TunneI Plug works

Workflow

Consolidationgrouting

ChjPPing forallsedion ofeconcrete surface

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26

Metalworksby others

Steel drain PiPe

forLOTIII

Back ml airvent PiPescooling PiPes

contact grout PiPes

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enbeded

Cooling shall becontinued

until estimated temPeratureis obtained

(Shall be cool down to the

surrounding ground rock

temPerature minus 2o C)

1

Lining concrete

Chipping for all of

concreteJoint surface

Plug concrete(13lift)

cooling

Procedure of plug works

Purpose is protection for headrace tunnel lining concrete

and a water tighteness for drain tunnel

Back fillgrouting

Metalworks

(Drain pipc install by others)

Back ml groutlng

cooling

27

Consolidation grouting

Pipe system instanation

Sce detailsketch ng,-Ang.,C

Contact groutlng

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.jl

Back filland contact grouting

Air vent pipe for back nn grouti

ng.-A

Cooling system

Pipe system illustration

/Airvenype forcontactgrou7ng

-11

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Air vent pipe for

back nll grouting

Profile

,NH ?77

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Plug concrete temperature meaJudng hole (depth 2.53m)

Plan

coolingpipe

Profile

water stop'- .

contact grout outjct valvc

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r 7 - - -

fig.-B

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/Tool3tee

icoolterpipe coohng

retumpipe/

Contact grouting

fig.-C

contact grout outlet valve

Groutstop

contact grout retum plpe

contract grout plpe

28

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1.Location map of defects

Concrete lining has ongoing ofthe headrace tunnel at the LOT I.

Location maPs ofthe fonowing defects subject to rcPair e rcquired.

1AIl cracks in the longitudinal directionshallbe repaired

2Cracks in the cross sectional directionwhich meet with either one of the next

conditions

awidth larger than 0.3 mm in dcondition ofcracks

bwater leakage is observed

3hegularities at horizonta1Joints between arch and invert linings.

4hegularities at constmction joints and at where insPection windows of steel

formwork were placed.

5Honeycomb

2.ylethod of repair

2.1 Cracks in longitudinal direction

Refer to Fig. 1.Details are shown stePwise as next

Step 1.Clean the rePai14ng area

Step 2.Drill holes on the surface of nningconcrete at acrack to be rePairedby

electric drillingmachine afterhardenjng of concrete. The depth of a hole

shd be about 5cm and hole intervalis about 0.8m.lnsert a brass nipple

about14mm at drilledhole.

Step 3.Seal with Sika monotop 615 HB the crack and itssurrounding area. The

sealinhajl be about 5mm thick. about 5cm wide 2,5 cm wide at one

side of the crack.lengthbeing as long as the crack.

Step4.Clean and moisten the hole

Step5. ect cement milk into the hole by using a manuany operated pump. The

mjx proportion in weight of cement mnk shallbe between l cement to 3

30

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water l cement to l water. A maximum of pressure of injedon shall be

2.0 kg/cm2 or as directlyinstructed by the Engineer at site.

Step 6. Stop injection of cement milk 10 mjnutes aner cement milk startsleakjng

from the mouth of the downward dircctlon crack on the surface of lining

concrete of 20 minutes aner reaching the maximum pressure of thc

uPwards crack.

Step.Fill the holc with Sika 102 by hand.

SteP 8.Remove the sejing and clean the surface of lining concrete. lnsPection

will be done for grouting results.

SteP 9.Epoxy coating aner completion

SteP 10. 1n casc thc leak of water from cracks is not stoPP{d by groutingthe

nlling method should be apPlied. U shape cut is better than v shaPecut

forPeelo.(refer to fig.1-2)

Step 101.U shaPe cut by electricbreaker and mk leakage locations.

Stcp 10 2. D?l holes for temporaly drain locations with a large quantities

ofleakage.

Step 10 3. Clean the grooes.

SteP 10 4.FiII Sika 102 from small seepage to leakage.Leaking water

sh?lbe concentrated to the temporadrin.

Step105.Put a nipPle to the drain holes and tighten.

SteP106.Plug the nipple and coverby Sika 102 aner hardening of

surrounding filledmaterial.

SteP107.Epoxy coating afterhardened.

2.2 Cracks in cross sectionaldirection

(The same method shown in 2.1 Cracks in longitudinal directionis applied)

2.3hTegularities at horizontaoints between arch and invert linings

(1)Small dcPressions at horizontalJoinls

Smooth ouoints by cuttingirregularitiesby grinder (refer to Fig. 2)

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More than 90of depressions at defective horizontal joints are repaired by this

method.

2Large depressions at horizontaljoints

Rcfer to Fig. 3. Detailsareshown stepwise as next

Step 1

Step 2

Step 3

he horizontaoint both holizontaland vertically.Remove

thc cut portion.

Clean the cut surface and coat with a special type of mortar such

as SIKA 73 1 to enhance the bondage between existing concrete

and newly nned mortar.

Fillthe cut portion with mortaf (mlx ProPortion in weight of 2

cement to l water and 2 sand)and smooth the surface.

(3)Pr(ctions.at horizontaljoints

Smooth out joints by cuttinrregulties by an elect14cpercussion breaker and

nnishing by grinderfertoFig.4)

2.4 1rregularitiesat construction joints and at where inspection windows of steel

formwork were Placed.

Smooth outjoints by cuttingirregularitiesby an percussion breaker and nnishing by

grinder(refer to Fig. 5)

2.5 Honeycomb

Dry condition ferto ng. 6l)Details afe shown as next

I Depth lessth5cm

Step 1:Cut the honeycomb portion (location ma and dePth shil be

directed by theEngineer)

Step 2 :Clean the cut surfaceand nll with strong bond tyPe of monar

(Sika monotop 615 HB)by hand.

SteP 3:Epoxy coatingafterhardened.

(1)-2 Depth more than 5cm

SteP 1:Cut the honeycomb untilthe fresh concrete exPose

Step 2:Clean chipped surface and moistening

32

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Step 3

Step 4

Step 5

Coat by Sika monotop 615 HB forbonding (t:2cm)

FiH cement mortar(C:W:S 1:I:2).

EPoxy coatinganer hardened.

2Leng water condition

Step l :Same as dry condition at step 1 (refer to ng. 6j)

SteP 2 :Clean the cut surface and then nll the Sika 102 with niPple and pipe for

leaking water divert(refer ng. 6-2)

Step 3 :Cement milk injectioninto the hole by using manually oPerated pump the

mix proportion on weight of cement milk shall be betwcen l cement to 3

water aJldl cement to l water. Maximum ofpressure ofinjection shan be

4 kg/cm2 or as directed by the Engineer at site.

Step 4 :Blockjng shbe calTied out at least 10 mjnutes after reaching the

maximumpressufe,alsoafterreachingmixProportionbyl:1.

SteP 5 :Fill the hole of niPple using Sika monotop 615 HB by hand after

confirming hardened grout material and leakage water stoPped.

Step 6 :Epoxy coating afterhafdened.

33? ? ? ? ?

3.Construction Tolerances for Tunnel Lining

with Clause 4.1.93iiiofTechnicaI Specification

a.DePartulflomestablishcd

alignment or from cstablished

grade but paralleltolt

varlation nom inside dimensions

variation ln thickness at any Point

Minus

Formed Surface

The dasscs of finished surfaces are designated by use of symbols FIF2,F3andF4.

(Clause 4.13(2)ofTechnicaI Specification)

FI

F2

F3

F4

Depression exceed

Abrupt irregularities shall not cxceed

Gradual irregularities shall not exceed

Abrupt irregularitiesshallnot exceed .

Gradual irregularitiesshallnot exceed

A11 gradual iITegularities

25 mm

10 mm

34

Shall not exceed for abmpt irregularities.

not parallel to the direction of now

Shan not exceed for abruPt irregularities

Parallelto the direction of now

A11abruptirregularitiesinexcessoftheallowedlimjtsshallbegroundtoa

slope of a verticalto20 horizontal.

Shall be applied dause F4 for water waytunnel lining

Repairing work also shan be accordance with thisclauses above.

Fig l

Fig.2

ng1-1ection method

ock

ngl-2 nlling method

Rock

PumP n)r injection ofcement milk

F poxy coated (ancr completion oFgrout)

Scaling Sika monotop 615HB(width5cm thickness)

U shapecut

ortaring(watertht?ngtypeofSikamonotop615HBorSika102

Width10~15mm

DepthO~15mm

Epoxy coated

Method of Repair of Cracks in Longitudinal and Cross Sectional Directions

Smooth by cutting by grinder

Epoxy coated

Method of Repair of Small Depressions at HorizontaI Joints

35

Figj

Fig.4

Fig.5

removc and fill with morlar

Coated by Sika monotop 61

Method of Repair of Large Deprcssions at Horizontaooints

Cutb

Arcb

breaker and nnish b

Epoxy coated

lnvert

Method of Repair of Projections at Horizontal ,loints

Construction Joint

inder

Method of Repair of lrrguralities at Construction Joints and at Where

lnspedion Windows of Steel Formwork Were Placed

36

Fig.6-I Repair method n)r dry condition of honeycomb

F6,1-l shallow hohcycomb

Epoxy coatcd

chippmgare

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HoneycombLining surcc

Repair mortar Sika monotop 615

Fig.6-1-2deeper honeycomb

Honeycomb

Sika monotop615HB

chipping area

Fig.6-2 Repairmethodforwaterleakageconditionofhoneycomb

chippingar/

Fig.6

Leakage water

HoneycombLining surface

condary repair mortar Sika l02 or

Sika monotop 615HB

Primary repair mortar Sika 102

Caukjng or nipple

Method of Repair of honeycomb

37

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I.1

l.2

create solid arca

NATM method

Shotcrete

friction coemcient shall be increased

nrst layer of shotcrete

2nd layer of shotcrete

stee1

Rockbolt

above method concePt is makc one body. with in the rock bolt area and be crcatc solid ea

and so agaillstground rock mass.

concrete lining shan not commenccd while convergent. is continued

shaH be observe ground sinkage ahecrown

38

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J = J -

Presplitting method blasting for smooth sloPe cutting

2

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8)/Z)

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Detail of pre splitting hole

P

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=

QJ-

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splitting line

ajdhojc

0,.Usual blasting h(lc

aidhole

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dctonagcoad

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