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Ground conditions including geological, geotechnical, and hydrological conditions, have a major impact on the planning, design, construction and cost of a road tunnel, and often determine its feasibility and final route.

Geophysical tests obtain subsurface informations over a large area quickly and economically (stratigraphy and general engineering characteristics) in order to help to define stratigraphy and to identify appropriate locations for performing borings.


Fundamentally, geophysical subsurface investigation is the most important type of investigations to obtain ground conditions, as it is the principal means for:

  • Define the subsurface profile (i.e. stratigraphy, structure, and principal soil and rock types)
  • Determine soil and rock material properties and mass characteristics;
  • Identify geological anomalies, fault zones and other hazards (squeezing soils, methane gas, etc.)
  • Define hydrogeological conditions (groundwater levels, aquifers, hydrostatic pressures, etc.); and
  • Identify potential construction risks (boulders, etc.).