bearing capacity of foundations -...
TRANSCRIPT
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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