recent trend on case histories of reinforced soil walls in ... · • number of applications of...

Recent Trend on Case Histories of Reinforced

Soil Walls in Japan

J. OTANIKumamoto University, Japan

Secretary of Technical Committee No.9 “Earth Reinforcement”, ISSMGE

13th Africa Regional Conference on SMGE, ISSMGELecture, Marrakech, December 11, 2003

Earth Reinforcement Technique in this three decades

Development for several geotechnical methods

Recently, Combined technology with other

techniques has been widely used.

Establishment of analysis and design methods

Development of seismic design

Improvement of new products and geotechnical methods

This 30 years

Rapid & spread

Lecture at 13ARC2003

Contents

• Methods– Geogrid Method, Multi-Anchored Method, Metallic Strip

Method

• Statistical data of performance– Application fields, Scale and Reinforcement layout,

and Fill and foundation materials

• New trend– Combined Method with other methods

State of the art report on reinforced soil wall technique in Japan


Based on the statistical study by Japanese Supporting TC9 members

Reinforced Soil Wall Methods in Japan

1. Geogrid method2. Multi-anchored method3. Metallic strip method


1. Geogrid method


Sandbags

Geosynthetics

Soil layer

Steel wire frame

Geosynthetics

Soil layer

GeosyntheticsPC

panelfacing

Soil layer

RCblockfacing

Geosynthetics

Soil layer

2. Multi-anchor methodConcrete Facing

Connector

Turn Buckle

Tie bar

NonwovenGeotextile

Spacer

Base Concrete

Anchor PlateLecture at 13ARC2003

3. Metallic strip method


Foundation

Metallic Strip

Concrete SkinConnective

Bolt and Nat

Metallic SkinBolt and Nat

Metallic Strip

Covered Joint

Statistical Data of Performance

1.Application fields2. Scale & layout of

reinforcements 3. Fill and foundation

materials


0

500

1000

1500

2000

2500

3000

3500

Bef

ore

1980

1981

1982

1983

1984

1985

1986

1987

1988

1989

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

Year of execution

Num

ber o

f app

licat

ions

(cas

es)

GeogridMulti-AnchorMetallic Strip

Lecture at 13ARC2003Number of applications

Only Metallic 3 methods


Purpose of constructions

0

10

20

30

40

50

60

70

Expr

essw

ayR

oad

Nat

iona

lR

oad

Roa

d(O

ther

s)

Rai

lway

Site

Prep

arat

ion

Perc

enta

ge b

y th

e pu

rpos

e of

con

stru

ctio

n (%

)Metallic StripMulti-AnchorGeogrid

0

10

20

30

40

50

60

70

< 10

0㎡

100㎡～

400㎡

400㎡～

700㎡

700㎡～

1000㎡

1000㎡～

2000㎡

≧ 2

000㎡

Perc

enta

ge b

y th

e w

all a

rea

(%)

Metallic StripMulti-AnchorGeogrid


Scale of the walls

0

10

20

30

40

50

60

70

< 3m

3≦H

<5m

5≦H

<9m

9≦H

<15m

≧15

m

Height of construction examples

Perc

enta

ge (%


Lecture at 13ARC2003Height of the walls

010

2030

4050

6070

8090

< 5m 5～10m 10～15m 15～20m ≧ 20m

Length of reinforcement

Perc

enta

ge (%


Lecture at 13ARC2003Length of the reinforcement

0

20

40

60

80

100

Sand

and

grav

elm

ater

ials

Rock

(Cla

stic

s)

Cohe

sive

soil

Tre

ated

soil

(Cla

y)

Wea

ther

ing

rock

Perc

enta

ge (%

) Metallic StripMulti-AnchorGeogrid

Lecture at 13ARC2003Fill materials

0

10

20

30

40

50

60

Soil

Bed

rock

Har

d C

lay

Soft

grou

nd

Soil

impr

ovem

ent

(Rep

lace

men

t)

Soil

impr

ovem

ent

(Sta

biliz

atio

n)

Eolia

nde

posi

t

Perc

enta

ge (%

)

Metallic StripMulti-AnchorGeogrid

Lecture at 13ARC2003Foundation materials

NEW TREND– COMBINED METHOD –

• Needs of High Performance– Application to more important and permanent

structures• Request of Cost Reduction

– One main factor in the selection of optimum geotechnical solution

• Reduction of Environmental Impact– Regional or global environmental aspect,

such as landscape design and others

Lecture at 13ARC2003Five Examples

Ex.1 RSW with Mixing of Cement & Fiber

2.0m

1.0m 2.7m0.7m

6.0m

0.3m

0.8m

GeogridTmax = 35kN/m

Fill materialc = 0 kN/m2

φ = 30 deg

c = 210 kN/m2

φ = 0 deg

Improved soil (soil / cement / short fiber)

Improvement of stability of connection portion (without connection)

Connection portion


Simple construction !

Mixing of Cement & Short Fiber

Example 1


Ex.2 RSW with Mixing of Foam Glass

Improved soil(recycled foam glass/ soil)φ = 41 degc = 20kN/m2

γt = 1.1 kN/m3

Achievement of required stability by shorter reinforcing member


Mixing of Foam Grass

Example 2


Ex.3 RSW with Deep Mixing and Grouting

Deep Mixing Zone

Jet Grouting Zone

Soft Soil

Reinforced soil wall

Prevention of undesirable deformation in neighboring construction


Deep Mixing and Grouting

Example 3


RC Slab

RC Slab

Cover soil

Sand

Tie bar

EPS Blocks

Ex.4 RSW with EPSReduce of overburden load


EPS Blocks

RC slab

EPS

Example 4


Tie rods

Ex.5 RSW with Preloading + PrestressingImprovement of vertical stiffness of RSW


Example 5

Preloading + Prestressing


Conclusions• Number of applications of reinforced soil wall in

the year of 2000 is about one hundred times as much as those in 1981.

• The main application field is road construction and the height of the wall which is from 5m to 15m was most commonly used.

• Reinforced soil wall method combined with the other method such as soil improvement and others is a powerful solution for earth reinforcement technique.



Proceedings of IS Kyushu2001 Proceedings of 12th ARC Vol.2

Vol.2

I would like to say thank you to all the Japanese Supporting Committee Members of TC9 who gave me all the valuable data shown in this lecture.

ACKNOWLEDEGMENT


Thank you and

Merci beaucoupSee you soon See you soon

at 16at 16thth

ICSMGE in ICSMGE in Osaka, 2005 !Osaka, 2005 !

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