use of cpt in geotechnical earthquake engineering of cpt in geotechnical earthquake engineering ......

Use of CPT in Geotechnical Earthquake Engineering

Prof. Scott M. Olson, PhD, PE

Use of Cone Penetration Test for Foundation Analysis and Design2006 Annual Meeting

Transportation Research Board

Geotechnical Earthquake Engineering

• Ground shaking• Structural hazards• Liquefaction• Landslides

• Retaining structure failures

• Lifeline hazards• Tsunamis & seiches

Ground Shaking & Site Response • Code based

– Vs profile• Site-specific

– Soil profile– Small strain

shear modulus

Seismic CPT

xyz

Geophone array

Friction sleeve

PiezoelementCone tip

Pushrods

Body waves

Beam

Hammer

Trigger

SeismographCPT computerThrust machine

xyz

Geophone array

Friction sleeve

PiezoelementCone tip

Pushrods

Body waves

Beam

Hammer

Trigger

SeismographCPT computerThrust machine

Liquefaction • Level ground (cyclic liquefaction)• Liquefaction-induced settlement• Flotation of buried structures• Lateral spreading• Sloping ground / flow failure

Level Ground Liquefaction

1,1 cFCcsc qCq ⋅=Clean sandbase curve

Newman, Stark, & Olson(in review)

Level Ground Liquefaction

Newman, Stark, & Olson (in review)

MSF

r

FS

dv

v

L

'ga0.65

CRR

CSRCRR

DemandResistance

max

σσ≈

≈

≈

Liquefaction-induced Settlement

Ishihara & Yoshimine (1992) Zhang, Robertson, &Brachman (2002)

Post-liquefaction volumetric strain, εv (%)

Lateral Spreading

(qc1N~45)

(qc1N~60)

(qc1N~80)

(qc1N~110)

(qc1N~160)

(qc1N~200)

modified from Ishihara & Yoshimine (1992)

Zhang, Robertson, &Brachman (2004)

Sloping Ground / Flow Failure• Susceptibility• Triggering• Post-triggering

stability

Olson & Stark (2003)

CONTRACTIVE DILATIVE


stability



stability


voothervoseismicavgvostatic

vouTriggering

yieldsFS'''

')(

, στστστσ

++≈

Sloping Ground / Flow Failure

• Susceptibility• Triggering• Post-triggering

stability

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0 2 4 6 8 10 12

qc1

τ / σ

' vo

100

200

300

400

500

600

Limiting boundaries based on σ'vo (kPa)contractive/dilative boundary

Olson and Stark (2003)range of su(yield)/σ'vo

Level ground CRR(Stark & Olson 1995)

Approximate limiting boundary based ondrained shear strength for φ 'ss = 30o

Olson et al. (2006, in press)

qc1 (MPa)

s u(y

ield

)/σ' vo


stability


Great River Bridge• 22,550 ft of bridge• 1400 ft cable stay

main span• Elevated crossings

over levees• Foundations

– piles– drilled shafts– hydraulic caissons

GRB Seismicity• 2% PE in 50 years• B/C pga = 0.14g• Design EQ

controlled by NMSZ– MW 7.7– R = 200 km

ProjectSite

ProjectSite

Uses of sCPTu at GRB• Detailed stratigraphy• Soil properties

– static– dynamic (Vs)

• Liquefaction analysis– level ground / settlement– lateral spreading– sloping ground / flow

failure

GRB Subsurface Profile

GRB Dynamic Soil Properties

GRB Level Ground LiquefactionGeneral Information Soil Information Earthquake Information Analysis Information

Location: Arkansas City, AR Average γt: 120 pcf MW: 8.1 FC relation: FC calculated from Ic (Robertson & Wride 1997)Project No. 23-20010054.00 GWT depth: 10 ft amax: 0.18 g MSF: 0.85 Idriss (1999) TRB presentation

Date: 08/10/01 rd relation: Idriss (1999) TRB presentation

Sounding A-CPT-1

0

10

20

30

40

50

60

70

0 100 200 300qc1N

Dep

th (f

t)

0 2 4 6F (%)

0 1 2 3 4Ic

0 25 50 75 100Apparent FC (%)

0 100 200 300(qc1N)cs

0 0.2 0.4 0.6CRR7.5 & CSR

0 1 2 3FSLIQ

GRB Level Ground Liquefaction

GRB Liquefaction Settlement

120 140 160 180 200 220 240 260 280 300 320 340 360

Station (ft) *100

30

24

18

12

6

0

Liqu

efac

tion-

Indu

ced

Settl

emen

ts (i

nche

s)

West ofAbandoned

ChannelAbandoned

ChannelWest of Abandoned

ChannelPointBar

MississippiFloodplain

RiverEast

GRB Lateral Spreading• Arkansas pointbar → 3 to 13 ft• Mississippi cutbank → negligible

GRB Sloping Ground / Flow Failure

Conclusions • sCPTu is an excellent site investigation

tool when conditions are appropriate – quality & quantity of data – rapid & versatile– cost-effective– repeatable

Conclusions • sCPTu is a versatile design tool well-suited

to geotechnical earthquake engineering – site response (ground shaking) – liquefaction engineering– site characterization & soil properties for:

• landslides (seismic slope stability)• seismic foundation & retaining structure design • lifeline engineering

Conclusions • sCPTu works particularly well for

liquefaction engineering– loose & soft materials– thin layer identification– level ground liquefaction, settlement, flotation– lateral spreading– sloping ground & flow failure

Thank You!

Questions???

use of cpt in geotechnical earthquake engineering of cpt in geotechnical earthquake engineering ......

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