Geological and geotechnical data

Geological and geotechnical investigations at the site are typically carried out with the following objectives  

It is recommended that the soil profile be physically identified (e.g. through drilling) to a depth equal to at least one half of the maximum foundation depth. The depth to firm bearing strata may also be determined using boreholes and/or geophysical methods. 

For hazard category 1 and 2 research reactors, dynamic characteristics of the soil profile may be determined by means of cross holes or geophysical methods up to the base rock or to a depth of at least 1.5 times the maximum foundation depth. The dynamic characteristics of the soil material for each layer may include  

Curves g-y and d-y are necessary for soft soil conditions and for hazard category 1 and 2 research reactors. The soil characteristic curves can be determined by laboratory test or by generic curves which are available in the technical literature [26]. For hazard category 3 research reactors, standard curves can be used from the technical literature for the identified soil conditions. 

In parallel with the foundation investigation and the use of available geological or geotechnical data, studies may be carried out at the site to assess possible hazards which could result in permanent soil deformation (including surface rupture, liquefaction, collapse, slope instability). If these investigations indicate potential consequences from such hazards, further studies may be necessary or the site has to be rejected. 

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