Download - Compaction Lecture
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8/6/2010
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COMPACTION INNOVATIONS AND CONTROL BASED ON
SOIL MODULUS
ByJean-Louis BRIAUD
President of ISSMGEProfessor, Texas A&M University, USA
J-L Briaud, Texas A&M University
ACKNOWLEDGEMENTS
Hans Kloubert, BOMAG Roland Anderegg, AMMANN Carl Petterson, GEODYNAMIK Dermot Kelly, LANDPAC Derek Avalle, BROONS Kukjo Kim, Texas A&M Univ. Jeongbok Seo, Texas A&M Univ.
J-L Briaud, Texas A&M University
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8/6/2010
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Current compaction practice
Future practice
Modulus and dry density
Intelligent compaction
Non cylindrical roller compaction
J-L Briaud, Texas A&M University
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8/6/2010
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CURRENT PRACTICEBased on Density
LAB: Proctor test to get dry density vs. water content curve
SPEC: x% of Jd max within range of w opt
FIELD: Compact and check that Jd and w meet the specs
J-L Briaud, Texas A&M University
LAB : Proctor Test
J-L Briaud, Texas A&M University
CURRENT PRACTICEBased on Density
Water Content (%)
3 9 15 2114
16
18
20
Dry
Den
sity
(kN
/m3 )
Jd max
w opt
S = 1S = 0.9
Water Content (%)
3 9 15 2114
16
18
20
Dry
Den
sity
(kN
/m3 )
Jd max
w opt
S = 1S = 0.9
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SPECIFICATIONS. X % of Jd max within range of w opt
FIELD
J-L Briaud, Texas A&M University
Nuclear Density MeterFor Jd and w
CURRENT PRACTICEBased on Density
Dry Density: Advantages and Disadvantages
1. AdvantagesAccumulated knowledgeWell defined parameterIndication of solids per unit volume
2. DisadvantagesNot related to designNot very sensitiveNot easy to measure quickly in field
J-L Briaud, Texas A&M University
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FUTURE PRACTICEBased on Modulus
LAB: Modulus test to get modulus vs. water content curve
SPEC: x% of E max within range of w opt
FIELD: Intelligent compaction and check that E max and w meet the specs
J-L Briaud, Texas A&M University
FUTURE PRACTICEBased on Modulus
LAB : Modulus Test
J-L Briaud, Texas A&M University
Water Content (%)6 10 14 18
Mod
ulus
(MPa
)
0
20
40
Sand
Clay
E max
w opt
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SPECIFICATIONS X % of E max within range of w opt
FIELD
J-L Briaud, Texas A&M University
Modulus MeterFor E and w
Intelligent Compaction
EIC
FUTURE PRACTICEBased on Modulus
Modulus: Advantages and Disadvantages
1. AdvantagesDirectly related to designVery sensitive to water contentEasy to measure quickly in field
2. DisadvantagesMany influencing factorsNo lab test to get E vs. wNo target valuesNew concept
J-L Briaud, Texas A&M University
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Texas A&M University
Stiffness or Modulus?
K = F/x in MN/mE ~ / in MN/m2 or MPaE = F/BxK = F/x = EB/
J-L Briaud, Texas A&M University
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Stiffness or Modulus?
Stiffness depends on the size of the roller.
Modulus does not; it is a property of the soil only.
Use the modulus, not the stiffness
J-L Briaud, Texas A&M University
CALCULATION OF MODULUS
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Which Modulus?
DEFINITIONInitialSecantTangentUnload-ResilientCyclicReload
J-L Briaud, Texas A&M University
WHICH MODULUS?
J-L Briaud, Texas A&M University
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Which Modulus?
STATE FACTORSDensityStructureWater contentStress historyCementation
J-L Briaud, Texas A&M University
Which Modulus?
LOADING FACTORSStress levelStrain levelStrain rateNumber of cyclesDrainage
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WHICH MODULUS?
J-L Briaud, Texas A&M University
Which Modulus? PLATE MODULUS in FIELD
J-L Briaud, Texas A&M University
BPT: Briaud Plate Test
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Which Modulus? PLATE MODULUS in LAB
J-L Briaud, Texas A&M University
BPT: Briaud Plate Test
Range of Modulus
Steel: 200,000 MPaConcrete: 20,000 MPaWood, Plastic: 13,000 MPaRock: 2,000 to 30,000 MPaAsphalt: 150 to 25000 MPaSoil: 5 MPa to 1000 MPaMayonnaise: 0.5 MPa
J-L Briaud, Texas A&M University
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Asphalt Modulus
150 to 300 MPa at 140oC
3000 to 4500 MPa at 20oC
25000 MPa at -10oC
J-L Briaud, Texas A&M University
NGES Sand
16.0
16.5
17.0
17.5
18.0
18.5
19.0
0 2 4 6 8 10 12 14Water Content (%)
Dry
Uni
t Wei
ght (
kN/m
3 )
Compaction Curve Mold #5
Compaction Curve Mold #6
J-L Briaud, Texas A&M University
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Example of same modulus testin lab and in field
J-L Briaud, Texas A&M University
BCD Test: Briaud Compaction Device
BCD on Proctor Mold BCD in the Field
0
10
20
30
40
50
60
0 2 4 6 8 10 12 14Water Content (%)
Mod
ulu
s (M
Pa)
.
0
4
8
12
16
20
Dry
Un
it W
eigh
t (k
N/m
3 ) .
Plate Reload Modulus (MPa)
Dry Unit Weight (kN/m^3)
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NGES Silty Sand (Mold #5)
0
10
20
30
40
0 2 4 6 8 10 12 14Water Content (%)
Mod
ulus
(MPa
)
0
4
8
12
16
20
Dry
Uni
t Wei
ght (
kN/m
3 )
Plate Reload Modulus (MPa)
Dry Unit Weight (kN/m^3)
J-L Briaud, Texas A&M University
Modulus measured with BPT: Briaud Plate Test
NGES Silty Sand (Mold #6)
0
10
20
30
40
0 2 4 6 8 10 12Water Content (%)
Mod
ulus
(MPa
)
0
4
8
12
16
20
Dry
Uni
t Wei
ght (
kN/m
3 )
Plate Reload Modulus (MPa)
Dry Unit Weight (kN/m^3)
J-L Briaud, Texas A&M University
Modulus measured with BPT: Briaud Plate Test
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NGES Silty Sand
0
10
20
30
40
50
0 2 4 6 8 10 12 14Water Content (%)
Mod
ulus
(Mpa
)
0
4
8
12
16
20
Dry
Uni
t Wei
ght (
kN/m
3 )
Plate Reload Modulus (MPa)
Dry Unit Weight (kN/m^3)
J-L Briaud, Texas A&M University
Modulus measured with BPT: Briaud Plate Test
17.5
18.0
18.5
19.0
19.5
0 4 8 12 16Water Content (%)
Dry
Unit
Wei
ght (
kN/m
3 )
Compaction Curve Mold #5Compaction Curve Mold #6
NGES Sand + Porcelain Clay
J-L Briaud, Texas A&M University
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NGES Sand + Porcelain Clay (Mold #5)
0
10
20
30
40
0 2 4 6 8 10 12 14 16Water Content (%)
Mod
ulus
(M
Pa)
0
4
8
12
16
20
Dry
Uni
t W
eigh
t (k
N/m
3 )
Plate Reload Modulus (MPa)
Dry Unit Weight (kN/m^3))
J-L Briaud, Texas A&M University
Modulus measured with BPT: Briaud Plate Test
NGES Sand + Porcelain Clay (Mold #6)
0
10
20
30
40
0 2 4 6 8 10 12 14 16Water Content (%)
Mo
du
lus
(MP
a)
0
4
8
12
16
20
Dry
Un
it W
eig
ht
(kN
/m3 )
Plate Reload Modulus (MPa)Dry Unit Weight (kN/m^3)
J-L Briaud, Texas A&M University
Modulus measured with BPT: Briaud Plate Test
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NGES Sand + Porcelain Clay
J-L Briaud, Texas A&M University
Modulus measured with BPT: Briaud Plate Test
0
20
40
60
0 2 4 6 8 10 12 14 16Water Content (%)
Mo
du
lus
(Mp
a)
0
4
8
12
16
20
Dry
Un
it W
eig
ht
(kN
/m3 )
Plate Reload Modulus (MPa)
Dry Unit Weight (kN/m^3)
0
20
40
60
0 2 4 6 8 10 12 14 16Water Content (%)
Mo
du
lus
(Mp
a)
0
4
8
12
16
20
Dry
Un
it W
eig
ht
(kN
/m3 )
Plate Reload Modulus (MPa)
Dry Unit Weight (kN/m^3)
Only one of those three is not enough
Two of those three are sufficient
All three would be niceJ-L Briaud, Texas A&M University
1. Density?2. Modulus?3. Water Content?
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CompactionControl Methods
Conventional Compaction Intelligent Compaction Non cylindrical Compaction
J-L Briaud, Texas A&M University
Conventional Compaction (static or vibratory smooth drum
or sheep-foot)
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IntelligentCompaction
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Non Cylindrical Compaction
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Intelligent Vibratory Compaction
Instrumented vibrating rollers Measure roller accel. as a function of time Calculate a soil modulus That modulus is/not independent of the roller Intelligent roller modifies automatically &instantaneously its own settings (force, ampl.,freq.) to meet the target modulus
J-L Briaud, Texas A&M University
Texas A&M University
History
First Intelligent Compaction Compactor: 1992
BOMAG (Germany)
AMMANN Compaction Expert (ACE, Switzerland)
Geodynamik (Sweden)
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Slide 43
Recompaction of soft formation area with VARIOCONTROL automatic mode, presetting ( target value ) EVIB = 80 MN/m
Intelligent Compaction
Intelligent CompactionTests in the U.S.A.
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From Acceleration to Stiffness
2 cos( ) ( )B d d u u f dF m x m r t m m g# : : d u udx m rd ud uB B d B dF k x d x# dxd
FB: soil-drum-interaction-force md: mass of the drum (kg)xd: vert. disp. of drum (m) : acceleration of drummf: mass of the frame (kg) mu: unbalanced mass (kg)ru: radial distance for mu = g: acc. due to gravity (m/sec2) f: frequency of rotating shaft (Hz)
: velocity of drum kB: stiffness of soildB: damping coefficient (dB ~ 0.2)
dxdx
dxd
dx
2 fS f
dx : dx
d (k )
J-L Briaud, Texas A&M University
4 2 -2
200
Soil Reaction Force (kN)
Fx max
-4
Fstat
xFx
1st Pass2nd Pass
3rd Pass
Drum Oscillation (mm)
Force-Displacement Curves
J-L Briaud, Texas A&M University
From BOMAG
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From Stiffness to Modulusdxdx
Gb
BF
Gb
BF
),( EFf B G
lF
ERb B)1(16
2QS
H. Hertz, 1895 :
)ln8864,1(212
bl
lF
EB S
QG
G. Lundberg, 1939 :
J-L Briaud, Texas A&M University
From Stiffness to Modulus(theoretical)
dxdx
> @
32
2
MN m12 1 2.14 ln2 1 16
B
f d
E LkL Em m R g
SSQ Q
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From Stiffness to Modulus(experimental)
J-L Briaud, Texas A&M University
From AMMANN
Soil Modulusfor Intelligent Compaction
Soil: 5 MPa unacceptable200 MPa excellent
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Soil layers Density Bearing capacity Eveness(Standard Proctor) (load bearing test, EV2) (4 m straight edge)
Laying and compaction specification for road construction in Germany
Subbase 100 - 103 % * 100 - 150 MN/m * 20 mm
Capping layer 100 - 103 % * 100 - 120 MN/m * 40 mm
Formation 97 - 100 % * 45 - 80 MN/m * 60 mm
* depending on road classification and road design
Specifications based on Modulus
J-L Briaud, Texas A&M University
From BOMAG
Texas A&M University
Why Intelligent Compaction?
TYPE OF CONTRACTS (EUROPE)
Best-value awards rather than low bid Design-build rather than prescriptive specifications Performance contracting Continuous Compaction Control (CCC) in national
standards: Austria (RVS 8S.02.6), Germany (ZTVEStB94), Sweden (VG 94), and Finland
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Texas A&M University
Why Intelligent Compaction? WARRANTY
SpainUK 6)
0
5
10
15
20
25
30
SpainUK 1)
Germany 2) DenmarkSweden
UK 3)
DenmarkSweden 4)
Germany 5)
Dur
atio
n of
War
rant
y (y
ears
)
1~24
5
11~16
20
25~30
SpainUK 6)
0
5
10
15
20
25
30
SpainUK 1)
Germany 2) DenmarkSweden
UK 3)
DenmarkSweden 4)
Germany 5)
Dur
atio
n of
War
rant
y (y
ears
)
1~24
5
11~16
20
25~30
0
5
10
15
20
25
30
SpainUK 1)
Germany 2) DenmarkSweden
UK 3)
DenmarkSweden 4)
Germany 5)
Dur
atio
n of
War
rant
y (y
ears
)
1~24
5
11~16
20
25~30 1) Material and Workmanship2) Material and Workmanship3) Performance4) Pavement Performance
Contracts5) Pavement Performance
Contracts Functional6) Design-Build Finance Operate
ECONOMICS More than 30% reduction in labor time and fuel costs Reduce the number of conventional spot tests Increase the rollers useful life
1. Reference modulus = plate test?
2. Develop simple lab modulus test
3. Study modulus vs water/asph. Content
4. Demonstrate that IC is better than CC
5. Calibrate rollers against plate modulus
6. Use same modulus test (lab and field)
ISSUES
J-L Briaud, Texas A&M University
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Example of same modulus testin lab and in field
J-L Briaud, Texas A&M University
BCD Test: Briaud Compaction Device
BCD on Proctor Mold BCD in the Field
Example of same modulus testin lab and in field
J-L Briaud, Texas A&M University
BCD Test: Briaud Compaction Device
BCD on Proctor Mold BCD in the Field
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7. Develop specs based on modulus fordiff. pavement cond.
8. Can the asphalt modulus be isolated from the soil modulus
9. Use modulus control equipment
10. Demonstrate the IC equipment
11. First International Conference on Compaction?
ISSUES
J-L Briaud, Texas A&M University
Non cylindrical compaction
Triangular and polygonal rollers Impact generated Landpac Broons Bomag
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LANDPAC
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Modeling and methodology Simulation results
Cylindrical
Visualized Compaction Mechanism
Es = 10MPa
Es = 30MPa Es = 50MPa 66
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Triangular drum
Simulation results
Modeling and methodology Simulation results
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Modeling and methodology Simulation results
TriangularSoil = 10MPa
Visualized Compaction Mechanism(continued)
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Landpac drum
Simulation results
Modeling and methodology Simulation results
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Visualized Compaction Mechanism(continued)
Modeling and methodology Simulation results
LandpacSoil = 10MPa
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Pentagonal drum
Simulation results
Modeling and methodology Simulation results
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Modeling and methodology Simulation results
PentagonalSoil = 10MPa
Visualized Compaction Mechanism(continued)
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Octagonal drum
Simulation results
Modeling and methodology Simulation results
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Modeling and methodology Simulation results
OctagonalSoil = 10MPa
Visualized Compaction Mechanism(continued)
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Soil Modulus = 10MPa
75
The depth of influence
Modeling and methodology Simulation results
Soil Modulus = 50MPaSoil Modulus = 30MPa
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Es = 10 MPa
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Es = 50 MPa
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Modeling and methodology Simulation results
Surface settlement (continued)
Es = 10MPa Es = 30MPa Es = 50MPa
Triangular drum: 32.89mm, 22.82mm, and 10.92mm, respectively
Es = 10MPa Es = 30MPa Es = 50MPa
Landpac drum: 26.02mm, 17.28mm, and 8.42mm, respectively
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Modeling and methodology Simulation results
Surface settlement (continued)
Es = 10MPa Es = 30MPa Es = 50MPa
Pentagonal drum: 22.25mm, 14.42mm, and 5.49mm, respectively
Es = 10MPa Es = 30MPa Es = 50MPa
Octagonal drum: 20.13mm, 5.21mm, and 2.26mm, respectively
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Bomag field test results
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Bomag field test results
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Bomag field test results
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Bomag field test results
Broons field test results
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Texas A&M University simulations
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
1.1
1.2
0 0.1 0.2 0.3 0.4 0.5 0.6
Dep
th (m
)
Strain (%)
Strain after 1 pass(Soil modulus = 10MPa)
Cylindrical (10MPa)
Triangular (10MPa)
Pentagonal (10MPa)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
1.1
1.2
0 0.1 0.2 0.3
Dep
th (m
)
Strain (%)
Strain after 1 pass(Soil modulus = 30MPa)
Cylindrical (30MPa)
Triangular (30MPa)
Pentagonal (30MPa)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
1.1
1.2
0 0.05 0.1 0.15 0.2
Dep
th (m
)
Strain (%)
Strain after 1 pass(Soil modulus = 50MPa)
Cylindrical (50MPa)
Triangular (50MPa)
Pentagonal (50MPa)
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FORSSBLAD (1980)
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BROONS FIELD DATA
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Predicted surface settlement
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CONCLUSIONS
The width of the contact area between the drum and the soil controls the depth of compaction. The softer the soil is, the deeper the roller sinks in the soil, the wider the contact area is, and the deeper the compaction is. Therefore the depth of compaction depends on the stiffness of the soil. As such the depth of compaction decreases with the number of passes.
The surface pressure controls the degree of compaction. This pressure is higher for the impact rollers than for the cylindrical rollers due to the dynamic effect. Yet the distribution of the pressure is much more uneven for impact rollers than for cylindrical rollers.
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CONCLUSIONS
The depth of compaction is larger for impact rollers because they impart higher stresses which increase the penetration of the roller drum into the soil thereby increasing the width and therefore depth of influence.
It is also possible that the increase depth of influence is due to wave propagation during the impact. These waves can propagate much deeper than the typical depth of influence for static loading.
The loosening effect of the surface is more prominent for the impact rollers than for the cylindrical rollers.
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RECOMENDATIONS
Compact first with an impact roller and use several passes to minimize the extent of the areas between impacts.
Finish by using a cylindrical roller to optimize the compaction of the shallow layers.
This process combines the benefits of both types of rollers: compaction of the deep layers (0.5 to 1.5 m) with the impact roller but loosening of the shallow layers (0 to 0.5 m) followed by compaction of the shallow layers (0 to 0.5 m) with the cylindrical roller without disturbing the deep layers.
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THANK YOU
J-L Briaud, Texas A&M University