REVISITATION OF EXPANSIVE SOILS
Transcript of REVISITATION OF EXPANSIVE SOILS
11
REVISITATION
OF
EXPANSIVE SOILS
ROBERT L. LYTTON, PhD
Foundation Performance Association
Houston, Texas
December 13, 2006
22
Building Foundations
Pavements
Embankments, Cuts and Slopes
CONSTRUCTED WORKSIMPACTED BY
EXPANSIVE SOILS
33
Site Investigation
Laboratory Characterization
Relating Field-to-Lab Properties
CONSTRUCTED WORKSIMPACTED BY
EXPANSIVE SOILS
44
Slabs
Drilled Shafts
Basements
Retaining Walls
Design Methods
Building Foundations
55
Pavements
New Construction
Airport
Highway
Reliable Design Methods
Sulfate Swell Problem
Remediation
66
Embankments, Cuts, and Slopes
Shallow Slope Failure
Downhill Creep
Dams and Levees
77
Site Investigation
Boring and Sampling
Resistivity
Conductivity for Soluble Sulfates
Ground Penetrating Radar
88
Site Investigation
Depth of the Active Zone
Moisture Active Zone
Movement Active Zone
Vegetation
Crack Fabric in Soil Masses
Field-to-Laboratory Diffusivity Ratios
99
Index Properties
Suction Measurement
Diffusivity Measurements
Constitutive Relationships
Shallow Foundations
Major Earthworks
Laboratory Characterization
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1111
1212
1313
1414
1515
1616
1717
1818
1919
2020
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2323
2424
2525
2626
2727
2828
2929
3030
3131
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3333
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3636
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Dry Season
(-) Suction Ground Surface
Wet Season
Equilibrium
Dep
th
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4040
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Equilibrium Soil Suction vs. TMIEquilibrium Soil Suction vs. TMI
Note: Modified curve and equation ofcurve provided in 3rd Edition Manual.
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Diffusion Test SetupDiffusion Test Setup
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PsychrometerPsychrometer Installation Installation
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Diffusion CoefficientDiffusion Coefficient
Diffusion Coefficient for BHC 2
3
3.5
4
4.5
5
5.5
6
100 1000 10000 100000
Drying Time (minutes)
Su
cti
on
, u
(p
F)
L = 15.93 cm
x = 14.23 cm
ua = 5.91 pF
u0 = 3.51 pF
he = 0.54 cm-1
á = 0.001 cm2/min
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DEPTHBELOW
SOILSURFACE
CRACKING SPACING
SOURCE : MICHAEL KNIGHT PH. D. DISSERTATATION, GEOLOGY UNIVERSITY OF MELBOURNE (AUSTRALIA) 1972
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Field to laboratory diffusion coefficient ratioField to laboratory diffusion coefficient ratio(Cont(Cont’’d)d)
Rel
iabi
lity
Field α/laboratory α0
4949
5050
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Design Program - Winpres
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Design Program - Winpres
60.0
80.0
100.0
120.0
140.0
160.0
180.0
200.0
0 5 10 15 20 25 30
Time (yrs)
Inte
rna
tio
na
l R
ou
gh
ne
ss
In
de
x (
IRI)
(in
/mil
es
)
SN 5.06 in, ACP 4.0 in, LTS 2.5 ft, Inert 2.5 ft
SN 5.28 in, ACP 4.5 in, LTS 2.5 ft, Inert 1.5 ft
SN 5.50 in, ACP 5.0 in, LTS 2.5 ft, Inert 1.5 ft
SN 5.72 in, ACP 4.0 in, LTS 3.0 ft, Inert 1.5 ft
Flexible Pavement
FWD 10,000 psi
Reliability 90 %
ADT (T= 0) 42,850
ADT (T=30) 67,950
W18 8,415,520
IRI versus Time
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ROOT ZONE
Crack Spacing Gets Larger with Depth
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RUNOFF WATER
DRY LIMIT
WET LIMIT
4.0
2.0
4.0
2.5
pF
SUCTION RANGE
BETWEEN CRACKS
WATER
SOAKS
INTO
SOIL 2.0
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SULFATE SWELLING PROBLEMS
LIME +
SULFATE +
WATER +
CLAY = PAVEMENT BUCKLING
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Williamson County Soil MapWilliamson County Soil Map
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MagnetometerMagnetometer
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Variation of Sulfate along slope of theVariation of Sulfate along slope of thesurfacesurface
12345678B1
C3C5
0
5000
10000
15000
20000
25000
30000
Sulfates
(ppm)
Depth
Locations
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Stability Models or Phase DiagramsStability Models or Phase Diagrams290 Soil - Depth of 24-inches290 Soil - Depth of 24-inches
5 6 7 8 9 10 11 12 13 14–5
–4
–3
–2
–1
0
1
2
3
pH
log
a S
O4--
290 Soil B1 2ft @ pH12 Extract
¢
Al(OH)4
-
Al(SO4)
2
-
C4AH
13
Ettringite
Gibbsite
Monoaluminosulfate
25°C
Sac hin Kunagal l i Mon May 10 2004
Dia
gra
m A
l(O
H)
4-,
T
=
25
°C
, P
=
1
.01
3 b
ars
, a
[m
ain]
=
1
0–4.5
53
, a
[H2
O]
=
1
, a
[ SiO
2(a
q)]
=
1
0–7
.46
, a
[C
a++]
=
1
0–2.4
67
; S
up
pre
sse
d:
Gro
ssu
lar
Soluble Sulfates= 18,700 ppm
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VOID RATIO CONSTITUTIVE SURFACEVOID RATIO CONSTITUTIVE SURFACEOF A SOIL AT ARLINGTON, TEXASOF A SOIL AT ARLINGTON, TEXAS
0
0.6
1.2
1.8
2.4
3
0
1.2
2.4
3.6
4.8
6
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
Void Ratio
e
Mechanical
Stress
log 10 ( !m-u a )
(kPa)
Matric Suction
log 10 ( u a -u w ) (kPa)
0.60-0.70
0.50-0.60
0.40-0.50
0.30-0.40
0.20-0.30
0.10-0.20
0.00-0.10
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Building Foundations
Pavements
Embankments, Cuts and Slopes
CONSTRUCTED WORKSIMPACTED BY
EXPANSIVE SOILS
6666
REVISITATION
OF
EXPANSIVE SOILS
ROBERT L. LYTTON, PhD
Foundation Performance Association
Houston, Texas
December 13, 2006