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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
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
ISPRA, 28-30 May 2013 Research Project PROPWALL, Lead User G. Viggiani
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;
ISPRA, 28-30 May 2013 Research Project PROPWALL, Lead User G. Viggiani
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
ISPRA, 28-30 May 2013 Research Project PROPWALL, Lead User G. Viggiani
d/h = 0.43
B
L
ALLUMINIUM PLATESt = 254 mmB
h
d
L
h
d
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
PROPPED WALLS
PWU1 and PWU2
ISPRA, 28-30 May 2013 Research Project PROPWALL, Lead User G. Viggiani
d/h = 0.43
B
L
ALLUMINIUM PLATESt = 254 mmB
h
d
L
h
d
ISPRA, 28-30 May 2013 Research Project PROPWALL, Lead User G. Viggiani
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
ISPRA, 28-30 May 2013 Research Project PROPWALL, Lead User G. Viggiani
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
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
ISPRA, 28-30 May 2013 Research Project PROPWALL, Lead User G. Viggiani
CANTILEVERED WALL, CWU1, DR = 38% Acceleration time histories within the soil mass
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
A very important reduction in amplitude occurs during wave propagation, see
accelerometers ACC4 and ACC5
ISPRA, 28-30 May 2013 Research Project PROPWALL, Lead User G. Viggiani
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
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
ISPRA, 28-30 May 2013 Research Project PROPWALL, Lead User G. Viggiani
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
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
ISPRA, 28-30 May 2013 Research Project PROPWALL, Lead User G. Viggiani
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
ISPRA, 28-30 May 2013 Research Project PROPWALL, Lead User G. Viggiani
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
ISPRA, 28-30 May 2013 Research Project PROPWALL, Lead User G. Viggiani
CANTILEVERED WALLS, Dense Sand (DR = 80%) Wall deflection profiles for EQ3
Wall rotations are compatible to what expected for a cantilevered retaining strcuture
ISPRA, 28-30 May 2013 Research Project PROPWALL, Lead User G. Viggiani
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
ISPRA, 28-30 May 2013 Research Project PROPWALL, Lead User G. Viggiani
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
ISPRA, 28-30 May 2013 Research Project PROPWALL, Lead User G. Viggiani
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
ISPRA, 28-30 May 2013 Research Project PROPWALL, Lead User G. Viggiani
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
ISPRA, 28-30 May 2013 Research Project PROPWALL, Lead User G. Viggiani
PROPPED WALL, PWU1, DR = 38% EQ2, Bending moments profiles
Bending moments gradually vary during EQ2 until they become positive (change in sign)
ISPRA, 28-30 May 2013 Research Project PROPWALL, Lead User G. Viggiani
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
ISPRA, 28-30 May 2013 Research Project PROPWALL, Lead User G. Viggiani
PROPPED WALL, PWU1, Loose sand, DR = 38% Pore pressure ratio ru
ISPRA, 28-30 May 2013 Research Project PROPWALL, Lead User G. Viggiani
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%)
ISPRA, 28-30 May 2013 Research Project PROPWALL, Lead User G. Viggiani
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);
ISPRA, 28-30 May 2013 Research Project PROPWALL, Lead User G. Viggiani
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.
ISPRA, 28-30 May 2013 Research Project PROPWALL, Lead User G. Viggiani
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
ISPRA, 28-30 May 2013 Research Project PROPWALL, Lead User G. Viggiani
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, Lead User G. Viggiani
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)
ISPRA, 28-30 May 2013 Research Project PROPWALL, Lead User G. Viggiani
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)
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
ISPRA, 28-30 May 2013 Research Project PROPWALL, Lead User G. Viggiani
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)
ISPRA, 28-30 May 2013 Research Project PROPWALL, Lead User G. Viggiani
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
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
ISPRA, 28-30 May 2013 Research Project PROPWALL, Lead User G. Viggiani
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
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
ISPRA, 28-30 May 2013 Research Project PROPWALL, Lead User G. Viggiani
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
ISPRA, 28-30 May 2013 Research Project PROPWALL, Lead User G. Viggiani
CANTILEVERED WALLS, Dense Sand (DR = 80%) Displacements at the position of the LVDTs
Three stages: 1. INTERMEDIATE (I) 2. RESIDUAL (R) 3. POST SEISMIC (S)
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
ISPRA, 28-30 May 2013 Research Project PROPWALL, Lead User G. Viggiani
CANTILEVERED WALLS, Dense Sand (DR = 80%) Bending moments for RW, Pore pressures
Three stages: 1. INTERMEDIATE (I) 2. RESIDUAL (R) 3. POST SEISMIC (S)
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
ISPRA, 28-30 May 2013 Research Project PROPWALL, Lead User G. Viggiani
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)
ISPRA, 28-30 May 2013 Research Project PROPWALL, Lead User G. Viggiani
PROPPED WALLS, Loose Sand (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
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
ISPRA, 28-30 May 2013 Research Project PROPWALL, Lead User G. Viggiani
PROPPED WALLS, Loose Sand, DR = 38% Bending moments and pore pressures time histories
Three stages: 1. INTERMEDIATE (I) 2. RESIDUAL (R) 3. POST SEISMIC (S)
R2
PS1
R1 I2
I1