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UnternehmenspräsentationGeosynthetic Reinforced Wall Design acc. to EBGEO
UnternehmenspräsentationGeosynthetic Reinforced Wall Design acc. to EBGEO 12.11.2015
Workshop – Reinforced fills with GeosyntheticsMarie-Therese van Keßel, M.Sc.
Engineering Department, Huesker Synthetic GmbH
Geosynthetic Reinforced Wall Design
acc. to EBGEO
2
UnternehmenspräsentationGeosynthetic Reinforced Wall Design acc. to EBGEO
Outline
12.11.2015 3
Geotechnical Design Guidelines in Germany
EBGEO
Introduction
Safety Analysis
Large Scale Tests and Monitoring
Case Study
Conclusion
UnternehmenspräsentationGeosynthetic Reinforced Wall Design acc. to EBGEO
Geotechnical Design in Germany
Overview
12.11.2015 4
Figure 1: German regulation overview (modification Witt)
UnternehmenspräsentationGeosynthetic Reinforced Wall Design acc. to EBGEO
Geotechnical Design in Germany
Partial Safety Factors
12.11.2015 5
Figure 1: Partial Safety Factors for Effects (DIN 1054), Part I Figure 2: Partial Safety Factors for Effects (DIN 1054), Part II
UnternehmenspräsentationGeosynthetic Reinforced Wall Design acc. to EBGEO
Geotechnical Design in Germany
Partial Safety Factors
12.11.2015 6
Figure 1: Partial Safety Factors for Geotechnical parameters (DIN 1054)
Figure 2: Partial Safety Factors for Geotechnical parameters for Resistance (DIN 1054)
gM
UnternehmenspräsentationGeosynthetic Reinforced Wall Design acc. to EBGEO
EBGEO
Introduction
12.11.2015 7
Recommendations for Design and Analysis of Earth Structures using
Geosynthetic Reinforcements – EBGEO
Embankment on Soft Soil
Reinforced Foundation Pads
Transport Routes
Retaining Structures
Landfill Engineering
Piled Embankments
Geosynthetic Encased Columns
Sinkholes
UnternehmenspräsentationGeosynthetic Reinforced Wall Design acc. to EBGEO
EBGEO
Design Strength of Reinforcement
12.11.2015 8
EBGEO, section 3.3.1
Rb,k=RB,k0
A1∙A2∙A3∙A4∙A5, RB,d =
RB,k
gMRb,k Characterstic long term strength
Rb,k,0 Characterstic short term strength
Rb,d Design strength
A1 Reduction factor for creep
A2 Reduction factor for installation damage
A3 Reduction factor for processing
A4 Reduction factor for environmental/chemical impact
A5 Reduction factor for dynamic loads
gM Material Partial Safety Factor
UnternehmenspräsentationGeosynthetic Reinforced Wall Design acc. to EBGEO
90°
EBGEO
Retaining Structure
12.11.2015 9
Figure 1: Geosynthetic Reinforced Retaining Structure (GRS)
Figure 2: Geosynthetic Reinforced Retaining Structure (GRS)
UnternehmenspräsentationGeosynthetic Reinforced Wall Design acc. to EBGEO
EBGEO
Retaining Structure
12.11.2015 10
Demands and Boundary Conditions (Section 7.2.1)
Ground conditions below and behind and below the retaining structure
Location of ground water table
Impact of perched water
Any excavation battering angle or existing slopes
Height and inclination of the reinforced retaining structure
Design and requirements of facing
Planned design working life
Actions on the structure
Allowable deformations
Properties of intended materials
UnternehmenspräsentationGeosynthetic Reinforced Wall Design acc. to EBGEO
EBGEO
Retaining Structure - Analysis
12.11.2015 11
Analysis LS EBGEO-section
Ultimate Limit State ULSGeneral Failure/Slope Failure GEO 7.4.4
Bearing Capacity Failure STR 7.4.5
Sliding STR 7.4.6
Position Of Bearing Pressure Resultant EQU 7.4.7
Failure On Slip Planes Penetrating The Retaining Structure GEO 7.4.1
Design Strength Of Reinforcement STR 7.4.3
Pull-Out Resistance Of Reinforcement GEO 7.4.3
Analysis Of Connections STR 7.6
Analysis Of Reinforcement Overlapping/Joining (Reinforcement Junctions) STR 7.6
Serviceability Limit State SLSPosition Of Bearing Pressure Resultant SLS 7.5.2
Deformation Of The Structure SLS 7.5
Settlement In The Contact Zone SLS 7.5
UnternehmenspräsentationGeosynthetic Reinforced Wall Design acc. to EBGEO
EBGEO
Retaining Structure – Slope Failure (DIN 4084)
12.11.2015 12
Figure 1: Internal failure lines Figure 2: External / global failure lines Figure 3: Compound faillure lines
UnternehmenspräsentationGeosynthetic Reinforced Wall Design acc. to EBGEO
EBGEO
Retaining Structure – General Failure / Slope Failure (DIN 4084)
12.11.2015 13
Figure 1: External Failure Analysis, 7 Slices, (Bishop) Figure 2: External Failure Analysis, 50 Slices, (Bishop) Figure 3: External Failure Analysis, 150 Slices (Bishop)
UnternehmenspräsentationGeosynthetic Reinforced Wall Design acc. to EBGEO
Lessons Learnt
Retaining Structure – General Failure / Slope Failure (DIN 4084)
12.11.2015 14
Figure 1: External Failure Analysis, 50 Slices (Bishop) Figure 2: External Failure Analysis, (Vertical Slice)
UnternehmenspräsentationGeosynthetic Reinforced Wall Design acc. to EBGEO
EBGEO
Retaining Structures - Design Strength and Pull-out of
reinforcement
12.11.2015 15
Figure 1: Sketch, Distribution of forces, EBGEOFigure 2: Sketch, Failure mode Rupture of
Reinforcement, EBGEO
Figure 3: Sketch, Failure mode Pull-out, EBGEO
RA,k = sv,k ∙ LA ∙ fsg,k ∙ n• RA,k characteristic pull-out resistance relative to 1 m width
• sv,k characteristic normal stress in reinforcement plane
• LA anchorage length behind the failure plane
• fsg,k characteristic mean friction coefficient (2.2.4.11)
• n number of adoptable frictions surfaces
UnternehmenspräsentationGeosynthetic Reinforced Wall Design acc. to EBGEO
EBGEO
Retaining Structure – Bearing Capacity, Overturning, Sliding
12.11.2015 16
Figure 1: Sketch (EBGEO), Bearing Capacity Failure (STR),
based on DIN 1054 and DIN 4017
Figure 2: Sketch (EBGEO), Sliding Failure (STR), based on DIN
1054
Figure 3: Sketch (EBGEO), Overturning
Failure (EQU and SLS), based on DIN 1054
Figure 4: Kernel width, DIN 1054 (7.5.1)
UnternehmenspräsentationGeosynthetic Reinforced Wall Design acc. to EBGEO
EBGEO
Retaining Structures - Analysis of Facing Elements
12.11.2015 17
SLS
in accordance with DIN 4085
Rb,i or RAi,d ≥ Efacing
Efacing = efacing ∙ lv
efacing = hg∙ Kagh,k ∙ gk∙ H ∙ gG + hq ∙ Kaqh,k ∙ q ∙ gQ
Calibration factor Earth pressure angle
hg hq d
0 < h ≤ 0.4 H 0.4 H < h ≤ H
Non-deformable
facing elements1.0 1.0 1.0
Analogous to
DIN 4085
Partially deformable
facing elements1.0 0.7 1.0 1/3 j’ to 1.0 j’
Deformable
facing elements1.0 0.5 1.0 0.0
Table 1: Calibration factor, EBGEO (7.6)
Figure 1: Earth pressure, EBGEO
RAi,d – design value of the entire pull-out
resistance provided by friction or as
connection force (design value determining
using gB
Rb,i – design value of the long-term tensile
strength of the geosynthetics in the nth
reinforcement layer
UnternehmenspräsentationGeosynthetic Reinforced Wall Design acc. to EBGEO
EBGEO
Retaining Structures - Deformation of the structure
12.11.2015 18
Intrinsic settlements vE
0.2% ∙ H ≤ vE ≤ 1.0% ∙ H
Horizontal displacements vhi
Tensile force → axial stiffness → strain
distribution → change in length
Numerical model
Shear deformations vS
30% ∙ vHi,max ≤ vs ≤ 50% ∙ vHi,max
Ground settlements vu
Settlement on top of retaining
structure
90
°
vu – ground settlements
vhi – horizontal
displacement of the
slope front at the level of
reinforcement i
vE – intrinsic settlement of
the fill material
vS – shear deformations
vE + vu + vs
UnternehmenspräsentationGeosynthetic Reinforced Wall Design acc. to EBGEO
Large Scale Tests and Monitoring
Monitoring Parameter and Devices
12.11.2015 19
Deformations
Strain
Forces
Figure 1: Geosynthetic Reinforced Retaining Structure (GRS)
UnternehmenspräsentationGeosynthetic Reinforced Wall Design acc. to EBGEO
Large Scale Tests and Monitoring
Large Scale Test LGA, Nürnberg
12.11.2015 20
Large-scale test LGA, Nürnberg
4.5 m high GRS loaded by max.
600 kPa (3 x usual loads for
bridge super structures and
traffic)
Figure 1:Experimental setup, Large scale GRS, LGA Nürnberg, Germany
Source: Alexiew, D. und Detert, O.: Analytical and Numerical Analyses of a Real Scaled Geogrid Reinforced Bridge Abutment Loading Test, EuroGeo4, (2008).
UnternehmenspräsentationGeosynthetic Reinforced Wall Design acc. to EBGEO
Large Scale Tests and Monitoring
Large Scale Test LGA, Nürnberg
12.11.2015 21
Large-scale test LGA, Nürnberg
Max. vertical settlements 18 mm
Max. horizontal deformation 10 mm
Figure 2:Results, horizontal deformation at the GRS faceFigure 1: Results, settlements of concrete beam
Source: Alexiew, D. und Detert, O.: Analytical and Numerical Analyses of a Real Scaled Geogrid Reinforced Bridge Abutment Loading Test, EuroGeo4, (2008).
UnternehmenspräsentationGeosynthetic Reinforced Wall Design acc. to EBGEO
Large Scale Tests and Monitoring
Railway Line Köln-Mülheim
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Figure 1: Horizontal Displacement (related to initial measurement)
Figure 2: Typical cross section and location of inclinometer
UnternehmenspräsentationGeosynthetic Reinforced Wall Design acc. to EBGEO
Large Scale Tests and Monitoring
Riga South Bridge – Front Facing Deformation
12.11.2015 23
Figure 1: Typcial cross section, Riga South bridge
UnternehmenspräsentationGeosynthetic Reinforced Wall Design acc. to EBGEO
Large Scale Tests and Monitoring
Riga South Bridge – Front Facing Deformation (static)
12.11.2015 24
0
0.5
1
1.5
2
2.5
0 1 2 3 4 5
horizonta
l dis
pla
cem
ent [m
m]
Wall Height [m]
project
step 1
step 1 const
step 2
step 2 const
step 3
unload step 2
unload step 1 Figure 2: Loading of geosynthetic reinforced wall
Figure 1: Horizontal displacement over wall height
UnternehmenspräsentationGeosynthetic Reinforced Wall Design acc. to EBGEO
Large Scale Tests and Monitoring
Riga South Bridge – Front Facing Deformation (dynamic)
12.11.2015 25
Figure 1: Horizontal displacement over wall height
-0.5
0
0.5
1
1.5
2
2.5
3
3.5
4
0 1 2 3 4 5
horizonta
l dis
pla
cem
ent [m
m]
Wall Height [m]
project
unload step 1
step 4
step 5
step 6Distance from facing
step 4: 5 m
step 5: 3 m
step 6: 1 m
Figure 2: Loading of geosynthetic reinforced wall
UnternehmenspräsentationGeosynthetic Reinforced Wall Design acc. to EBGEO
Large Scale Tests and Monitoring
Riga South Bridge – Front Facing Deformation (dynamic)
12.11.2015 26
Figure 1: Riga South Bridge, Google maps
UnternehmenspräsentationGeosynthetic Reinforced Wall Design acc. to EBGEO
Case Study
A 74 Bridge Abutment, Netherland
12.11.2015 27
Two ecoducts with a geosynthetic
reinforced bridge abutment
Subsoil
soft clay (first 3 m, replaced with sand)
firm sand
very stiff clay layer (20 m below surface)
Preload to compensate settlements
during construction
Attaching half-gabion facing after
settlement completion
Figure 1: Artist impression for A74 bridge abutment
UnternehmenspräsentationGeosynthetic Reinforced Wall Design acc. to EBGEO
Case Study
A 74 Bridge Abutment, Netherland
12.11.2015 28
Figure 1: A 74 Bridge Abutment constuction phase Figure 2: A 74 Bridge Abutment construction phase, construction with formwork
UnternehmenspräsentationGeosynthetic Reinforced Wall Design acc. to EBGEO
Case Study
A 74 Bridge Abutment, Netherland
12.11.2015 29
Figure 1: A 74 Bridge Abutment with preload, 100 kPa over 3 m for 10 days (8th April – 18th April 2011) Figure 2: A 74 Bridge Abutment with preload
UnternehmenspräsentationGeosynthetic Reinforced Wall Design acc. to EBGEO
Case Study
A 74 Bridge Abutment, Netherland
12.11.2015 30
Typical cross section
20 layers of PVA geogrid
26 markers along 4 verticals
4th April – 24th August 2011
Preload 300 kPa (≈ bridge deck)
April 2011
Final load 510 kPa
July 2011
Figure 1: A 74 Bridge Abutment, Typical cross section
Figure 2: A 74 Bridge Abutment, measurement system
UnternehmenspräsentationGeosynthetic Reinforced Wall Design acc. to EBGEO
Difference between both curves describe the settlements within fill
Settlements below geosynthetic abutment dominates
Settlements after bridge deck installation doubles initial settlement
Resulting from back fill installed simultaniously with bridge deck
Case Study
A 74 Bridge Abutment, Netherland
12.11.2015 31
Figure 1: A 74 Bridge Abutment, Vertical Deformation, top of abutment, van
Duijnen et al. (2012)
Figure 2: A 74 Bridge Abutment, Vertical Deformation, bottom of abutment, van
Duijnen et al. (2012)
UnternehmenspräsentationGeosynthetic Reinforced Wall Design acc. to EBGEO
Case Study
A 74 Bridge Abutment, Netherland
12.11.2015 32
Figure 1: A 74 Bridge Abutment with bridge deck, upon completion, August 2011 Figure 2: A 74 Bridge Abutment, 2014
UnternehmenspräsentationGeosynthetic Reinforced Wall Design acc. to EBGEO
Conclusion
12.11.2015 33
Geosynthetic Reinforced Wall Design in Germany
is regulated in EBGEO (2010)
based on Eurocode 7, DIN 1054 (German Annex), DIN 4084, DIN 4017, DIN
4085…
slopes, steep slopes, walls, abutments are designed using the same approach
partial safety factors for effects, resistances and geotechnical parameters are
given in DIN 1054
no distinction between filling soil, back fill, subsoil
Large Scale Test and Monitoring
geosynthetic reinforced walls have been built, tested and monitored
performance very good
Proper design and installation is from a high importance
UnternehmenspräsentationGeosynthetic Reinforced Wall Design acc. to EBGEO 12.11.2015
Thank you very much for your attention!
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