PROPWALL Centrifuge study of the seismic performance of ... · PPT8 LVDT4 LVDT5 LC1/LC2 PPT6. Research Project PROPWALL, Lead User G. Viggiani ISPRA, 28-30 May 2013 PROPPED WALLS,

PROPWALL

Centrifuge study of the seismic performance of

propped retaining walls embedded in saturated

sand

Aversa S., de Sanctis L., Maiorano R., Tricarico M. UNIVERSITA’ DI NAPOLI PARTHENOPE

Viggiani G., Conti R. UNIVERSITA’ DI ROMA TOR VERGATA

Madabhushi S.P.G., Stringer M., Heron C. UNIVERSITY of CAMBRIDGE

OPERE E SISTEMI GEOTECNICI

Lead User G. Viggiani

Geotechnical Centrifuge of Cambridge University Engineering Department

ISPRA, 28-30 May 2013 Research Project PROPWALL, Lead User G. Viggiani


LAMINAR BOX, Knappett (2006) Alternating layers of aluminium and cylindrical bearings

Experimental activity on the behaviour of embedded walls

RESEARCH PROJECT

PUBLIC FUNDS ACADEMIC

INSTITUTIONS TESTs

HYDRAULIC CONDITION

ReLUIS 2005-2008

IT Emergency Management Agency (DPC)

UniROMA2, UniParthenope, Cambridge Univ.

6 CW 3 SPW (PW1, PW2, PW3)

DRY

MIUR-PRIN 2007

Italian Ministry for University and Research

(MIUR)

UniROMA2, UniParthenope

Cambridge Univ.

1 SPW 1 DPW

DRY

PROPWALL TNA to SERIES

EUROPEAN UNION

FP7/2007-2013 GA No. 227887

UniROMA2, UniParthenope, Univ. Coimbra

Cambridge Univ.

2 CWU 2 PWU

GWT Dredge Level

ReLUIS 2009-2013

IT Emergency Management Agency (DPC)

UniROMA2, UniParthenope

Cambridge University

1 CWU 1 PWU

GWT Dredge Level

(Contact pressure)

CW = cantilevered, SPW = Single Propped with Props near the top,

DPW = Double Propped with a second prop at dredge level, U = Piezometric head at dredge level


Research Project PROPWALL, Motivations

MAIN OBJECTIVES

1. Enhancement of the scientific database on the seismic performance of flexible retaining walls;

2. Understanding the mechanism controlling the seismic response of retaining structures embedded in saturated

sand; 3. Extending the validity of the main findings coming from

previous tests on dry sand;


Model scale Prototype scale

Modello DR (%)

N h (mm)

d (mm)

s (mm)

Z (mm)

B (mm)

h (m)

d (m)

s (m) Z (m)

B (m)

CWU1 38 40 90 110 - 400 200 3.6 4.4 - 10.8 8

CWU2 80 40 90 110 - 400 200 3.6 4.4 - 10.8 8

PWU1 38 40 140 60 9 400 200 5.6 2.4 0.45 10.8 8

PWU2 80 40 140 60 9 400 200 5.6 2.4 0.45 10.8 8

CANTILEVERED AND PROPPED WALLS

CWU1 and CWU2 PWU1 and PWU2

d/h = 0.82


d/h = 0.43

B

L

ALLUMINIUM PLATESt = 254 mmB

h

d

L

h

d


Modello DR (%)

N h (mm)

d (mm)

s (mm)

Z (mm)

B (mm)

h (m)

d (m)

s (m) Z (m)

B (m)

CWU1 38 40 90 110 - 400 200 3.6 4.4 - 10.8 8

CWU2 80 40 90 110 - 400 200 3.6 4.4 - 10.8 8

PWU1 38 40 140 60 9 400 200 5.6 2.4 0.45 10.8 8

PWU2 80 40 140 60 9 400 200 5.6 2.4 0.45 10.8 8

PROPPED WALLS

PWU1 and PWU2


d/h = 0.43

B

L

ALLUMINIUM PLATESt = 254 mmB

h

d

L

h

d


CANTILEVERED WALLS, CWU1, DR = 38% Seismic excitation, Measurement devices

Measurement devices included: Accelerometers, LVDTs, Strain

gauges, Pore pressure transducers

SG2

SG3

SG4

SG5

500

200

CWU1

290

90

110

90

Accelerometers LVDTsStrain GaugesPore Pressure Transducers

LVDT3

LVDT4ACC8

LVDT5

LVDT6

ACC5

LVDT1 LVDT2

ACC4

ACC3

ACC2

PPT1

PPT2

ACC7

PPT4

PPT3

ACC6

PPT5

PPT8

PPT7

PPT6ACC1

WAVE f (Hz)

amax (g)

Duration (s)

EQ1 1.25 0.1 25

EQ2 1.25 0.2 25


CANTILEVERED WALLS, CWU1, DR = 38% Seismic excitation, Measurement devices

Train of quasi sinusoidal waves. Acceleration positive rightwards. Acceler. Recorded by ACC1 is the

input signal.

SG2

SG3

SG4

SG5

500

200

CWU1

290

90

110

90


LVDT3

LVDT4ACC8

LVDT5

LVDT6

ACC5

LVDT1 LVDT2

ACC4

ACC3

ACC2

PPT1

PPT2

ACC7

PPT4

PPT3

ACC6

PPT5

PPT8

PPT7

PPT6ACC1


CANTILEVERED WALL, CWU1, DR = 38% Acceleration time histories within the soil mass

SG2

SG3

SG4

SG5

500

200

CWU1

290

90

110

90


LVDT3

LVDT4ACC8

LVDT5

LVDT6

ACC5

LVDT1 LVDT2

ACC4

ACC3

ACC2

PPT1

PPT2

ACC7

PPT4

PPT3

ACC6

PPT5

PPT8

PPT7

PPT6ACC1

A very important reduction in amplitude occurs during wave propagation, see

accelerometers ACC4 and ACC5


CANTILEVERED WALLS, CWU1 (DR = 38%) Displacements at the position of the LVDTs

Three stages: 1. INTERMEDIATE (I) 2. RESIDUAL (R) 3. POST SEISMIC (S)

I1 R2 PS1

R1

I2

SG2

SG3

SG4

SG5

500

200

CWU1

290

90

110

90


LVDT3

LVDT4ACC8

LVDT5

LVDT6

ACC5

LVDT1 LVDT2

ACC4

ACC3

ACC2

PPT1

PPT2

ACC7

PPT4

PPT3

ACC6

PPT5

PPT8

PPT7

PPT6ACC1


CANTILEVERED WALLS, Loose Sand (DR = 38%) Displacements at the position of the LVDTs

EQ2: Wall rotations opposite to those expected for a cantilevered wall

SG2

SG3

SG4

SG5

500

200

CWU1

290

90

110

90


LVDT3

LVDT4ACC8

LVDT5

LVDT6

ACC5

LVDT1 LVDT2

ACC4

ACC3

ACC2

PPT1

PPT2

ACC7

PPT4

PPT3

ACC6

PPT5

PPT8

PPT7

PPT6ACC1


CANTILEVERED WALLS, Loose Sand (DR = 38%) Pore pressure ratio ru

The pore water pressure ratio:

ru = Du/s’0

sxceeds unity for ppts on the excavated side


CANTILEVERED WALL, Dense Sand, DR = 80% Seismic excitation, Measurement devices

Accelerometers

PPTs

MEMS Accelerometers

LVDTsStrain Gauges

Potentiometer

POT1MEMS1

ACC8

PPT8

PPT7

LVDT1

LVDT2ACC7/LVDT4

ACC4/PPT3

ACC3/PPT2

ACC2

PPT5/ACC6

LVDT3

PPT4/ACC5

PPT6

200CWU2

500

290

PPT1

ACC1

SG2

SG3

SG4

SG5

SG6

WAVE f (Hz)

amax (g)

Duration (s)

EQ1 1.25 0.075 ~25

EQ2 1.25 0.1 ~25

EQ3 1.25 0.2 ~25

Train of quasi-harmonic waves with gradually increasing amplitude

Accelerometers

PPTs

MEMS Accelerometers

LVDTsStrain Gauges

Potentiometer

POT1MEMS1

ACC8

PPT8

PPT7

LVDT1

LVDT2ACC7/LVDT4

ACC4/PPT3

ACC3/PPT2

ACC2

PPT5/ACC6

LVDT3

PPT4/ACC5

PPT6

200CWU2

500

290

PPT1

ACC1

SG2

SG3

SG4

SG5

SG6


CANTILEVERED WALLS, Dense Sand (DR = 80%) Wall deflection profiles for EQ3

Wall rotations are compatible to what expected for a cantilevered retaining strcuture


CANTILEVERED WALLS, Dense Sand (DR = 80%) Pore pressure ratio ru

The pore water pressure ratio:

ru = Du/s’0

is always below unity

WAVE f (Hz)

amax (g)

Duration (s)

EQ1 1.25 0.1 25

EQ2 1.25 0.2 25


PROPPED WALLS, Loose Sand (DR = 38%) Seismic excitation, Measurement devices

Measurement devices included: Accelerometers, LVDTs, Pore

pressure transducers, Strain gauges, Potentiometers, Load

Cells

SG2

SG3

SG4

SG5

200PWU1

500

290

140

60

Accelerometers

LVDTs

PPTs

AC

Potentiometer

SG

ACC5

LVDT1

ACC4

ACC2

ACC6

ACC7/PPT4

PPT3 PPT5PPT1

ACC3/PPT2

ACC8LVDT3

LVDT2

POT1

ACC1

PPT7PPT8

LVDT4

LVDT5

LC1/LC2

PPT6


PROPPED WALLS, Loose Sand (DR = 38%) Acceleration time histories within the soil mass

A very important reduction in amplitude occurs during wave propagation, see

alignment ACC2-ACC4-ACC5

SG2

SG3

SG4

SG5

200PWU1

500

290

140

60

Accelerometers

LVDTs

PPTs

AC

Potentiometer

SG

ACC5

LVDT1

ACC4

ACC2

ACC6

ACC7/PPT4

PPT3 PPT5PPT1

ACC3/PPT2

ACC8LVDT3

LVDT2

POT1

ACC1

PPT7PPT8

LVDT4

LVDT5

LC1/LC2

PPT6


PROPPED WALLS, Loose Sand (DR = 38%) EQ2, Displacements at the position of the LVDTs

SG2

SG3

SG4

SG5

200PWU1

500

290

140

60

Accelerometers

LVDTs

PPTs

AC

Potentiometer

SG

ACC5

LVDT1

ACC4

ACC2

ACC6

ACC7/PPT4

PPT3 PPT5PPT1

ACC3/PPT2

ACC8LVDT3

LVDT2

POT1

ACC1

PPT7PPT8

LVDT4

LVDT5

LC1/LC2

PPT6

Maximum displacement of 165 mm

SG2

SG3

SG4

SG5

200PWU1

500

290

140

60

Accelerometers

LVDTs

PPTs

AC

Potentiometer

SG

ACC5

LVDT1

ACC4

ACC2

ACC6

ACC7/PPT4

PPT3 PPT5PPT1

ACC3/PPT2

ACC8LVDT3

LVDT2

POT1

ACC1

PPT7PPT8

LVDT4

LVDT5

LC1/LC2

PPT6


PROPPED WALL, PWU1, DR = 38% EQ2, Bending moments profiles

Bending moments gradually vary during EQ2 until they become positive (change in sign)


PROPPED WALL, PWU1, DR = 38% EQ2, Bending moments profiles and Axial force in the props

The change in sign of BM is fully consistent with the reduction of axial forces in the props occurring during EQ2


PROPPED WALL, PWU1, Loose sand, DR = 38% Pore pressure ratio ru


PWU1 vs PWU2 Comparison between BM profiles

The behaviour of propped walls in dense sand is markedly different, in this case BM do not change in sign

Dense sand (DR = 80%) Loose Sand (DR = 38%)


AMPLIFICATION EFFECTS DRY SAND vs SATURATED SAND

CONCLUDING REMARKS

1. For embedded walls in loose sand the maximum acceleration at the ground

surface is much lower than the magnitude of the input acceleration; this is

not the case of model tests of dense sand (CWU2 and PWU2);


4. A failure condition due to soil liquefaction probably occurs under the last

earthquake for both cantilevered and propped walls embedded in

saturated, loose sand. As a result, care must be taken on this aspect when

the seismic performance of these geotechnical structures is being

assessed.

3. Model tests of retaining walls embedded in loose sand. For CWU1 wall

rotations are ‘counter-intuitive’, while for PWU1 axial forces in the props

may even reduce to zero, depending on the magnitude of the applied wave;

2. Both cantilevered and propped walls experience significant permanent

displacements, as for model tests in dry sand;

FUTURE DEVOLPMENTS

1. Additional tests on pairs of embedded walls with measurements of contact

pressures at soil-wall interface (ReLUIS 2009-2013);

2. Interpretation of centrifuge tests on embedded walls in saturated sand by

numerical analysis with advanced constitutive models;

3. Development of performance based design criteria oriented towards the

evaluation of seismic permanent displacements, as performance indicator,

for retaining walls embedded in both dry and saturated sand.


Scala del modello Scala del prototipo

Modello DR (%)

N h (mm)

d (mm)

s (mm)

Z (mm)

B (mm)

h (m)

d (m)

s (m)

Z (m)

B (m)

CW1 84 80 50 50 - 200 75 4 4 - 16 6

CW2 53 80 50 50 - 200 75 4 4 - 16 6

CW3 73 80 50 50 - 200 100 4 4 - 16 8

CW4 55 80 50 50 - 200 100 4 4 - 16 8

CW5 49 80 50 50 - 200 75 4 4 - 16 6

CW6 69 80 50 50 - 200 100 4 4 - 16 8

PW1 78 40 140 60 9 400 150 5.6 2.4 0.3 16 6

PW2 42 40 140 60 9 400 150 5.6 2.4 0.3 16 6

PW3 44 40 140 60 9 400 200 5.6 2.4 0.3 16 8

APPENDIX A ReLUIS Research Project 2005-2008 Experimental programme

Aversa et al. 2008, Conti, 2010


APPENDIX A Research Project ReLUIS 2005-2008

67,5

15

14

20

26

6,3

40

LC1/LC2

ACCELEROMETER

LVDT

LOAD-CELL

LVDT1

LVDT2

ACC7

ACC8

ACC9

ACC14

ACC13

ACC12

ACC11

ACC10ACC15

ACC6

ACC5

ACC4 ACC1

ACC2

ACC3

PARATIE CON UN SOLO LIVELLO DI PUNTONI

Input sismico: treno di

onde quasi-sinusoidali

N = 40

(Conti, 2010)

d/h = 0,428 Aversa et al. 2008 Conti, 2010


ISPRA, 28-30 May 2013 Research Project PROPWALL, User Leader G. Viggiani

SATURATION

Main results from previous tests on embedded retaining walls in dry sand (ReLUIS 2005-2008, MIUR-PRIN 2007)


1. The instantaneous occurrence of limit conditions in the systems during an earthquake does not necessarily imply the collapse of the structure;

2. No permanent displacements are measured when the current wave is less severe than earthquakes previously occurred;

3. Retaining walls have to accumulate permanents displacements before the passive resistance be fully mobilized;

4. Permanent displacements can be predicted within reasonable accuracy by a Newmark calculation –type, provided that the critical acceleration is not defined as

that corresponding to limit equilibrium conditions (Conti et al. 2012)


Modello DR (%)

N h (mm)

d (mm)

s (mm)

Z (mm)

B (mm)

h (m)

d (m)

s (m) Z (m)

B (m)

CWU1 38 40 90 110 - 400 200 3.6 4.4 - 10.8 8

CWU2 80 40 90 110 - 400 200 3.6 4.4 - 10.8 8

PWU1 38 40 140 60 9 400 200 5.6 2.4 0.45 10.8 8

PWU2 80 40 140 60 9 400 200 5.6 2.4 0.45 10.8 8

CANTILEVERED AND PROPPED WALLS


Leighton Buzzard sand, 100/70, fraction E,

reconstituted at two values of DR

emax = 1.014 (DR = 38%),

emin = 0.613 (DR = 80%)

Extensively characterized in the Dynalab of

the University of Napoli Federico II

(Visone e Santucci de Magistris, 2009)


CANTILEVERED WALL, Loose Sand, DR = 38% Bending moments and pore pressures time histories

1. INTERMEDIATE (I) 2. RESIDUAL (R) 3. POST SEISMIC (S)

I1 R2

PS1

R1 I2

SG2

SG3

SG4

SG5

500

200

CWU1

290

90

110

90


LVDT3

LVDT4ACC8

LVDT5

LVDT6

ACC5

LVDT1 LVDT2

ACC4

ACC3

ACC2

PPT1

PPT2

ACC7

PPT4

PPT3

ACC6

PPT5

PPT8

PPT7

PPT6ACC1


CANTILEVERED WALLS, Loose Sand (DR = 38%) Bending moments profiles for EQ2

Limit equilibrium analysis: 1. Angle of shearing resistance at peak

condition by Bolton (1986) φp = φcrit + 5IR·[DR(%)(10-lnp’f)-1]

SG2

SG3

SG4

SG5

500

200

CWU1

290

90

110

90


LVDT3

LVDT4ACC8

LVDT5

LVDT6

ACC5

LVDT1 LVDT2

ACC4

ACC3

ACC2

PPT1

PPT2

ACC7

PPT4

PPT3

ACC6

PPT5

PPT8

PPT7

PPT6ACC1


CANTILEVERED WALL, Dense Sand (DR = 80%) AMPLIFICATION EFFECTS

Accelerometers

PPTs

MEMS Accelerometers

LVDTsStrain Gauges

Potentiometer

POT1MEMS1

ACC8

PPT8

PPT7

LVDT1

LVDT2ACC7/LVDT4

ACC4/PPT3

ACC3/PPT2

ACC2

PPT5/ACC6

LVDT3

PPT4/ACC5

PPT6

200CWU2

500

290

PPT1

ACC1

SG2

SG3

SG4

SG5

SG6

Reduction in amplitudes, even if less pronounced than those observed for CWU1

Accelerometers

PPTs

MEMS Accelerometers

LVDTsStrain Gauges

Potentiometer

POT1MEMS1

ACC8

PPT8

PPT7

LVDT1

LVDT2ACC7/LVDT4

ACC4/PPT3

ACC3/PPT2

ACC2

PPT5/ACC6

LVDT3

PPT4/ACC5

PPT6

200CWU2

500

290

PPT1

ACC1

SG2

SG3

SG4

SG5

SG6


CANTILEVERED WALLS, Dense Sand (DR = 80%) Displacements at the position of the LVDTs


I1 R2 PS1

R1

I2 PS2 R3

Accelerometers

PPTs

MEMS Accelerometers

LVDTsStrain Gauges

Potentiometer

POT1MEMS1

ACC8

PPT8

PPT7

LVDT1

LVDT2ACC7/LVDT4

ACC4/PPT3

ACC3/PPT2

ACC2

PPT5/ACC6

LVDT3

PPT4/ACC5

PPT6

200CWU2

500

290

PPT1

ACC1

SG2

SG3

SG4

SG5

SG6


CANTILEVERED WALLS, Dense Sand (DR = 80%) Bending moments for RW, Pore pressures


I1 R2

PS1

R1 I2

PS2

R3

Accelerometers

PPTs

MEMS Accelerometers

LVDTsStrain Gauges

Potentiometer

POT1MEMS1

ACC8

PPT8

PPT7

LVDT1

LVDT2ACC7/LVDT4

ACC4/PPT3

ACC3/PPT2

ACC2

PPT5/ACC6

LVDT3

PPT4/ACC5

PPT6

200CWU2

500

290

PPT1

ACC1

SG2

SG3

SG4

SG5

SG6


CANTILEVERED WALLS, Dense Sand (DR = 80%) Bending moment profiles for EQ3

Bending Moment Profiles 1. INTERMEDIATE, corresponding to the

maximum attained at SG4 for RW 2. RESIDUAL (R) 3. POST SEISMIC (PS)


PROPPED WALLS, Loose Sand (DR = 38%) Displacements at the position of the LVDTs


I1 R2 PS1

R1 I2

SG2

SG3

SG4

SG5

200PWU1

500

290

140

60

Accelerometers

LVDTs

PPTs

AC

Potentiometer

SG

ACC5

LVDT1

ACC4

ACC2

ACC6

ACC7/PPT4

PPT3 PPT5PPT1

ACC3/PPT2

ACC8LVDT3

LVDT2

POT1

ACC1

PPT7PPT8

LVDT4

LVDT5

LC1/LC2

PPT6

SG2

SG3

SG4

SG5

200PWU1

500

290

140

60

Accelerometers

LVDTs

PPTs

AC

Potentiometer

SG

ACC5

LVDT1

ACC4

ACC2

ACC6

ACC7/PPT4

PPT3 PPT5PPT1

ACC3/PPT2

ACC8LVDT3

LVDT2

POT1

ACC1

PPT7PPT8

LVDT4

LVDT5

LC1/LC2

PPT6


PROPPED WALLS, Loose Sand, DR = 38% Bending moments and pore pressures time histories


R2

PS1

R1 I2

I1

Documents

PROPWALL Centrifuge study of the seismic performance of ... · PPT8 LVDT4 LVDT5 LC1/LC2 PPT6. Research Project PROPWALL, Lead User G. Viggiani ISPRA, 28-30 May 2013 PROPPED WALLS,