compaction lecture

8/6/2010

1

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.


8/6/2010

2

Current compaction practice

Future practice

Modulus and dry density

Intelligent compaction

Non cylindrical roller compaction


8/6/2010

3

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


LAB : Proctor Test



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

8/6/2010

4

SPECIFICATIONS. X % of Jd max within range of w opt

FIELD


Nuclear Density MeterFor Jd and w


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


8/6/2010

5

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



LAB : Modulus Test


Water Content (%)6 10 14 18

Mod

ulus

(MPa

)

0

20

40

Sand

Clay

E max

w opt

8/6/2010

6

SPECIFICATIONS X % of E max within range of w opt

FIELD


Modulus MeterFor E and w

Intelligent Compaction

EIC


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


8/6/2010

7

Texas A&M University

Stiffness or Modulus?

K = F/x in MN/mE ~ / in MN/m2 or MPaE = F/BxK = F/x = EB/


8/6/2010

8

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


CALCULATION OF MODULUS


8/6/2010

9

Which Modulus?

DEFINITIONInitialSecantTangentUnload-ResilientCyclicReload


WHICH MODULUS?


8/6/2010

10

Which Modulus?

STATE FACTORSDensityStructureWater contentStress historyCementation


Which Modulus?

LOADING FACTORSStress levelStrain levelStrain rateNumber of cyclesDrainage


8/6/2010

11

WHICH MODULUS?


Which Modulus? PLATE MODULUS in FIELD


BPT: Briaud Plate Test

8/6/2010

12

Which Modulus? PLATE MODULUS in LAB


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


8/6/2010

13

Asphalt Modulus

150 to 300 MPa at 140oC

3000 to 4500 MPa at 20oC

25000 MPa at -10oC


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


8/6/2010

14

Example of same modulus testin lab and in field


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)

28

8/6/2010

15

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 )




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 )





8/6/2010

16

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 )





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


8/6/2010

17

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 )


Dry Unit Weight (kN/m^3))



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)



8/6/2010

18

NGES Sand + Porcelain Clay



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 )



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 )



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?

8/6/2010

19

CompactionControl Methods

Conventional Compaction Intelligent Compaction Non cylindrical Compaction


Conventional Compaction (static or vibratory smooth drum

or sheep-foot)


8/6/2010

20

IntelligentCompaction

40

Non Cylindrical Compaction

8/6/2010

21

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



History

First Intelligent Compaction Compactor: 1992

BOMAG (Germany)

AMMANN Compaction Expert (ACE, Switzerland)

Geodynamik (Sweden)

8/6/2010

22

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.

8/6/2010

23

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 )


4 2 -2

200

Soil Reaction Force (kN)

Fx max

-4

Fstat

xFx

1st Pass2nd Pass

3rd Pass

Drum Oscillation (mm)

Force-Displacement Curves


From BOMAG

8/6/2010

24

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 :


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


8/6/2010

25

From Stiffness to Modulus(experimental)


From AMMANN

Soil Modulusfor Intelligent Compaction

Soil: 5 MPa unacceptable200 MPa excellent


8/6/2010

26

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


From BOMAG


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

8/6/2010

27


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)


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)


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


8/6/2010

28









8/6/2010

29

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


Non cylindrical compaction

Triangular and polygonal rollers Impact generated Landpac Broons Bomag


8/6/2010

30

60

8/6/2010

31

LANDPAC

8/6/2010

32

8/6/2010

33

65

Modeling and methodology Simulation results

Cylindrical

Visualized Compaction Mechanism

Es = 10MPa

Es = 30MPa Es = 50MPa 66

8/6/2010

34

Triangular drum

Simulation results


67


TriangularSoil = 10MPa

Visualized Compaction Mechanism(continued)

68

8/6/2010

35

Landpac drum

Simulation results


69



LandpacSoil = 10MPa

70

8/6/2010

36

Pentagonal drum

Simulation results


71


PentagonalSoil = 10MPa


72

8/6/2010

37

Octagonal drum

Simulation results


73


OctagonalSoil = 10MPa


74

8/6/2010

38

Soil Modulus = 10MPa

75

The depth of influence


Soil Modulus = 50MPaSoil Modulus = 30MPa

76

8/6/2010

39

77

Es = 10 MPa

78

8/6/2010

40

Es = 50 MPa

79


Surface settlement (continued)

Es = 10MPa Es = 30MPa Es = 50MPa

Triangular drum: 32.89mm, 22.82mm, and 10.92mm, respectively


Landpac drum: 26.02mm, 17.28mm, and 8.42mm, respectively

80

8/6/2010

41


Surface settlement (continued)


Pentagonal drum: 22.25mm, 14.42mm, and 5.49mm, respectively


Octagonal drum: 20.13mm, 5.21mm, and 2.26mm, respectively

81

Bomag field test results

82

8/6/2010

42


83


84

8/6/2010

43

85


Broons field test results

86

8/6/2010

44

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 (%)


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 (%)


Cylindrical (50MPa)

Triangular (50MPa)

Pentagonal (50MPa)

87

FORSSBLAD (1980)

88

8/6/2010

45

BROONS FIELD DATA

89

Predicted surface settlement

90

8/6/2010

46

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.

91

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.

92

8/6/2010

47

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.

93

THANK YOU

[email protected]


compaction lecture

Documents

modulus lab

plate modulus

universitywhich modulus

modulus testj

university8620109which

density lab

range of w

dry density knm3 jd