5 Geotechnical investigation

5.1 General

5.1.1 The geotechnical investigation shall fulfil the requirements of EN 1997-1 and EN 1997-2.

NOTE Indications are given in EN 1997-2:2007, Annex B on the depth and the contents of geotechnical investigations.

5.1.2 The geotechnical investigation report shall be available in time, to allow for reliable design and execution of the special geotechnical works.

5.1.3 The geotechnical investigation shall be checked to see whether it is sufficient for the design and execution of the special geotechnical works.

5.1.4 If the geotechnical investigations are not sufficient, a supplementary investigation shall be conducted.

5.2 Special aspects of soil nailing

5.2.1 The interaction between the nail and the ground shall be considered. The site investigation shall establish (or confirm) the nature and the mechanical characteristics of the ground in order to assess the soil nail interface properties directly or by comparable experience.

5.2.2 Stability of the face during construction shall be considered, with special respect to geotechnical, hydro-geological and hydrological conditions (see 9.3.4).

5.2.3 Excavation tests should be performed to evaluate the stability during construction, if bulk excavation is to take place.

5.2.4 If necessary on account of site conditions, specific instrumentation (inclinometers, piezometers, etc.) should be installed.

5.2.5 An assessment of the aggressiveness of ground and groundwater shall be established in order to define the durability requirements of the soil nail material with respect to design life, see Annex B.