Influence of soil nonlinearities on

dynamic soil-structure interaction

OECD-NEA Workshop on SSI, Oct. 2010, J-F Semblat 1

(1) LCPC, Paris, France (Univ. Paris-East)

Dept of Geotechnics, Water and Risks (2) IRSN, Fontenay-aux-Roses, France

A. Gandomzadeh1,2, J.F. Semblat1,

L.Lenti1, M.P.Santisi1,2, F.Bonilla2

(semblat@lcpc.fr)

OECD-NEA Workshop on SSI, Oct. 2010, J-F Semblat 2

SSI: what is the right scale?

Seismic waves vs SSI?

OECD-NEA Workshop on SSI, Oct. 2010, J-F Semblat 3

Ground motion

F0=VS/4H

Soil-structure interaction

Large scale interactions

Structure to structure interaction

• BEM simulations + centrifuge experiments

OECD-NEA Workshop on SSI, Oct. 2010, J-F Semblat 4

f=0.2 Hz f=0.4 Hz f=0.6 Hz

OECD-NEA Workshop on SSI, Oct. 2010, J-F Semblat 5

Large scale interactions in basins

• BEM

density 1

density 2

density 3

density 4

density 5

OECD-NEA Workshop on SSI, Oct. 2010, J-F Semblat 6

500 1000 1500 20000

0

5

10

15

20

TIM

E [s

]

perturbations

distance (m)

0

5

10

15

20

time

[s]

perturbations

500 1000 1500 20000

distance (m)

Radiated wavefield

H=25m

0 1 2 3 4 5 6

frequency (Hz)

H=12.5m

frequency (Hz)

0.1

0.3

0.5

0.7

0.9

0.4

0.5

0.6

0.7

0.8

0.9

1

0.4

0.5

0.6

0.7

0.8

0.9

1

FreeField

heterog.

homog. (N=16)

L /LU L /LU

P

0 1 2 3 4 5 6

H=50m

0.4

0.5

0.6

0.7

0.8

0.9

1

0.1

0.3

0.5

0.7

0.9

0.1

0.3

0.5

0.7

0.9

co

rre

latio

n le

ng

th

OECD-NEA Workshop on SSI, Oct. 2010, J-F Semblat 7

Frequency match & coherency

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

Gro

und

en

erg

y/f

ree

field

en

erg

y r

atio

Gro

und

en

erg

y/f

reefie

ld e

ne

rgy r

atio

N=16N=25

N=33

N=10

E

N=16N=25

N=33

N=10

EP

-1000 -750 -500 -250 0 250 500 750 1000

f =0.8HzR

f =0.8HzR

f =2HzR

f =2HzR

-1000 -750 -500 -250 0 250 500 750 10000

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

B1S

B1S

B2S

B2S

distance (m) distance (m)

distance distance

heterogeneous

incoherent field

OECD-NEA Workshop on SSI, Oct. 2010, J-F Semblat 8

SSI vs strong motion?

OECD-NEA Workshop on SSI, Oct. 2010, J-F Semblat 9

Strong motion: influence of soil

• SSI depends on:

– Soil stiffness

– Geometrical damping

• Strong motions lead to:

– Stiffness reduction

– Dissipation increase

kh

kh

k

ch

ch

m

h

c

k

c

10-5

0

0.2

0.4

0.6

0.8

1

G(

)/G

0

déformation

10-4

10-3

10-2

10-10

0.05

0.1

0.15

0.2

0.25

strain

‘Nonlinear’ soil models

OECD-NEA Workshop on SSI, Oct. 2010, J-F Semblat 10

• Lin. equivalent: iterative, layer response,

• Intermediate: freq. dep. (Kausel, Assimaki), ‘X-NCQ’,

• Plasticity models, coupled models (pore pressure), etc.

Hysteretic model

frequency

1/Qth()

distorsion

1/Q()

X-NCQ: nonlinear viscoelastic

(J.Eng.Mech., ASCE, 135(11), 2009)

Validation of the hysteretic model

• Homogeneous layer (50m)

• Various codes/approaches (EERA, NERA)

• Various excitation levels

OECD-NEA Workshop on SSI, Oct. 2010, J-F Semblat 11

OECD-NEA Workshop on SSI, Oct. 2010, J-F Semblat 12

SSI for strong quakes

• NL-SSI model:

– Linear struct.

– NL stratified soil (hyst.)

– Initial stress state

– Interface: slid./frict./uplift

– Abs. layers (‘CALM’,

IJNME, sept. 2010)

• Analyses:

– Influence of the excitation level

on the SSI

– Amplitude (time, freq.)

– Dissipation into the soil

OECD-NEA Workshop on SSI, Oct. 2010, J-F Semblat 13

Response of the structure

OECD-NEA Workshop on SSI, Oct. 2010, J-F Semblat 14

NL response of the soil

• Energy dissipation

(ratio shear/total)

• Hysteretic loops for two

excitation levels and different depths

SSI for strong quakes in a basin

• Alluvial basin in the city of Nice

• Non horizontal soil layers

• NL soil response

• Seismic motion: PGA=0.25 g

• Dissipated energy (J/m^3)

OECD-NEA Workshop on SSI, Oct. 2010, J-F Semblat 15

• Data needed!!! (in the nonlinear range!!)

3D effects? (or ‘1D-3C’!)

OECD-NEA Workshop on SSI, Oct. 2010, J-F Semblat 16

(Ge

op

hysic

al J

al In

t., 2

00

9)

Measurements in Grenoble

(Ch

aill

at,

Se

mb

lat,

Bo

nn

et,

CiC

P, 2

01

0)

Fast-BEM approach

17

Thank you!

Bard P.Y., Chazelas J.L., Guéguen P., Kham M., Semblat

J.F. (2005). Assessing and managing earthquake risk -

Chap.5 : Site-city interaction,, Springer.

Bonnet M. (1999). Boundary integral equation methods for

solids and fluids, Wiley, Chichester, UK.

Chaillat S., Bonnet M., Semblat J.F. (2008). A multi-level

fast multipole BEM for 3-D elastodynamics in the

frequency domain, Comp. Meth. in Applied Mech. & Eng.

197, pp.4233-4249.

Chaillat S., Bonnet M., Semblat J.F. (2009). A new fast

multi-domain BEM to model seismic wave propagation

and amplification in 3D geological structures,

Geophysical Journal International, 177(2), pp.509-531.

Dangla P., Semblat J.-F., Xiao H.H., Delépine N. (2005). A

simple and efficient regularization method for 3D BEM:

application to frequency-domain elastodynamics, Bull. of

Seismological Soc. of America, 95(5): 1916-1927.

Delépine N., Bonnet G., Lenti L., Semblat J.F. (2009).

Nonlinear viscoelastic wave propagation: an extension of

Nearly Constant Attenuation models, Journal of Eng.

Mechanics (ASCE), 135(11), pp.1305-1314.

Gandomzadeh A., Santisi d’Avila M.P., Semblat J.F.,

Lenti L., Bonilla F., (2010). Influence of soil

nonlinearities on dynamic soil-structure interaction, Fifth

Int. Conf. on Recent Advances in Geotechnical

Earthquake Eng. and Soil Dynamics, San Diego, USA.

Kham M., Semblat J.F., Bard P.Y., Dangla P. (2006). Site-

City Interaction: Main Governing Phenomena Through

Simplified Numerical Models, Bull. Seism. Soc. Am., 96(5):

1934-1951.

Semblat J.F., Pecker A. (2009). Waves and vibrations in

soils, IUSS Press, 499 p.

Semblat J.F., Kham M., Bard P.Y. (2008). Seismic wave

propagation in alluvial basins and influence of Site-City

Interaction, Bull. Seism. Soc. of America, 98(4).

Semblat J.F., Kham M., Parara E., Bard P.Y., Pitilakis K.,

Makra K., Raptakis D. (2005). Site effects: basin

geometry vs soil layering, Soil Dynamics and Earthquake

Eng., 25(7-10), pp.529-538.

Semblat J.F., Duval A.M., Dangla P. (2000). Numerical

analysis of seismic wave amplification in Nice (France) and

comparisons with experiments, Soil Dynamics and

Earthquake Eng., 19(5): 347-362.

Semblat J.F., Brioist J.J. (2000). Efficiency of higher order

finite elements for the analysis of seismic wave

propagation, Jal of Sound & Vibration, 231(2), pp.460-467.

Semblat J.F., Luong M.P., Gary G. (1999). 3D-Hopkinson

bar : new experiments for dynamic testing on soils, Soils

and Foundations, 39(1), pp.1-10.

Semblat J.F., Luong M.P. (1998). Wave propagation through

soils in centrifuge experiments, Journal of Earthquake

Engineering, 2(1), pp.147-171.

OECD-NEA Workshop on SSI, Oct. 2010, J-F Semblat

http://perso.lcpc.fr/semblat.jean-francois

Absorbing layer method

• ‘CALM’: Cauchey Absorbing Layer Method

(IJNME, sept.2010)

• Absorbing layer with adequate Rayleigh/

Cauchey damping parameters

OECD-NEA Workshop on SSI, Oct. 2010, J-F Semblat 18