Nov. 17, 2015 Spectral-Analysis-of-Surface- Waves (SASW ...

Sung-Ho Joh

Department of Civil EngineeringChung-Ang University

Surface Wave Techniques to Evaluate Subsurface Stiffness Structure

Nov. 17, 2015

Spectral-Analysis-of-Surface-Waves (SASW) Method

0 5 10 15 20 25 30 35Location, m

-10

-5

0

Dept

h, m

2

Principles and Concepts of the SASW Method

3

Setup for SASW Measurements

DR

Dynamic Signal Analyzerwith anti-aliasing filter Frequency Span: 25~52000 Hz Real-time FFT 2 to 4 input channels

Geophones4.5 Hz (for D=0.5~1m)1.0 Hz (for D ≥ 2m)Shielded Cables

Impact SourceAssorted Hammers 100-kg Drop WeightBulldozer

Inter-Receiver Spacings0.5, 1.0, 2.0, 4.0, 8.0 m (for Hammers)16.0, 32.0 m (for 100-kg Drop Weight)64.0, 128.0 m (for Bulldozer)

Source-Receiver DistanceR=D (Conventional SASW)R=1, 2, 4, 8, and 16 D

(for CAP-SASW)

4

FFT Analyzer Seismic Sources

Geophones

5

Principles of Phase-Velocity Measurement

360sec 01504.0t

Frequency = 66.48 HzPeriod = 0.01504 sec

phase difference:travel time:

ft

2

Relationship between and t :

2 m

m/sec 0.13301504.0

0.2

tDvphPhase Velocity:

fDvph

2

Receiver 1

Receiver 2

6

Receiver 1

3

2

1

0Spec

tral A

mpl

itude

8006004002000

Frequency, Hz

D D

2000

1000

0U

nwra

pped

Pha

se, d

eg

8006004002000Frequency, Hz

Spec

tral A

mpl

itude 3

2

1

0 8006004002000Frequency, Hz

FFT

Phase Difference :

2 – 1

600

400

200

0

Phas

e Ve

l., m

/sec

1 10 100Wavelength, m

ExperimentalDispersion Curve

Receiver 2

FFT

-150-100-50

050

100150

Phas

e An

gle,

deg

8006004002000Frequency, Hz

Phase Unwrapping

(a)

(b)

(c)

Impact, Swept Sinusoidal Vibration, orRandom Noise

D=1m

Phase-Velocity Determination in SASW Method

7

-150

-100

-50

0

50

100

150

Phas

e An

gle,

deg

8006004002000

Frequency, Hz

-150

-100

-50

0

50

100

150

Phas

e An

gle,

deg

4003002001000

Frequency, Hz

-150

-100

-50

0

50

100

150

Phas

e An

gle,

deg

200150100500

Frequency, Hz

-150

-100

-50

0

50

100

150

Phas

e An

gle,

deg

100806040200

Frequency, Hz

-150

-100

-50

0

50

100

150

Phas

e An

gle,

deg

50403020100

Frequency, Hz

-150

-100

-50

0

50

100

150

Phas

e An

gle,

deg

2520151050

Frequency, Hz

800

600

400

200

0

Phas

e Ve

loci

ty, m

/sec

3 4 5 6 71

2 3 4 5 6 710

2 3 4 5 6 7100

2 3

Wavelength, m

D = 1m

D = 2m

D = 4m

D = 8m

D = 16m

D = 32m

25

20

15

10

5

0

Dep

th, m

8006004002000Shear Wave Velocity, m/sec

InversionAnalysis

CompositeExperimental Dispersion Curve

Inversion Analysis in the SASW Method

8

Global Average Dispersion Curve

Wavelength, ft1 10 100

Phas

e Ve

loci

ty, f

t/sec

0

500

1000

15005 ft10 ft20 ft40 ft80 ftAverage

Composite

Dispersion Curve for Global Inversion Analysis

Theoretical vs. Global Average Dispersion Curve


Phas

e Ve

loci

ty, f

t/sec

0

500

1000

1500AverageTheoretical

Dispersion Curve for Array Inversion Analysis

Array Average Dispersion Curves


Phas

e Ve

loci

ty, f

t/sec

0

500

1000

1500Composite5 ft10 ft20 ft40 ft80 ft


Phas

e Ve

loci

ty, f

t/sec

0

500

1000

1500

5 ft10 ft20 ft40 ft80 ft

5 ft10 ft20 ft40 ft80 ft

Average Theo ret ical

Theoretical vs. Global Average Dispersion Curve

Inversion Analysis for the SASW Method: Global and Array Inversion Analyses

9

Shear Wave Velocity, ft/sec

0 500 1000 1500

Dep

th, f

t

0

10

20

30

Starting ModelFinal ModelExact

Shear Wave Velocity, ft/sec0 500 1000 1500

Dep

th, f

t

0

10

20

30

Starting ModelFinal ModelExact

Global Inversion Array Inversion

Inverted Shear-wave Velocity Profiles

10

Impulse Response Filtration (IRF) Technique Random Noise Added to the Theoretically Determined Displacements

Time, sec0.0 0.5 1.0

Time, sec0.0 0.5 1.0

Impulse Response

Frequency, Hz0 10 20 30 40 50

-180

0

180

Phas

e An

gle,d

eg

10 20 30 40 50Frequency, Hz

0.0

0.1

0.2

0.3

0.4

0.5

-72

-62

-52

-42

-32

-22

Tim

e, s

ec0

11

Comparison of the Original and IRF-Enhanced Phase Spectra

Frequency, Hz0 10 20 30 40 50Ph

ase

Angl

e,de

g

-180-90

090

180

Time, sec0.0 0.5 1.0

Frequency, Hz0 10 20 30 40 50

Phas

e An

gle,

deg

-180

0

180

OriginalIRF-Enhanced

10 20 30 40 50

Frequency, Hz

0.0

0.1

0.2

0.3

0.4

0.5

-72

-62

-52

-42

-32

-22

Tim

e, s

ec0

12

WinSASW, Dedicated Software for the SASW Method

13

D=(1,2,4,8,16,32) m

1 2

S=D

Receivers100 kg

Far SourceNearSource (5 kg)

D=2~4 m

1 2

S=(1,2,4,8,16)D

ReceiversNear SourceFar Source100 kg (5 kg)

Recent Development in the SASW Method

Common-Mid-Point (CMP) SASW Method

Common-Array-Profiling (CAP) SASW Method

CL

14

1000

800

600

400

200

0

Pha

se V

eloc

ity, m

/sec

0.1 1 10 100 1000Wavelength, m

(c) Case C

1000

800

600

400

200Pha

se V

eloc

ity, m

/sec

(b) Case B

1000

800

600

400

200Pha

se V

eloc

ity, m

/sec

CAP SASW2 m4 m8 m16 m32 m64 m128 m

(a) Case ACMP SASW1,2,4,8,16,32,64,128 m

Normal ModesSource Not Specified

[Source Offset]

40

30

20

10

0

Dep

th, m

4002000VS, m/sec

40

30

20

10

0

Dep

th, m

4002000VS, m/sec

40

30

20

10

0

Dep

th, m

4002000VS, m/sec

Shear-WaveVelocity Profile Phase-Velocity Dispersion Curve

CMP SASW Method vs. CAP SASW Method

15

D=3 m

1 2

S=3, 6, 12, 24, and 48 m

ReceiversNear SourceFar Source

40

30

20

10

0

Dep

th, m

25000Vs., m/sec

0

5

10

15500 5 10 15 20 25 30 35 40 45

Location, m

Dep

th, m

55

Evaluation of 2-D Shear-Wave Velocity Profiles

CAP SASW Method

(100kg) (5kg)

16

12

2 m

1 2 11

Receivers

0

5

10

1550 550 5 10 15 20 25 30 35 40 45

Location, m

Dep

th, m

40

30

20

10

0

Dep

th, m

20000Vs., m/sec

MASW Method

(5kg)(5kg)

Near SourceFarr Source

17

SASW Method for Deep Profiling

Low-frequency vibroseis, 64,000 lb-heavy Liquidator

Typical time histories of a vibroseis source 250

200

150

100

50

0

Dep

th, m

2000150010005000Shear-Wave Velocity, m/s

250

200

150

100

50

0

-Wave Velocity, m/sec

Mean16th and 84th PercentileMean16th and 84th Percentile

18

Applications of the SASW Method

19

Applications of the SASW Method

Geotechnical Sites Pavement Systems Concrete Structures

• NDE of asphalt pavements• Modulus and thickness of

pavement layer, subgrade and grade

• Evaluation of Compaction Quality• Site Investigation of

- MSW Landfill- Road bed or Railroad bed

• Evaluation of Vacuum Consolidation• Shear-Wave Velocity Profile for

Seismic Analysis

• Structural Integrity test of- Tunnel Concrete Lining- Concrete Bridge Deck- Retaining Wall

20

• Compaction by Hydraulic Hammer:

Runway of Inchon International Airport

Quality Assurance of Compaction

21

Comparison of Shear-Wave Velocity before and after Compaction

Shear Wave Velocity, m/sec

0 200 400 600 800

Dep

th, m

0

10

20

30

40

50

60

70

80

BeforeAfter


0 100 200 3000

1

2

3

4

5

6

7

8

9

10

BeforeAfter

22

• Stiffness Profiling of Engineering Fill

Treasure Island in San Francisco

Site Investigation at Man-Made Island

23

00 500 1000 1500

Dep

th, f

t50

100

150


SASW (Array Inversion)Crosshole (UT)

Comparison of Shear-Wave Velocity Profiles from SASW and Crosshole Tests

24

140

120

100

80

60

40

20

0

Dep

th, f

t

150010005000

Shear Wave Velocity, ft/sec

SASW OYO Suspension

Logging

• Vs Profiling of OII Landfill at LA, USA:

Comparison between SASW Results and Results ofOYO Suspension Logging

Site Investigation of MSW Landfill Site

25

• Vs Profiling of Ballast and Railroad Bed to Investigate Mud Pumping

Stiffness Profiling of Ballast and Railroad Bed

26

Shear-Wave Velocity Profiles from Inversion Analyses

2.0

1.5

1.0

0.5

0.0

Dep

th, m

5004003002001000Shear Wave Velocity, m/sec

철도 레일 직하 철도 노견

27

Vs Profiling of Asphalt Pavement System

28

Vs Profiles from SASW Tests

Comparison between Results of SASW Testsand CPT

5

4

3

2

1

0

Dep

th, m

25002000150010005000

Shear Wave Velocity from SASW, m/sec

25002000150010005000

Sleeve Friction from CPT, kPa

CPT on Soil SASW on Soil SASW on Asphalt

5

4

3

2

1

0

Dep

th, m

5004003002001000

Shear Wave Velocity from SASW, m/sec

5004003002001000

Sleeve Friction from CPT, kPa

CPT on Soil SASW on Soil

29

Wavelength, ft

.1 1 10 100

Phas

e Ve

locit

y, ft

/sec

0

2000

4000

6000

8000

Wavelength, ft

.1 1 10 100

Phas

e Ve

locit

y, ft

/sec

0

2000

4000

6000

8000

Before Tunneling

JFK Airport, New York

After Tunneling

Soil Layer under Runway

Stiffness Evaluation of Soil Layers under Airport Runway

30

Experimental DataBest-Fit Curve

200

400

600

800

1000

Surfa

ce W

ave

Vel

ocity

(fps

)

10 40Wavelength (ft)

200

400

600

800

1000

10

Wavelength (ft)

40

Surfa

ce W

ave

Vel

ocity

(fps

)

Experimental DataBest-Fit Curve

Before Tunneling

Experimental Dispersion Curve for Runway of JFK Airport (Expanded for Long Wavelengths)

After Tunneling

31

• NDE for Tunnel Concrete Lining:

Road Tunnel

Investigation for Tunnel Concrete Lining (1)

32

0.5

0.4

0.3

0.2

0.1

0.0D

epth

, m

500040003000200010000

Shear Wave Velocity, m

Concrete Lining

Water-Proofing Membrane

Shotcrete and Original MaterialNot much reliable

1-D Shear Wave Velocity Profile

33

1-D Phase Velocity profile in Wavelength-Distance Domain

:추정된방수막위치

1.0

0.8

0.6

0.4

0.2

0.0

Wav

elen

gth,

m

3.02.52.01.51.00.50.0

Distance, m

2-D Stiffness Profile

34

:추정된방수막위치

0.4

0.3

0.2

0.1

0.0

Dep

th, m

3.02.52.01.51.00.50.0

Distance, m

2-D Shear-Wave Velocity Profile of Tunnel Concrete Lining in Depth-Distance Domain

35

ConcreteLiner

Grout

Rock

tconcrete

tgrout

ConcreteLiner

Grout

Rock

tconcrete

tgrout

Rock

Grout

LinerReceivers

HammerSource

SASWArray Axes

“Crown” InvestigationPlane

SpringlineInvestigationPlane

Rock

Grout

LinerReceivers

HammerSource

SASWArray Axes



(a) Generalized Tunnel Cross Section

SASW testing performed inside a concrete-lined tunnel (from Stokoe and Santamarina, 2000)

(b) SASW Testing Arrangement and Planes of Investigation

Shear Wave Velocity, VS , m/sec

Station 1(Springline)

concrete liner(thickness ~ 35 cm)

rock behind liner stiffer than concrete

0

2

4

6

80 1000 2000 3000

Dep

th, m

4000Shear Wave Velocity, VS , m/sec




0

2

4

6

80 1000 2000 3000

Dep

th, m

4000

concrete liner(thickness >40 cm)

grout(good stiffness

and thickness > 30 cm)

Rock behind liner softer than concrete

Station 2 (Crown)

{{

0

4

80 1000 2000 3000


Dep

th, m

6

2

concrete liner(thickness >40 cm)




Station 2 (Crown)

{{

0

4

80 1000 2000 3000


Dep

th, m

6

2

(a) Interpreted Vs profile at a springline station

Examples of Vs profiles measured inside a concrete-lined tunnel (from Stoke and Santamarina, 2000)

(b) Interpreted Vs profile at a “crown” station

Investigation for Tunnel Concrete Lining (2)

36

(a) Generalized Tunnel Cross Section (b) SASW Testing Arrangement and Planes of Investigation

RockGrout

LinerReceivers

HammerSource

SASWArray Axes



RockGrout

LinerReceivers

HammerSource

SASWArray AxesConcrete

Liner

Grout

Rock

tconcrete

tgrout

Rock

tconcrete

tgrout

(b) Interpreted Vs profile at a springline station (b) Interpreted Vs profile at a “crown” station

Examples of Vs profiles measured inside a concrete-lined tunnel (from Stoke and Santamarina, 2000)





0

2

4

6

80 1000 2000 3000

Dep

th, m

4000

( )



0

2

4

6

80 1000 2000 3000

Dep

th, m

4000

concrete liner(thickness > 40cm)




Station 2 (Crown)

0

4

80 1000 2000 3000


6

2

0

4

80 1000 2000 3000


6

2

Dep

th, m

37

Dep

th, m

0.00

0.05

0.10

0.15

0.20

Dep

th, m

0.00

0.05

0.10

0.15

0.20

Dep

th, m

0.00

0.05

0.10

0.15

0.2095.1C95.1C 95.1N95.1N 94.4S94.4S 94.4C94.4C 94.4N94.4N 94.3S94.3S 94.3C94.3C 94.3N94.3N

57.3S 57.3C 57.3N 57.2S 57.2C 57.2N 57.1S 57.1C 57.1N57.3S57.3S 57.3C57.3C 57.3N57.3N 57.2S57.2S 57.2C57.2C 57.2N57.2N 57.1S57.1S 57.1C57.1C 57.1N57.1N

Concrete Slab ID

Defects Small Modulus

Good Material Large Modulus

1.4

1.2

1.0

0.8

0.6

0.4

0.2

0.0

Dep

th, m

500040003000200010000Shear-Wave Velocity, m/sec

P.Section 94.4(Row 5) 57.2(Row 5) 57.2(Row 3)

Investigation of Surface Cracks in Concrete Runway

38

4.0m

2.0mMeasurement ArrayFor Tomograhpy

Investigation of Damanaged Area after Explosion

39

100

200

300

400

500

600

700

800

900

1000

1100

1200

Wav

elen

gth,

m

Wav

elen

gth,

m

Distance from Cliff, m2 3 4 5 6

0

2

4

6

8

10

12

14

16

18

20

0

2

4

6

8

10

12

14

16

18

20

2 3 4 5 6

Surface-WaveVel. m/sec

Distance from Cliff, m

Before Explosion After Explosion

40

Thank you for your attention!

감사합니다.

Nov. 17, 2015 Spectral-Analysis-of-Surface- Waves (SASW ...

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