2.1 General (p. I)

(1)P Site investigations consist of desk studies, field and laboratory investigations and all other investigations performed in order to establish knowledge of the ground; soil, rock and groundwater conditions, and to determine the properties of the soil and rock. Site investigations may also include appraisal of existing constructions, tunnels, embankments and slopes and the environmental impact of the project.

(2) Ground investigations are normally performed in phases depending on the questions raised during planning, design and construction of the actual project, see 3.2.1 of ENV 1997-1. The following phases are treated separately in this section:

  • preliminary investigations for positioning and preliminary design of the structure, see 2.3;
  • investigations for design and construction, see 2.4;
  • control investigations, see 2.5.

(3) The provisions in this document are planned primarily for geotechnical category 2 projects (see 2.1 of ENV 1997-1) and based on the fact that the results from investigations recommended in one phase are available before the next phase is started. In cases where all investigations are performed at the same time, both 2.3 and 2.4 should be considered simultaneously.

(4) The ground investigation requirements for category 1 projects are normally limited as the verifications often will be based on local experience. For category 3 projects the amount of investigations required will normally be at least the same as indicated for category 2 projects in the following sections. In addition complementary investigations related to the circumstances that place the project in category 3 may apply.

(5)P The composition and the extent of each phase of the investigations shall be based on the following:

  • the topographical, geological and hydrogeological conditions on the site and pertinent available information about them;
  • the type and design of the construction, e.g. type of foundation, improvement method or retaining structure, location and depth of the construction;
  • the local experience and climate conditions.

(6)P When composing the investigation programme both for field and laboratory tests, the knowledge from desk studies of the following documents, if available, and the results of a site examination shall be accounted for (see 3.2.3 of ENV 1997-1):

  • topographical maps;
  • old city maps describing the previous use of the site;
  • geological maps and descriptions;
  • engineering geological maps;
  • geohydrological maps and descriptions;
  • geotechnical maps;
  • aerial photos and previous photo interpretations;
  • aerogeophysical investigations;
  • previous investigations at the site and in the surroundings;
  • previous experiences from the area;

(7)P the use of preliminary investigations shall be considered.

(8) The extent of direct field investigations and sampling with subsequent classification and laboratory testing depends on the geology, type of structure and the local experience.

(9)P The preliminary investigations shall be planned in such a way that adequate data are obtained, when applicable, concerning:

  • the overall stability of the area;
  • suitable positioning of the structure;
  • possible foundation methods and ground improvements;
  • possible effects to neighbouring buildings;
  • preliminary costs for foundations and ground improvements;
  • preliminary costs for provisional constructions;
  • proposals for design investigation.

For planning and execution of preliminary investigations reference is made to 2.3.

(10)P Investigations for the design and construction phase shall provide sufficient information to the following questions, when applicable:

  • location of construction;
  • foundation methods and levels;
  • erosion protection;
  • protection against swelling and shrinkage;
  • ground improvements or other stabilizing measures;
  • foundation design;
  • design of temporary constructions;
  • excavatability;
  • driveability for piles;
  • drainages and filters;
  • frost susceptibility;
  • methods and order of construction/operations;
  • requirements for the selection of filling material;
  • slope inclination;
  • existing hindrance such as old constructions and service pipes and cables;
  • durability of construction material in the ground.

For planning and execution of investigations for design and construction reference is made to 2.4.

(11) Annex A provides a flow chart which can be used for the selection of a proper fieldinvestigation method for the various soil investigation stages.

(12)P Where construction elements are applied in the geotechnical structures of which the durability may be affected by the surrounding soil and groundwater, the aggressiveness of the soil and groundwater shall be determined, to enable provisions when applicable, (see 2.3 of ENV 1997-1).

(13) To determine the aggressiveness of the ground and groundwater a selection of chemical analyses often should be undertaken and the results compared to available experience on the aggressiveness to various construction materials and protection techniques. Chemical analyses often require groundwater sampling and thus special provisions in the borehole.

Eurocode 7 Geotechnical design — Part 3: Design assisted by fieldtesting