Reference Rock Site Condition for Central and Eastern ......0,ref Recommendation ! EPRI (1993) reported a median κ 0,ref of 0.006 sec and initially proposed a σ ln of 0.40. ! EPRI

23 August 2013

1

NGA East Geotechnical Working Group

Youssef M. A. Hashash, Albert R. Kottke, Kenneth W. Campbell, Byungmin Kim, Cheryl Moss, Sissy Nikolaou, Ellen M. Rathje, Walter J.

Silva, and Jonathan P. Stewart

Presented by Albert R. Kottke, Ph.D. Bechtel Corp

Tuesday August 20th, 2013 Session: Earthquake Loads - Seismic Hazard Assessment II

8/20/2013 NGA-East GWG: Reference Rock 1

Reference Rock Site Condition for Central and

Eastern North America

Outline n  Reference rock site condition

n  Definition n  Importance for seismic hazard

n  Existing recommendation n  Reference velocity

n  Defining reference velocity n  Evaluation of collected data n  Recommendation

n  Reference local attenuation n  Published models n  Recommendation

n  Conclusions


23 August 2013

2

Reference Rock Site Condition n  Defined by:

n  Shear-wave velocity (Vs) n  Compression-wave velocity (Vp) n  Local attenuation (κ0,ref) n  Unit weight

n  Appropriate for the Central and Eastern North America (stable continental)


Importance of Reference Condition •  Present in all

velocity profiles in the region

•  Interface between regional and site-specific models

•  The reference condition for amplification models


Regional Characteristics

Site Specific Models

Reference Condition

23 August 2013

3

Existing Vs,ref Recommendation •  EPRI (1993) study is the

basis of current values •  Vs,ref of 2.83 km/sec

(9,200 ft/sec) •  Based on 16 crustal

structure regions •  Vs values computed from

Vp inversions and an assumed Poisson’s ratio of 0.25


n  Published GMPEs use 2.00 to 2.88 km/sec n  Based on simulations n  Vs,ref values based on top of assumed crustal profile

4 6 8 10VP (km/s)

2 3 4 5VS (km/s)

60

50

40

30

20

10

0

Depth(km)

Existing κ0,ref Recommendation n  EPRI (1993) reported a median κ0,ref

of 0.006 sec and initially proposed a σln of 0.40.

n  EPRI (1993) and Toro et al. (1997) used equally weighted values 0.0003, 0.006, and 0.012 sec


23 August 2013

4

Collection of Velocity Data n  Vs and Vp measurements that

penetrate hard-rock were collected n  Journal publications and technical

reports n  Nuclear power plant applications

n  Located 283 profiles in study region n  68 Vs,ref values at 27 different locations n  60 Vp,ref values at 22 different locations


Locations of Collected Data


23 August 2013

5

Example Velocity Profile


Definition of Reference Velocity n  Based on characteristics of collected

velocity profiles n  Typical profiles transition from soil to

weathered rock to intact rock n  Established a criteria based on:

1.  Velocity 2.  Measurement penetration 3.  Velocity gradient 4.  Geologic age


23 August 2013

6

Reference Vs Measurements


2000220024002600280030003200340036003800

S-W

ave

Vel

ocity

,Vs

(m/s

)

Bel

l Ben

d N

PP -

8B

elle

font

eN

PP -

8B

rons

on-A

valo

n-1

Cal

law

ay N

PP -

2C

alve

rt C

liffs

-3

Cha

lkR

iver

,Ont

ario

-1C

linto

n N

PP -

1C

oman

che

Peak

NPP

- 1

Ferm

i NPP

- 2G

rand

Rem

ous,

Ont

ario

- 1

Har

tford

-1H

ayes

- 1M

ontic

ello

Res

ervo

ir - 3

Nin

e M

ile N

PP -

1N

orth

Ann

aN

PP-2

Otta

wa,

Ont

ario

- 1

PSEG

NPP

- 1

Riv

er B

end

NPP

-1

Shea

ron

Har

ris N

PP -

1Tu

rkey

Poi

nt N

PP- 1

Tyne

side,

Ont

ario

-1

V.C

.Sum

mer

NPP

-8V

ogtle

NPP

- 3

Wat

erbu

ry -

1W

esle

yvill

e, O

ntar

io -

1W

illia

msb

urg,

Ont

ario

- 1W

illia

m S

tate

s Lee

III N

PP -

12Reference Vp Measurements


3000

3500

4000

4500

5000

5500

6000

6500

7000

P-W

ave

Vel

ocity

,Vp

(m/s

)

Bel

l Ben

d N

PP- 8

Bel

lefo

nte

NPP

-8

Cal

law

ay N

PP -

2C

alve

rt C

liffs

- 3C

linto

n N

PP -

1C

oman

che

Peak

NPP

-1D

anie

lset

al,U

PH3

-1Fe

rmiN

PP -

3H

ayes

-1

Luet

gert

etal

(94)

,SP1

-1Lu

etge

rt et

al (

94),

SP2

- 1Lu

etge

rt et

al (

94),

SP3

-1Lu

etge

rt et

al (

94),

SP4

- 1Lu

etge

rt et

al(9

4), S

P5- 1

Mon

ticel

loR

eser

voir

-3N

ine

Mile

NPP

- 1

Nor

th A

nna

NPP

-2

PSEG

NPP

- 2

Riv

erB

end

NPP

- 1

Shea

ron

Har

ris N

PP -

1V

.C.S

umm

erN

PP-8

Will

iam

Sta

tes L

ee II

INPP

-9

23 August 2013

7

Trend with Depth

n  Compared selected reference velocities with depth

n  Potential to select higher velocities at greater depth (bias)

n  Part of the QA process

n  No trend observed


Within-Profile Vs,ref Distribution


Comparing assumed normal and log-normal distributions indicated that velocities tended to be normally distributed

-4 -3 -2 -1 0 1 2 3 4Theoretical Quantiles

-2000

-1000

0

1000

2000

Ord

ered

Vs,

ref -

( V

s,re

f) pr(m

/s)

Theoretical

(b)

R2 = 0.95

-2000 -1000 0 1000 2000Vs,ref - ( Vs,ref)pr (m/s)

0

0.02

0.04

0.06

0.08

0.1

Probability

(a)

-0.6 -0.4 -0.2 0 0.2 0.4 0.6ln[ /(Vs,ref)prVs,ref ]

0

0.02

0.04

0.06

0.08

0.1

Probability

(a)

-4 -3 -2 -1 0 1 2 3 4Theoretical Quantiles

-0.6-0.4-0.2

00.20.40.6

Ord

ered

ln[

/(Vs,ref) pr

V s,ref

]

(b)

R2 = 0.96

23 August 2013

8

Characterizing the Uncertainty


The observed trend in the standard deviation with mean profile velocity is removed by characterizing the uncertainty using the coefficient of variation (standard deviation / mean)

2000 3000 4000 5000 6000 7000Mean Profile Velocity (m/s)

0

200

400

600

800

Prof

ile S

tand

ard

Dev

iatio

n (m

/s)

S-Wave P-Wave

2000 3000 4000 5000 6000 7000Mean Profile Velocity (m/s)

0

0.04

0.08

0.12

0.16

0.2

Prof

ile C

oeffi

cien

t of V

aria

tion

Within-Region Vs,ref Distribution


Theoretical

2000 2400 2800 3200 3600Vs,ref (m/s)

0

0.05

0.1

0.15

0.2

0.25

Prob

abili

ty

(a)

-2 -1 0 1 2Theoretical Quantiles

2000

2400

2800

3200

3600

Ord

ered

Vs,ref

(m/s

)

(b)

R2 = 0.98

Distribution of mean values from each location indicate a slightly skewed distribution that can be approximated by a normal distribution.

23 August 2013

9

Poisson’s Ratio


Bel

l Ben

d N

PPB

elle

font

eN

PPC

alla

way

NPP

Cal

vert

Clif

fsC

linto

n N

PPC

oman

che

Peak

NPP

Ferm

i NPP

Hay

esM

ontic

ello

Res

ervo

irN

ine

Mile

NPP

Nor

th A

nna

NPP

PSEG

NPP

Riv

er B

end

NPP

Shea

ron

Har

risN

PPTu

rkey

Poi

nt N

PPV

.C.S

umm

er N

PPW

illia

m S

tate

s Lee

IIIN

PP

0.24

0.26

0.28

0.3

0.32

0.34Po

isss

on's

Rat

ioCalculatedAssumed

Mean value of 0.28

Weathered Zone n  Collected

information on the weathered rock

n  Clearly observed at four locations

n  Identified: •  Thickness •  Velocity range


100

80

60

40

20

0

Dep

th(m

)

1000

1500

2000

2500

3000

3500

4000

S-W

ave

Vel

ocity

(m/s)

Bell Bend NPPBellefonte NPPNorth Anna NPPWilliams States Lee III NPP

(a) (b)

23 August 2013

10

Weathered Zone Properties


1 10 100Weathered Zone Thickness (m)

1.2

1.3

1.4

1.5

1.6

1.7

1.8

1.9

2

S-W

ave

Vel

ocity

Rat

io

Bell Bend NPPBellefonte NPPNorth Anna NPPWilliams States LEE III NPP

Mean thickness = 15 mMean Vs ratio = 1.53

Velocity Gradient n  Defined by

increase in velocity with depth

n  Mean gradient: n  Reference rock

2 per sec n  Weathered rock

165 per sec


0 200 400 600Velocity Gradient [(m/s)/m]

0

1

2

3

4(b) Weathered rock

µ = 165 (1/s)

-100 0 100 200 300 400Velocity Gradient [(m/s)/m]

0

10

20

30

40

Cou

nt

(a) Reference rockµ = 2 (1/s)

0 100 200 300 400 500 600 700Velocity Gradient Difference [(m/s)/m]

0

1

2

3

4

5

Cou

nt

23 August 2013

11

Range of Vs,ref n  Collected data indicate Vs,ref varies

between locations n  Two potential methods define the

range: n  Statistics:

n  95% confidence interval: 2.12 to 3.78 km/sec n  Influence of Vs,ref range on the ground motion?

n  Amplification n  Specify range using 5% difference in

amplification n  Amplification estimated by √𝑉↓1 / 𝑉↓2    n  2.7 to 3.3 km/sec


Recommended Reference Velocity

Best Es'mate Range

Vs,ref 3.0 km/sec 2.7 -‐ 3.3 km/sec

Vp,ref 5.5 km/sec 5.0 -‐ 6.1 km/sec


23 August 2013

12

Reference Local Attenuation (κ0,ref) n  Local a<enua>on parameter κ0,ref characterizes high-‐frequency a<enua>on

n  Defined from high-‐frequency characteris>cs of recorded ground mo>ons

n  Interpreted as damping due to near-‐site effects (addi>onal to Q)


AOer Anderson and Hough (1984)

n  Existing studies used:

n  Use recorded CENA ground motions

Sources Considered


Anderson (91) Edwards (12) Atkinson (84) Hough et al. (88) Atkinson (96) Silva and Darragh (95) Atkinson and Boore (06) Silva et al. (88) Campbell (09) Silva et al. (99) Chandler et al. (06) Toro and McGuire (87) Chapman et al. (03) Van Houtte et al. (11)

23 August 2013

13

Local Attenuation Models


Recommended local attenuation


Distribution Parameter Value Type of Distribution Lognormal Median, 0,refκ (sec) 0.006

Aleatory Standard Deviation, 0,ln refκφ (sec) 0.43

Epistemic Standard Deviation, 0,ln refκε (sec)

Excluding source, path, and site uncertainty Including source, path, and site uncertainty

0.12 0.20

Total Standard Deviation, 0, 0, 0,

2 2ln ln lnref ref refκ κ κσ φ ε= +

Excluding source, path, and site uncertainty Including source, path, and site uncertainty

0.45 0.47

Coefficient of Variation ( )2COV exp( ) 1σ= −

Aleatory variability Epistemic uncertainty Excluding source, path, and site uncertainty Including source, path, and site uncertainty

0.45

0.47 0.50

95th Confidence Interval; 2σ± Range (sec) Excluding source, path, and site uncertainty Including source, path, and site uncertainty

0.0024 – 0.0148 0.0023 – 0.0154

23 August 2013

14

Conclusions n  Reference rock velocity

n  Vs,ref = 3,000 m/s (2,700 -3,300 m/s)

n  Vp,ref= 5,500 m/s (5,000 -6,100 m/s)

n  Local attenuation n  κ0,ref = 0.006 sec n  Log-normal distribution n  Log standard deviation = 0.43 n  Recorded motions will be incorporated once

they become available


Acknowledgments n  Funding

n  U.S. Nuclear Regulatory Commission n  U.S. Department of Energy n  Electric Power Research Institute n  U.S. Geological Survey

n  Support from: n  Bechtel

n  Farhang Ostadan n  Tarek Elkhoraibi

n  Fugro n  Jeff Bachuber n  Michael Gray

n  US NRC n  Richard Rivera-Lugo

n  Undergraduate and graduate students: n  Michael Musgrove n  Khatereh Khodaverdi n  Ataya Eltibi n  Paul Khauli


Documents

Reference Rock Site Condition for Central and Eastern ......0,ref Recommendation ! EPRI (1993) reported a median κ 0,ref of 0.006 sec and initially proposed a σ ln of 0.40. ! EPRI