Ground Investigation Reports and Geotechnical Design Reports

We are experienced in preparing Ground Investigation Reports and Geotechnical Design Reports in accordance with Eurocode 7 for projects ranging from small slope stability projects to major motorway projects in the UK and Ireland. Eurocode 7 is the harmonised design standard for geotechnical structures in the European Union and further afield.

The use of Eurocode 7 (and the relevant National Annex if applicable) for geotechnical design is mandatory for public projects, and considered best practice for all projects, in the European Union. The sequence outlined in Eurocode 7 for geotechnical design is:

  1. Investigation
  2. Design

Investigation is fundamental to geotechnical design, so the logic of this apparently self-referencing format should be appreciated. Investigation usually leads to two reports:

1a. Factual report. Not named in Eurocode 7 but often produced because of how investigations are usually procured. A factual report typically outlines the scope and methods of investigation and testing, observations and results obtained from field tests and observations and results from laboratory testing. Strata encountered are described in accordance with the relevant code, for example BS 5930:2015, to minimise the degree of judgement and ambiguity present. Records of groundwater behaviour are made. Factual reports are normally prepared by the ground investigation contractor.

1b. Ground Investigation Report (GIR). Named and defined in Eurocode 7 (Part 1, §3.4, Part 2, §6.1). A GIR usually gives the designer’s interpretation or judgement of the ground conditions as they pertain to the planned works and an assessment of the ground risks. It must involve a review of the factual information obtained and the use of the factual information to support the parameters used in design, e.g. strength, stiffness and compressibility. A GIR may be prepared by the ground investigation contractor but more often is prepared by the designer. It is necessarily interpretative in nature but is NOT an “Interpretative Report” – the commonly-used term Interpretative Report is deprecated under Eurocode 7, its contents being distributed between the GIR and the GDR.

Design should lead to one report:

2. Geotechnical Design Report (GDR). Named in Eurocode 7 (Part 1, §2.8). This shows how the information from the Ground Investigation Report has been used to produce a safe and serviceable design. This report should reference or include the Ground Investigation Report referred to above.

There is often confusion between the three terms Ground Investigation Report, Interpretative Report, and Geotechnical Design report, possibly because of the similar acronyms commonly assigned and the potential overlap in the information contained in them. Hopefully this summary will lead to greater clarity.

For further information and should you require advice on the delivery of such report, please contact us.