settlement of shallow foundation final-eslahi

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Shallow Foundation Settlement���� ��� � ��

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Settlement

Immediate Settlement: Occurs immediately after the construction. This is computed using elasticity theory (Important for Granular soil)

Primary Consolidation: Due to gradual dissipation of pore pressure induced by external loading and consequently expulsion of water from the soil mass, hence volume change. (Important for Inorganic clays)

Secondary Consolidation: Occurs at constant effective stress with volume change due to rearrangement of particles. (Important for Organic soils)________________________________________________________________For any of the above mentioned settlement calculations, we first need vertical stress increase in soil mass due to net load applied on the foundation

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Stress Due to a Concentrated Load

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Stress due to a Circularly Loaded Area

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Distribution of Stress(from a vertical line load)

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Stress below a Rectangular Area

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Stress Influence Chart

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2:1 method

Approximate methods

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Elastic Settlement

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Elastic settlement Based on theTheory of Elasticity

IMMEDIATE SETTLEMENT

General Equation (Harr, 1966)• Flexibel Foundation

– At the corner of foundation

– At the center of foundation

– Average

• Rigid Foundation

(((( ))))2

1Eq.B

S 2s

s

oe

ααααµµµµ−−−−====

Es = Modulus of elasticity of soil

B = Foundation width

L = Foundation length

(((( ))))ααααµµµµ−−−−==== 2s

s

oe 1

Eq.B

S

(((( )))) r2s

s

oe 1

Eq.B

S ααααµµµµ−−−−====

−−−−++++++++++++++++

−−−−++++++++++++

ππππ====αααα

1m1

1m1ln.m

mm1

mm1ln

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2

2

2

(((( )))) av2s

s

oe 1

Eq.B

S ααααµµµµ−−−−====

B

Lm =; ; H = ∞∞∞∞

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Elastic Settlement of Rectangular footings

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Es = ��� !�"#��$� %&'(

IMMEDIATE SETTLEMENT

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Elastic Settlement on Saturated Clay

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Elastic Settlement Using the Strain Influence Factor: [Schmertman & Hartman Method (1978)]

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Elastic Settlement Using the Strain Influence Factor: [Schmertman Method (1978)]

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Procedure for Schmertman Method (1978)

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Procedure for Schmertman Method (1978)

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Procedure for Schmertman Method (1978)