19 octobre 2026 · Géotechnique
G1, G2 AVP, G2 PRO, G3, G4 and G5: which geotechnical study, when?
Geotechnical engineering connects ground conditions with the proposed works. NF P 94-500, November 2013, listed as current by AFNOR when checked on 19 October 2026, defines design, construction and diagnostic assignments. G2 PRO is a phase of G2; G5 addresses a specific question.
| Assignment / phase | When | Purpose |
|---|---|---|
| G1 · ES / PGC | Early stage | Identify site characteristics, initial risks and possible construction principles. |
| G2 AVP | Preliminary design | Compare feasible geotechnical solutions for the project. |
| G2 PRO | Project design | Develop and substantiate the geotechnical design. |
| G2 DCE / ACT | Tendering | Prepare geotechnical tender information and contribute to bid assessment. |
| G3 | Construction · contractor | Develop execution studies and monitor geotechnical construction. |
| G4 | Construction · owner | Supervise the execution studies and their geotechnical monitoring. |
| G5 | Specific question | Investigate a defined geotechnical issue on a project or existing structure. |
Synthèse : tableaux de classification, Géorisques.
G2 AVP and G2 PRO: different design stages
G2 AVP alone is not a complete G2 assignment. PRO develops the selected solution; DCE/ACT supports tendering. Project information must keep pace: layouts, levels, structural loads and neighbouring structures.
G3 and G4: supporting construction
G3 acts for the contractor, while G4 acts for the owner. Their roles are complementary. Define information exchanges, hold points and how deviations will be handled.
G5 is a targeted diagnostic
A question concerning an existing element or observed damage may call for G5. Its scope must be explicit. If remedial works are proposed, the relevant design and execution studies still need to be arranged; G5 does not replace them.
DIS and the geotechnical specialist
DIS coordinates the brief, schedule and interfaces between geotechnical engineers, structural engineers, architects and contractors. The appointed specialist performs investigations, interpretation and geotechnical justification. Assemble drawings, loads, existing studies and the precise question before consulting. Select the scope with the specialist rather than treating a borehole price as a complete study.
Syntec-Ingénierie — Recommandations d’application de la NF P 94-500
An overview of assignments, not a specification for an individual site. Applicable obligations and contractual scope must be checked for each project.