Geotechnical Engineering

DHARM

104 GEOTECHNICAL ENGINEERING

Give typical name; indi-cate degree and characterof plasticity, amount andmax. size of coarse grains;colour in wet condition,odour, if any; local or geo-logic name and other per-tinent descriptive infor-mation and symbol in pa-renthesis.For undisturbed soils addinformation on structure,stratification, consistencyin undisturbed and re-moulded states, moistureand drainage conditions.Example :Clayey silt, brown;slightly plastic; small per-centage of fine sand;numberous vertical rootholes; firm and dry inplace, loess (MI).

ML CL OL MI CI OI MH CH OH Pt

Inorganic silts and veryfine sands, rock flour, siltyor clayey fine sands, orclayey silts with none tolow plasticity.Inorganic silts, gravellyclays, sandy clays, siltyclays, lean clays of lowplasticity.Organic silts and organicsilty clays of low plastic-ity.Inorganic silts, silty orclayey fine sands, orclayey silts of mediumplasticity.Inorganic clays, gravellyclays, sandy clays, siltyclays, lean clays of me-dium plasticity.Organic silts and organicsilty clays of medium plas-ticity.Inorganic, silts of highcompressibility, mica-ceous or diatomaceoousfine sandy or silty soils,elastic silts.Inorganic clays of highplasticity, fat clays.Organic clays of mediumto high plasticity.Peat and other highly or-ganic soils with very highcompressibility.

Fine-grained soils

More than 50% of the material is smaller than 75-IS Sieve Size

Silts and clays with

high comp

ressibility and liq-

uid limit greater

than 50%

Silts and clays with

low compressibility

and liquid limit less

than 35%.

Silts and clays with

medium com-

pressibility and liq-

uid limit greater

than 35% and less

than 50%

Identification procedures(on fraction smaller than 425

μ IS Sieve sizes)

Drystre-ngthNone tolow

Dila-tancyQuick

Tough-nessNone

Me-dium

Noneto veryslow

Me-dium

LowLow

SlowQuickto slow

LowNone

Me-dium tohigh

None

Me-dium

Low tome-dium

Slow

Low

Low tome-dium

Slowtonone

Low tome-dium

High toveryhigh

None

High

Me-dium tohigh

Noneto veryslow

Low tome-dium

Readily identified by col-our, odour, spongy feeland frequency by fibroustexure.

NOTE.

‘‘Boundary classification’’ : Soil possessing characteristics of two groups are designated by combinations of group symbols, for example, GW-GC,

well-graded, gravel-sand mixture with clay binder.

Highly organic soils