BEHAVIOR OF MASSIVE EARTH RETAINING WALLS UNDER EARTHQUAKE SHAKING Comparisons to EC-8 Provisions

UNIVERSITY OF PATRAS DEPARTMENT OF CIVIL ENGINEERING Laboratory of Geotechnical Engineering BEHAVIOR OF MASSIVE EARTH RETAINING WALLS UNDER EARTHQUAKE SHAKING Comparisons to EC-8 Provisions Prof. G. Athanasopoulos V. Kitsis, MSc V. Vlachakis, MSc Prof. A. Athanasopoulos Zekkos Győr, October 2015

1. INTRODUCTION MASSIVE EARTH RETAINING WALLS Free standing Components of infrastructure works An earth retaining structure may be: 1) yielding (translation/rotation is allowed) 2) non-yielding (restrained against movement)

1. INTRODUCTION Components of thrust: 1)Static earth pressure, P static 2)Dynamic earth pressure (increment), P earthquake 3)Wall inertia, P inertia Wall P inertia Backfill P Earthquake P static Design of the wall (must know): 1)Magnitude of each component & point of application 2)Phase differences

2. YIELDING RETAINING WALLS Two cases were analyzed Harmonic excitation f = 3Hz, a g = 0.05g, 0.10g, 0.15g, 0.20g, 0.30g, 0.40g, 0.70g

2. YIELDING RETAINING WALLS Time histories of recorded earthquakes: a) Erzincan, Turkey, earthquake, (1992) & b) Loma Prieta, USA, earthquake (1989)

2. YIELDING RETAINING WALLS Numerical models of gravity walls Validated through comparisons to centrifuge results by Nakamura (2006) Athanasopoulos Zekkos et al. 2013, Soil Dynamics and Earthquake Engineering 55, 59-70

2. YIELDING RETAINING WALLS

2. YIELDING RETAINING WALLS Seismic response of backfill The computed horizontal acceleration at point A is used as the mean backfill acceleration. Α

2. YIELDING RETAINING WALLS Seismic response of backfill for H = 4m

2. YIELDING RETAINING WALLS Seismic response of backfill for H = 7.5m

2. YIELDING RETAINING WALLS Dyn. Increm. EC-8, Part 5, 7.3.2.3 Dyn. Increm. EC-8, Part 5, 7.3.2.3 P Num P M-O 1/2 EC-8, Part 5, Annex E.4 1/2 Distribution of computed peak active earth pressures along the height of retaining walls and comparison with the M-O method.

2. YIELDING RETAINING WALLS Phase difference between seismic thrust and wall inertia The phase difference is described by the ratio Δσ /Δσmax where: Δσmax: maximum value of seismic increment of soil pressure at the middle of the wall Δσ: value of seismic increment at the instant of maximum wall inertia

2. YIELDING RETAINING WALLS Backfill acceleration (g) Normalized value of dynamic earth thrust (compared to its maximum value) acting at the instant of maximum wall inertia (Η = 4.0m)

2. YIELDING RETAINING WALLS Backfill acceleration (g) Normalized value of dynamic earth thrust (compared to its maximum value) acting at the instant of maximum wall inertia (Η = 7.5m)

2. YIELDING RETAINING WALLS EC-8 Provisions Type of retaining structure r 1/r Free gravity walls that can accept a displacement up to d r = 300aS (mm) 2 0.5 Free gravity walls that can accept a displacement up to d r = 200aS (mm) 1.5 0.67 Flexural reinforced concrete walls, anchored or braced walls, reinforced concrete walls founded on vertical piles, restrained basement walls and bridge abutments 1 1 The numerical analyses indicate that the wall design could be based on a much reduced (r = 1.67 to 5) seismic increment, especially for strong ground motions.

3. ΑΝΕΝΔΟΤΟΙ 3. NON-YIELDING 3. ΑΡΙΘΜΗΤΙΚΗ ΤΟΙΧΟΙ ΕΔΑΦΙΚΗΣ RETAINING ΠΡΟΣΟΜΟΙΩΣΗ ΑΝΤΙΣΤΗΡΙΞΗΣ WALLS Η Retaining Tοίχος αντιστήριξης wall Ε, ν, γ Υλικό Backfill επίχωσης E, v, γ, φ Συνθήκες Fixity conditions πάκτωσης a g Simplified model of non-yielding retaining wall

3. ΑΝΕΝΔΟΤΟΙ 3. NON-YIELDING 3. ΑΡΙΘΜΗΤΙΚΗ ΤΟΙΧΟΙ ΕΔΑΦΙΚΗΣ RETAINING ΠΡΟΣΟΜΟΙΩΣΗ ΑΝΤΙΣΤΗΡΙΞΗΣ WALLS Numerical model of non-yielding massive wall (v.2012.01) Finite element mesh for wall height Η=4.0m

4. ΑΠΟΤΕΛΕΣΜΑΤΑ ΠΑΡΑΜΕΤΡΙΚΩΝ ΑΝΑΛΥΣΕΩΝ 3. ΑΝΕΝΔΟΤΟΙ ΤΟΙΧΟΙ ΕΔΑΦΙΚΗΣ ΑΝΤΙΣΤΗΡΙΞΗΣ 3. NON-YIELDING RETAINING WALLS Input acceleration (g) Seismic response of backfill for H = 4m

4. ΑΠΟΤΕΛΕΣΜΑΤΑ ΠΑΡΑΜΕΤΡΙΚΩΝ ΑΝΑΛΥΣΕΩΝ 3. ΑΝΕΝΔΟΤΟΙ ΤΟΙΧΟΙ ΕΔΑΦΙΚΗΣ ΑΝΤΙΣΤΗΡΙΞΗΣ 3. NON-YIELDING RETAINING WALLS Input acceleration (g) Seismic response of backfill for H = 7.5m

4. 3. ΑΠΟΤΕΛΕΣΜΑΤΑ ΑΝΕΝΔΟΤΟΙ 3. NON-YIELDING ΤΟΙΧΟΙ ΠΑΡΑΜΕΤΡΙΚΩΝ ΕΔΑΦΙΚΗΣ RETAINING ΑΝΤΙΣΤΗΡΙΞΗΣ WALLS ΑΝΑΛΥΣΕΩΝ P ΔP (αsγh 199kN/m 115.2kN/m 2 ) num(dyn.inc.) d 0.53, (EC-8, Part 5, Annex E.9, = 1/2) (EC-8, Part 5, Annex E.9) Distribution of earth pressure (total, static, dynamic increment) along the height of the wall and values of computed dynamic increment from PLAXIS and Wood s equation.

4. 3. ΑΠΟΤΕΛΕΣΜΑΤΑ ΑΝΕΝΔΟΤΟΙ 3. NON-YIELDING ΤΟΙΧΟΙ ΠΑΡΑΜΕΤΡΙΚΩΝ ΕΔΑΦΙΚΗΣ RETAINING ΑΝΤΙΣΤΗΡΙΞΗΣ WALLS ΑΝΑΛΥΣΕΩΝ 1.0 0.8 PLAXIS (total pressure) static pressure PLAXIS (dynamic increment) Wood (dynamic increment) H=7.5m, φ=35 ο, a h =0.5g 0.6 P ΔP (αsγh 773kN/m 708.75kN/m 2 ) num(dyn.inc.) 0.4 d h/h 0.2 0.52, (EC-8, Part 5, Annex E.9, = 1/2) (EC-8, Part 5, Annex E.9) 0.0 0 50 100 150 200 250 300 σ h (kn/m 2 ) Distribution of earth pressure (total, static, dynamic increment) along the height of the wall and values of computed dynamic increment from PLAXIS and Wood s equation.

4. 3. ΑΠΟΤΕΛΕΣΜΑΤΑ ΑΝΕΝΔΟΤΟΙ 3. NON-YIELDING ΤΟΙΧΟΙ ΠΑΡΑΜΕΤΡΙΚΩΝ ΕΔΑΦΙΚΗΣ RETAINING ΑΝΤΙΣΤΗΡΙΞΗΣ WALLS ΑΝΑΛΥΣΕΩΝ Normalized value of dynamic earth thrust (compared to its maximum value) acting at the instant of maximum wall inertia (Η = 4.0m)

4. 3. ΑΠΟΤΕΛΕΣΜΑΤΑ ΑΝΕΝΔΟΤΟΙ 3. NON-YIELDING ΤΟΙΧΟΙ ΠΑΡΑΜΕΤΡΙΚΩΝ ΕΔΑΦΙΚΗΣ RETAINING ΑΝΤΙΣΤΗΡΙΞΗΣ WALLS ΑΝΑΛΥΣΕΩΝ Normalized value of dynamic earth thrust (compared to its maximum value) acting at the instant of maximum wall inertia (Η = 7.5m)

3. NON-YIELDING RETAINING WALLS EC-8 Provisions Type of retaining structure r 1/r Free gravity walls that can accept a displacement up to d r = 300aS (mm) 2 0.5 Free gravity walls that can accept a displacement up to d r = 200aS (mm) 1.5 0.67 Flexural reinforced concrete walls, anchored or braced walls, reinforced concrete walls founded on vertical piles, restrained basement walls and bridge abutments 1 1 The numerical analyses indicate that the wall design could be based on the maximum value (r 1) of seismic increment, especially for strong ground motions.

4. 3. ΑΠΟΤΕΛΕΣΜΑΤΑ ΑΝΕΝΔΟΤΟΙ 3. NON-YIELDING ΤΟΙΧΟΙ ΠΑΡΑΜΕΤΡΙΚΩΝ ΕΔΑΦΙΚΗΣ RETAINING ΑΝΤΙΣΤΗΡΙΞΗΣ WALLS ΑΝΑΛΥΣΕΩΝ Comparison of the behavior of non-yielding and yielding retaining walls Non-yielding retaining walls Yielding retaining walls

4. CEPHALONIA EARTHQUAKES 2014

4. CEPHALONIA EARTHQUAKES 2014 (LXRB) PGA=0.54g (1 st ) PGA=0.68g (2 nd ) (2 nd ) M w 6.0 03/02/2014 0.76g (2 nd ) M w 6.1 26/01/2014 (1 st ) (ARG2) PGA=0.43g (1 st ) PGA=0.27g (2 nd )

4. CEPHALONIA EARTHQUAKES 2014

Cemeteries 4. CEPHALONIA EARTHQUAKES 2014

4. ΑΝΤΙΚΕΙΜΕΝΟ ΠΕΡΑΙΤΕΡΩ ΕΡΕΥΝΑΣ 4. CEPHALONIA EARTHQUAKES 2014

4. ΑΝΤΙΚΕΙΜΕΝΟ ΠΕΡΑΙΤΕΡΩ ΕΡΕΥΝΑΣ 4. CEPHALONIA EARTHQUAKES 2014 The reconnaissance performed by the UPATRAS team provided information regarding the behavior of earth retaining structures.

4. 4. ΑΝΤΙΚΕΙΜΕΝΟ CEPHALONIA ΠΕΡΑΙΤΕΡΩ EARTHQUAKES ΕΡΕΥΝΑΣ 2014 1 st Case study CONCRETE CANTILEVER RETAINING WALL Height: (varies from 0.6m to 2.5m) Measured horizontal displacement: 12cm Stem tilt: 2.5

4.4. ΑΝΤΙΚΕΙΜΕΝΟ ΕΡΕΥΝΑΣ CEPHALONIA ΠΕΡΑΙΤΕΡΩ EARTHQUAKES 2014

4. 4. ΑΝΤΙΚΕΙΜΕΝΟ CEPHALONIA ΠΕΡΑΙΤΕΡΩ EARTHQUAKES ΕΡΕΥΝΑΣ 2014 2 nd Case study CONCRETE GRAVITY RETAINING WALL Height: (varies from 3.2m to 3.9m) Measured horizontal displacement: 4cm Measured vertical displacement: 7cm Crack opening in the retained roadway (extending to a length of 150m)

4. 4. ΑΝΤΙΚΕΙΜΕΝΟ CEPHALONIA ΠΕΡΑΙΤΕΡΩ EARTHQUAKES ΕΡΕΥΝΑΣ 2014 3 rd Case study MASONRY GRAVITY RETAINING WALL (flanked by concrete walls) Height: 3.3m Horizontal displacement: 21cm Vertical displacement: 20cm Cracks opening in the church s front yard supported by the wall (extending to a length of about 24m).

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