digplanet beta 1: Athena
Share digplanet:


Applied sciences






















In geotechnical engineering, bearing capacity is the capacity of soil to support the loads applied to the ground. The bearing capacity of soil is the maximum average contact pressure between the foundation and the soil which should not produce shear failure in the soil. Ultimate bearing capacity is the theoretical maximum pressure which can be supported without failure; allowable bearing capacity is the ultimate bearing capacity divided by a factor of safety. Sometimes, on soft soil sites, large settlements may occur under loaded foundations without actual shear failure occurring; in such cases, the allowable bearing capacity is based on the maximum allowable settlement.

There are three modes of failure that limit bearing capacity: general shear failure, local shear failure, and punching shear failure.


A foundation is the part of a structure which transmits the weight of the structure to the ground. All structures constructed on land are supported on foundations. A foundation is, therefore, a connecting link between the structure proper and the ground which supports it.

General shear failure[edit]

The general shear failure case is the one normally analyzed. Prevention against other failure modes is accounted for implicitly in settlement calculations.[1] There are many different methods for computing when this failure will occur.

Terzaghi's Bearing Capacity Theory[edit]

Karl von Terzaghi was the first to present a comprehensive theory for the evaluation of the ultimate bearing capacity of rough shallow foundations. This theory states that a foundation is shallow if its depth is less than or equal to its width.[2] Later investigations, however, have suggested that foundations with a depth, measured from the ground surface, equal to 3 to 4 times their width may be defined as shallow foundations.[2]

Terzaghi developed a method for determining bearing capacity for the general shear failure case in 1943. The equations are given below.

For square foundations:

 q_{ult} = 1.3 c' N_c + \sigma '_{zD} N_q + 0.4 \gamma ' B N_\gamma \

For continuous foundations:

 q_{ult} = c' N_c + \sigma '_{zD} N_q + 0.5 \gamma ' B N_\gamma \

For circular foundations:

 q_{ult} = 1.3 c' N_c + \sigma '_{zD} N_q + 0.3 \gamma ' B N_\gamma \


 N_q = \frac{ e ^{ 2 \pi \left( 0.75 - \phi '/360 \right) \tan \phi ' } }{2 \cos ^2 \left( 45 + \phi '/2 \right) }
 N_c = 5.7 \ for φ' = 0
 N_c = \frac{ N_q - 1 }{ \tan \phi '} for φ' > 0
 N_\gamma = \frac{ \tan \phi ' }{2} \left( \frac{ K_{p \gamma} }{ \cos ^2 \phi ' } - 1 \right)
c′ is the effective cohesion.
σzD′ is the vertical effective stress at the depth the foundation is laid.
γ′ is the effective unit weight when saturated or the total unit weight when not fully saturated.
B is the width or the diameter of the foundation.
φ′ is the effective internal angle of friction.
K is obtained graphically. Simplifications have been made to eliminate the need for K. One such was done by Coduto, given below, and it is accurate to within 10%.[1]
 N_\gamma = \frac{ 2 \left( N_q + 1 \right) \tan \phi ' }{1 + 0.4 \sin 4 \phi ' }

For foundations that exhibit the local shear failure mode in soils, Terzaghi suggested the following modifications to the previous equations. The equations are given below.

For square foundations:

 q_{ult} = 0.867 c' N '_c + \sigma '_{zD} N '_q + 0.4 \gamma ' B N '_\gamma \

For continuous foundations:

 q_{ult} = \frac{2}{3} c' N '_c + \sigma '_{zD} N '_q + 0.5 \gamma ' B N '_\gamma \

For circular foundations:

 q_{ult} = 0.867 c' N '_c + \sigma '_{zD} N '_q + 0.3 \gamma ' B N '_\gamma \

 N '_c,  N '_q and  N '_y , the modified bearing capacity factors, can be calculated by using the bearing capacity factors equations(for  N_c, N_q, and N_y, respectively) by replacing the effective internal angle of friction(\phi ') by a value equal to  : tan^{-1}\, (\frac{2}{3} tan \phi ') [2]

Factor of Safety[edit]

Calculating the gross allowable-load bearing capacity of shallow foundations requires the application of a factor of safety(FS) to the gross ultimate bearing capacity, or:

 q_{all} = \frac{q_{ult}}{FS} [2]

Meyerhof's Bearing Capacity theory[edit]

In 1951, Meyerhof published a bearing capacity theory which could be applied to rough shallow and deep foundations.[3] Meyerhof (1951, 1963) proposed a bearing-capacity equation similar to that of Terzaghi's but included a shape factor s-q with the depth term Nq. He also included depth factors and inclination factors. For more information click here.

See also[edit]


  1. ^ a b Coduto, Donald (2001), Foundation Design, Prentice-Hall, ISBN 0-13-589706-8 
  2. ^ a b c d Das, Braja (2007), Principles of Foundation Engineering (6th ed.), Stamford, CT: Cengage Publisher 
  3. ^ {{|publisher=CRC Press LLC|id=|}}

External links[edit]

Original courtesy of Wikipedia: http://en.wikipedia.org/wiki/Bearing_capacity — Please support Wikipedia.
This page uses Creative Commons Licensed content from Wikipedia. A portion of the proceeds from advertising on Digplanet goes to supporting Wikipedia.

100 news items

FINNBAY (press release)
Sun, 26 Oct 2014 04:15:00 -0700

The supervisors announce OP-Pohjola Group to have a strong financial standing. The Group's capital adequacy remained strong both in the European Central Bank's comprehensive assessment, which looked at European banks' assets using uniform ...
Wed, 29 Oct 2014 07:37:30 -0700

Cost-saving measures included the widespread use of retail buildings as factories—including at Rana Plaza—adding weight that sometimes exceeded the load-bearing capacity of the structures. As Scott Nova, executive director of the Worker Rights ...

New Civil Engineer

New Civil Engineer
Wed, 29 Oct 2014 05:17:11 -0700

Caldbeck adds that for cohesive soils, flooding the pores with the geopolymer increases the bearing capacity of the ground. Where soil is more granular, geopolymer injection has a consolidating effect. The injected geopolymer resin has an almost ...

Clinton Herald

Clinton Herald
Wed, 22 Oct 2014 19:37:30 -0700

Craft said the foundation of the building "lost its bearing capacity" on Wednesday when crews from BWC Excavating, a Solon company under contract with the city to complete the separation project, removed the soil next to the building. This caused a ...


Sun, 26 Oct 2014 23:56:15 -0700

One aria has bare-bones cello and bass accompaniment, another has fluffy, busy duo-flute obbligatos that belong on a birthday cake, and one recitative goes far beyond its usual information-bearing capacity with two voices starting out in harmony and ...

Clinton Herald

Clinton Herald
Fri, 24 Oct 2014 07:55:54 -0700

What started as a 4-foot-wide hole grew larger over the next four hours as the building's bearing capacity continued to lose its ability to support the building. And after the entire corner wall failed, collapsing without a prompt at around 2:30 p.m ...
Wed, 29 Oct 2014 03:37:13 -0700

The seismic surveys are conducted in order to clarify the geological structure, define the range of distribution of hydrocarbons and study the oil-bearing capacity of the area. "The data, which were obtained as a result of the research are already ...
Tue, 28 Oct 2014 16:48:45 -0700

... uni-axle trucks having carrying capacity upto 9 tons are allowed to operate in the State of Manipur and whereas in the case of multi-axle trucks are allowed only upto 15 tons due to restrictions of maximum load bearing capacity as certified by BRO ...

Oops, we seem to be having trouble contacting Twitter

Support Wikipedia

A portion of the proceeds from advertising on Digplanet goes to supporting Wikipedia. Please add your support for Wikipedia!

Searchlight Group

Digplanet also receives support from Searchlight Group. Visit Searchlight