Comparing Liquefaction Evaluation Methods Using Penetration-VS

RelationshipsRonald D. Andrus

Clemson University

withP. Piratheepan, Brian S. Ellis, Jianfeng Zhang,

and C. Hsein Juang

U.S.-Taiwan Workshop on Soil Liquefaction National Chiao Tung University, Hsin-Chu, Taiwan

November 3-5, 2003

Acknowledgements

• The U.S. Geological Survey (USGS) and the South Carolina Department of Transportation (SCDOT) funded part of this work

• Many individuals assisted with data collection, including:

T. L. Holzer, M. J. Bennett, J. C. Tinsley, & T. E. Noce of USGS

T. N. Adams of SCDOT

T. J. Casey & W. B. Wright of Wright Padgett Christopher

W. M. Camp & E. Cargill of S&ME, Inc.

F. Syms of Bechtel Savannah River, Inc.

S. L. Gassman of University of South Carolina

Database

• Data from California, South Carolina, Canada, Japan, and Taiwan

• 45 Holocene (< 10,000 years) soil layers, and 55 older soil layers

• Only sands with FC ≤ 20 % or Ic ≤ 2.25

• All measurements below water table

• Both non-liquefied and liquefied sites

Criteria for Selecting Data

• Thick, uniform soil layers based on CPT data, or several SPT and VS measurements

• Penetration test within 6 m of Vs test

• At least 2 Vs measurements and corresponding test intervals within layer

• Time history records used for Vs determination have “easy picks” for shear wave arrivals; if time histories are not available, at least 3 Vs measurements within layer

Corrected S-Wave Velocity

111111 ScsacsSacsaS VKKVKV

where

VS1 = stress-corrected VS

(VS1)cs = stress- and fines content-corrected VS

Kcs = fines content correction factor (Juang et al. 2002)

Ka1 = age correction factor (Andrus & Stokoe 2000)

0

0.1

0.2

0.3

0.4

0.5

0.6

100 150 200 250

Liquefaction

No Liquefaction

Corrected S-Wave

Velocity, (V S1 )csa1 , m/s

M W = 7.5

Andrus & Stokoe

(2000)

0

0.1

0.2

0.3

0.4

0.5

0.6

0 50 100 150 200 250

Robertson& Wride(1998)

Liquefaction

No Liquefaction

Corrected CPT Tip

Resistance, (q c1N )cs

M W = 7.5

D 50 = 0.25-2 mm

Three Curves for Evaluating Liquefaction Resistance

0

0.1

0.2

0.3

0.4

0.5

0.6

0 10 20 30 40 50

Cyc

lic R

esis

tanc

e R

atio

, C

RR

M W = 7.5

Liquefaction

No Liquefaction

ModifiedSeed et al.

(1985)

Corrected SPT Blow

Count, (N 1 )60cs

100

150

200

250

300

0 10 20 30 40 50 60Cor

rect

ed S

-Wav

e V

eloc

ity,

(V

S1

) cs, m

/s

YoundOldY LO L

Implied from CRR curves

Mean for Holocene data:

(V S1 )cs = 87.7[(N 1 )60cs ]0.253

Corrected SPT Blow Count, (N 1 )60cs

SPT – VS Relationships forHolocene Sands

Age, years< 500 > 500 Non-liquefied Liquefied

100

150

200

250

300

0 50 100 150 200 250 300

Cor

rect

ed S

-Wav

e V

eloc

ity,

(V

S1) c

s, m

/s

YoundOldY LO L

Implied from CRR curves

Mean for Holocene data:

(VS1 )cs = 67.6[(q c1N )cs ]0.213

Corrected CPT Tip Resistance, (q c1N )cs

CPT - VS Relationships for Holocene Sands

Age, years< 500 > 500 Non-liquefied Liquefied

0

10

20

30

40

50

60

0 50 100 150 200 250 300

Cor

rect

ed S

PT

Blo

w

Cou

nt,

(N1

) 60c

s

YoundOldY LO L

Implied from CRR curves

Mean for Holocene data:

(N 1 )60cs = 0.488[(q c1N )cs ]0.779

Corrected CPT Tip Resistance, (q c1N )cs

CPT – SPT Relationships for Holocene Sands

Age, years< 500 > 500 Non-liquefied Liquefied

VS – CRR Equation(Andrus & Stokoe 2000)

2

115.7 100

022.0

csaS

cs

VCRR

215

1

215

18.2

11 csaSVwhere

CRR7.5cs = CRR curve for MW = 7.5 and FC ≤ 5 %

(VS1)csa1 = corrected VS

New SPT – CRR Equation

506.06015.7 0169.0 cscs NCRR

215

1

7.87215

18.2

253.0601 csN

where

CRR7.5cs = CRR curve for MW = 7.5 and FC ≤ 5 %

(N1)60cs = corrected SPT blow count

New CPT – CRR Equation

426.015.7 0101.0 csNccs qCRR

215

1

6.67215

18.2

213.01 csNcq

where

CRR7.5cs = CRR curve for MW = 7.5 and IC ≤ 1.64

(qc1N) cs = corrected CPT tip resistance

NEW CRR Curves Based on Penetration – VS Equations

0

0.1

0.2

0.3

0.4

0.5

0.6

100 150 200 250

Liquefaction

No Liquefaction

Corrected S-Wave

Velocity, (V S1 )csa1 , m/s

M W = 7.5

Andrus & Stokoe

(2000)

0

0.1

0.2

0.3

0.4

0.5

0.6

0 50 100 150 200 250

Liquefaction

No Liquefaction

Corrected CPT Tip

Resistance, (q c1N )cs

M W = 7.5

D 50 = 0.25-2 mm

New CRR

Curve

Robertson& Wride(1998)

0

0.1

0.2

0.3

0.4

0.5

0.6

0 10 20 30 40 50

Cyc

lic

Res

ista

nce

Rat

io, C

RR

M W = 7.5

No Liquefaction

Corrected SPT Blow

Count, (N 1 )60cs

New CRR

Curve

ModifiedSeed et al.

(1985)

Liquefaction

Comparison of CRR Curves with Liquefaction Probability = 26 %

0

0.1

0.2

0.3

0.4

0.5

0.6

100 150 200 250

Corrected S-Wave

Velocity, (V S1 )csa1 , m/s

Andrus & Stokoe (2000);

Juang et al. (2002) Model 3

Juang et al.(2002) Model 2

Juang et al.(2002) Model 1

0

0.1

0.2

0.3

0.4

0.5

0.6

0 50 100 150 200 250

Juanget al.

(2002)Model 1

Corrected CPT Tip

Resistance, (q c1N)cs

Topraket al.

(1999)

New CRR Curve

Juang et al.(2002)

Model 2

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0 10 20 30 40 50

Cyc

lic

Res

ista

nce

Rat

io, C

RR

Cetin et al. (2000)

Youd & Noble (1997)

Corrected SPT Blow

Count, (N 1 )60cs

New CRR Curve

Liaoet al.

(1988)

Juang et al.(2002) Model 2

Juanget al.

(2002)Model 1

Topraket al. (1999)

100

150

200

250

300

350

0 10 20 30 40 50 60

Cor

rect

ed S

-Wav

e V

eloc

ity,

(V

S1

) cs, m

/s

O L

Implied from CRR curves

Mean for Holocene data:

(VS1 )cs = 87.7[(N 1 )60cs ]0.253

Corrected SPT Blow Count, (N 1 )60cs

SPT - VS Relationships for Older Sands

Ten Mile Hill (Liquefied)

100

150

200

250

300

350

0 50 100 150 200 250 300Cor

rect

ed S

-Wav

e V

eloc

ity,

(V

S1

) cs, m

/s

YoundOldY LO LSeries7Series8Series9

Implied from CRR curves

Mean for Holocene data:

(V S1 )cs = 67.6[(q c1N )cs ]0.213

Corrected CPT Tip Resistance, (q c1N )cs

CPT - VS Relationships for Older Sands

Non-Liq Liq Merritt Sand Wando Ten Mile Hill Dry Branch Taiwan Sand

0

10

20

30

40

50

60

0 50 100 150 200 250 300

Cor

rect

ed S

PT

Blo

wC

ount

, (N

1) 6

0cs

O L

Implied from CRR curves

Mean for Holocene data:

(N 1 )60cs = 0.488[(q c1N )cs ]0.779

Corrected CPT Tip Resistance, (q c1N )cs

CPT – SPT Relationships for Older Sands

Ten Mile Hill (Liquefied)

0.8

1.0

1.2

1.4

1.6

1.8

1.E+00 1.E+02 1.E+04 1.E+06 1.E+08Age, years

Age

Sca

ling

Fac

tor,

ASF ASF = 0.073log(age)+0.92

R 2 = 0.843

< 100 years

Merritt Sand

100-500 years

Dry Branch

Ten Mile Hill

0.5-10 ka

Wando

Age Scaling Factors for Penetration – VS Equations

SPT-VS data CPT-VS data

Age, years

100 102 104 106 108

Age Correction Factors

Time

(years)

Age Correction Factor,

Ka1 (≈ 1/ASF)

1 1.09

10 1.01

100 0.94

1,000 0.88

10,000 0.83

100,000 0.78

Conclusions• For the compiled Holocene data, the VS-based CRR

curve by Andrus and Stokoe is on average more conservative than the SPT- and CPT-based curves.

• Values of VS from liquefied sands are lower than those from non-liquefied sands with similar penetration resistances.

• The penetration-VS equations developed for Holocene sands change by a factor of about 0.073 per log cycle of time, based on data from non-liquefied sands.

• The VS-based CRR curve is characterized for soils with age of roughly 10 years; and new age scaling factors are proposed.