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8/3/2019 Chapter 3 Soil Mechanics Part II
http://slidepdf.com/reader/full/chapter-3-soil-mechanics-part-ii 1/34
Jonathan Rivera Dungca, D.Eng.
Associate Professor
FOUNDES
Soil Mechanics/Review(Part 2)
De La Salle University -ManilaDepartment of Civil and Engineering
8/3/2019 Chapter 3 Soil Mechanics Part II
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Chapter 3: Soil Mechanics
Lecture No.1
3.1 Soil Composition
Soil-a 3-phase material Soil Characterization (particle size,
soil plasticity)
3.2 Soil Classification 3.3 Groundwater
3.4 Stress (Total vs. Effective)
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Chapter 3: Soil Mechanics
Lecture No.2
3.5 Compressibility and
settlementLecture No.3
3.6 Strength
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3.5 Compressibility & Settlement
Settlement requirements oftencontrol the design of foundations
This chapter provides a generaloverview of principles involved insettlement analysis
The subject will be dealt with in
greater detail in Chapter 7.
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Case Study
Settlement must be withinacceptable limits …..
Palacio de las Bellas
Artes, Mexico CityBuilt 1932-1934
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Palace of Fine Arts in Mexico CitySettled 3m!
Lacustrine Clay deposited in former LakeTexcoco
Av. Water content 281%, Void Ratio 6.90Groundwater withdrawal; increase in
effective stress
Resulting Consolidation43-story Tower Latino Americana
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Case Study
Tower of Latino
Americana, MexicoCityBuilt ihn 1956
44 stories; 597-ft
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Increase in Vertical Effective Stress
Due to a Placement of a fill
Due to an external load
fill fill z zf H
0
induced z z zf 0
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VoidsVoids
Solids
H
V v = eV s
V s
c
e
V v = (e - e)V s
V s Solids
z
′
z
′
z0′
z0′
z0′
z0′
} z f ′
} z f ′
Before After
Consolidation
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u0
0
Before Loading
Point, P
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u0+u
0 +
ImmediatelyAfter Loading
Point, P
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0 +
u0+u
u0
0 +
Shortly after LoadingNo settlement
Long after LoadingSettlement Complete
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Settlement
Distortion Settlement (Immediate)
Consolidation (Time Dependent)
Secondary Compression time
Settlement
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Laboratory Consolidation Test
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Consolidation Test
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Test Results
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Consolidation Plot
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Test ResultsIdealizedData
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Compression Index andRecompression Index
a zb z
bac
eeC
)(log)(log
c zd z
d c
r
ee
C )(log)(log
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Compression Ratio andRecompression Ratio
a zb z
b za zcc
e
C C
)(log)(log
)()(
1 0
c zd z
c zd zr r
e
C
C )(log)(log
)()(
1 0
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Normally andOver-Consolidated Soils
c zo ….. Normally consolidated
c zo ….. Over consolidated
c zo ….. Under consolidated
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Normal vs. Over-Consolidation
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Normal vs. Over-Consolidation
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Over-Consolidation Margin & Over-consolidation Ratio
zocm ….. Over-consolidation
Margin
zo
cOCR
….. Over consolidation ratio
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Typical Range of OC Margins
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Compressibility of Sand andGravels (Table 3.7)
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Example 3.3
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Settlement PredictionsN.C. Clays
00
log
1 z
zf cc H
e
C
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Settlement PredictionsO.C. Clays…… Case I
00
log
1 z
zf r c H
e
C
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Settlement PredictionsO.C. Clays…… Case II
c
zf c
z
cr c H
eC H
eC
log
1log
1 000
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Ex. 3.4
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Example 3.4
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Ex. 3.5
E l