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5. Conditions of use for subgrade materials
According to the definition proposed by the GTR, a subgrade is a structure that adapts the random and dispersed characteristics of the backfill or excavated material to the permanent characteristics required in the pavement design.
Calculation and selection of the pavement structure are based on an economic study of the earthworks, subgrade and pavement package, carried out to optimize the project. This study must be validated in the field, using geotechnical surveys and test beds.
The subgrade is a support layer for the pavement. It is important to stress that its design is inseparable from the characteristics of the layer constituted by the upper part of the earthworks (PST).
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Conditions of use for subgrade materials
Classification and sizing of platforms
Bibliography
References
Calculation software
ALIZÉ – LCPC: software overview http//www.lcpc.fr/fr/produits/alize/doc/alize.pdf
Standardization
- Earthworks – Classification of materials for use in the construction of road infrastructure embankments and subgrades Classification number : P11-300 - NF P11-300 - 09-92
- Earthworks – Terminology Classification number : P11-301 - NF P11-301 - 12-94
- Soils: reconnaissance and testing – Platform load-bearing capacity – Part 1: Modulus under static plate loading (EV2) - NF P94-117-1 - 04-00
- Soils: reconnaissance...
Platform bearing capacity tests
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Module under static loading EV2
The test is defined by standard NF P94-117-1 published in April 2000 (see § Standardization in this "To find out more" section).
It involves two static loadings on a rigid 60 mm diameter plate. The EV2 modulus is determined using Boussinesq's formula:
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