Transmission And Substation Foundations - Technical Design Manual (TD06088E)

SPECIFICS OF THE UNIFIED SOIL CLASSIFICATION SYSTEM

Major Divisions

Group Symbols

Typical Descriptions

Well-graded gravels and gravel-sand mixtures. Little or no fines. Poorly graded gravels and gravel-sand mixtures. Little or no fines.

GW

Clean Gravels

Gravels - 50% or more of coarse fraction retained on #4 sieve.

GP

GM Silty gravels. Gravel-sand-silt mixtures.

Gravels with Fines.

Coarse Grained Soils- more than 50% retained on #200 sieve.*

GC

Clayey gravels. Gravel-sand-clay mixtures.

Well-graded sands and gravelly sands. Little or no fines. Poorly graded sands and gravelly sands. Little or no fines.

SW

Clean Sands.

Sands - 50% or more of coarse fraction passes #4 sieve.

SP

SM Silty sands. Sand-silt mixtures.

Sand with Fines

SC

Clayey sands. Sand-clay mixtures.

Inorganic silts, very fine sands, rock flour, silty or clayey find sands. Inorganic clays of low to medium plasticity, gravelly clays, sandy clays, silty clays, lean clays. Organic silts and organic silty clays of low plasticity. Inorganic silts, micaceous or diatomaceous fine sands or silts, elastic silts.

ML

Silts and Clays - Liquid limit less than 50.

CL

Fine-Grained Soils - 50% or more passes #200 sieve.*

OL

MH

Silts and Clays - Liquid limit 50 or more

SOIL MECHANICS

CH

Inorganic clays of high plasticity, fat clays.

OH

Organic clays of medium to high plasticity.

Highly Organic Soils.

PT

Peat, muck and other highly organic soils.

*Based on the material passing the 3” (76 mm) sieve.

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