Identification and classification of soil

Identification and classification of soil is covered by International Standard EN ISO 14688, which is divided into three parts covering description (Part 1), classification (Part 2), and data transfer (Part 3).6 EN ISO 14688 is referenced extensively in EN 1997-2.

4.3.1 Soil description

Figure 4.6 illustrates the logic for identifying soils according to EN ISO 14688-1. The main soil types are divided into made ground, organic soil, volcanic soil, and very coarse, coarse, and fine soils. Very coarse soils are sub-divided into large boulders, boulders, and cobbles; coarse soils into gravels and sands; and fine soils into silts and clays. Gravel, sand, and silt are further qualified as coarse, medium, or fine.

Columns Eurocodes
Figure 4.6. Flow-chart for identification of soils

Figure 4.7 indicates the boundaries between these descriptions, based on particle-size, and summarizes their two-letter abbreviations (e.g. Gr for gravel, Sa for sand, Cl for clay). The boundary between the particle size of fine and coarse soils is now 0.063mm, which is the same as the corresponding EN ISO sieve size and slightly larger than the 0.06mm boundary specified in BS 5930.7

Particle Size Sieve

Figure 4.7. Particle-size fractions

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