Geological and hydrogeological conditions are determining factors for underground projects. Encountering unforeseen aspects may stop a project or even make it unfeasible.
Therefore it is absolutely necessary from the beginning to have an "image" as precise as possible of all caracteritics of soils or rocks . 
| - Support planning & define project feasibility
| - Identify items that may need contingency plans | - Determine most economical and appropriate
| - Route and depth - Excavation and support methods | - Define physical characteristics of the soil, rock, and groundwater
| - govern the behavior of the tunnel | - To minimize uncertainties of physical conditions for thebidder & to improve safety
| | - Provide specific data needed to evaluate
| - constructability - cost - productivity - schedule | - To document as- built conditions of the completed project
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- Inventaire des données géologiques - Levé géologique de surface - Prospection géophysique - Gravimétrie - Magnétométrie - résistivité électrique - electro magnétique - réfraction sismique
- Borings - Horizontal - Vertical - dirigés
- Inventaire des données - Levé hydrogéologique de surface - Géophysique - résistivité
- Borings - Mesure de perméabilité
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