jap an’s first technique f for box culvert to increase the ... · this is a single layer 3 span...

Jap

(Constr

1. Intr

Tok

of 1envinteexisthe

The

Narenvnorm

pan’s First T

ruction Proj

roduction

kyo Outer Ri15 km fromvironment in ersects the JRsting viaductground to in

e JR Sobu Lirita Express vironment, thmal national

Outer Ring

Technique f

ject of a New

ing Road (hem the city cenn the center R Sobu Linet on the JR Sntersect (Fig.

ine is an impthat connect

he railway vl road were c

Road

for Box Culv

w Railway BMotoyawat

ereafter referrnter is beingof Tokyo. In

e (between Icobu Line, th1).

Fig. 1 C

portant railwats the city ceviaduct and tconstructed w

Chiba Prefectureconstruction sectio

- 1 -

vert to IncreRC Viaduc

Bridge on thta on the JR

red to as “Oug constructedn the sectionchikawa and

he Outer Ring

Construction

ay line with aenter with Nathe 2 layer r

without hinde

JR S(bet

e on

Ichik

ease the Spat

he Outer RinR Sobu Line)

uter Ring Rod with the on in Chiba Pd Motoyawatg Road below

location

an extremelyarita Airport road space oering operatio

Sobu Line intersectiontween Ichikawa and

Motoyawata)

kawa Station

an and Repla

ng Road betw)

oad”) that linkobjective of iPrefecture, thta). This projw ground, an

y high frequealso runs on

of the Outeron of the trai

JR Sobu Line Ichikawa Minam

Norm

To Matsudo

To Kaigan Dori

JR Sobu Li

ace an Exist

tween Ichika

nks the area aimproving tthe Outer Rioject was to nd the norma

ency of trainsn this line. Ur Ring Roadins (Fig. 2, F

mi IC

mal road

Expressway (Outer Ring Road)

ri

Motoyawata Station

Line

ting

awa and

at a radius the traffic ing Road allow the al road on

s, and the Under this d and the Fig. 3).

2. Out The

RC Outconchaordespannorm

In th

beatracwithwheprob

F

tline of the P

e Sobu Line moment res

ter Ring Roansideration thanged to an uer to achieven beam formmal national

the past this tams directly cks by the cuhin the railwen the trains blems of de

To T

North

Box c

Fig. 2 Outline

Fig. 3

Project

was elevatedsisting viaduad passing ovhe span divisiundergrounde this grade s

mat, to ensurel road.

type of constbelow the t

ut and cover mway lines, and

were stoppeegradation o

Tokyo

Nor

ExpresswayRo

Support beam

side

culvert

Box culv

e of the proje

Outline of th

d in the 1970uct and singlever the railwions of the vi

d scheme dueseparated intee the space fo

truction was tracks of themethod. Howd would be cd, and the w

of the surrou

rmal road

y (Outer Ring oad)

m under the railway lin

vert B1

- 2 -

ect (perspecti

he structure (

0s, during whe T beams. I

way, so the spviaduct. Theree to considerersection, it wor the underg

frequently ce railway, anwever, this cocarried out o

work would bunding envi

JR Sobu Line

ne

Box culvert B2

ive view whe

(normal to th

hich this inteInitially the Opace of the ieafter the schrations of thewas necessarground road

carried out bynd large-scaonstruction m

over a period be carried outironment, le

e

2

en completed

he road)

ersection wasOuter Ring Rintersecting rheme of the Oe surroundinry to modifybox culvert a

y a combinatle excavatiomethod woulof several h

t in a narrow engthening th

To

SRC portal frame m

Box culvert

Box culvert B3

d)

s constructedRoad schemroad did not Outer Ring Rng environmy the viaduct and the abov

tion of instalon directly bld require mu

hours during w space, whicthe construct

Chiba

moment resisting bridge

South side

t

d from an me had the

take into Road was ent, so in to a long

ve ground

lling steel below the uch work the night

ch had the tion, and

e pier

incrtechtechinveloca

F

Before chan

After chang

reasing the chnique to rehnique for cestigated (Fiation of the in

Fig. 5 Increas

nge

ge

cost. In ordereplace the bconstructing ig. 4). Fig. 5 ntersection. T

sing the span

■ Technique RC viaduct

■ Technfoundaspan b

r to deal withbeams in ord

the undergrsummarizes

The structure

Fig. 4

n of the viadu

for increasing tht and replacing

nique for construations for the br

beams

- 3 -

h these problder to increaround box cs the changee consists of

Techniques a

uct (above: b

the span of the ethe beams

ucting box culvridge piers supp

lems, in this ase the span

culvert to sue in the divisf the followin

applied

efore change

existing

vert that form thporting the long

project a men of the exiupport the loion of spans

ng parts (1) to

e, below: afte

he g

ethod of comisting viaducong span bes of the viaduo (3).

er completio

mbining a ct, and a

eams was uct at the

n)

- 4 -

(1) Box culvert structure This is a single layer 3 span box culvert 35.5 m wide, and about 12 m high (internal height about

8.6 m). Three box culverts were constructed: Box culvert B1 (L = 20 m) on the north side of the viaduct, Box culvert B2 (L = 20 m) directly below the viaduct, and Box culvert B3 (L = 20 m) on the south side.

(2) Supporting beam below the railway line This was installed to replace the beam and slab of the viaduct, which was removed as it was an

obstruction to the national road at ground level. This was a continuous beam with a total length of about 50 m formed in a lattice shape. The main beams are arranged in three rows, north, center, and south, made from a PRC structure.

(3) Portal frame type bridge piers

Four of these were constructed to support the supporting beams below the railway line. Of the

four sets of bridge piers, the set on the Tokyo side was an RC type with in situ driven piles as the foundations. The 3 sets on the Chiba side were SRC structure portal frame type moment resisting piers, supported by Box culvert B1 and Box culvert B3 via anchor frames.

3. Construction steps

The main construction steps in this project were as follows.

(1) Construct the box culverts on both sides of the existing viaduct, the inside of which is to be used as the Outer Ring Road and which form the support structure for replacement of the existing viaduct, (hereafter referred to as Box culvert B1 and Box culvert B3) (Fig. 6). The pneumatic caisson method was adopted as the method of construction of Box culverts B1 and B3, in order to minimize any large-scale temporary works and measures against groundwater.

(2) Afrasuloinwpopothco

Ththcovire

(1

After the caissame type bupporting beongitudinal bnstallation powas lifted up ortal frame tyortal frame tyhe viaduct usoncrete was p

hen the oute

hen the transvonstructed. Tiaduct on botemoving core

1) Caisson sink

(1) Caisson sin

sons were cobridge piers eams under beams and sosition. Therand installed

ype bridge piype bridge psing a 500 t poured inside

er main beamverse beams

The transversth sides in thes, inserting P

king

nking

Fig. 6 Ste

ompleted, thewere constrthe railway

slab of the refore, after cd in its final iers were con

piers was divcrane from

e and around

ms of the sups that connecse beams wehe axial direcPC steel, and

- 5 -

tep 1 (caisson

he supportingructed (Fig. y line was existing viaconstructingl position. Anstructed witvided, and era cradle on

d the structur

pport beams ct the outer ere installed ction of the bd tensioning.

n sinking)

g beams belo7, Fig. 8).installed in

aduct, so it wg it directly bAfter installati

th an SRC strected by thea caisson b

ral steel.

under the ramain beamssandwiching

bridge, and in

ow the railwaThe center

n a positionwas difficultbelow the inion of the cetructure. The e method of pox culvert, a

ailway line ws and the ceng the bridge ntegrated wit

ay line and tr main beam

n surroundedlt to construnstallation poenter main b

e structural stpulling it upand after ere

were construnter main bee piers of theith the bridge

the portal m of the d by the uct at the osition, it beam, the teel of the p to under ection the

ucted, and eam were e existing e piers by

(3) Aw(Ffrasp

(2) Ere

(1) Erepier

(3) Ererail

(1) Eli

Fig

After completwas taken by Fig. 9) In thisame type mopace for the r

ection of new brid

ction of new bridrs

ection of support lway line

Erection of supporine

Fig.

g. 8 Step 3: C

tion of the suthe new brid

s operation, toment resistinroad on the g

dge piers

dge

beams under

rt beams under ra

7 Step 2: Co

Construction

upport beamdge piers. (Hthe positionsng bridge pie

ground. This

ailway

- 6 -

onstruction of

n of support b

ms under the Hereafter this of the beamers were dispwas accomp

f new bridge

beams under

railway lines operation i

ms of the exiplaced relativplished using

e piers

the railway l

e, the load ofis referred toisting viaducve to each othg a “top sur

line

f the existingo as “underpct and the SRher, in order rface jack”

g viaduct pinning”.) RC portal to ensure installed

be“bfrapire

(4) Ainredi

(5) A

coBcodi

4. Tec

(1) Co

(F To

mthHof

(4) Tran(5) Cut

(1) Tr

etween the bbottom surfacame type briiers by underemoved.

After removalnstalled undeemoved. Theirections with

After replaceonstructed by1 and B3 duompleted by istribution rei

chniques use

onstruction oFig. 10).

o construct tmain beams ohereby constrHere, in order f the membe

nsfer load using hexisting columns

ransfer load using

beams of the ce jack” instidge piers. Arpinning, the

l of the coluer the main be top surfaceh non-shrink

ment of thy the cut and ue to this ex

y inverted coinforcement

ed in constru

of the lattice

the long spanon both sideructing the lto construct

ers in accord

hydraulic jacks s

g hydraulic jacks

existing viatalled betweeAfter transfere columns of

Fig. 9 S

umns the beabeams and njacks were

k mortar.

e viaduct, Bcover metho

xcavation, thonstruction m

using mecha

uction

PC beams to

n beams, firses and finalllattice PC bet the new PCdance with th

- 7 -

aduct and theen the supporring the loadf the existing

Step 4: Under

aring structunon-shrink mfixed, the hy

Box culvertod. In order t

he top deck omethod. The anical joints.

o integrate w

rst the centerly the transveams below

C beams, it whe design, an

e support beaort beams undd of the exisg viaduct (24

rpinning

ure was instamortar pouredydraulic pres

t B2 directto minimize of Box culvbox culvert

.

with the beam

r main beamverse beamsthe beams

was necessarynd integrate

(2) Cut existin

ams under thder the railwsting viaduct4 No.) were

alled. After rd, the bottomssure remov

ly underneaany displaceert B2 was cts were integ

ms and slab o

m was construs were constand slab of

y to introducethe existing

ng columns

he railway liway line and tt onto the necut by wire

rubber bearinm surface ja

ved, and jack

ath the viadement of Boxconstructed grated by co

of the existin

ucted. Next tructed in th

f the existinge the prestresviaduct and

ine, and a the portal ew bridge e saw and

ngs were acks were keted in 3

duct was x culverts first, and

onnecting

ng viaduct

the outer hat order, g viaduct. ss in each d the new

bestaexfo

(2) Tr

Insustainexthmlone

eams with thages, and thexisting viaduorm.

ransfer of loa

n order to miurface jacks aages to the

nstalled at thexisting bridghe tracks durimm) of the moad was comew structure.

■ Integrationaccomplis

he tension foe tensioning

uct into a long

ad to the new

inimize any and bottom snew bridge

e bearing loce piers wereing construct

maintenance mpleted witho

n of the existingshed by constru

orce. Therefooperation wag span. Also

Fig. 10 La

w bridge piers

displacemensurface hydrpiers. After

cations, and ae cut, therebytion due to trstandard valout generatin

g viaduct beamsucting the memb

- 8 -

fore, the conswas carried ouo, the weight

attice PC beam

rs using jacks

nt of the tracraulic jacks wr transferringafter complety smoothly ransfer of loalue to enableng unaccept

ms and slab with bers in stages an

struction of ut in stages inof the beam

am structure

s (Fig. 11)

cks on the vwere installedg the load, tion of the bcompleting t

ad to the beame the trains ttable crackin

the PC beams wnd prestressing

each memben 7 steps, to

ms was reduce

viaduct, a totad, and the lorubber shoeeam structurthe transfer. ms was mainto operate.

ng in the lon

was

er was carrirationally coed with this

tal of 52 of toad was transes and stoppre, the columThe displac

ntained withiAlso, transf

ng span beam

ed out in onvert the structural

the upper sferred in pers were mns of the cement of in 20% (3 fer of the ms of the

(3) M

InvifocaBHinjacpoca

Minimization

n this projectiaduct. As a rorce would baisson, whichH columns

ncrease the cacks was adoossible to maisson to with

of deformati

t, the caissonresult of FEMbe produced h would causwas installeaisson sinkinopted for co

maintain the hin 15% (2 m

Fig.

ion to existin

n box culverM analysis caon the found

se displacemd to isolate ng accuracy,ontrol of thedisplacemen

mm) of the tr

- 9 -

11 Underpin

ng structures

rts were sunkarried out in

ndation soil oment of the via

the existing, a hydraulice caisson attint of the viarack mainten

■

nning

when sinkin

k at positionadvance, it w

of the viaducaduct. There

g viaduct froc system usinitude. As a

aduct due tonance standar

Using 52 hydratransferred to th

ng the caisson

ns extremely was anticipatct due to the efore, a wall fom the caissong ground anresult of thesinking the

rd value.

aulic jacks, loadhe new bridge p

n (Fig. 12)

y close to theted that a larg

e effect of sinformed fromon. Also, in

anchors and hese measuree cutting edg

d was smoothlypiers

e existing ge pull-in nking the

m a row of n order to hydraulic es, it was ge of the

y

5. Res

TheBy posconmonconsafe

By

elevto rcontechcha

Durinfrictio

PrAtachhy

sults and Ou

e following icarrying ou

ssible to grenstruction pernths and re

nstruction wiety of operati

using this tevated railwayrealize the intntrol standardhnique can banging existin

ng sinking, a largeon

ressure sinking system ttitude control of the ca

chieved with ground anydraulic jacks

Fig. 1

utlook for th

is a compariut underpinnieatly reduce riod and econeduce the coithout any stion of the tra

echnique, it wy in an area wtersection ofd values for dbe widely usng spatial usa

e inward force is

aisson was nchors and

IsolatiMinimforces

12 Minimizin

he Future

son of the ming and effecthe environnomics, it wost by aboutoppage or sains.

was possible with high denf new plannedisplacementsed to greatlage.

generated on the

on with a wall formed mize the effect on the vi

produced during caiss

- 10 -

ng the effect

method used ctively using

nmental loadwas possible tut 15%. In slowing of tr

to rationallynsity of train

ed roads and t and deformly change th

e foundation soils

from a row BH columiaduct of the skin frictioson sinking

of caisson si

in this projeg the structud due to theto shorten the

addition, itrains during

y increase thens. In additionthe Shinkan

mation duringhe form of in

by skin

mnson

inking

ect with the cure of the exie constructioe constructiot was possibconstruction

e width of then, it can be a

nsen (bullet trg operation. Intersecting in

Hydraulic jack

Ground anchor

conventionalxisting viaducon. Also, it on period by ible to compn, and to inc

he road intersapplied as a train), which It is expectednfrastructure

l method. ct, it was terms of about 14

mplete the crease the

secting an technique has strict

d that this e, without

Fi

Before change

After change

ig. 13 View wwhen compl

- 11 -

leted (when uunderpinningg is completeed)