fines content correction factors for spt n values – liquefaction

Fines Content Correction Factors for SPT N Values – Liquefaction Resistance

Correlation

Marawan ShahienProfessor of Geotechnical Engineering & Foundations

Stuctural Engineering Department

Tanta University, Tanta, Egypt

Content

• Introduction• Liquefaction Resistance – SPT N Correlations• Existing Fines Content Correction Factors

• Motivation and Aim of the Paper

• Proposed Correction Factors: Methodology

• Influence of FC on (N1)60

• Influence of FC on CRR

• Influence of FC on CRR-(N1)60

• Proposed Relationship

• Concluding Remarks

Liquefaction Resistance – SPT N Correlations

Liquefaction Resistance – SPT N Correlation

Existing Fines Content Correction Factors

Liq

uef

act

ion

Res

ista

nce

, CR

R

Base Curve Clean Sand (FC≤5%)

Sand with Fines

(N1)60 Values

D(N1)60

(N1)60-CS(N1)60

601601601

NNCS

N D

Existing Fines Content Correction FactorsForm Reference

(N1)60-CS = (N1)60 + D(N1)60

D(N1)60 = constant Seed et al. (1983)

D(N1)60 = f(FC) Tokimatsu and Yoshimi (1983)

Seed et al.(1984) –

Terzaghi et al (1996)

Kayen and Mitchell (1997)

Shahien and Mesri (1999)

Youd et al. (2001)

Idriss and Boulanger (2006)

D(N1)60=g[FC,(N1)60] Idriss and Seed (1996)

Robertson and Wride (1996)

(N1)60-CS = Cfines(N1)60

Cfines= k[FC,(N1)60] Cetin et al. (2004)

Existing Fines Content Correction Factors

Form Reference

(N1)60-CS = (N1)60 + D(N1)60

D(N1)60 = constant Seed et al. (1983)

D(N1)60 = f(FC) Tokimatsu and Yoshimi (1983)

Seed et al.(1984) –

Terzaghi et al (1996)

Kayen and Mitchell (1997)

Shahien and Mesri (1999)

Youd et al. (2001)

Idriss and Boulanger (2006)

D(N1)60=g[FC,(N1)60] Idriss and Seed (1996)

Robertson and Wride (1996)

(N1)60-CS = Cfines(N1)60

Cfines= k[FC,(N1)60] Cetin et al. (2004)

Shahien &Mesri (1999)

Motivation and Aim of the Paper

Green et al. (2006)

examined FC correction factors

used 98 case records of SPT N

with liquefaction/no liquefaction

14 earthquakes

Proposed Correction Factors: Methodology

(1)Correct for influence of FC on (N1)60, and

(2)Correct for influence of FC on CRR.

Combining both correction factors

Correction for influence of FC on CRR versus (N1)60

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0 10 20 30 40 50

Cyc

lic R

esis

tan

ce R

atio

, CR

R

(N1)60

FC≤5%

SPT Clean Sand Base Curve

((N1)60-CS, CRR)

Correction For Influence of Fines Content on Penetration ResistanceInfluence of FC on penetration resistance

Standard Penetration Test (SPT) is a dynamic test.

Du develops during penetration & rate of Du dissipation depends on k of soil

FC contractiveness

Du & k

slower dissipation Du

N’

Correction For Influence of Fines Content on Penetration ResistanceInfluence of FC on penetration resistance

Fines Content, FC, %

1 10 100

N'

1

10

(Data from Seed et al. (1984))

Correction For Influence of Fines Content on Penetration ResistancePenetration resistance versus Relative Density correlation

Meyerhof (1957) 412

1 ba

Dr

N

Skempton (1986) ba

Dr

N

2

1

Cubrinovski & Ishihara (1999), (2000) & (2001)

7.1

maxmax

9

2

601

eeD

C

Dr

N

(emax-emin) : void ratio range

min

Correction For Influence of Fines Content on Penetration ResistanceRelationship between void ratio range and FC

0.0

0.2

0.4

0.6

0.8

1.0

0 20 40 60 80

Vo

id R

atio

Ran

ge e

max

-em

in


Rang e by Cubrinovski & Ishihara (2002)

Cubrinovski & Ishihara (2002)

Proposed

Back calculated Based on Youd et al (2001)

7.1

maxmax

9

2

601

eeD

C

Dr

N

min

Correction For Influence of Fines Content on Penetration ResistanceProposed correction for influence of FC on N

0.0

0.2

0.4

0.6

0.8

1.0

0 20 40 60 80

Vo

id R

atio

Ran

ge e

max

-em

in




Proposed


7.1

maxmax

9

2

601

eeD

C

Dr

N

0

10

20

30

40

0 20 40 60 80 100

SPT

(N1) 6

0

Fines Content, FC, %,

Dr, %100

80

6550

35

Correction For Influence of Fines Content on Penetration ResistanceProposed correction for influence of FC on N

0.0

0.2

0.4

0.6

0.8

1.0

0 20 40 60 80

Vo

id R

atio

Ran

ge e

max

-em

in




Proposed


7.1

maxmax

9

2

601

eeD

C

Dr

N

0

10

20

30

40

0 20 40 60 80 100

SPT

(N1) 6

0


Dr, %100

80

6550

35

0.0

0.2

0.4

0.6

0.8

1.0

0 20 40 60 80 100

RN

FC=N

60/N

60

-CS=

(N1) 6

0/(N

1) 6

0-C

S


Correction For influence of FC on CRR

0.0

0.2

0.4

0.6

0.8

1.0

1.2

0 20 40 60 80 100

RC

RR

FC=C

RR

FC/C

RR


Limiting Fines Content

Transition Zone

Non/Low Plastic Silt Behavior

Coarse grained Behavior

Polito (1999)

Polito and Martin (2001)

LFC

Cubrinovski and Ishihara (2002)

Yatesville silt/sand mixture Dr = 30%

0.0

0.1

0.2

0.3

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0.6

0 10 20 30 40 50

Cyc

lic R

esis

tan

ce R

atio

, CR

R

(N1)60

Combined Correction For influence of FC on CRR-(N1)60 Relationship

FC≤5%


Correction for FC≤LFC

0.0

0.2

0.4

0.6

0.8

1.0

1.2

0 20 40 60 80 100

RC

RR

FC=C

RR

FC/C

RR



Transition Zone



0.0

0.2

0.4

0.6

0.8

1.0

0 20 40 60 80 100

RN

FC=

N6

0/N

60

-CS=

(N1) 6

0/(N

1) 6

0-C

S


((N1)60-CS, CRR)

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0 10 20 30 40 50

Cyc

lic R

esis

tan

ce R

atio

, CR

R

(N1)60


FC≤5%


Correction for FC≤LFC

0.0

0.2

0.4

0.6

0.8

1.0

1.2

0 20 40 60 80 100

RC

RR

FC=C

RR

FC/C

RR



Transition Zone



0.0

0.2

0.4

0.6

0.8

1.0

0 20 40 60 80 100

RN

FC=

N6

0/N

60

-CS=

(N1) 6

0/(N

1) 6

0-C

S


0.0

0.1

0.2

0.3

0.4

0.5

0.6

0 10 20 30 40 50

Cyc

lic R

esis

tan

ce R

atio

, CR

R

(N1)60

((N1)60-CS, CRR)

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0 10 20 30 40 50

Cyc

lic R

esis

tan

ce R

atio

, CR

R

(N1)60


FC≤5%


Correction for FC>LFC

0.0

0.2

0.4

0.6

0.8

1.0

1.2

0 20 40 60 80 100

RC

RR

FC=C

RR

FC/C

RR



Transition Zone



0.0

0.2

0.4

0.6

0.8

1.0

0 20 40 60 80 100

RN

FC=

N6

0/N

60

-CS=

(N1) 6

0/(N

1) 6

0-C

S


((N1)60-CS, CRR)

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0 10 20 30 40 50

Cyc

lic R

esis

tan

ce R

atio

, CR

R

(N1)60


FC≤5%


Correction for FC>LFC

0.0

0.2

0.4

0.6

0.8

1.0

1.2

0 20 40 60 80 100

RC

RR

FC=C

RR

FC/C

RR



Transition Zone



0.0

0.2

0.4

0.6

0.8

1.0

0 20 40 60 80 100

RN

FC=

N6

0/N

60

-CS=

(N1) 6

0/(N

1) 6

0-C

S


((N1)60-CS, CRR)

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0 10 20 30 40 50

Cyc

lic R

esis

tan

ce R

atio

, CR

R

(N1)60


0.0

0.1

0.2

0.3

0.4

0.5

0.6

0 10 20 30 40 50

Cyc

lic R

esis

tan

ce R

atio

, CR

R

(N1)60

≤5%

SPT Clean Sand Base Curve(Figure 1)

1535

FC

50%

60%80%

Field Case Records Consideration and Proposed Relationship

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0 10 20 30 40 50

Cyc

lic R

esis

tan

ce R

atio

, CR

R

(N1)60

≤5%

SPT Clean Sand Base Curve(Figure 1)

1535

FC

50%

60%80%

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0.1

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0.5

0.6

0 10 20 30 40 50

Cyc

lic R

esis

tan

ce R

atio

, CR

R

(N1)60

LiquefactionNo Liquefaction

Green et al. (2006)35<FC ≤92%

50

6080

Youd and Idriss (2001)FC ≥ 35%

(This Paper)FC = 35%

Proposed -This PaperFC > 35%

Field Case Records Consideration and Proposed Relationship

0.0

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0.5

0.6

0 10 20 30 40 50

Cyc

lic R

esis

tan

ce R

atio

, CR

R

(N1)60

≤5%


1535

FC

FC > 35% - Proposed

Concluding Remarks

• This paper presents an alternative approach to obtain FC

correction to the liquefaction resistance versus

penetration resistance ((N1)60) relationship.

• The obtained correction confirmed the already existing

one for FC≤ 35% (Youd et al., 2001).

• However, it provided new correction for FC> 35% that is

consistent with field case records.

Thank you

fines content correction factors for spt n values – liquefaction

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