history of japanese railway and development of geosynthetics … · 2018-06-27 · drainage layer s...

Railway Technical Research InstituteRailway Technical Research Institute

History of Japanese railway and

Development of Geosynthetics

Reinforced-soil Structure

Kenji Watanabe

The University of Tokyo, JAPAN

(formerly Railway Technical Research Institute, RTRI)

18, April, 2018 UK-IGS

1


JR Hokkaido

JR East

JR Central

JR West

JR Kyushu JR Shikoku

JR Freight

RTRI

2

Railway Technical Research Institute

Railway Information Systems Co., Ltd.

7 railway companies

1987Division and privatization

Railway companies in Japan

Japan national

railways

Publishing design standard

for railway structure(Technical guide line, practical manual, etc)

Supporting railway company (providing technical solutions)


Contents1. Background (Technical issues around 1990)

6. Overview of recent application

2. Development of GRS retaining wall(1990’s)

3

4. Design of GRS RWs

3. Application of GRS to bridge abutment(2000’s - 2010’s)

5. Advantages of GRS RWs

7. Other examples of GRS structure

Kago

shima-

Chuo

Hakata

TokyoNagoya

Nagano

Shin-OsakaNagasaki

Sanyo Shinkansen

Kyushu Shinkansen

Hachinohe

Morioka

Sapporo

Shin-Aomori

Sendaii

Tsuruga

Total length in operation : 2,764km

2010

2002

1982

1982

1997

1964

1975

2011

2004

Maximum

Speed:

300km/h

Shinkansen is a backbone line

supporting nation’s Development

JR East

JR Central

JR West

JR Kyushu

UnderConstruction

Planned line

Niigata

4

Courtesy of MLIT

Maximum

Speed:

260km/h

Maximum

Speed:

320km/h

Tohoku Shinkansen

Tokaido Shinkansen

Maximum

Speed:

270km/h

Earth Structure 82%

Type of Structure and Composition of Japanese Railway

Conventional

lines

(24300km)

Shinkansen*

lines

(2400km)

21%

Earth Structure

Bridge

Tunnel

Viaduct

Bridge, Viaduct 48% Tunnel 31%

8% 10%

*Shinkansen ： High speed bullet train in Japan 5

Tokaido Shinkansen (1964)Ballasted track on embankment

Bearing capacity of embankment was not very high.(using clay, low compaction control etc)Settlement of ballasted track became very large after opening.

Kagoshima-Chuo

Hakata

TokyoNagoya

Nagano

Shin-OsakaNagasaki

Hachinohe

Morioka

Sapporo

Shin-Aomori

Sendaii

Tsuruga

2010

2002

19821982

1997

19641975

20112004

Niigata

2016

Track Type of Japanese Railway

6

Opening of Shinkansen Shinkansen CTC Center

Tokaido Shinkansen (1964.10.1)

Service section: between Tokyo and Shin-osaka (Distance: 515.4 km)

Time: 3 hours 10 minutes

Maximum speed: 210 km/hr

7

Tokyo Olympic (1964.10.10 - 10.24)

Much infrastructure (Shinkansen,

highway, Metropolitan Expressway)

were constructed just before

the Tokyo Olympic.

<Metropolitan Expressway, Tokyo>

Construction period was too short !

8

Tokaido Shinkansen (1964)Ballasted track on embankment

Bearing capacity of embankment was not very high.(using clay, low compaction control etc)Settlement of ballasted track became very large after opening.

Kagoshima-Chuo

Hakata

TokyoNagoya

Nagano

Shin-OsakaNagasaki

Hachinohe

Morioka

Sapporo

Shin-Aomori

Sendaii

Tsuruga

2010

2002

19821982

1997

19641975

20112004

Niigata

2016

Sanyo Shinkansen(1975)Slab track on viaduct.

Hokuriku Shinkansen(1997)Slab track on high quality embankment

Track Type of Japanese Railway

9

Continuous RC slab track

Rail

SlabCA mortar

SubgradeRC roadbed

JointTie bar

Relatively high construction cost

Very small allowable settlement of subsoil

Large reduction of maintenance cost

Less than 15cm (Restorability after severe EQ)

10mm/10years (Serviceability)

10

11

Technical issues around 1990s

Earth structure which is strong enough

against natural hazard

How can we construct ?

Earth structure which can support slab track

Earth structure with minimum land acquisition

Material selection and

sufficient compaction


Co

ncr

ete

road

bed

Trac

k

CA mortar 50mm

Reinforced concrete300mm

Well graded crushedstone 150mm

Prime coat

Sub

grad

e(e

mb

ankm

ent)

Slab

Subgrade

Drainage Layer

Sｌａｂ

Filling layer (CA mortar)

Reinforced concrete

Well gradedcrushed stone

Slab track on earth structure(Example in cutting section)

Slab

Concrete roadbed

Subgrade

12

Subgrade:K30 ≧ 110MN/m3

Cross section of slab track on earth structure

13

Major categories Medium categories Minor categoriesSoil material category Soil category Categorized mainly by observation Categorized by triangular coordinates

Coarse soil Cm

fraction > 50%

Gravel soil [G]

Gravel fraction >

sandy fraction

Sandy soil [S]

Sandy fraction ≧gravel fraction

Fine fraction <

15%

Fine fraction <

15%

Gravel containing fine

fraction [GF]

15% ≦ fine fraction

Sand containing fine

fraction [SF]

15% ≦ fine fraction

Gravel [G]

Sand fraction < 15%

Sandy Gravel [GS]

15% ≦ Sand fraction

Sand [S]

Gravel fraction <

15%

Gravely sand [SG]

15% ≦ gravel fraction

Gravel [G]

Fine fraction < 5%

Sand fraction < 5%

Gravel containing sand [G-S]

Fine fraction < 5%

5% ≦ Sand fraction < 15%

Gravel containing fine fraction [G-F]

5% ≦ Fine fraction < 15%

Sand fraction < 5%

Gravel containing fine sand [G-FS]

5% ≦ Fine fraction

5% ≦ Sand fraction < 15< 15%%

Sandy gravel [GS]

Fine fraction < 5%


Sandy gravel containing fine fraction [GS-F]

Fine fraction < 5%


Fine-grained gravel [GF]


Sand fraction < 5%

Fine gravel containing sand [GF-S]


5% ≦ Sand fraction < 15%

Fine sandy gravel [GFS]



Sand [S]Fine fraction < 5%

Gravel fraction < 5%

Sand containing gravel [S-G]Fine fraction < 5%

5% ≦ Gravel fraction < 15%

Sand containing fine fraction [S-F]5% ≦ Fine fraction < 15%


Sand containing fine gravel [S-FG]

5% ≦ Fine fraction < 15%


Gravel Sand [SG]

Fine fraction < 5%

15% ≦ Gravel fraction

Fine Sand [SF]5% ≦ Fine fraction < 15%


Fine sand [SF]15% ≦ Fine fraction


Fine sand containing gravel [SF-G]



Fine gravely sand [SFG]15% ≦ Fine fraction


Gravel

Group A :(For slab track)

Group B:(For ballasted track)

Material for subgrade (upper part of embankment)

Degree of compaction (Dc) ≥ 95%

K30 ≥ 110MN/m3

Degree of compaction (Dc) ≥ 90%

K30 ≥ 150MN/m3

Upper part of the embankment

Lower part of the embankment

Gravel: Dc ≥ 90%

Sand : Dc ≥ 95%

Compaction control for subgrade for slab track3

m

Lower part

Upper part 0.3m

1：1.8

1.5m

Extended geogrid

Short geogrid

<Plate loading test>

※Dc=100 x rd/rdmax

or

15

0 100 200 300 400 0.000

0.001

0.002

0.003

0.004

路床の残留沈下率

路床の K30値（MN/m3）

○：細粒分質砂 ●：細粒分質砂 ▲：礫質砂 ■：砂質礫白抜き：有道床軌道黒抜き：省力化軌道

Resid

ual sett

lem

ent

ratio

K30 of subgrade

Sandy gravelGravely sand

Fine sandFine sand

White: Ballasted trackBlack: Ballastless track

K30 vs residual settlement

80 90 100 110 0.000

0.001

0.002

0.003

0.004

路床の残留沈下率

路床の締固め密度比（%）

○：細粒分質砂 ●：細粒分質砂 ▲：礫質砂 ■：砂質礫白抜き：有道床軌道黒抜き：省力化軌道

Sandy gravel

Gravely sand

Fine sand

Fine sand

White: Ballasted track

Black: Ballastless track

Degree of compaction Dc (%)

Resid

ual sett

lem

ent

ratio

Full-scale loading test result(after 1.5 million cyclic loading)

Dc vs residual settlement

16

Technical issues around 1990s

Earth structure which is strong enough

against natural hazard

How can we construct ?

Earth structure which can support slab track

Earth structure with minimum land acquisition

Material selection and

sufficient compaction

Retaining structure

Terre-Armée method

Terre-Armée was applied around 1970’s for Japanese Railway,

but there were some technical problems.

Corrosion of metal strip caused by electric currentThere is no design method against large earthquake

Japan Railway tried to develop other reinforced-

soil structure using Geosynthetics from 1988（Collaborative research between RTRI and Univ. of Tokyo) 17




18





Laboratory Test

Loading set-up Molding specimen

Belloframcylinder

(unit:mm)

MembraneGrease

Load cell

Bearing

Load cell

footingLoad cell

Imbrications

Acryl

810 4101220 400

60

0


Sand backfill

Clay backfill

Construction of Full-Scale Test Embankment


Section Ⅰ5.0

m

ⅠS

ⅠN

ⅡS

ⅡN

ⅢS

ⅢN

Section Ⅱ

Section Ⅲ

2.0m

1.5m

2.0m

Ⅰ Ⅱ Ⅲ

Ⅰ Ⅱ Ⅲ

SEGMENT ⅡN

SEGMENT ⅠN SEGMENT ⅢN

Three Tested Sections of Embankment (Sand)

Plan

21


The rigidity of facing, connection between

facing and geosynthetics are very important.

Long term stability was also confirmed from this

full scale test embankments.

Vertical loading tests

22


Geosynthetics Reinforced Soil Retaining Wall

CONTINUOUS

Geotextile

(GRS RW)

23

Trademark


5)5) Completion of

wrapped-around wall

4)4) Second layer3)3) Backfilling & compaction

2)2) Placing geosynthetic &

gravel gabions

Gravel gabionGeotextile

1) Leveling pad for facing

Drain hole

6)6) Casting-in-place

RC facing

24

Geotextile

Construction procedure

After sufficient compression

of backfill and ground

鉄製のアンカー(直径

30 cm 30 cm120 cm

30 c

m

60 c

m

Backfill

Geogrid

Frame

Fresh

concreteSeparator

Steel reinforcement

Welding

Anchor

plate

60 cm

Soil

bagSteel rod (13 mm in dia.）鉄製のアンカー(直径

30 cm 30 cm120 cm

30 c

m

60 c

m

Backfill

Geogrid

Form

Fresh

concreteSeparator

Steel reinforcement

Welding

Anchor

plate

60 cm

Soil

bagSteel rod (13 mm in dia.）

Firm connection



RC facing

Firm connection

5)5) Completion of

wrapped-around wall

鉄製のアンカー(直径13 mm）

30 cm 30 cm120 cm

30 c

m

60 c

m

Backfill

Geogrid

Frame

Fresh

concreteSeparator

Steel reinforcement

Welding

Anchor

plate

60 cm

Soil

bagSteel rod (13 mm in dia.）鉄製のアンカー(直径13 mm）

30 cm 30 cm120 cm

30 c

m

60 c

m

Backfill

Geogrid

Form

Fresh

concreteSeparator

Steel reinforcement

Welding

Anchor

plate

60 cm

Soil

bagSteel rod (13 mm in dia.）

Casting-in-place concrete directly on the

geogrid-wrapping-around wall face:

1) Fresh concrete enters the gravel bags

through the aperture of the geogrid (PVA has

very high resistance against high PH).

2) A firm connection between the facing and the

reinforcement is ensured (PVA has a good

adhesiveness with concrete)

10 cm

Typical polymer geogrid:

bi-axial made of PVA

Railway Technical Research InstituteRailway Technical Research InstituteNear Shinjuku Station, Tokyo,

constructed during 1995 – 2000

Geogrid

Central section

(11k340m)

2,9103,9132,9001,173 0.300

41,484

Gravel-filled gabions

(all units in mm)

640 1,000

3,000 2,000 2,500

34,570

200 100

6,9

14

230

21 x

300=

6,3

00

Full-height

rigid facing

384

Yamanote line

Chuo

line

26

GRS RW supporting extremely busy urban trains

Construction of backfill

Construction of rigid facing

Passenger: 6.4million/day


Kobe earthquake 1995 (M=7.3)

27

Many damages to conventional type RW


Immediately after completion, 1992

GRS RW with a FHR facing

for a rapid transit at Tanata

Geogrid

(TR= 29 kN/m)

H-shaped

pile

0.8 m

H= 4.5 m

0.5 m

A week after the 1995 Kobe Earthquake

The wall survived!

Performance of GRS-RW during severe earthquake

28

GRS RWs performed very well during severe earthquakes !

Kobe earthquake (1995, M=7.3)


GRS RWs for railways (including high-speed trains) that had been

constructed in the affected area of the 2011 Great East Japan EQ

Co

Aomori: 58

Iwate: 23

Miyagi 9

Akita: 1

Yamagata: 3

Fukushima: 1

(total) 95

300 300 (All unit in mm)

100 575

100

600

5,400

Adjacent to Natori River,

Sendai City

Completed 1994

Wall length= 400 m

- Designed against very high seismic

load (level 2); and

- No damage to all the GRS RWs.

These facts validate the current

seismic design code for railway RWs. 29

Railway Technical Research InstituteRailway Technical Research Institute30Other application (bridge abutment)30

0

20

40

60

80

100

120

140

160

180

0

5

10

15

20

25

30

H1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 281995 20001990 2005 2010 2015

Total

1995 Kobe

Earthquake

Annual

Restart of construction

of new lines of HSR

(ShinKanSen)

2004 Niigata-ken-Chuetsu

Earthquake

Research: from 1982 at University of Tokyo

from 1988 at Railway Technical Research Institute

Tota

l （

km）A

nnual w

all

length

（km）

180

80

140

120

100

60

30

10

0

202011 Great

East Japan

EQ





31






Typical differential settlement at the transition zone

Bridgeabutment

Soft ground

Bearing layerpile foundation

Boxculvert

This transition zone is often suffering from differential subsidence which requires frequent maintenance works.

Differentialsubsidence

embankment embankment

Differential subsidence

Maintenance and reinforce of existing embankment at

transition zone are still major technical issue in Japan.


Application of GRS to the bridge abutment

(upside-down triangle shape)

Well-graded

gravel

Well-graded gravel

(trapezoidal shape)

In order to avoid a

sudden change of the

support rigidity, gravel

zone was change to

be trapezoidal shape

1967

1978

History of standard for railway structure

Isn’t it better to apply

GRS method to the

transition zone?

33

Bridge girder

Geogrid

reinforce -

ment

Cement-mixed gravel, reinforced with geogrid layers connected to the parapet

Uncemented backfill

RC facing structure

Bridge girder

Geogrid

reinforce-

ment

Cement- mixed gravel,

reinforced with geogrid

layers

Uncemented

backfill

RC facing

(abutment)

Connected

A modification of GRS-RW by

1. Placing a girder directly on the top of the facing

2. cement-mixing the backfill behind the facing.

34

Soil backfill

12

55

0Cement-mixed

gravel

Polymer geogridR.L 1400

1000 Kyushu Island

Sedimentarytalus

Crystallineschist

0 10 20 30 40 50

3

4

8

14

16

2650/30

50/23

50/16

20% of cost reduction was realized by this proposed method

(Unit in mm)150m

Application to the permanent structure of Shinkansen

35

Total cost

RC 0.61

0.28

Backfill 0.29

0.26

0.1

Reinforcement0.29 Total=0.83

Soil backfill

11

75

0

7500

Well graded gravel

R.L 1800

1800

Soil backfill

1500

12

55

0Cement-mixed

gravel

Polymer geogridR.L 1400

1000

GRS bridge abutment Conventional type

Sedimentarytalus

Crystallineschist

0 10 20 30 40 50

3

4

8

14

16

2650/30

50/23

50/16

Total=1.0

1)Conventional type

2) Proposed type

Cost comparison with conventional type

Low construction cost & High seismic stability !




37





Railway Technical Research InstituteRailway Technical Research Institute38

Design and construction of GRS RWs & Abutment

Design standard for railway structure

- Earth structure

- Earth retaining structure

- bridge abutment

- Seismic design

RRR-B Method

Material manual

RRR Method

Association

Earth structure

Earth retaining

structure

Performance based

Design

P.5-6

39

Soil

type

Classification

according to the Japanese

Geotechnical Society

γt

（kN/m3）

Seismiccondition（Level 2）

Non-seismiccondtion

Seismic condtion（Level 1）

φpeak(°) φres(°) φ(°)

1G, G-S, GSG-F, G-FS, GS-Fhard rock（low fissility）

20 55 40 40

2

S, S-G, SGS-F, S-FG, SG-Fhard rock（high fissility）,soft rock fallSoft brittle rock

19 50 35 35

3GF, GF-S, GFSSF, SF-G, SFG 18 45 30 30

4ML, CL, MH, CHOL, OH, OV, Pt, MkVL, VH1, VH2

16 40 30 30

Determined by comprehensive laboratory tests and literature

investigation（252 samples total）

Compaction level for slab track

P.8-39Design values of backfill


Fellenius method

The stability for the failure

plane located below the base

of the facing depth of

embedment is examined.

Reinforcement

Facin

g

T n

T

TS

Mrd

M LdO

Failure plane

P.8-39External stability analysis of GRS-W

40

Axle load

Surcharge load


(surcharge loads)(external loads)

Backfill (Φ, c)

Design ground

surface Subsoil (Φg, cg)

facing geotextile

P.8-39Internal stability analysis of GRS-RW

Two-wedge method Searching 2 failure planes both

in reinforced zone and

unreinforced zone against

“Sliding” and “Overturning”41

Sliding mode Overturning

Axle load


42

P.8-39Design of wall facing

Wall facing is assumed as the elastic beam supported

by multi spring, which is assured by the strong

connection between wall facing and reinforcement

Wall facing thickness can be reduced as compared with

conventional retaining wall.

Axle load

43

5.6 Reinforcements used in reinforced-backfill retaining walls

The reinforcements used inreinforced-backfill retaining walls

shall be those whose qualityhas been ascertained and theircharacteristic values anddesign values shall beappropriately determined takinginto account various factors, such asthe variability of test values and theexperimental conditions.

＜Geogrid＞

＜Laying of geotextiles＞

[Notification]

α１： Reduction factor considering alkaline resistance

α２：Reduction factor related to damage during construction

α３： Reduction factor related to creep α４：Reduction factor for momentary load

α５：Reduction factor related to train load

Action combinationReduction factors（○：Considered）α1 α2 α3 α4 α5

Permanent action ○ ○ ○ －－

Permanent action＋variable action

(train) ○ ○ －－ ○

Permanent action＋seismic action（L1

seismic ground motion）＋secondary

variable action○ ○ － ○ －

Permanent action＋seismic action（L2

seismic ground motion）＋secondary

variable action○ ○ － ○ －

During construction － ○ －－－

44

Table 5.6.2 Combination of reductions factors used in calculation of material factor , feg


45

(1) Minimum thickness of the facing- Minimum thickness of facing : 200 mm (generally 300mm)

- The inclination of the front side of the facing ：Vertical or 1：0.05 in V/H

（2）Arrangement reinforcementArranged every 30 cm; every 1.5 m in the vertical spacing

Basic length 1.5m or 35 % of H

Ｈ（W

all

hei

ght）

φ (Internal friction angle)

Ｌ

30cm

1.5m

Basic length

Ｈ45˚+φ/2

Ｌ

Structural details





46






Advantage of GRS RWs in construction

47

Conventional RWs GRS RWs

Extremely

weak

Relatively

weak

Good

Subsoil

condition



Extremely

weak

Pile foundation and

ground improvement is

needed.

Ground improvement

is needed.

Subsoil

condition

①

④⑤

②

①

③

②

④

③




Relatively

week

RC facing can be constructed after settlement finished

Pile foundation is needed because settlement of the RWs is not allowed.

Subsoil

condition

①

④

②①

②

③

③



Conventional RWs GRS RWsSubsoil

condition

①

②

③

Good

①②

③

Large footing is

required.Large footing is not

needed.



51


Extremely

weak

Relatively

weak

Good

RC facing can be

constructed

after settlement

finished

Pile foundation is

needed because

settlement of the RWs

is not allowed.

Large footing is

required.

Large footing is not

needed.

Pile foundation and

ground improvement is

needed.

Ground improvement

is needed.

Subsoil

condition



Backfill:

Backfill:

Ground (clayey soil, N=10,

20 m-thick)

soil density: 1.6 g/cm3;

ϕ= 0, c= 62 kPa)

Backfill:

soil density: 2.0 g/cm3

ϕ= 35o, c= 0

13.5 13.5

0.5 3.25 3.253.03.25 0.5

5.0

1.7

*dia.= 1.0 m; length: 20 m

c-to-c spacing in the track

direction: 4.0 m

Cast-in-

place

piles*2.54.5

Geogrid

(Tk= 37.5 kN/m)

Geogrid

(Tk= 76 kN/m)

Backfill:

Backfill:

soil density:

2.0 g/cm3

ϕ= 35o, c= 0

0.5 3.25 3.253.03.25 0.5

5.0

Leveling concrete

Gravel blanket 1.8

All units in m

Leveling concrete

Gravel blanket

Cost ratio for typical GRS RW versus conventional type RW

Construction Maintenance Total

20 m-thick relatively soft ground:

- piles for conventional type RWs

- no piles for GRS RWs

(the case shown in the figure)

0.32 0.5 0.33

Relatively stiff ground:

- no piles for conventional type

RWs & GRS RWs

0.81 0.51 0.77

Designed

by using

(kh)design= 0.2Cost of conventional

wall = 1.0

0.28 0.29

0.98 0.50 0.90

0.50





53






Sapporo

Kagoshima Chuo

Shin-Osaka

Nagoya

Tsuruga

Kanazawa

Omiya

Niigata

Tokyo

Nagasaki

In service 2,764.5 km（Since 2000： 929.4 km）

Under

construction

Hokkaido (extension) 211.5km

Hokuriku (extension) 125.2km

Kyushu (Nagasaki route) 66.0km

54

Hokkaidoopened March 2016

Shin-Hakodate Hokuto

Hokuriku

Kyushu（Nagasaki route）

to be completed 2022

Hakata

High-Speed Railway (HSR, Shinkansen), January 2017

Tokaidoopened Oct. 1964


211km

149km

Seikan tunnel (54km)

Shin-Aomori

Okutugaru

To Tokyo

Existing line (82 km)

Hachinohe Shichinohe-

towada

Kikonai

Shin-Hakodate

Shin-Yakumo

Oshamanbe

Kuthyan

Shin-Otaru

Sapporo

Hokkaido Island

Main Island

Toh

oku

Sh

inka

nse

n

Hokka

ido

Sh

inka

ns

en

Shin-Yakumo

Hokkaido High-Speed Train Line (Shin-kansen)

Completed

Construction

started 2013

Opened 26 March 2016

A number of GRS

structures were

densely constructed in

place of conventional

type structures


GRS structures

for Hokkaido HST line;

1) GRS retaining walls having full-height

rigid facing for a length of 3.5 km,

totally in place of conventional type

cantilever RWs


RC facing

Backfill

Geogrid

Girder

Abutment

Cement-mixed gravelly soil

Bearing

2) 29 GRS bridge abutments,

totally in place of conventional

type bridge abutments

Integrated girder and

a pair of facing

Geogrid

Cement-mixed gravelly soil

Backfill

Firm connection

3) A GRS integral bridge

(1) Box culvert

(2a) Geogrid-reinforced compacted cement-mixed gravelly soil (approach block) (3) Connection concrete

(2b)Backfil

l

4) Three GRS box culvert structures

integrated to GRS RWs

5) Eleven GRS protection

structures at the tunnel entrance


A new HST line (Hokkaido Shinkansen)

GRS structure Length or

number

Max. height

（m）

R GRS RW 3,528 m 11.0

A GRS abutment 29 13.4

I GRS integral bridge 1 6.1

B GRS box culvert 3 8.4

T GRS tunnel protection 11 12.5

Various GRS structures at Hokkaido Shinkansen (2013)

T

A

R

B

A

R

57


Type GRS RW

Construction

Mitsui Zosen corp.

Rinkai Nissan corp.

Taisei corp.

Cienco 1(Vietnum）Height 1.8～5.7 m

Length 1,485 m

Date 2013/July

Reinforcement 60 kN/m 93,000㎡Design and

management

Japan Transportation

Consultants

High Speed Railway Projects on Hanoi - Vinh

VietnamHanoi

Vinh

China

Raos

Thai

Cambodia Nha Trang

Ho Chi Minh

58





60






Construction on the soft ground or

liquefiable ground

(Cement treated gravelly soil slab)

61


Cement-mixed gravel is often used for

important structure for railway allowing a

limited amount of deformation.

What is Cement-mixed gravel?

After the

construction

Sedimentarytalus

Crystalline

schist

01020304050

3

48

14

16

2650/30

50/23

50/16

Soil backfill

150

1255 Cement-

mixed gravel

Polymer geogridR.L140

100

(Unit in cm)

TokyoTokyo

Kyushu

Shinkansen

GRS bridge abutment

Well-graded gravel with a little volume of cement;

geomaterial in-between soil and concrete.

62


Geogrid Tension member

Cement-mixed gravel

Compression member

Is there any other application of this composite material?

Applying to the construction of embankment on soft ground

as bending member (slab).

Embankment

Soft

ground

Improved pile

Conventional method

minimum

improvement

ratio is 25%

Proposed method

gravel

Embankment

Soft

ground

Geogrid

Improved pile

Cement-mixed

63


Bending loading Tests of

Cement-treated gravel slab

Cement-mixed gravel GeogridExternal load

(unit in mm)

200

700

50

Cement-mixed gravel

well-graded gravel, crushed sandstonecement/gravel ratio in weight : 2.5%

geogrid polymer geogrid, tensile strength: 30 kN/m

specimen two rectangular parallelepiped specimens

with geogrid and without geogrid

64


Application for the actual project (1)Construction of embankment on

soft ground at Japan railway

cement-mixed gravel

geogrid

Compaction of gravel

<After the ground improvement>

<Construction of the slab, 2009/4>

This composite material could be

constructed much easier and faster

than RC.

50% of cost reduction was realized

by this method

Volcanic clay (N-value: 2 -10)

φ=1.2m, L=6.2m

Improvement ratio: 10-14%

2 - 3m

6.2m

0.6m

65


Application for the actual project (2)Construction of embankment

on liquefiable ground

<Arrangement of geogrid >

< Construction of the slab>

By allowing a slight global

subsidence (=even

subsidence) after the

earthquake, the embankment

was constructed without

ground improvement.

slabLiquefiable ground

66


Conclusion

GRS-RW was developed in order to reduce the maintenance cost, land acquisition cost.

This technique was applied to bridge abutment

Full-height rigid facing which is contacted strongly to geosynthetics is the key aspect of this technique.

Cement-mixed gravel slab can be the one of the rational method to construct railway embankment on soft ground. 67

The cost effectiveness of GRS increases when it is applied to the construction

- on soft ground- under heavy axial load- for the high retaining wall- against large natural hazard

Thank you for your attention

The University of Tokyo, JAPAN

(formerly Railway Technical Research Institute, RTRI)

Kenji [email protected]

history of japanese railway and development of geosynthetics … · 2018-06-27 · drainage layer s...

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