Bearing capacity of foundations -...

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Bearing capacity of foundations Bearing capacity of surface foundation

Transcript of Bearing capacity of foundations -...

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Bearing capacity of foundations

Bearing capacity of surface foundation

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Failure mechanism of surface foundation

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Failure zones below surface foundation-Terzaghi’s method

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Terzaghi’s bearing capacity theroy

γγγ SBNSNqScNq qqccu '5.0++=

Bearing Capacity Factors: Nc, Nq, Nr = f(φ)

0.611.3Round

1.01.01.0Continuous

0.811.3Square

SrSqScShape Factor

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General (Vesic’s) Bearing Capacity Equation

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Vesic’s Bearing capacity factors

2.0

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Selection of Strength Parameters

Always use saturated strengthFor plain strain condition

φ can be increased by 10%

Drained or undrained strength If positive excess water pressure is generated during loading, use undrainedstrength, otherwise use drained strength

Plain strain friction angle

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Punching failure

Effective stress analysis of foundation on sand

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Bearing capacity of footing in sand

Bearing capacity of footing in sand (layered soil)

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Footing in excavation

Groundwater Table

γγ

γγγγ

γγγγ

=+>

−⎟⎟⎠

⎞⎜⎜⎝

⎛ −+=+<<

−==<

eqfw

fweqfwf

wsateqfw

BDD

B

DDBDDD

DD

'

)'(''

''

Use worst case Dw

γγγ SBNSNqScNq eqqqccu '5.0++=

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Effect of hydraulic gradient on bearing capacity

Effect of adjacent footing in slope

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Effect of horizontal load on bearing capacity

Effect of eccentric load on bearing capacity

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Equivalent area of surface footing

Total stress analysis of foundation in clay

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Effect of soil layer on bearing capacity of footing in clay

Effect of overburden pressure on bearing capacity in clay

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Pressure distribution below footing in clay and sand

Pull out resistance of shallow footing

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Pull out resistance of footing at depth

Bearing capacity on rock