Cohesion

in Parameters

The cohesion is a term used in describing the shear strength soils. Its definition is mainly derived from the Mohr-Coulomb failure criterion and it is used to describe the non-frictional part of the shear resitance which is independent of the normal stress. In the stress plane of Shear stress-effective normal stress, the soil cohesion is the intercept on the shear axis of the Mohr-Coulomb shear resistance line

Typical values of soil cohesion for different soils

Some typical values of soil cohesion are given below for different soil types. The soil cohesion depends strongly on the consistence, packing, and saturation condition. The values given below correspond to normally consolidated condition unless otherwise stated. These values should be used only as guidline for geotechnical problems; however, specific conition of each engineering problem often needs to be considered for an appropriate choice of geotechnical parameters.

Description USCS Cohesion [kPa] Reference
min  max Specific value
Well graded gravel, sandy gravel, with little or no fines GW - - 0 [1],[2],[3], 
Poorly graded gravel, sandy gravel, with little or no fines GP - - 0 [1],[2], [3], 
Silty gravels, silty sandy gravels GM - - 0 [1],
Clayey gravels, clayey sandy gravels GC - - 20 [1],
Well graded sands, gravelly sands, with little or no fines SW - - 0 [1],[2], [3], 
Poorly graded sands, gravelly sands, with little or no fines SP - - 0 [1],[2], [3], 
Silty sands SM - - 22 [1],
Silty sands - Saturated compacted SM - - 50 [3],
Silty sands - Compacted SM - - 20 [3],
Clayey sands SC - - 5 [1],
Clayey sands - Compacted SC - - 74 [3],
Clayey sands -Saturated compacted SC - - 11 [3],
Loamy sand, sandy clay Loam - compacted SM, SC 50 75   [2],
Loamy sand, sandy clay Loam - saturated SM, SC 10 20   [2],
Sand silt clay with slightly plastic fines - compacted SM, SC - - 50 [3],
Sand silt clay with slightly plastic fines - saturated compacted SM, SC - - 14 [3],
Inorganic silts, silty or clayey fine sands, with slight plasticity ML - - 7 [1],
Inorganic silts and clayey silts - compacted ML - - 67 [3],
Inorganic silts and clayey silts - saturated compacted ML - - 9 [3],
Inorganic clays, silty clays, sandy clays of low plasticity  CL - - 4 [1],
Inorganic clays, silty clays, sandy clays of low plasticity - compacted CL - - 86 [3],
Inorganic clays, silty clays, sandy clays of low plasticity - saturated compacted CL - - 13 [3],
Mixture if inorganic silt and clay - compacted ML-CL - - 65 [3],
Mixture if inorganic silt and clay - saturated compacted ML-CL - - 22 [3],
Organic silts and organic silty clays of low plasticity OL - - 5 [1],
Inorganic silts of high plasticity  - compactd MH - - 10 [1],
Inorganic silts of high plasticity - saturated compacted MH - - 72 [3],
Inorganic silts of high plasticity  MH - - 20 [3],
Inorganic clays of high plasticity  CH - - 25 [1],
Inorganic clays of high plasticity - compacted CH - - 103 [3],
Inorganic clays of high plasticity - satrated compacted CH - - 11 [3],
Organic clays of high plasticity  OH - - 10 [1],
Loam - Compacted ML, OL, MH, OH 60 90   [2],
Loam - Saturated ML, OL, MH, OH 10 20   [2],
Silt Loam - Compacted ML, OL, MH, OH 60 90   [2],
Silt Loam - Saturated ML, OL, MH, OH 10 20   [2],
Clay Loam, Silty Clay Loam - Compaced ML, OL, CL, MH, OH, CH 60 105   [2],
Clay Loam, Silty Clay Loam - Saturated ML, OL, CL, MH, OH, CH 10 20   [2],
Silty clay, clay - compacted OL, CL, OH, CH 90 105   [2],
Silty clay, clay - saturated OL, CL, OH, CH 10 20   [2],
Peat and other highly organic soils Pt - -    

 

REFERENCES

  1. Swiss Standard SN 670 010b, Characteristic Coefficients of soils, Association of Swiss Road and Traffic Engineers
  2. Minnesota Department of Transportation, Pavement Design, 2007
  3. NAVFAC Design Manual 7.2 - Foundations and Earth Structures,SN 0525-LP-300-7071, REVALIDATED BY CHANGE 1 SEPTEMBER 1986

 

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