Allowable bearing capacity: The maximum pressure that can be applied to the soil from the foundation so that the two requirements are satisfied:

1. Acceptable safety factor against shear failure below the foundation
2. Acceptable total and differential settelement

Ultimate bearing capacity: The minimum pressure that would cause the shear failure of the supporting soil immediately below and adjacent to the foundation.

Typical values of soil bearing capacity

For preliminary design purposes, BS 8004 [1] gives typical values of allowable bearing capacity which should result in an adequate factor of safety against shaer failure without accounting for the setllemenet criteria [2].

Ultimate bearing capacity for shallow foundations according to Terzaghi

The utimate bearing capacity for shallow foundations can be calculated using the relation proposed by Terzaghi [3]:

and the net ultimate bearing capacity:

With the bearing capacity factors:

	factor for surcharge
	factor for cohesion
	factor self-weight [4]
	factor self-weight [5]

and

B, L, D	Width, Length and Depth of foundation,
	cohesion, effective frinaction angle and effective unit weight

In case of a rectangular foundation, the terms of the above relations should be multiplied by the respective shape factors as follows [6]:

In case the loads are not applied vertically, additional factors should be also considered for inclined loads.

SpreadSheet for Soil Bearing capacity: Free download

REFERENCES

1. BS 8004: (1986): Code of practice for foundations
2. Craig, R. F. (1986), Soil Mechanics, 4th ed., ISBN 0-412-38430-2
3. Tezaghi, K. (1943): Theoretical soil mechanics, John Wiley and sons, New York
4. Hansen, J. B. (1968): A revised extended formula for bearing capacity. Danish Geotechnical Institute Bulletin, No. 28
5. Meyerhof, G. G. (1963). Some recent research on the bearing capacity of foundations. Canadian geotechnical journal Vol. 1 No. 1
6. Terzaghi, K. and Peck, R. B. (1967): Soil mechanics in engineerin practice (2nd ed). John Wiley and Sons, New York

Citation :
Geotechdata.info, Soil Bearing capacity, http://geotechdata.info/parameter/bearing-capacity.html (as of April 15, 2015).

Soil void ratio (e) is the ratio of the volume of voids to the volume of solids:

e = (V_v) / (V_s)

Where V_v is the volume of the voids (empty or filled with fluid), and V_s is the volume of solids.

Void ratio is usually used in parallel with soil porosity (n) , which is defined as the ratio of the volume of voids to the total volume of the soil. The posoity and the void ratio are inter-related as follows:

e = n /(1-n)      and      n = e / (1+e)

The value of void ratio depends on the consistence and packing of the soil. It is directly affacted by compaction. Some typical values of void ratio for different soils are given below only as general guidelines.

Typical values of soil void ratio for different soils

Some typical values of void ratio are given below for different USCS soil types at 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.

 REFERENCES

1. Swiss Standard SN 670 010b, Characteristic Coefficients of soils, Association of Swiss Road and Traffic Engineers
2. Das, B., Advanced Soil Mechanics. Taylor & Francis, London & New York, 2008.
3. Hough, B., Basic soil engineering. Ronald Press Company, New York, 1969.
4. Terzaghi, K., Peck, R., and Mesri, G., Soil Mechanics in Engineering Practice. Wiley, New York, 1996.
5. Obrzud R. & Truty, A.THE HARDENING SOIL MODEL - A PRACTICAL GUIDEBOOK Z Soil.PC 100701 report, revised 31.01.2012

Citation :
Geotechdata.info, Soil void ratio, http://geotechdata.info/parameter/soil-void-ratio.html (as of November 16, 2013).

The soil permeability is a measure indicating the capacity of the soil or rock to allow fluids to pass through it. It is often represented by the permeability coefficient (k) through the Darcy’s equation:

V=ki

Where v is the apparent fluid velocity through the medium i is the hydraulic gradient , and K is the coefficient of permeability (hydraulic conductivity) often expressed in m/s

K depends on the relative permeability of the medium for fluid constituent (often water) and the dynamic viscosity of the fluid as follows.

K= (Gamma_w)*K/ (eta)

where Where Gamma_w is the unit weight of water Eta is the dynamic viscosity of water K is an absolute coefficient depending on the characteristics of the medium (m2)

The permeability coefficient can be determined in the laboratory using falling head permeability test, and constant head permeability test. On the field, the permeability can be estimated using Lugeon test.

Typical values of soil permeability

Some typical values of permeability coefficient are given below for different soil types. It refers to normally consolidated condition unless otherwise mentioned. 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.

Empirical relations for dtermine the soil permeability coefficient

For Sands, the coefficient of permeability can be estimated from the Hazen's equation:

is the effevtive size in mm.

 REFERENCES

1. Swiss Standard SN 670 010b, Characteristic Coefficients of soils, Association of Swiss Road and Traffic Engineers
2. Carter, M. and Bentley, S. (1991). Correlations of soil properties. Penetech Press Publishers, London.
3. Leonards G. A. Ed. 1962, Foundation ENgineering. McGraw Hill Book Company
4. Dysli M. and Steiner W., 2011, Correlations in soil mechanics, PPUR
5. West, T.R., 1995. Geology applied to engineering. Prentice Hall, 560 pp.

Citation :
Geotechdata.info, Soil void ratio, http://geotechdata.info/parameter/permeability.html (as of October 7, 2013).

Soil void ratio (e) is the ratio of the volume of voids to the volume of solids:

e = (V_v) / (V_s)

Where V_v is the volume of the voids (empty or filled with fluid), and V_s is the volume of solids.

Void ratio is usually used in parallel with soil porosity (n) , which is defined as the ratio of the volume of voids to the total volume of the soil. The posoity and the void ratio are inter-related as follows:

e = n /(1-n)      and      n = e / (1+e)

The value of void ratio depends on the consistence and packing of the soil. It is directly affacted by compaction. Some typical values of void ratio for different soils are given below only as general guidelines.

Typical values of soil void ratio for different soils

Some typical values of void ratio are given below for different USCS soil types at 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.

 REFERENCES

1. Swiss Standard SN 670 010b, Characteristic Coefficients of soils, Association of Swiss Road and Traffic Engineers
2. Das, B., Advanced Soil Mechanics. Taylor & Francis, London & New York, 2008.
3. Hough, B., Basic soil engineering. Ronald Press Company, New York, 1969.
4. Terzaghi, K., Peck, R., and Mesri, G., Soil Mechanics in Engineering Practice. Wiley, New York, 1996.
5. Obrzud R. & Truty, A.THE HARDENING SOIL MODEL - A PRACTICAL GUIDEBOOK Z Soil.PC 100701 report, revised 31.01.2012

Citation :
Geotechdata.info, Soil void ratio, http://geotechdata.info/parameter/soil-void-ratio.html (as of November 16, 2013).

Soil Young's modulus (E), commonly reffred to as soil elastic modulus, is an elastic soil parameter and a measure of soil stiffness. It is defined as the ratio of the stress along an axis over the strain along that axis in the range of elastic soil behaviour. The elastic modulus is often used for estimation of soil settement and elastic deformation analysis.

Soil elastic modulus can be estimated from laboratory or in-situ tests or based on correlation with other soil properties. In laboratory, it can be determined from triaxial test or indirectly from oedometer test. On field, it can be estimated from Standard penetration test, Cone penetration test , pressuremeter or indirectly from dilatometer test.

Typical values of soil Young's molulus for different soils according to USCS

In general, the soil stiffness and elastic modulus depends on the consistensy and packing (density) of the soil. Typical values of soil Young's modulus are given below as guideline.

Typical values of Young's modulus for granular material (MPa) (based on Obrzud & Truty 2012 complied from Kezdi 1974 and Prat et al. 1995)

Typical values of Young's modulus for cohessive material (MPa) (based on Obrzud & Truty 2012 compiled from Kezdi 1974 and Prat et al. 1995)

 REFERENCES

1. Obrzud R. & Truty, A.THE HARDENING SOIL MODEL - A PRACTICAL GUIDEBOOK Z Soil.PC 100701 report, revised 31.01.2012
2. Kezdi, A. (1974). Handbook of Soil Mechanics. Elsevier, Amsterdam.
3. Prat, M., Bisch, E., Millard, A., Mestat, P., and Cabot, G. (1995). La modelisation des ouvrages. Hermes, Paris.

Citation :
Geotechdata.info, Soil Young's modulus, http://geotechdata.info/parameter/soil-elastic-young-modulus.html (as of September 17.09.2013).

Soil unit weight, as referred to as Specific weight, is the weight per unit volume of soil. It may refer to

- Wet unit weight: Unit weight of the soil when the pore are fully or partially filled with water.
- Dry unit weight: Unit weight of the soil the pores are filled only with air without any water.

Gamma_d = Gamma / (1 + w)

where

Gamma_d : dry unit weight
Gamma : unit weight
w: soil water content

Typical values of soil porosity for different soils

The soil unit weight, of course, depends on the packing, compaction, and humidity condition of the soil. Some typical values of dry unit weight are given below for different soils. The values 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.

REFERENCES

1. Swiss Standard SN 670 010b, Characteristic Coefficients of soils, Association of Swiss Road and Traffic Engineers

Citation :
Geotechdata.info, Dry unit weight, http://geotechdata.info/parameter/soil-dry-unit-weight.html (as of August 29, 2013).

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.

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

<span ">Soil friction angle is a shear strength parameter of soils. Its definition is derived from the Mohr-Coulomb failure criterion and it is used to describe the friction shear resistance of soils together with the normal effective stress.Soil friction angle is a shear strength parameter of soils. Its definition is derived from the Mohr-Coulomb failure criterion and it is used to describe the friction shear resistance of soils together with the normal effective stress.

In the stress plane of Shear stress-effective normal stress, the soil friction angle is the angle of inclination with respect to the horizontal axis of the Mohr-Coulomb shear resistance line.

Typical values of soil friction angle

Some typical values of soil friction angle are given below for different USCS soil types at 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.

Correlation between SPT-N value, friction angle, and relative density

Refrences

1. Swiss Standard SN 670 010b, Characteristic Coefficients of soils, Association of Swiss Road and Traffic Engineers Swiss Standard SN 670 010b, Characteristic Coefficients of soils, Association of Swiss Road and Traffic Engineers 
2. JON W. KOLOSKI, SIGMUND D. SCHWARZ, and DONALD W. TUBBS, Geotechnical Properties of Geologic Materials, Engineering Geology in Washington, Volume 1, Washington Division of Geology and Earth Resources Bulletin 78, 1989, Link
3. Carter, M. and Bentley, S. (1991). Correlations of soil properties. Penetech Press Publishers, London. 
4. Meyerhof, G. (1956). Penetration tests and bearing capacity of cohesionless soils. J Soils Mechanics and Foundation Division ASCE, 82(SM1). 
5. Peck, R., Hanson,W., and Thornburn, T. (1974). Foundation Engineering Handbook. Wiley, London. 
6. Obrzud R. & Truty, A.THE HARDENING SOIL MODEL - A PRACTICAL GUIDEBOOK Z Soil.PC 100701 report, revised 31.01.2012 
7. Minnesota Department of Transportation, Pavement Design, 2007