Foundation settlements

Settlements of foundations

Stress distribution below point load

Stress below strip load

Stress below strip load

2:1 - method

2:1 - method at corner of footing

Settlement below footing

Settlements in clay and siltBased on lab tests

Settlements in sandBased on in situ tests

Immediate settlements in clay

Estimate of modulus of elasticity in clay

Determination of compression index

Determination of settlements from compression test

Principle of settlement calculation

Settlement below footing

Determination of precosolidationpressure

Determination of coefficient of consolidation (logarithmic)

Coefficient of consolidation (square root)

Secondary consolidation

Summary of settlement on clay

To get an accurate estimate of settlement must have good estimate of σ’p

Important to adjust for 3-D effect (Skempton-Bjerum Modification) δp= ψ δp, ψ ≤ 1.0

spiT δδδδ ++=

Can be importantfor soft clay

Usually mostimportant

Important fororganic

Settlement on Sand

Schmertmann's Method

∑ Δ=

sE

zIqCCC εδ '321

⎟⎟⎠

⎞⎜⎜⎝

⎛−=

'

'5.011 q

C zDσ

⎟⎠⎞

⎜⎝⎛+=

1.0log2.012

tC

73.0/03.003.13 ≥−= BLC

Depth factor

Secondary creep factor

Shape factor

Net bearing pressureStrain influence factor at midpoint of soil layer

Thickness of soil layer

Equivalent modulus

zpp

qI

'

'1.05.0

σε +=

Soil modulus from cone penetration test (CPT)

Estimate of modulus of elasticity from Standard penetration test (SPT)

Settlement analysis based on plate load test

Estimate of settlements below footing on sand

Settlements of footing on clay

qu = qu,0.3

Effect of plate diameter on bearing capacity of plate on sand

qu = qu,0.3*B/0.3

Allowable settlement below building

Damage due to foundation settlements

Floating foundation

Effect of ground water lowering from tunnel on building settlements

Effect of trees on ground water near building

Differential settlements between adjacent buildings

Negative skin friction due to ground water lowering

Swelling potential of soil below building

Effect of pile installation on adjacent building

Allowable differential settlements below structure

Tolerable settlement of buildings

Definitions of parameters for differential settlement

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