2.2 Sequence of ground investigations
(1)P The composition and the extent of the ground investigations shall be based on the anticipated type and design of the construction, e.g. type of foundation, improvement method or retaining structure, location and depth of the construction;
(2)P The results of the desk studies and the site inspection shall be considered when selecting the investigation methods and locating the various investigation points. Investigations shall be targeted at points representing the variation in ground conditions for soil, rock and groundwater.
(3) Ground investigations should normally be performed in phases depending on the questions raised during planning, design and construction of the actual project. The following phases are treated separately in Section 2:
- preliminary investigations for positioning and preliminary design of the structure (see 2.3) ;
- design investigations (see 2.4);
- controlling and monitoring (see 2.5).
NOTE The provisions in this document arc based on the premise that the results from investigations recommended in one phase are available before the next phase is started.
2.3 Preliminary investigations
(1) The preliminary investigations should be planned in such a way that adequate data are obtained, if relevant, to:
- assess the overall stability and general suitability of the site;
- assess the suitability of the site in comparison with alternative sites;
- assess the suitable positioning of the structure;
- evaluate the possible effects of the proposed works on surroundings, such as neighbouring buildings, structures and sites;
- identify borrow areas;
- consider the possible foundation methods and any ground improvements;
- plan the design and control investigations, including identification of the extent of ground which may have significant influence on the behaviour of the structure,
(2) A preliminary ground investigation should supply estimates of soil data concerning, if relevant:
- the type of soil or rock and their stratification;
- the groundwater table or pore pressure profile;
- the preliminary strength and deformation properties for soil and rock;
- the potential occurrence of contaminated ground or groundwater that might be hazardous to the durability of construction material.