way, any significant geological phenomena or change in the geomechanical properties of the formations are detected well in advance of the passage of the TBM. With this information at hand, further boring can be planned in such a way as to minimise any potential risk to the TBM.

Logging

See under Logging