1

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

3

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

4

5

6

7

8

10

Stress Due to a Concentrated Load

11

Stress due to a Circularly Loaded Area

12

Distribution of Stress(from a vertical line load)

13

Stress below a Rectangular Area

14

Stress Influence Chart

15

2:1 method

Approximate methods

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19

20

Elastic Settlement

21

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

12

2

2

2

(((( )))) av2s

s

oe 1

Eq.B

S ααααµµµµ−−−−====

B

Lm =; ; H = ∞∞∞∞

23

Elastic Settlement of Rectangular footings

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Es = ��� !�"#��$� %&'(

IMMEDIATE SETTLEMENT

28

29

Elastic Settlement on Saturated Clay

30

31

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

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33

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

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35

Procedure for Schmertman Method (1978)

36

Procedure for Schmertman Method (1978)

37

Procedure for Schmertman Method (1978)