Central Con Presa

B. LeistH. EversW. LeechJ. KroyerJune 12, 2007

B. LeistH. EversW. LeechJ. KroyerJune 12, 2007

Kárahnjúkar HEP

Extreme Underground ConstructionKárahnjúkar HEP

Extreme Underground Construction

Project Overview

Design

Construction

Conclusions

Project Overview

− Project location

− Key figures

− Tunnel alignment

Snæ-fell

Eyja-bakkar

12.2003

Jökulsá á DalFjarðaál

Egilsstaðir

Reyðarfjörður

FL 3&42x220 kV

Laga

rfljót

Þrándar-jökull

Mývatn

Jöku

lsáá Fjöllum

Ódáðahraun

Jökuldals-heiði

Krafla60 MW

Bjarnarflag3 MW

Héraðs-flói

Brúar-öræfi

Vestur-öræfi

Askja

Herðu-breið

Krep

pa

Kverkfjöll Hraun

Dyngjujökull

Kröflulína 2132 kV

132 kV

132 kV

Kárahnjúkar HEP690 MW

Kára-hnjúkar

Headracetunnel

Jöku

lsáí F

ljótsd

al

Hálslónreservoir

KárahnjúkarPowerhouse

Kelduárlónreservoir

V A T N A J Ö K U L L G L A C I E R

BrúarjökullGlacier

Ufsarlónreservoir N

Kárahnjúkar HEP800 m a.s.l.

Pressure shaftHeadrace tunnel

Power station26,5

m a.s.l.

625 m a.s.l.Kárahnjúkar dam Longitude section

Mt. Fremri-Kárahnjúkur

Sauðárdalurdam

River Jökulsáá

Dal

Hafrahvammar Canyon

Desjarárdalur

Mt. KverkfjöllVatnajökull glacier

Kárahnjúkardam

Desjará dam

Hálslónreservoir

Installed capacity 690 MWNumber of units 6 (115 MW each)Energy production 4.6 TWhGross head 600 mRated discharge 144 m3/sHeight of Kárahnjúkar dam 200 mHálslón reservoir 57 km²Hálslón storage 2100 GlAll tunnels 73 kmHeadrace tunnel (diameter) 7.2-7.6 mConstruction time 2003-2008

Kárahnjúkar Project in figures

Spillway

Upstream cofferdam

Concrete Slab

Road

Rock protection

Diversion tunnel

Toe WallBottom outlet intake

Access tunnel

Bottom outlet

Kárahnjúkar dam

ca 100 m

Kárahnjúkar Dam Cross Section

Kárahnjúkar Dam Schematic Longitudinal View

Concrete Slab

Upstream cofferdam

Toe Wall

RCC concrete

Material 1

Material 4

Material 5A

Material 5B and 6A

Material 8

Concrete Slab

Toe Wall

Consolidation Grouting

Grout Curtain

Spillway and Tunnels

Jöku

lsáí

Fljót

sdal

Jöku

lsáí

Fljót

sdal

Lagarfljót

TeigsbjargTeigsbjarg

ValþjófsstaðurValþjófsstaður

PenstockPenstock

PowerhouseFljótsdalsstöðPowerhouseFljótsdalsstöð

Adit 1Adit 1

Headracetunnel

Headracetunnel

Tailracetunnel

Tailracetunnel

Tailrace-canal

Tailrace-canal

Surgeshaft

Surgeshaft

Kárahnjúkar HEP Powerhouse area

AdittunnelAdit

tunnel

Kárahnjúkar HEPPowerhouse area

Substation

Tailrace tunnel

Entrance buildingCable tunnel

Access tunnel

Fljótsdalsstöðpowerhouse

Pressure shafts

Transformer hall

Valve chamber (intake)

Jökulsá í Fljótsdal

Tailracecanal

Dam Toe WallJuly 2004

Sept 2004

May 2005

Slipforming of face slab

October 25th 2005

Kárahnjúkar dam

13. July 2006

Kárahnjúkar dam

July 2006

March 28, 2007

Kárahnjúkar dam

January 16nd 2007

Powerhouse

TBM 1TBM 2TBM 3Drill & Blast 1Drill & Blast 2Drill & Blast 3Drill & Blast 4Drill & Blast 5Drill & Blast 6

5 km

10 km

15 km

20 km

25 km

30 km

35 km

Adit 1

Adit 2

Adit 3Adit 4

Power intake

Surge tunnel

Drainagetunnel

Jökulsá diversion tunnelø 7,2 m

Headrace tunnelø 7,6 m


Tunnel alignment

TBM 3

TBM 2TBM 1

Waterways – Scematic Profile

Adit 2 Junction

Design

− Geology

− Excavation classes (D&B and TBM)

− Bore classes

Geology

• Shallow dipping strata(3 to 5°)

• Basalt flows with sediments and móberg formations in between

• Móberg is volcanic rock formed in water or glacical environment

• Faults & dykes at ~200 m spacing

Lithology

• Each basalt lava flow is divided into three parts:– Top scoria (10-30% of the thickness)

– Dense crystalline middle part (65-85% of the thickness) – tholeiitic or olivine

– Bottom scoria (5-10% of the thickness)

• Thin sedimentary layers between lava flow (typically 0,1 to 1m)

Sediment

Lava flow

Sediment

Excavation classes (D&B and TBM)

• Typical cross-sections on Drawings

• Excavation classes based on hindrance to advance

• Determination of excavation class using measurable criteria (i.e. nos. of rockbolts, extent of sprayed concrete)

• Risk associated with geological conditions with Owner

Excavation classes, TBM

Excavation classes, D&B

Bore classes

Scoria/Móberg >90%

H1 H2 H3 M1 M2

Sediments >90% <10% >50%

& <50%

<90%

>10% >50%

Basalt <10% <10% >90% & &

<50% <90%

Homogenous Face Mixed Face

Construction

− Robbins TBM

− Challenges encountered

− Mitigation measures

− Actual progress

− Utilization

Robbins TBMs

7,2 m dia 2 no7,6 m dia 1 noMotors 10Power Each 300 kWMax Thrust 14.305 kNStroke 1,87 mCutterhead speed 0-8,3 rpmCutters 47-49Size 483 mmMax load/cutter 311 kNTBM weight 600 tonCutterhead torque 6.275 kNm at 50 HzGripper load 3500 ton

Challenges encountered

• Red sedimentary layers, HRT 1

• Fault zone, HRT 2

• High water inflow, HRT 3

Fault zone, TBM 2, Headrace Tunnel

Fault #1 Fault #2 Fault #3

Steal arches& shotcrete

43 m

Concretebackfill80 m3

Concretebackfill120 m3

Concretebackfill 600 m3

Consolidation of rock withpolyurethan and cement

Void

CutterHead

Waterinflow

Waterinflow

Fault Zones

Block Size

Closely-Spaced Steel Arches

Steel Laggings with closely-spaced Steel Arches

Fault No.1 Spiling

Fault No.1 (in front of cutterhead)

Concrete Plug (in front of cutterhead)

PU Foam

Post-ExcavationWater Ingress

Post-Excavation Water Ingress

Water ingress

Water inflow

• TBM3 turned around

• Adit 4

• Vertical pump & concrete shafts

• Revised design

• Reschedule finishing works

Mitigation measures

TBM 1TBM 2TBM 3Drill & Blast 1Drill & Blast 2Drill & Blast 3Drill & Blast 4Drill & Blast 5Drill & Blast 6

5 km

10 km

15 km

20 km

25 km

30 km

35 km

Adit 1

Adit 2

Adit 3Adit 4

Power intake

Surge tunnel

Drainagetunnel

Jökulsá diversion tunnelø 7,2 m



Tunnel alignment

TBM 3

TBM 2TBM 1

ADIT 4

Adit 4

Shaft chainage 5204 for pumps

TBM Actual progress

Utilization – TBM 1Between dates: 21.09.2004 - 09.09.2006

Cuttlers = Cutter Change + Cutter CheckTBM = TBM Maintenance + TBM Mech. Breakdown + TBM Elec. BreakdownUtilities = Conveyor Install + Conveyor Repairs + Service ExtensionOther + Cutter Cleaning + Downtime + Other + HolidayProbing Time also includes time for CoringGrouting Activities are under Other

Based on 24 days

BoringRegripSupportCuttersRepair TBMRepair BUSUtilitiesProbingOther

28.4%

0.4%

3.9%5.8%

2.1%

13.2%

6.7%

3.6%

35.8%

43%5%

10%5%7%4%6%9%

11%

TypicalPredicted

values



Based on 24 days


30.8%

1.2%15.1% 4.7%

7.2% 14.9%

2.3%

20.6%43%

5%10%

5%7%4%6%9%

11%

TypicalPredicted

values

3.3%


without 6 months EOT section


Based on 24 days


22.7%

5.5%1.3% 4.0%

19.4%

3.0%4.9%

27.3%43%

5%10%

5%7%4%6%9%

11%

TypicalPredicted

values

11.8%

Utilization – TBM 3 usBetween dates: 02.08.2004 - 07.07.2005


Based on 24 days


29.8%

8.3%

13.8% 2.1%

11.4%

3.0%

1.9%

22.1%43%

5%10%

5%7%4%6%9%

11%

TypicalPredicted

values

7.7%

Utilization – TBM 3 dsBetween dates: 19.12.2005 - 05.11.2006


Based on 24 days


13.1%

7.0%0.7% 5.1%

25.8%

3.4%

14.2%

27.2%43%

5%10%

5%7%4%6%9%

11%

TypicalPredicted

values

3.6%

Cross- Over Station

TBM 3 Break-through 5 Dec. 2006

Best day 92 m

Best week 324 m

Best month 1193 m

TBM Actual progress

April 11, 2007

Conclusions− First use of TBMs in Iceland− TBMs are generally well suited for

Icelandic mixed faced basaltic rock− Challenging ground

−Mixed face− Fault zones−Water ingress

− Conveyors can be effective for long, large diameter tunnel drives

March 28, 2007March 28, 2007

Thank you for your attention!

Central Con Presa

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