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1
CONTRIBUTIONS OF FIELD CASE HISTORIES TO GEOTECHNICAL EARTHQUAKE ENGINEERING
presented by
I. M. Idriss, Professor EmeritusUniversity of California at Davis
e-mail: [email protected]
Presented at the dinner meeting of the
ASCE SEATTLE SECTION -- GEOTECHNICAL GROUP
Seattle, Washington
September 30, 2010
Materials for this talk are based on work by I. M. Idriss and R. W. Boulanger
Idriss & Boulanger (2008). "Soil Liquefaction During Earthquakes." Monograph MNO-12, EERI.
Idriss & Boulanger (2010). "SPT-based liquefaction triggering procedures. "Report UCD/CGM-10/02, University of California, Davis, CA.
The "Peck Lecture", which was presented at ASCE's GeoFlorida Conference on February 21, 2010 by I. M. Idriss.
The full text of the "Peck Lecture" (by I. M. Idriss and R. W. Boulanger) is to be published in the Geotechnical Journal of ASCE in 2011 or 2012, depending on the length of the review process.
2
PECK AWARD
The Ralph B. Peck Award recognizes an individual's contributions to the geotechnical engineering profession through the publication of a thoughtful, carefully researched case history or histories, or the publication of recommended practices or design methodologies based on the evaluation of case histories.
Case Histories have always played a strong role in geotechnical engineering. They have been an essential means for:
improving understanding;
Calibrating analytical procedures;
Designing & interpreting physical model tests; and
developing semi-empirical procedures
Under static as well as during earthquake and post-earthquake loading conditions.
ROLE OF CASE HISTORIES
3
SIGNIFICANT EARTHQUAKES SINCE 19601962 Mexico City1964 ALASKA1964 NIIGATA1966 Parkfield 1967 Caracas1968 Tokachi-Oki1971 SAN FERNANDO1975 Oroville1975 Haicheng1976 Gazli (USSR)1976 Tangshan1978 Miyagiken-Oki1978 Santa Barbara1978 Tabas1979 Coyote Lake1979 IMPERIAL VALLEY1980 Livermore
1992 Petrolia1992 Landers1992 Big Bear1994 NORTHRIDGE1995 KOBE1999 KOCAELI1999 CHI-CHI1999 Duzce2001 Bhuj2001 Nisqually 2004 Niigata2010 Chile
1980 Mammoth Lake1982 Miramichi1983 Coalinga1985 Chile1985 MEXICO CITY1985 Nahani1986 NORTH PALM SPRINGS1987 WHITTIER-NARROWS1988 Armenia1988 Saguenay1989 LOMA PRIETA1990 Manjil1990 Philippine1991 Costa Rica1991 Sierra Madre1992 Turkey1992 Joshua tree
OUTLINE OF THIS TALK
Case Histories of large deformationsinvolving soft cohesive soils:
Case Histories involving liquefaction of cohesionless soils:
4
LIQUEFACTION OF COHESIONLESS SOILS
Examples of Surface Evidence of Liquefaction
1978 Miyagiken-Oki earthquake
LIQUEFACTION OF COHESIONLESS SOILS
5
1964 Niigata earthquake (photo: NISEE)
LIQUEFACTION OF COHESIONLESS SOILS
1971 San Fernando earthquake (photo: California DWR)
LIQUEFACTION OF COHESIONLESS SOILS
6
LIQUEFACTION OF COHESIONLESS SOILS
1999 CHI-CHI earthquake
LIQUEFACTION OF COHESIONLESS SOILS
Information needed for each case history
1. Site information:i. Location, adjacent topography;ii. Adjacent physical features;iii. Surface [Evidence/No Evidence] of liquefaction.
2. Subsurface information: i. Borings, samples – methods used;ii. Water table measurements;iii. Standard penetration tests – details used;iv. Cone penetration resistance data;v. Shear wave measurements – method(s) used.
3. Earthquake & earthquake ground motions informationi. Mw, distance, nearby recordings, site "classification".
7
LIQUEFACTION OF COHESIONLESS SOILS
Use of liquefaction case histories started in 1968. At that time, there were only 23 cases with observed surface evidence of liquefaction and 12cases with no observed evidence of liquefaction.
These case histories were used in the development of the Seed-Idriss simplified liquefaction procedure, which was published in the Journal of ASCE's SM&FE Division in 1971.
LIQUEFACTION OF COHESIONLESS SOILS
Since then, the number of cases has dramatically increased.
While in 1968 correlation was made to relative density and SPT blow count only, correlations are now made with:
SPT blow count; CPT tip resistance, and Vs, shear wave velocity.
More recently, correlations with dilatometer measurements have been proposed.
8
1 60 N E R B S mN C C C C C N
. , vM 7 5 1 1 60csCRR f N
Analysis framework
CYCLIC RESISTANCE RATIO (CRR)[Framework is similar for SPT, CPT, or Vs correlations]
1 1 160cs 60 60N N N . , ,
vcM 7 5 1 1 60CRR f N FC
1 60 N E R B S mN C C C C C N
. , vM 7 5 1 1 60csCRR f N
Analysis framework
Cyclic resistance ratio (CRR)[Framework is similar for SPT, CPT, or Vs correlations]
1 1 160cs 60 60N N N . , ,
vcM 7 5 1 1 60CRR f N FC
CN = f('v; DR; FC)
CR = f(depth; rod stick-up length)
9
v
v dM
v
a rCSR 0 65
max, .
Analysis framework
Earthquake-induced
CYCLIC STRESS RATIO (CSR)
based on using the Seed-Idriss (1971) Simplified Procedure
rd = f(depth; ground motion characteristics; dynamic soil properties)
Acc
eler
atio
n
Time
Acc
ele
rati
on
Time
Acc
eler
atio
n
Time
Effects of duration
M = 5.1
M = 6.5
M = 7.3
vM , ' vo max dM 7.5
vo
CSR a r 1CSR 0.65
MSF ' MSF
10
Cyclic triaxial test results for clean Fraser Delta sand showing cyclic stress and CRR to cause 3% shear strain in 10 uniform cycles at DR of 31-72% and
effective consolidation stresses of 50-400 kPa (data from Vaid & Sivathayalan 1996).
EFFECTS OF INITIAL EFFECTIVE VERTICAL STRESS, 'v
Cyclic stress to cause 3% strain in 10 uniform cycles versus effective consolidation stress in ICU cyclic triaxial tests on Fraser Delta sand
(data from Vaid & Sivathayalan 1996)
EFFECTS OF INITIAL EFFECTIVE VERTICAL STRESS, 'v
11
Effects of 'v
v
v
M. ' vo max dM 7.5 , ' 1 atm
vo
CSR a r 1 1CSR 0.65
MSF K ' MSF K
Framework includes 5 functions that describe fundamental aspects of dynamic site response, penetration testing, and soil behavior:
rd = f(depth; ground motion characteristics; dynamic soil properties)
CN = f('v; DR; FC)
CR = f(depth; rod stick-up length)
K = f('v; DR; FC)
MSF = f(ground motion characteristics; DR; FC)
These functions should be based on a synthesis of experimental and theoretical methods, as they guide the application to conditions outside those that are represented in the case history database.
Analysis framework
12
Many questions have been raised over the years regarding evaluation of liquefaction potential during earthquakes.
I will attempt to address in this presentation 4 of the most recurring questions.
LIQUEFACTION OF COHESIONLESS SOILS
LIQUEFACTION OF COHESIONLESS SOILS
Corrected standard penetration, (N1)60
0 10 20 30 40
Cyc
lic s
tres
s ra
tio
0.0
0.1
0.2
0.3
0.4
0.5
0.6Curves derived by
FC5%
Seed & Idriss (1982)
Seed et al (1984) & NCEER/NSF Workshops (1997)
Idriss & Boulanger (2004)
Seed (1979)
Cetin et al (2004)
1
2
3
5
3
21
5
4
4
13
QUESTIONS RAISED
Q-2. Can we treat these differences as "epistemic" uncertainty and hence can use all models with "assigned weights"?
Q-3. Can we use site response analyses to obtain CSR or do we have to always use the simplified stress ratio equation?
Q-4. How should we treat liquefaction at depths exceeding those included in the liquefaction case histories?
Q-1. Why are the published curves of CRR versus (N1)60 or versus (N1)60cs different, depending on whose model is implemented?
QUESTION No. 1
Q-1. Why are the published curves of CRR versus (N1)60 or versus (N1)60cs different, depending on whose model is implemented? In particular, why is the Cetin et al correlation so much lower than the other correlations?
Equivalent clean sand corrected standard penetration, (N1)60cs
0 10 20 30 40
CR
R
0.0
0.1
0.2
0.3
0.4
0.5
0.6Curves derived by 3
5 4Seed et al (1984) & NCEER/NSF Workshops (1997)
Idriss & Boulanger (2004)
Cetin et al (2004)
3
4
5
14
QUESTION No. 1
The best way to address this question is to examine each model in terms of how the interpretations were made for those case histories that control the position of the correlation.
Specifically, it is essential that the derived liquefaction triggering correlation for M = 7.5 and 'v = 1 atm be supported by the case histories with 'v close to 1 atm.
Differences in the treatment of key case histories near 'v = 1 atm (where differences in CN and K are smallest) were found to be the primary cause of differences in the correlations.
1 60 N E R B S mN C C C C C N
. , vM 7 5 1 1 60csCRR f N
Cyclic Resistance Ratio
Cyclic resistance ratio (CRR)[Framework is similar for SPT, CPT, or Vs correlations]
1 1 160cs 60 60N N N . , ,
vcM 7 5 1 1 60CRR f N FC
CN = f('v; DR; FC)
CR = f(depth; rod stick-up length)
15
Where the functions are
v
v
M. ' vo max dM 7.5 , ' 1 atm
vo
CSR a r 1 1CSR 0.65
MSF K ' MSF K
Shear stress induced by theearthquake ground motions
Sensitivity of case history interpretation to MSF
16
0 10 20 30 40 50
(N1 )60
16
12
8
4
0
Dep
th b
elo
w g
rou
nd
su
rface (
m)
Liquefaction
Marginal
No liquefaction
0 0.2 0.4 0.6 0.8
CSRM=7.5,=1
16
12
8
4
0
5 6 7 8 9
M
16
12
8
4
0
Dep
th b
elo
w g
rou
nd
su
rfa
ce (
m)
0 20 40 60 80 100
FC (%)
16
12
8
4
0
Effects of duration
Earthquake moment magnitude, M
5 6 7 8
Mag
nit
ud
e sc
alin
g f
acto
r, M
SF
0.5
1.0
1.5
2.0
2.5
Cetin et al (2004)
Idriss & Boulanger (2004)
Seed et al (1984)
17
Effects of 'v
v
v
M. ' vo max dM 7.5 , ' 1 atm
vo
CSR a r 1 1CSR 0.65
MSF K ' MSF K
Sensitivity of case history interpretation to K
EFFECTS OF INITIAL EFFECTIVE VERTICAL STRESS, 'v
K relations recommended by Youd et al (2001) for a relative density of40, 60 and 80% (solid lines) and relation used by Cetin et al (2004)
Vertical effective stress, 'v (atm)
0 1 2 3
K
0.0
0.5
1.0
1.5
Cetin et al (2004)
Youd et al (2001);DR = 40, 60 & 80%
18
LIQUEFACTION OF COHESIONLESS SOILS
Vertical effective stress, 'v (atm)
0 1 2 3
K
0.0
0.5
1.0
1.5 Boulanger & Idriss (2004);DR = 40, 60 & 80%
K relations recommended by Boulanger and Idriss (2004)for a relative density of 40, 60 and 80%
LIQUEFACTION OF COHESIONLESS SOILS
Vertical effective stress, 'v (atm)
0.0 0.5 1.0 1.5 2.0
K
0.0
0.5
1.0
1.5
Boulanger & Idriss (2004); DR = 60
Youd et al (2001); DR = 60
Cetin et al (2004)
19
LIQUEFACTION OF COHESIONLESS SOILS
Vertical effective stress, 'v (atm)
0.6 0.8 1.0 1.2 1.4 1.6
K
0.8
0.9
1.0
1.1
1.2
Boulanger & Idriss (2004); DR = 60
Youd et al (2001); DR = 60
Cetin et al (2004)
Case histories of Liquefaction/ No Liquefactionpublished by Cetin et al (2004)
Effective vertical stress, 'v (psf)
0 500 1000 1500 2000 2500 3000
Cu
m. D
istr
ibu
tio
n (
%)
0
20
40
60
80
100
0.8 atm
1.2 atm
1 atm
Values of 'v as listed in Cetin et al (2004) for
the "liquefaction" & "marginal" case histories
0.65 atm
20
Case histories of Liquefaction/ No Liquefactionpublished by Cetin et al (2004)
(N1)60cs
0 10 20 30 40
CS
R (
adju
sted
to
M =
7.5
&
' v =
1 a
tm)
0.0
0.1
0.2
0.3
0.4Cetin et al (2004)
M = 7.5; 'v = 1 atm
12
3
45
67
89
1011
Triangles: 1984 cases; Circles: 2000 cases;Squares: Kobe proprietary cases.Filled-in symbols: liquefaction;Open symbols: no liquefaction;Cyan symbol: marginal.
Cases for 'v = 0.65 to 1.5 atm
Data and parameters fromCetin et al (2004); Points 1 -- 11identified for further examinationas described in text.
Case histories of Liquefaction/ No Liquefactionpublished by Cetin et al (2004)
Point identified in next figure Site name Earthquake
1 Miller Farm CMF-10 1989 Loma Prieta earthquake; M = 6.9
2 Malden Street, Unit D 1994 Northridge earthquake; M = 6.7
3 Kobe #6 1995 Hyogoken-Nambu (Kobe) earthquake; M = 6.9
4 Kobe #7 1995 Hyogoken-Nambu (Kobe) earthquake; M = 6.9
5 Miller Farm CMF-5 1989 Loma Prieta earthquake; M = 6.9
6 Rail Road #2 1964 Niigata earthquake; M = 7.6
7 Port of Oakland POO7-2 1989 Loma Prieta earthquake; M = 6.9
8 Port of Oakland POO7-3 1989 Loma Prieta earthquake; M = 6.9
9 Panjin Chemical Fertilizer Plant
1975 Haicheng earthquake; M = 7.0
10 Shuang Tai Zi River 1975 Haicheng earthquake; M = 7.0
11 San Juan B-3 1974 Argentina earthquake; M = 7.4
Sites identified for further examination because they dictate the location of the liquefaction triggering curve for M = 7.5 & 'v = 1 atm
21
Case histories of Liquefaction/ No Liquefactionpublished by Cetin et al (2004)
Point identified in next figure Site name Earthquake
1 Miller Farm CMF-10 1989 Loma Prieta earthquake; M = 6.9
2 Malden Street, Unit D 1994 Northridge earthquake; M = 6.7
3 Kobe #6 1995 Hyogoken-Nambu (Kobe) earthquake; M = 6.9
4 Kobe #7 1995 Hyogoken-Nambu (Kobe) earthquake; M = 6.9
5 Miller Farm CMF-5 1989 Loma Prieta earthquake; M = 6.9
6 Rail Road #2 1964 Niigata earthquake; M = 7.6
7 Port of Oakland POO7-2 1989 Loma Prieta earthquake; M = 6.9
8 Port of Oakland POO7-3 1989 Loma Prieta earthquake; M = 6.9
9 Panjin Chemical Fertilizer Plant
1975 Haicheng earthquake; M = 7.0
10 Shuang Tai Zi River 1975 Haicheng earthquake; M = 7.0
11 San Juan B-3 1974 Argentina earthquake; M = 7.4
Sites identified for further examination because they dictate the location of the liquefaction triggering curve for M = 7.5 & 'v = 1 atm
misclassified cases
Point 1 – Miller Farm CMF-10
Profile across the failure zone at the Miller (south side of Pajaro River) during the 1989 Loma Prieta Earthquake (Holzer et al. 1994)
22
Cetin et al (2004)
From Cetin et al (2000)
Geotechnical Engineering Research Report No. UCB/GT-2000/09
Point 2 – Malden St.Unit D
Point 2: Malden Street , Unit D
Profile across the failure zone at the Malden Street site during the 1994 Northridge Earthquake (Holzer et al. 1998)
23
Expanded profile across the failure zone (Holzer et al. 1998)[additional details in Bennett et al. 1998]
Point 2: Malden Street , Unit D
Point 3 – Kobe proprietary site 6
Original table from Tokimatsu (2010)
From Cetin et al (2000)
Geotechnical Engineering Research Report No.
UCB/GT-2000/09
24
Point 10 – Shuang Tai Zi River
Point 10 – Shuang Tai Zi River
From original source: Shengcong & Tatsuoka (1984)
25
Point 10 – Shuang Tai Zi River
From Seed et al (1984)
Points 1, 2, 3 & 10 were designated as "No Liquefaction" by the original investigators of these sites; Cetin et al (2004) listed these as "Liquefaction" sites.
Point 1 Miller Farm CMF 10 'v 0.70 atm
Point 2 Malden Street 'v 1.2 atm
Point 3 Kobe No. 6 'v 0.68 atm
Point 10 Shuang Tai Zi R. 'v 0.69 atm
Case histories of Liquefaction/ No Liquefactionpublished by Cetin et al (2004)
26
Case histories of Liquefaction/ No Liquefactionpublished by Cetin et al (2004)
(N1)60cs
0 10 20 30 40
CS
R (
adju
sted
to
M =
7.5
&
' v =
1 a
tm)
0.0
0.1
0.2
0.3
0.4Cetin et al (2004)
M = 7.5; 'v = 1 atm
12
3
45
67
8
9
1011
Triangles: 1984 cases; Circles: 2000 cases;Squares: Kobe proprietary cases.Filled-in symbols: liquefaction;Open symbols: no liquefaction;Cyan symbol: marginal.
Cases for 'v = 0.65 to 1.5 atm
Data and parameters fromCetin et al (2004); Points 1, 2, 3 & 10were designated as "No Liquefaction"by the original investigators ofthese sites; Cetin et al (2004) listed these as "Liquefaction" sites .
Case histories of Liquefaction/ No Liquefactionpublished by Cetin et al (2004)
0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
rd values from summary tables in Cetin et al (2004)
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
r d v
alu
es
com
pute
d u
sin
g C
etin
et
al's
eq
uat
ion
(on
ly fo
r ca
ses
with
out s
ite r
esp
on
se c
alcu
latio
nss
) Issue: The rd values computed using the Cetin et al (2004) equation do not agree with the rd values they usedin processing the case histories.
Discrepancy between rd values used in the Cetin et al (2004) database and the rd
values computed using their referenced rd equation
27
Case histories of Liquefaction/ No Liquefactionpublished by Cetin et al (2004)
Point identified in next figure Site name Earthquake
1 Miller Farm CMF-10 1989 Loma Prieta earthquake; M = 6.9
2 Malden Street, Unit D 1994 Northridge earthquake; M = 6.7
3 Kobe #6 1995 Hyogoken-Nambu (Kobe) earthquake; M = 6.9
4 Kobe #7 1995 Hyogoken-Nambu (Kobe) earthquake; M = 6.9
5 Miller Farm CMF-5 1989 Loma Prieta earthquake; M = 6.9
6 Rail Road #2 1964 Niigata earthquake; M = 7.6
7 Port of Oakland POO7-2 1989 Loma Prieta earthquake; M = 6.9
8 Port of Oakland POO7-3 1989 Loma Prieta earthquake; M = 6.9
9 Panjin Chemical Fertilizer Plant
1975 Haicheng earthquake; M = 7.0
10 Shuang Tai Zi River 1975 Haicheng earthquake; M = 7.0
11 San Juan B-3 1974 Argentina earthquake; M = 7.4
Sites identified for further examination because they dictate the location of the liquefaction triggering curve for M = 7.5 & 'v = 1 atm
rd
Case histories of Liquefaction/ No Liquefactionpublished by Cetin et al (2004)
(N1)60cs
0 10 20 30 40
CS
R (
adju
sted
to
M =
7.5
&
' v =
1 a
tm)
0.0
0.1
0.2
0.3
0.4
12
345
67
89
10
11
Cetin et al (2004)M = 7.5; 'v = 1 atm
Triangles: 1984 cases; Circles: 2000 cases;Squares: Kobe proprietary cases.Filled-in symbols: liquefaction;Open symbols: no liquefaction;Cyan symbol: marginal.
Cases for 'v = 0.65 to 1.5 atm
Data and parameters fromCetin et al (2004); CSR for Points3, 4, 6, 9. 10 & 11 recalculatedusing equation for rd in Cetin et al
(2004) in lieu of their listed values.
28
Case histories of Liquefaction/ No Liquefactionpublished by Cetin et al (2004)
Point identified in next figure Site name Earthquake
1 Miller Farm CMF-10 1989 Loma Prieta earthquake; M = 6.9
2 Malden Street, Unit D 1994 Northridge earthquake; M = 6.7
3 Kobe #6 1995 Hyogoken-Nambu (Kobe) earthquake; M = 6.9
4 Kobe #7 1995 Hyogoken-Nambu (Kobe) earthquake; M = 6.9
5 Miller Farm CMF-5 1989 Loma Prieta earthquake; M = 6.9
6 Rail Road #2 1964 Niigata earthquake; M = 7.6
7 Port of Oakland POO7-2 1989 Loma Prieta earthquake; M = 6.9
8 Port of Oakland POO7-3 1989 Loma Prieta earthquake; M = 6.9
9 Panjin Chemical Fertilizer Plant
1975 Haicheng earthquake; M = 7.0
10 Shuang Tai Zi River 1975 Haicheng earthquake; M = 7.0
11 San Juan B-3 1974 Argentina earthquake; M = 7.4
Sites identified for further examination because they dictate the location of the liquefaction triggering curve for M = 7.5 & 'v = 1 atm
SPT data not included
Point 4 – Kobe Proprietary Site No. 7 (from Cetin et al (2000)
Point 4(Kobe No. 7 site)
29
Case histories of Liquefaction/ No Liquefactionpublished by Cetin et al (2004)
Point 4 (Kobe No. 7 site) 'v 0.8 atm
Case histories of Liquefaction/ No Liquefactionpublished by Cetin et al (2004)
Selection of a representative (N1)60 for Point 4 (Kobe No. 7 site)Average 'v 0.86 atm
Avg
depth
(m)
Depth to
GWT (m) vc (kPa) 'vc (kPa) (Nm) (N1)60 CB CE CN CR CS FC (%) (N1)60,cs
3.3 3.2 62 60 8 10.4 1 1.22 1.26 0.85 1 0 10.4
4.3 3.2 82 71 21 28.2 1 1.22 1.16 0.95 1 0 28.2
6.3 3.2 124 93 32 37.7 1 1.22 1.02 0.95 1 12 39.8
7.3 3.2 144 104 23 25.6 1 1.22 0.96 0.95 1 0 25.6
8.3 3.2 165 114 21 23.4 1 1.22 0.92 1 1 0 23.4
Averages:
5.8 113 87 18.3 21.9 Average= 0 21.9
30
Case histories of Liquefaction/ No Liquefactionpublished by Cetin et al (2004)
(N1)60cs
0 10 20 30 40
CS
R (
adju
sted
to
M =
7.5
&
' v =
1 a
tm)
0.0
0.1
0.2
0.3
0.4
12
34 5
67
89
10
11
Cetin et al (2004)M = 7.5; 'v = 1 atm
Triangles: 1984 cases; Circles: 2000 cases;Squares: Kobe proprietary cases.Filled-in symbols: liquefaction;Open symbols: no liquefaction;Cyan symbol: marginal.
Cases for 'v = 0.65 to 1.5 atm
Data and parameters fromCetin et al (2004); CSR & (N1)60 for
Point 4 recalculated to includea sublayer below the water tablewith N = 8, which had not beenused by Cetin et al (2004).
Case histories of Liquefaction/ No Liquefactionpublished by Cetin et al (2004)
(N1)60cs
0 10 20 30 40
CS
R (
ad
just
ed t
o M
= 7
.5 &
' v
= 1
atm
)
0.0
0.1
0.2
0.3
0.4
12
34 5
67
89
10
11
Cetin et al (2004)M = 7.5; 'v = 1 atm
Triangles: 1984 cases; Circles: 2000 cases;Squares: Kobe proprietary cases.Filled-in symbols: liquefaction;Open symbols: no liquefaction;Cyan symbol: marginal.
Cases for 'v = 0.65 to 1.5 atm
Data and parameters fromCetin et al (2004); CSR & (N1)60 for
Point 4 recalculated to includea sublayer below the water tablewith N = 8, which had not beenused by Cetin et al (2004).
31
Point 6 – Rail Road-2 (from Cetin et al (2000)
Case histories of Liquefaction/ No Liquefactionpublished by Cetin et al (2004)
10 12 14 16 18 20 22
Average total unit weight (kN/m3)
12
10
8
6
4
2
0
Dep
th b
elow
gro
und
su
rfac
e (m
)
Idriss & Boulanger (this study)
Cetin et al (2004)
Seed et al. (1984), plus
Averages of all values
Kobe proprietary (Tokimatsu)
32
Case histories of Liquefaction/ No Liquefactionpublished by Cetin et al (2004)
(N1)60cs
0 10 20 30 40
CS
R (
adju
sted
to
M =
7.5
&
' v =
1 a
tm)
0.0
0.1
0.2
0.3
0.4
1
23
45
678
9
10
11
Cetin et al (2004)M = 7.5; 'v = 1 atm
Triangles: 1984 cases; Circles: 2000 cases;Squares: Kobe proprietary cases.Filled-in symbols: liquefaction;Open symbols: no liquefaction;Cyan symbol: marginal.
Cases for 'v = 0.65 to 1.5 atm
Data and parameters fromCetin et al (2004); CSR & (N1)60 for
Points 1 -- 11 recalculated using unit weights described in text.
(N1)60cs
0 10 20 30 40
CS
R (
adju
sted
to
M =
7.5
&
' v =
1 a
tm)
0.0
0.1
0.2
0.3
0.4
12
34 5
67
89
10
11
Triangles: 1984 cases; Circles: 2000 cases;Squares: Kobe proprietary cases.Filled-in symbols: liquefaction;Open symbols: no liquefaction;Cyan symbol: marginal.
Cases for 'v = 0.65 to 1.5 atm
Idriss & Boulanger (2004)M = 7.5; 'v = 1 atm NCEER/Youd (2001)
M = 7.5; 'v = 1 atm
Data and parameters fromCetin et al (2004); Changes toPoints 1 -- 11 described in text.
33
Case histories of Liquefaction/ No Liquefactionpublished by Cetin et al (2004)
10 12 14 16 18 20 22
Average total unit weight (kN/m3)
12
10
8
6
4
2
0
Dep
th b
elow
gro
und
su
rfac
e (m
)Idriss & Boulanger (this study)
Cetin et al (2004)
Seed et al. (1984), plus
Averages of all values
Kobe proprietary (Tokimatsu)
Case histories of Liquefaction/ No Liquefactionpublished by Cetin et al (2004)
Point identified in next figure Site name Earthquake
1 Miller Farm CMF-10 1989 Loma Prieta earthquake; M = 6.9
2 Malden Street, Unit D 1994 Northridge earthquake; M = 6.7
3 Kobe #6 1995 Hyogoken-Nambu (Kobe) earthquake; M = 6.9
4 Kobe #7 1995 Hyogoken-Nambu (Kobe) earthquake; M = 6.9
5 Miller Farm CMF-5 1989 Loma Prieta earthquake; M = 6.9
6 Rail Road #2 1964 Niigata earthquake; M = 7.6
7 Port of Oakland POO7-2 1989 Loma Prieta earthquake; M = 6.9
8 Port of Oakland POO7-3 1989 Loma Prieta earthquake; M = 6.9
9 Panjin Chemical Fertilizer Plant
1975 Haicheng earthquake; M = 7.0
10 Shuang Tai Zi River 1975 Haicheng earthquake; M = 7.0
11 San Juan B-3 1974 Argentina earthquake; M = 7.4
Sites identified for further examination because they dictate the location of the liquefaction triggering curve for M = 7.5 & 'v = 1 atm
Low total unit weights
34
(N1)60cs
0 10 20 30 40
CS
R (
adju
sted
to
M =
7.5
&
' v =
1 a
tm)
0.0
0.1
0.2
0.3
0.4
1
23
45
67
89
10
11
Triangles: 1984 cases; Circles: 2000 cases;Squares: Kobe proprietary cases.Filled-in symbols: liquefaction;Open symbols: no liquefaction;Cyan symbol: marginal.
Cases for 'v = 0.65 to 1.5 atm
Cetin et al (2004)M = 7.5; 'v = 1 atm
Idriss & Boulanger (2004)M = 7.5; 'v = 1 atm
Data and parameters fromCetin et al (2004); Changes toPoints 1 -- 11 described in text.
Conclusions re: Question No. 1
• The Cetin et al. triggering correlation, if it were updated after correcting the above problems, would thus be expected to move close to the Idriss-Boulanger correlation at overburden stresses of 0.65-1.5 atm.
• This would also cause the Cetin et al. K relationship to become flatter because it is regressed as part of their analyses and higher CRR values at higher confining stresses would dictate a flatter Ks relationship.
Q-1. Why are the published curves of CRR versus (N1)60 or versus (N1)60cs different, depending on whose model is implemented? In particular, why is the Cetin et al correlation so much lower than the other correlations?
35
• The combination of these changes would be expected to reduce the degree to which the Cetin et al. procedure predicts significantly smaller CRR values than the other liquefaction triggering correlations as depth increases.
• Until these issues are addressed, however, the Cetin et al. procedure should not be used.
Conclusions re: Question No. 1
Question No. 2
Q-2. Can we treat these differences as "epistemic" uncertainty and hence can use all models with "assigned weights"?
No, we should not treat these differences as "epistemic" uncertainty and hence can use all models with "assigned weights".
The examination I just summarized emphasizes the need to fully examine any model before it is adopted for use.
36
Question No. 3
Q-3. Can we use site response analyses to obtain CSR or do we have to always use the simplified stress ratio equation?
The answer is – it depends.
37
Shear wave velocity (m/sec)
0 200 400 600 800
Dep
th (
m)
0
20
40
60
80
100
120
140
160
Vs profile used in 1990
Vs profile used
in 1993 and 1996
1996
1993
Period (sec)
0.01 0.1 1 10
Sp
ectr
al a
ccel
erat
ion
(g
)
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
damping = 5 percent
Calculated Motion using 1990 Vs profile
Recorded Motion at Treasure Island
Rock Outcrop (Yerba Buena Island)
Calculated Motion using 1993 Vs profile
Calculated Motion using 1996 Vs profile
38
Period (sec)
0.01 0.1 1 10
Sp
ectr
al a
ccel
erat
ion
(g
)
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
damping = 5 percent
Spectral values for motionrecorded at Treasure Island
Spectral values calculated using
recording at Yerba Buenaas input motion
39
Period (sec)
0.01 0.1 1 10
Sp
ectr
al a
ccel
erat
ion
(g
)
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
damping = 5 percent
Spectral values for motionrecorded at Treasure Island
Spectral values calculated using
recordings at other rock sitesin the Bay Area as input motions
recording at Yerba Buenaas input motion
Maximum shear stress (kPa)
0 10 20 30 40
Dep
th (
m)
0
5
10
15
20
Maximum shear stresses calculated using:
recordings at other rock sitesin the Bay Area as input motions
recording at Yerba Buenaas input motion
average shear stresses for all cases
40
Period (sec)
0.01 0.1 1 10
Sp
ectr
al a
ccel
erat
ion
/ P
GA
0.0
0.5
1.0
1.5
2.0
2.5
3.0
damping = 5 percent
Target spectrum -- M = 6.9 at 80 km
Spectrum compatible motion -- SYN1
Spectrum compatible motion -- SYN2
Maximum shear stress (kPa)
0 10 20 30 40
Dep
th (
m)
0
5
10
15
20
Maximum shear stresses calculated using:
recordings at other rock sitesin the Bay Area as input motions
recording at Yerba Buenaas input motion
average shear stresses for all cases
Input: SYN1
41
Maximum shear stress (kPa)
0 10 20 30 40D
epth
(m
)0
5
10
15
20
Maximum shear stresses calculated using:
recordings at other rock sitesin the Bay Area as input motions
recording at Yerba Buenaas input motion
average shear stresses for all cases
Input: SYN2
Period (sec)
0.01 0.1 1 10
Sp
ectr
al a
ccel
erat
ion
/ P
GA
0.0
0.5
1.0
1.5
2.0
2.5
3.0
damping = 5 percent
Target spectrum -- pre-NGA
Target spectrum -- NGA
42
Period (sec)
0.01 0.1 1 10
Sp
ectr
al a
ccel
erat
ion
/ P
GA
0.0
0.5
1.0
1.5
2.0
2.5
3.0
damping = 5 percent
Target spectrum -- NGA
Spectra -- synthetic time series
Maximum shear stress (kPa)
0 10 20 30 40
De
pth
(m
)
0
5
10
15
20
Maximum shear stresses calculated using:
NGA-compatible time seriesas input motions
recording at Yerba Buenaas input motion
43
Maximum shear stress (kPa)
0 10 20 30 40D
epth
(m
)0
5
10
15
20
Maximum shear stresses calculated using:
NGA-compatible time seriesas input motions
recording at Yerba Buenaas input motion
average shear stresses synth time series
Using simplified equation (F = ma):
surfmax v d
surf
ar
g
a 0.16g
44
Stress reduction coefficient, rd
0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
Dep
th b
elo
w g
rou
nd
su
rfac
e (m
)0
4
8
12
16
20
24
28
M = 7½ M = 8Magnitude: M = 5½ M = 6½
Average of Range Publishedby Seed & Idriss (1971)
M = 6.9
Maximum shear stress (kPa)
0 10 20 30 40
De
pth
(m
)
0
5
10
15
20
Maximum shear stresses calculated using:
recordings at other rock sitesin the Bay Area as input motions
recording at Yerba Buenaas input motion
average shear stresses for all cases
Calculated usingrd for M = 6.9
45
Conclusions re: Question No. 3
• Use of an appropriate rd is adequate for most cases.
• For site response studies, you need to use at least 7 different rock outcrop motions.
Q-3. Can we use site response analyses to obtain CSR or do we have to always use the simplified stress ratio equation?
Q-4: How should we evaluate liquefaction at depths that exceed those represented in liquefaction case histories?
Two critical parameters affecting liquefaction potential with depth are CN and K.
Studies at Perris Dam provide valuable data on CN at large depths
Studies at Duncan Dam provide a valuable check on the complete liquefaction analysis procedure for large depths.
Question No. 4
46
A critical parameter affecting liquefaction potential with depth is the value of CN. Boulanger and Idriss (2004) recommended:
m
aN
vo
1 60
PC 1.7
m 0.784 0.0768 N
Note that m = ½, originally derived by Liao & Whitman has been extensively used, but it can produce unreasonably low CN values as the depth increases.
The investigations carried out at Perris Dam (CDWR 2005, Wehling and Rennie 2008) are very helpful is assessing the value of the exponent m as a function of denseness.
Perris Dam and CN
Aerial photo and boring locations at Perris Dam (Wehling & Rennie 2008)
47
SPT data by location and percentile groupings (Wehling & Rennie 2008)
0 20 40 60 80SPT (N1 )60
0
0.2
0.4
0.6
0.8
Exp
on
ent m
0 20 40 60 80SPT (N1 )60,CS
0
0.2
0.4
0.6
0.8
Exp
on
ent m
CN = (Pa /'v )m
Idriss & Boulanger (2008)[using (N1)60 as input]
Idriss & Boulanger (2008)
Perris dam foundation(Wehling & Rennie 2008)
Perris dam foundation(Wehling & Rennie 2008)
CN = (Pa /'v )m
48
Overburden normalization factor CN: (a) dependence on denseness, and (b) simpler approximations often used at shallower depths.
0 0.5 1 1.5
CN
10
8
6
4
2
0
Ve
rtic
alef
fect
ive
stre
ss,
' v/P
a
(N1)60cs=40
(N1)60cs=30
(N1)60cs=20
(N1)60cs=10
(N1)60cs=4
0 0.5 1 1.5
CN
2
1.5
1
0.5
0
Ver
tica
leffe
ctiv
est
ress
, ' v
/Pa
(a) (b)
(N1)60cs=4
(N1)60cs=30
Liao & Whitman (1986)CN = (Pa /'v )0.5
The investigations carried out at Duncan Dam (Special collection of papers in the Canadian Geotechnical Journal, 1994) are helpful in assessing the application of liquefaction triggering procedures to large depths.
Duncan Dam
49
Frozen sand samples obtained from Unit 3c at the toe, and tested at confining stresses of 2 to 12 atm.
Duncan Dam
Table 5.2. Summary of SPT and laboratory test data for Duncan Dam SPT data DSS tests Triaxial tests Conversion to 'v = 1 atm 'v (kPa)
CN N60 (N1)60 (N1)60cs Lab CRRN=10
Field CRRM=7.5
Lab CRRN=10
Field CRRM=7.5
Field CRRM=7.5
K Field CRRM=7.5,=1
200 0.70 16.4 11.5 11.6 0.14 0.118 0.169 0.121 0.120 0.93 0.128 400 0.50 26.5 13.3 13.4 0.149 0.126 0.171 0.123 0.124 0.86 0.145 600 0.42 34.0 14.1 14.2 0.143 0.121 0.168 0.120 0.120 0.81 0.149 1200 0.30 49.1 14.7 14.8 -- -- 0.170 0.122 0.122 0.73 0.168
Notes: (1) Original data from Pillai and Byrne (1994). (2) Average ratio of CRRDSS/CRRTX = 0.85 is used to convert triaxial test results to field simple shear conditions. (3) Cyclic strengths multiplied by 0.937 to convert from 10 to 15 equivalent uniform cycles (based on slope of
CRR versus number of uniform cycles curves). (4) Cyclic strengths multiplied by 0.90 to convert from 1D to 2D cyclic loading conditions. (5) Final value for field CRRM=7.5 taken as average of strengths from DSS and Triaxial tests.
SPT-based prediction of CRRM=7.5 versus depth (confining stress) depends on combination of triggering curve, CN, and K.
Duncan Dam
Corrected standard penetration, (N1)60
0 10 20 30 40
Cyc
lic s
tres
s ra
tio
0.0
0.1
0.2
0.3
0.4
0.5
0.6Curves derived by
FC5%
Seed & Idriss (1982)
Seed et al (1984) & NCEER/NSF Workshops (1997)
Idriss & Boulanger (2004)
Seed (1979)
Cetin et al (2004)
1
2
3
5
3
21
5
4
4
50
Pillai & Byrne (1994) used the Seed et al. (1984) triggering curve, in-situ SPT data, and laboratory test data on frozen sand samples to derive site-specific CN and K relationships.
Duncan Dam
0 0.2 0.4 0.6 0.8 1 1.2
CN
12
10
8
6
4
2
0
Ver
tical
effe
ctiv
est
ress
, ' v
/Pa
Boulanger &Idriss (2004):(N1 )60=10(N1 )60=20
Liao & Whitman (1986)
Pillai & Byrne (1994)
0 0.2 0.4 0.6 0.8 1 1.2
K
12
10
8
6
4
2
0
Ver
tical
effe
ctiv
est
ress
, ' v
/Pa
(a) (b)
Boulanger &Idriss (2004):
(N1 )60=10(N1 )60=20
Hynes & Olsen(1999);f = 0.722
Pillai & Byrne(1994)
Kayen etal (1992)
CRRM=7.5 predicted using the Pillai & Byrne (1994) site-specific relationships with the Seed et al. (1984) triggering curve.
Duncan Dam
0 10 20 30 40 50 60
SPT N60 values
12
10
8
6
4
2
0
Ve
rtic
al e
ffect
ive
str
ess
(atm
)
0 10 20 30
(N1 )60
12
10
8
6
4
2
00 0.1 0.2 0.3
CRRM=7.5
12
10
8
6
4
2
0
Computed using relations by Pillai & Byrne (1994)
CRRM7.5 from TX & DSS tests on frozen samples (Pillai & Byrne 1994)
Duncan Dam - Unit 3c:(Pillai & Stewart 1994)
51
Duncan Dam
0 10 20 30 40 50 60
SPT N60 values
12
10
8
6
4
2
0V
ert
ical
effe
ctiv
e s
tres
s (a
tm)
0 10 20 30
(N1 )60
12
10
8
6
4
2
00 0.1 0.2 0.3
CRRM=7.5
12
10
8
6
4
2
0
Computed using relations by Idriss & Boulanger (2008)
CRRM7.5 from TX & DSS tests on frozen samples (Pillai & Byrne 1994)
Duncan Dam - Unit 3c:(Pillai & Stewart 1994)
CRRM=7.5 predicted using the Idriss & Boulanger (2004, 2008) liquefaction triggering procedures.
Duncan Dam
0 10 20 30 40 50 60
SPT N60 values
12
10
8
6
4
2
0
Ve
rtic
al e
ffec
tive
stre
ss (
atm
)
0 10 20 30
(N1 )60
12
10
8
6
4
2
00 0.1 0.2 0.3
CRRM=7.5
12
10
8
6
4
2
0
Computed using relations by NCEER/NSF (Youd et al. 2001)
CRRM7.5 from TX & DSS tests on frozen samples (Pillai & Byrne 1994)
Duncan Dam - Unit 3c:(Pillai & Stewart 1994)
CRRM=7.5 predicted using the NCEER/NSF (Youd et al. 2001) liquefaction triggering procedures.
52
Duncan Dam
0 10 20 30 40 50 60
SPT N60 values
12
10
8
6
4
2
0V
ert
ica
l eff
ectiv
e st
ress
(at
m)
0 10 20 30
(N1 )60
12
10
8
6
4
2
00 0.1 0.2 0.3
CRRM=7.5
12
10
8
6
4
2
0
Computed using relations by Cetin et al. (2004)
CRRM7.5 from TX & DSS tests on frozen samples (Pillai & Byrne 1994)
Duncan Dam - Unit 3c:(Pillai & Stewart 1994)
CRRM=7.5 predicted using the Cetin et al. (2004) liquefaction triggering procedures.
Cetin et al. (2004) and Moss et al. (2006) used the same statistical analysis procedures to regress K from SPT and CPT case histories, respectively.
Regressing K from case histories
0 2 4 6 8 10Effective consolidation stress (atm)
0
0.5
1
1.5
K
Moss et al. (2006): From Bayesian regressionof CPT-based liquefaction triggering database
15(N1 )60 = 5
25
Boulanger & Idriss (2004): From combinationof lab- & field-derived CRR-R correlations
Cetin et al. (2004): From Bayesian regressionof SPT-based liquefaction triggering database
53
Q-4: How should we evaluate liquefaction at depths that exceed those represented in liquefaction case histories?
CN describes how penetration resistance varies with confining stress, and it fundamentally depends not only on 'v but also on soil denseness.
For v > 2 atm, the Liao-Whitman (1986) or Kayen et al. (1992) relationships for CN, as adopted for the NCEER/NSF (Youd et al. 2001) procedures, can lead to a significant under-estimation of (N1 )60 values for denser soils.
For v > 2 atm, the Boulanger-Idriss (2004) relationship for CN produces more realistic (N1 )60 values for denser soils, as supported by calibration chamber test data, penetration theory, and field studies.
Conclusions re: Question No. 4
K describes a fundamental soil behavior that also depends on 'v and on soil denseness.
The K relationships regressed from case history data by Cetin et al. (2004) & Moss et al. (2006) are not justifiable and should not be used.
The K relationships by Boulanger & Idriss (2004) or Hynes & Olsen (1998) are reasonable options.
The procedures by Idriss & Boulanger were in good agreement with data for Duncan Dam. The NCEER/NSF (Youd et al. 2001) procedures with the Hynes-Olsen Krelationship under-estimated CRR for the larger depths.
Conclusions re: Question No. 4
54
Three recurring questions regarding assessment of liquefaction potential were addressed.
1. Why are the published curves of CRR versus (N1)60 or versus (N1)60cs different so different if they are based on largely the same case history data?
2. Can we treat these differences as "epistemic" uncertainty and hence can use all models with "assigned weights"?
1. Can we use site response analyses to obtain CSR or do we have to always use the simplified stress ratio equation?
2. How should we treat liquefaction at depth exceeding those included in liquefaction case histories?
Summary