iceland hedinsfjordur tunnel 2010 page 22

HEDINSFJORDUR TUNNEL

DECEMBER 2010

WWW.TUNNELSONLINE.INFO

Blasting Iceland’s frozen northWe explore Metrostav’s Hedinsfjordur project

• Olafs Tunnel is 7.1km long

• Siglu Tunnel is 3.9km long

• Up to 800m of overburden

• Water ingress pressures up to 32 bar

• Water temperatures as low as 2oC

• 630 tonnes of PU resin grout used

• Work started in 2006

• Tunnel opened 2 October 2010

DECEMBER 2010 Tunnels & Tunnelling Hedinsfjordur Tunnel 3

welcome

HEDINSFJORDUR TUNNEL

DECEMBER 2010

WWW.TUNNELSONLINE.INFO

• Olafs Tunnel is 7.1km long

• Siglu Tunnel is 3.9km long

• Up to 800m of overburden

• Water ingress pressures up to 32 bar

• Water temperatures as low as 2oC

• 630 tonnes of PU resin grout used

• Work started in 2006

• Tunnel opened 2 October 2010

Blasting Iceland’s frozen northWe explore Metrostav’s Hedinsfjordur project

0

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On the coverMoment of detonation!

Workers make progress onthe Hedinsfjordur project

using drill and blast

contents4 OVERVIEW

Iceland has more road tunnel plans

7 PROJECT NEEDLinking remote communities, improving safety

10 GEOLOGYExtremely varied strata and disturbances to rock

13 PLANNING, DESIGN & PROCUREMENTPreparing for Hedinsfjordur Tunnel Project

15 EXCAVATION: SIGLUFJORDUR TUNNELThe shorter of the project’s two tunnels

19 EXCAVATION: OLAFSFJORDUR TUNNELA tunnelling challenge plagued by groundwater ingress

26 PORTALS & WFP LININGManufacturing-style approaches for harsh weather

29 OPENING & CELEBRATIONA change to life and safety – before the winter snows!

26 4

15 29

4 Tunnels & Tunnelling Hedinsfjordur Tunnel DECEMBER 2010 www.tunnelsonline.info

W ith its complex geology,Iceland presents a range ofchallenges to tunnellers. Thedesire for new passages to

be blasted through mountain ridges comesfrom the country’s small population seekingimproved and safer, transport links over theisland’s rugged terrain. Long and exposedwinding roads snaking up valleys or roundthe steep edges present difficult and time-consuming journeys, especially during thesevere winters and long hours of darkness.

Going underground, therefore, can offerbenefits both locally and, on a cumulativebasis, nationally – even if the traffic volumesare relatively small in general.

The tunnel solutions for the road networkhave come as single tubes of generallyincreasing length over the recent decadessince the late 1940s, culminating in thelongest scheme so far, HedinsfjordurTunnel, which has two tunnels of 11km totallength and was opened to traffic in Octoberby the Icelandic Road Administration(ICERA), or Vegagerdin.

Iceland’s road tunnels, including the twothat form the Hedinsfjordur project –Olafsfjordur and Siglufjordur – are near thecoast and have been excavated by drilland blast, including the first subseacrossing, at Hvalfjordur, which is its onlytoll tunnel, so far. That financing model isbeing considered for the 11th tunnelscheme on the island, Vadlaheidi, nearAkureyri, the main town in the north of thecountry and not so far from the latestaddition, Hedinsfjordur.

Traditional Nordic excavation by drilland blast has dominated the road tunnelmarket in Iceland and while no role hasbeen played as yet by TBMs – unlike theconstruction of hydropower tunnels in

Iceland, which are also more inland andgenerally longer – the possibility is there.At least on one prospective large roadtunnel project being studied, at Mid-Austurland, in east Iceland, which couldsee TBMs involved.

An immersed tube is one of thealternatives for the Sundabraut crossingwithin the capital, Reykjavik, though it issquaring off against a bridge option and arock tunnel in a tough economic climate.

Road tunnels - builtThe 10 tunnel schemes in Iceland rangefrom the shortest, Arnardalshamar, openedin 1948 near Isafjordur in the northwest ofthe country at barely 30m long, to thelongest, Hedinsfjordur. The most recentaddition, though by only a week, theHedinsfjordur scheme consists of twotubes – Olafsfjordur (7,100m long) andSiglufjordur (3,900m).

Most of the bores in the road network,except for two – Oddsskard (640m, openedin 1977) in the east and Straka (800m,1967), near Siglufjordur, are well over 1kmin length and carry two-lanes. Opened in2005, the Almannaskard tunnel in the

HEDINSFJORDUR TUNNEL | ICELANDIC TUNNELS

Iceland is building more roadtunnels, and they are gettinglonger. The most recent andlongest scheme to date, isHedinsfjordur Tunnel, which hastwo single tubes totalling 11km.Built by Metrostav-Hafell JV,the tunnels opened to trafficin October

Road Tunnels in IcelandOshlid

Botnsdalur,Tungudalur

HedinsfjordurStraka

Vadlaheidi

MuliDyrafjordurD fj dArnarfjordur-

Sundabraut

Breididalar,

Nordfjordur

OddsskardMid-Austurland

Vopnafjordur-Herad

LonsheidiAlmannaskard

Faskrudsfjordur

Hvalfjordur

Artic Circle

Built road tunnels

Planned road tunnels

Faskrudsfjordur Tunnel

Hvalfjordur Tunnel

Oshlid Tunnel

Muli Tunnel

Almannaskard Tunnel

Straka Tunnel

Oddsskard Tunnel

Arnardalshamar Tunnel

Double lane Single lane

5,900m

5,770m

5,400m

3,400m

1,300m

800m

640m

30m

Breididalur-Botnsdalur Tunnel 9,160m

Hedinsfjordur Tunnel 11,000m

Botnsdalar 2,907m

Olafsfjordur 7,100m

Breididalur 4,150m

Siglufjordur 3,900m

Tungudalur 2,103m

Above: Location of the key road tunnels built and in planning in Iceland

Left: Ranking of built road tunnels inIceland, the longest being the mostrecently built – Hedinsfjordur TunnelProject, which includes the Olafsfjordurand Siglufjordur tunnels

DECEMBER 2010 Tunnels & Tunnelling Hedinsfjordur Tunnel 5www.tunnelsonline.info

southeast is the shortest double lane tubeat 1,300m long.

However, there are longer single lanetunnels (with regular widened sections forpassing points), such as Muli (3,395m,1991), near Olafsfjordur, and alsoBreididalur (4,150m, 1996) and Botnsdalur(2,900m, 1996) which form two branchesout of three in the near T-junction on amajor northwest scheme.

The other three double-lane road maintunnels in Iceland are Faskrudsfjordur(5,900m including 200m of concreteportals, opened in 2005), the Hvalfjordursubsea tunnel (5,770m, 1998) and theOshlid Tunnel (5,400m), which opened inSeptember 2010.

Oshlid Tunnel was built betweenIsafjordur and Bolungavik in the northwestof the country by a JV of Marti with localfirm Islenskir adalverktakar. Excavation ofthe tunnel – 5,156m of which was in rock –was subcontracted to Slovakian firm Tubau,and 600m of concrete portal was built by alocal firm, Vestfirskir verktakar.

There is also another double-lane tube,which is part of a larger scheme mentionedbefore and is the third tunnel of the three inthe northwest T-junction scheme –Tungudalur (2,100m, 1996).

Road tunnels - PlannedIceland has had a number of potential roadtunnel projects under study for years and isgradually completing them in order, andwhile the weakened national economypresents a challenge for financing atpresent and the near future, the country hasstrategic plans to develop further schemes.

Despite the funding challenges to foreigntravel, for the time being, this strategy

needs the Icelandic tunnellers to stay activeand linked with the peers internationally, todiscuss the experiences and lessons oftunnelling with mainly basalts, tectonicallyactive areas, groundwater problems andrapidly changing sequences of strata.

Hreinn Haraldsson, director general ofVegagerdin and also the current presidentof the Icelandic Tunnelling Society, says:‘We not only want to, but we must continueto be involved in the internationalcommunity because we will construct a lotof tunnels in future.’

Key road tunnel projects in preparation orin studies, for development in the nearfuture, in Iceland, include: Vadlaheidi,Nordfjordur, Arnarfjordur-Dyrafjordur,Sundabraut, Mid-Austurland, and anothertunnel under Hvalfjordur.

In the longer-term, Vegagerdin isexamining road tunnel projects at Lonsheidiand Vopnafjordur-Herad.

Vadlaheidi TunnelVadlaheidi road tunnel is planned to be builtthrough the mountain ridge forming theeast side of the fjord at Akureyri, the maintown of north Iceland. The tunnel isdesigned as a single tube approximately7,800m long. The tunnel is to be 9.5m wideand maximum clearance for vehicles is astandard 4.6m for Iceland.

The scheme was envisaged in 2007 on aBOT model and then the planninganticipated tendering possibly in 2008.However, the project has yet to go ahead

due to the tightened financial climate, of thelast couple of years.

Talks are now underway with pensionfunds about loans to fund the project. Asthe state can’t take the loan, Parliament hasdecided to establish a special purposecompany, 51 per cent held by Vegagerdinand the balance by local interests, toundertake the project. Once the pensionfunds involvement is determined then it willbecome clear if an open call forinternational funding will also be made.

If funding agreement is reached with thepension funds before the end of the yearthen Vegagerdin would expect a pre-qualification call to contractors in early2011 and tendering shortly after for awardaround mid-year and work starting by thethird quarter. The project is expected totake three years to complete.

Vadlaheidi is projected to attract 1200vehicles per day, and traffic is estimated to

ICELANDIC TUNNELS | HEDINSFJORDUR TUNNEL

Right: Hreinn Haraldsson, directorgeneral of Icelandic Road Administration,Vegagerdin, and president of theIcelandic Tunnelling Society

Right and above: The newest road tunnel in Iceland – Hedinsfjordur Tunnel – was builtby Metrostav-Hafell JV and consists of two single tubes, Olafs and Siglu, togethermake the scheme the longest in the country


increase 8 per cent in first year of operationand 3-4 per cent annually afterwards, in theshort-term.

Nordfjordur TunnelIn the east of Iceland, a single tube roadtunnel is being studied in the area betweenEskifjordur and Nordfjordur. Plans in 2007envisaged a 6,200m long tube with a T-8profile and the project going to tender inlate 2009 for award for construction to startin 2010. Geology is basalt with interbeddedsedimentary layers.

Still in planning, the tunnel is nowplanned to be 7,800m long including theconcrete portals, with a width of 8.5m andthe standard 4.6m maximum heightclearance. The project is almost ready totender and bid call is expected in late 2011for construction to start in 2012. However,due to the challenges facing the publicfunding route this three-year project may bepostponed even further.

Arnarfjordur-Dyrafjordur TunnelLocated in northwest Iceland, between thefjords of Arnarfjordur and Dyrafjordur,slightly south of the Oshlid Tunnel and alsothe T-junction of the Breididalur, Botnsdalurand Tungudalur tunnels, this project hasbeen examining different alternatives at

lower and higher altitude. The present planis for a 5,300m long single tube with a T-8profile. Geology is basalt with interbeddedsedimentary layers.

Sundabraut TunnelThe intended project site is the northernpart of Reykjavik but the proposed 4,400mlong, undersea double tube (T-9.5 profiles)scheme is competing against a bridgeoption and an immersed tube in the currentdifficult financial climate. The project is tobe jointly developed by Vegagerdin andcity. The geology in the area is basalt andpalagonite – altered volcanic basaltic glass.

Mid-Austurland TunnelThe project is located in east Iceland andcould involve a series of road tunnelsbetween the town of Egilsstadir and otherson the coast, to the east and southeast.Studies have identified up to 14km oftunnel across the various alternative routesand tube combinations.

Depending on the elevation above sealevel and number of links, there could be asingle tunnel that is 11-14km long, or twotunnels with a combined length of 10-14km, or further alternatives. The schemeenvisages a single tube with possibly anadditional escape tube.

Hvalfjordur - expansionThe subsea toll crossing, which is slightlynorth of Reykjavik and provides a fast linkto Akranes, was conceived as a possiblescheme in the 1960s. Development finallygot underway in the 1990s under a specialpurpose company, Spolur, which haspublic and private interests and wasauthorised by Parliament.

Almost two-thirds – 3,750m – of thetunnel is below the sea bed and at itslowest point the tube is 165m below sealevel. The contractor was a JV of Istak,Skanska and Pihl & Son. Excavation wasdone over 1996-7 and achieved a bestmonthly advance of 517m.

A second, parallel subsea tunnel isbeing examined to meet safetyrequirements in future when trafficvolumes appraoch 10,000 vehicles perday. No decision has been made on thefinancing structure. The tunnel might bebuilt within the next 10 years.

Works at Muli and StrakaThe Muli and Straka tunnels are the originaltunnels in north Iceland that precedeHedinsfjordur Tunnel, and in fact were thecoastal, single tubes – to the south andnorth – that eased access to Olafsfjordurand Siglufjordur, respectively. Increasedtraffic volumes and public demandfollowing the recent opening ofHedinsfjordur Tunnel will determine howmuch of a bottleneck the older, shorter andsmaller tubes may represent and whichalternatives there are to improving trafficcapacity into the area.

Talking TunnelsIn holding the presidency of the NordicRoad Association (NVF) and as amember of the Executive Committeeof PIARC (World Road Association),Haraldsson is intensely involved, as hehas been throughout his career, in thebenefits of constructing and operatingroads in Iceland.

In 2012, Reykjavik will host NVF’s NordicRoad Congress for the first time.

Iceland will benefit from, and continuesto seek and need, good contact with thetunnelling community abroad, he says.

HEDINSFJORDUR TUNNEL | ICELANDIC TUNNELS

Left: Difficult geology andgroundwater ingress were significantaspects of drill and blast constructionof Hedinsfjordur scheme, particularlyon parts of Olafsfjordur Tunnel, whichat 7,150m long (including portals) isalso the longest, single tube,uninterrupted road tunnel in Iceland

Above: Hedinsfjordur Tunnel was opened on 2 October 2010, and links communitiesseparated by long, often impassable roads in winter on the coast of north IcelandPhoto Credit: Stepan Soukup


MEETING NEEDS | HEDINSFJORDUR TUNNEL

Days gone by but within livingmemories and tales oftenrecounted, and celebrated, theremote town of Siglufjordur in

North Iceland was a powerhouse of thenational fishing industry. The town grew andprospered on herring fishing and processing.

Boasting a sheltered harbour near thehead of Siglufjordur valley, the townexpanded where land meets water alongthe lower side slope of a long finger of amountain ridge, part of northernmost areaof the Trollaskagi peninsula. The fjord givesway to tough seas that hold the islandspeck of Grimsey, on the Arctic Circle andmuch farther beyond lies Greenland.

The town, though quite isolated by the

mountains and their plunging, rockycoastal slopes, was for a time during thefirst half of the 20th Century the largestherring centre in Iceland and briefly, somesay, the world. It had expanded rapidlyfrom being a hamlet to housing 23 saltingstations, five reducing factories and morethan 3,100 inhabitants. Exports wereimportant to the town, and the country.Good days, indeed.

But, the herring fishing then shifted focusa little as the waters off the east coastproved bountiful to new technology. Thenmore nations sought the shoals, leading toover-fishing and a collapse in the stocks.Competition and then the fall in herringnumbers were a double-hit to Siglufjordur.

The population of the town has reduced bymore than half since its peak, but there isstill fishing activity and also supportservices are being increasingly developedto support the wider region.

In more recent decades a number oflocal people in generations coming up havemoved to work elsewhere in Iceland,notably Akureyri and Reykjavik, and a fewmuch farther afield, but many returningwhen possible to the bonds of family andfriends. The town, like its neighbours – suchas is Olafsfjordur – still offers vibrantcommunity life.

Olasfsfjordur lies to the south east,separated by two mountain ridges and anuninhabited fjord – Hedinsfjordur. In the past,the town also benefited from the herringindustry though its population is now lessthan 1,000.

A proud community in its own right,Olafsfjordur has always has been the smallerof the two towns. Historically, they reliedmainly on boats, ships and horses fortransport before motor vehicles helped tonegotiate the coastal and mountain trailsbetween the towns and other neighbours,and to travel farther beyond.

0 5 10km

Siglufjordur

Olafsfjordur

Siglufjordur

Hedinsfjo

rdur

Olafsfjord

ur

8.5km

6.2m

3.1m

jMuli Tunnel

3.4km

Straka Tunnel800m

3.5km

4.7km

4.0km

75

7682

83

35

37

17

10

18

34

43

14

25 Siglufjordur

Olafsfjordur

DalvikGrenivik

Akureyri

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25 gl rdurSiglufjor

afsfjorddurOla

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Hofsos

audarkrokkurkrokSaS ku

A two-tunnel solutionwas chosen toovercome the coastalmountain barriers ofNorth Iceland toconnect the remote,former fishing hub ofSiglufjordur withneighbouringOlafsfjordur andbeyond

Ties thatbind

Above: Three alternative routes were studiedto link the towns of Olafsfjordur andSiglufjordur. The most direct route, havingalso the lowest elevation, was chosen

Left: Hedinsfjordur Tunnel project willhelp overcome the restrictions to travelfor the towns of Siglufjordur andOlafsfjordur due to the severe winterweather in near-Arctic region of NorthIceland


HEDINSFJORDUR TUNNEL | MEETING NEEDS

Tunnels arriveEfforts to improve access to Siglufjordurresulted in this corner of Iceland claimingthe country’s first reasonably long roadtunnel, Straka (the actual first road tunnelis only 30m long, at Arnardalshamar). TheStraka Tunnel was opened in 1967 andprovides an 800m long, single bore link(with emergency bays) out of Siglufjordurto the north.

The second road tunnel in the area was asingle tube bored to link to Olafsfjordur to

the south. This 3,400m long long tube,Muli, was opened in 1991 and gave rapidand direct access to other towns to thesouth, such as Dalvik but especiallyAkureyri, the principal community in NorthIceland. The portals were built big enoughfor the tunnel to be widened in future.

Now, this part of the country can alsoclaim Iceland’s longest road tunnel scheme– Hedinsfjordur Tunnel – which pierces thetwo mountain ridges between Siglufjordurand Olafsfjordur and is named after the

fjord between the natural walls.Hedinsfjordur Tunnel was opened inOctober 2010 and has two single tubes,one through each mountain ridge.

The latest addition to this cluster of roadtunnels was built to help improve links aswell as safety, the economy and the socialbond between the communities. Four yearsago, in anticipation of the coming closercontact and ties from Hedinsfjordur Tunnel,the towns voted to join their municipalitiesunder a new banner, Fjyallabyggd.

Alternative routes for tunnels to helpimprove road links between the towns werestudied, but the scheme selected providesthe shortest as well as the lowest altitude –and so least troubled by winter weather.

Direct, all-weather driving is nowpossible from Akureyri to Siglufjordur, andHedinsfjordur Tunnel is already proving tobe very popular, notes the Icelandic RoadAdministration, Vegagerdin.

It may not be long until the traffic capacitiesof the Muli and Straka tunnels needaddressing, leading to either expansions orpotentially fresh debates on how and whereto improve links to the south.

Above: Siglufjordur once was a major fisheries town and the new tunnel link will helpboost mobility and contact both from and to its remote fjord location

Above: Looking north in Hedinsfjordur, the peaceful valley between the tunnelswhich locked by the two mountain ranges separating the small towns ofSiglufjordur and Olafsfjordur

Icelandic Road Administration –www.vegagerdin.is

Community websites -www.siglufjordur.is, www.olafsfjordur.is,www.fjallabyggd.is and information (inclwebcams) www.sksigli.is

Herring Era Museum – www.sild.is

References

www.miningandconstruction.sandvik.com

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HEDINSFJORDUR TUNNEL | GEOLOGY

S parsely populated Iceland sitson the northern run of the Mid-Atlantic Ridge where theEurasian and North American

tectonic plates are moving apart to befilled with extrusive igneous rocks.However, not all of the country isexperiencing rifting and volcanism; theactive zone runs diagonally through theland, cutting from the southwest to thenortheast. This spine of the island isflanked by gently dipping basalts.

The Icelandic bedrock is dominated bysubaerial basalts (100MPa-300MPa) butthey are commonly faulted. The dominantfeatures of the bedrock are the relativelythin layers of the basalt succession ofporphyritic, tholeitic and olivine rocks, andthe gentle dip of the strata.

The top and bottom of each lava layerare composed of fragments, resulting inthe formation of porous breccia – scoria –which is usually well consolidated inTertiary bedrock. The upper zone of alayer often has sedimentary deposits.Below, in the body of the solidified lava

layer the rock usually has irregularcolumnar joints.

Most faults are sub-vertical and longthese zones there is usually breccia ofsheared and crushed rock that is well-cemented with the bedrock. There are alsofrequently basaltic dyke intrusions withhorizontal jointing patterns.

Groundwater typically runs along thelava contacts and cooling joints but theprime conduits are the faults and dykesthrough the layers, including sedimentaryinterbeds acting as impervious or semi-impervious barriers.

Groundwater ChallengeMany road tunnel excavations in Icelandhave met fairly reasonable conditions butthere have been occasions of difficultgroundwater inflows, such at a basalticdyke during excavation near the junctionfor Breidadalsheidi-Botnsheidi plateauscheme in the northwest of the country, onthe Muli tunnel works in the north andmost recently on the Hedinsfjordur Tunnelin the same vicinity.

Constructed in the mid-1990s, theBreidadalsheidi-Botnsheidi schemecomprises three branch tunnels –Breididalur, Botnsdalur and Tungudalur.Earlier tunnelling experience indicated theremight be considerable but scattered inflows(up to 50 l/s per km). On the 2.9km longBotnsdalur drive the inflows increasedsignificantly when excavation was 450mfrom the T-junction of the three tunnels –pressures began at 6-12 bar and eventuallyreached 19 bar; open joints were up to10cm wide and connected, which resultedin little success with cement grouting – usedfor the first time in Iceland. Competent rock,relief boreholes and resumed excavationeventually helped take the drive forward.

However, on the 4.1km, long Breididalurdrive, some 800m from the T-junction – andwhile anticipating major faults but despiteusing long probeholes – the right side of thetunnel unexpectedly collapsed on the uphilldrive. The cold inflows from the crown wereinitially 2,500-3,000 litres per second butreduced to almost half the rate in a fewweeks. The drive was halted and work

Iceland’s complex geology canprovide for markedly varied tunnellingconditions and sometimesgroundwater problems, such asfaced on some earlier road tunnelsand also more recently at OlafsfjordurTunnel on the Hedinsfjordur project

Geologicalchallenge

1000900800700600500400300200100

07000 7500 8000 8500 9000 9500 10000 10500 11000 11500 12000 22500 13000 13500 13800

m.a.s.l.NW SE SE

Hedinsf Jordur

VatnsendahnJukur Pverf Jall

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Osbrekkuf Jall

Olafsf Jordur

Cross faults

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Water

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100001000

1005010

27 bar 32 bar28 bar

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02200 2500 3000 3500 4000 4500 5000 5500 6000Cross faults

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Tertiery rockPorphyritic basalt formationTholeitic basalt formationOlivine basalt formationDykesSillsMain weakness zonesFaultsTunnel routeSigns of high stress


GEOLOGY | HEDINSFJORDUR TUNNEL

focused elsewhere on the project.Eventually, an extensive combination ofbolting and shotcrete support, drainageholes and channels, and grouting –including the use of chemical grout withpolyurethane (PU), enabled the section tobe passed. But the flow, while reducedsignificantly, has never stopped. Instead, itwas piped to become a replacementspring-fed water supply for the town ofIsafjordur, and is also now used for smallhydropower generation.

A key lesson drawn from the project isthat post-grouting with cement mix is verydifficult, if not impossible, in hightransmissivity basalts.

Groundwater atedinsfjordur TunnelTrollaskagi mountain range in the north ofIceland is formed by a complex of basic tointermediary rock types with sedimentaryinterbeds. The volcanic complex is of alower Tertiary age, when short periodicallava eruptions alternated with short periodsof volcano clastics sedimentation.

In the late 1980s, road tunnelling worksin the area also experienced somegroundwater problems, on part of the3.4km long Muli project, near the smalltown of Olasfjordur. While the problemswere somewhat similar to those later meton the Breidadalsheidi-Botnsheidi schemethe challenge of the inflow rates andpressures were not so great.

But the challenge of high inflows andpressures was met again in the region, onthe recently-built tunnel at the other side ofthe Olafsfjordur valley – the almost 7km

long tube, called Olafsfjordur (‘Olafs’)Tunnel, that is part of the HedinsfjordurTunnel scheme.

Olafs and its sister tunnel, Siglufjordur(‘Siglu’), pass through mainly olivine basaltexcept for a relatively short section ofporphyritic rock close to one end of Siglu.Along their alignments, the rocks are sub-horizontally bedded, disturbed by north-south trending tectonic faulting. As per thegeneral context of bedrock in Iceland,along their alignments the rock massholds many faults, dykes and joints. Thesemade for often difficult – and sometimesexceedingly tough – tunnelling work insome sections.

The overburden height varies between 5-800m. Some rock bursting was anticipatedalong stretches of high overburden.Spalling occurred where the overburdenwas more than 500m, though began inSiglu with a depth of around 400m. Thelayered basalt lava succession in thetunnels with thin scoria and sedimentaryinterbeds resulted in mixed face conditionsfor a large proportion of the excavation.

While olivine basalt with sub-horizontalbedding is dominant in Siglu (with changingporosity and transfer to fine-grained facia)the tunnel has faults of 1-5m thickness.Groundwater conditions were easier andthe temperature not as cold on Olafs butthe challenge arose on the downhill driveand some cement grouting was done andoccasionally some PU pre-grouting.

Geology along Olafs is mostly fine-to-medium grained basalts and partiallyvolcano clastics, and there were someinterbedded, nearly horizontal fine-grained

tuff layers. The main joint sets are eitherperpendicular or parallel to the axis, but dipsteeply. In many places the rock is heavilybroken due to tectonics. The tunnelencountered many dykes but more brittleand broken than Siglu.

While the possibility existed for thermalinflows, and there was monitoring to assessany effects on geothermal water sourcesnear some portals, in the event it wasinflows of cold water that were encounteredstarting about 1km into the uphill drive fromOlafsfjordur and continuing for a further3.5km. In all, almost two-thirds of Olafs hadgroundwater problems.

Oshlid TunnelJust to show the variation in tunnellingexperience in the complex geology ofIceland, relatively little water problems weremet in construction of the 5.4km longmined section of Oshlid Tunnel (nearBreidadalsheidi-Botnsheidi scheme).

The Oshlid tunnelling works did, however,experience some rock stability difficulties insections where there were thicksedimentary layers between basalt layers.

Future challenges - VadlaheidiTunnelTo be constructed through the mountaineast of Akureyri, the 7.8-8km longVadlaheidi road tunnel is to be a singletube toll route.

If funding is agreed before the end of theyear, Vegagerdin anticipates aprequalification call to contractors in 2011.

Geology along the tunnel alignment isbasalt with interbedded sedimentary layers,and expected to be reasonably similar tothat of Hedinsfjordur. Medium quality rock,in general, is expected with groundwaterproblems expected in some locations. Theoverburden is up to 450m.

Further core drilling is underway – 600min total - in vertical and inclined bores -which follows earlier site investigation(2005) that performed 915m plus 200m ofpercussion drilling. Most of the core drillingis near the portals, others are further up inthe mountain.

Icelandic Rock Tunnelling Quality, byHardarson, B.A.

Harnessing the Catastrophic Flood (re:Isafjordur projects, Iceland), 1996; byHardarson, B.A. and Haraldsson, H.

References

Left: Cold, high-pressure water wasfrequently encountered during tunnelling


planning and design process for thescheme took about 12 years.

Vegagerdin was assisted in the processby Icelandic design companies Mannvit,Verkis, Raftakn, VerkfraedistofaNordurlands and Teikn. The geologicalconsultant was Jardfraedistofan Reykjavik,and construction supervision was providedby GeoTek.

The tunnels broadly run northwest tosoutheast and their horizontal alignmentsare almost in a straight line apart from beingoffset slightly where they break out into theopen to cross Hedinsfjordur valley. In termsof the vertical alignment, the roads slopesinto and out of the valley at 3 per cent andthe remainder of each tunnel drop from itscrest at 1 per cent towards the towns.

Chainage along the alignment ismeasured from the northwest, Siglufjordurend where the new road connects with theexisting. The route rises on rockfill acrossFjardara valley at the head of Siglufjordurfjord into Skutudalur valley on the approachto Chainage 2.275km and the 125m longportal structure, constructed in open cut. Inthe mined tunnel the road continues to rise,at 1 per cent slope, to crest at Chainage4.025km and fall off at 3 per cent towardsHedinsfjordur valley. The tunnel is namedafter the nearest town – Siglufjordur.

The alignment cross the valley on arockfill embankment and crosses a riverwith a 14m long reinforced concrete singlespan bridge. From there it weaves uptowards the next portal, and tunnel –Olafsfjordur (‘Olafs’) Tunnel – at Chainage6.775km. It rises at 1.39% slope to crest atChainage 8.9km. After this point it fallsaway towards the town of Olafsfjordur,exiting the portal at Chainage 13.925kmand tying in to the existing road atChainage 14.1km.

Hedinsfjordur Tunnel is a two-lane tube(one lane of traffic in either direction) witha cross sectional area of 52.83m2 andclearance of Norwegian profile T 8.5. Atregular intervals of around 500m along thetunnels there are widened sections,referred to and equipped as EmergencyBays. In Siglu Tunnel there are six baysand 13 along Olafs Tunnel, and they havea cross sectional area of 75.25m2. Threeof the bays are extra wide to be largeturning areas.

The excavation would be undertaken bydrill and blast method and guidance onsupport was for use of shotcrete andvarying concentrations of rockbolts, asrequired. Iceland has a minimal, lighter

Hedinsfjordur Tunnel – Key StatisticsSiglufjordur Olafsfjordur

Tunnel Tunnel

Total length 3875m 7150m

Mined Section

Mined section length 3650m 6925m

Mined cross section (T 8.5) 52.83m2 52.83m2

Mined cross section at widening 75.25m2 75.25m2

No. of widenings 6 13

Mined section volume 200,000m3 380,000m3

Portals

Open cut (west portal) 125m 150m

Open cut (east portal) 100m 75m

* Note: Hedinsfjordur Tunnel has two single bores – Siglufjordur Tunnel andOlafsfjordur Tunnel

Below: Metrostav divisional director Vaclav Soukup andVegagerdin director general Hreinn Haraldsson at openingPhoto credit: Stepan Soukup

Above: GeoTek’s Bjorn A Hardarson and Oddur Sigurdsson provided the technicaland contract supervision services for the client, Vegagerdin

Right: Jon Magnusson, clientrepresentative to the Hedinsfjordur project

DESIGN | HEDINSFJORDUR TUNNEL


approach to support along the Nordictunnelling lines, explains Bjorn A.Hardarson of Icelandic consultant GeoTek,which provided technical and contractsupervision services to the client – akin to aResident Engineer, monitoring but alsoadvising on permanent support in thetunnels. He has extensive experience onroad and hydro tunnels in Iceland. Whilewryly emphasising that the approach is notto build heavily reinforced pipes as tunnels,he notes that there has been a gradualincrease in support.

Waterproof and frost protection (WFP)lining protection was to be installed,positioned proud of the rock withpositioning bolts and leaving a water drip-zone gap. A thin layer of shotcrete wouldcomplete the permanent lining.

Procurement and constructionProcurement for the construction contractgot underway in 2005 but it wasn’t the firsttime. Four years earlier the project hadbeen put out to tender in the EU zone andin 2003 the bids were opened. However,the Government postponed theconstruction phase of the scheme.

A prequalification process began in 2005.Tenders were issued early the followingyear. Five bids were received and wereopened in March 2006.

A joint venture of Czech contractorMetrostav and local firm Hafell submittedthe lowest tender and a contract for theconstruction works was signed with themin May 2006. The contract value was ISK5.74bn (USD 91.53M in 2006 exchangerates). The next nearest was ISK 5.85bnand the others were more than ISK 6.1bn –the highest being almost ISK 9bn.

The contract is on a conventional unitprice basis with the client responsible forquantities, ground conditions, key changesand standard Icelandic contract conditionsfor civil engineering projects. The technicalspecification and all contract documentswere written in Icelandic since 2003 whenthe country moved away from FIDICcontract conditions.

Works started in June 2006 withMetrostav undertaking the undergroundworks and Hafell the surface works,including open cut of the portal areas inpreparations for excavation.

In total, the new route would add adirect route of just over 14km to the roadnetwork and link Siglufjordur andOlafsfjordur but until then the contractorhad to face the circuitous journey betweenthe towns like the locals – the shortest triparound the coastal and mountain valleyscovering 62km in good weather but withharsh winter conditions the trip each waywould stretch to 260km. As aconsequence, the constructions campsset up near the portals were quiteindependent, and the constructionsupervisor operated in a similar fashionwith two offices.

It would turn out that such commutingwould be the lesser of their challenges. Verydifficult ground conditions with large, highpressure inflows in Olafs Tunnel led tosetbacks and tunnelling challenges whichcame to be understandable to allconcerned as creating delay against theoriginal programme to complete the entireproject by late 2009. The groundwaterproblems were eventually overcomethrough persistence and extra applicationof expensive chemical grout. The

tunnellers’ tenacity brought recognition toMetrostav, from the client and constructionsupervisor and the communities.

Hardarson notes that the inflows caused‘huge work’ and was the prime challengeamong others that included high-pressure,low water temperatures and achievinggrouting solutions in the jointed rock. Whileaspects of these conditions have beenseen in some other road tunnels, he saysthese were ‘difficult conditions’.

A further challenge came from outsideduring the contract period, however, whenthe economy of Iceland and its currencysuffered their own tectonic shocks, hittingthe exchange rates.

Local engineering nous was key to afresh approach on the WFP lininginstallation, including positioning bolts. Theworks were undertaken by local firm VKContractors – their staff also worked on theconcrete tunnel portal construction using itsown, custom-made travelling formwork.The name behind the technical preparationand innovations is Helgi Valur Einarsson,managing director of VK. Hafell completedthe drainage and road surfacing worksthrough the tunnels.

Construction was completed inSeptember 2010, and Hedinsfjordur Tunnelwas officially opened on 2 October.

HEDINSFJORDUR TUNNEL | DESIGN

Vegagerdin – www.vegagerdin.is

Metrostav – www.metrostav.cz

Hafell – www.hafell.is

VK Contractors – www.vkc.is

GeoTek – www.geotek.is

References

Above: Ermin Stehlik (right), Metrostav’s project manager for Hedinsfjordur Tunnel

Above: Johann Gunar Stefansson,general manager of Hafell, which jointventured with Metrostav on theHedinsfjordur project, being interviewedby local media at opening


Then, in Hedinsfjordur valley, the activitywould be joined by a carefully landed fromthe sea construction plant for the cross-valley earthworks that would provide theroute up to the new portal opening on theopposite mountai range. Then, Siglu’stunnellers would commence blasting atOlafs, driving from the opposite direction tothat already underway.

Starting at SigluBlasting of Siglu tunnel began inSeptember 2006 at Chainage 2.400kmalong the new route from the existing roadnear Siglufjordur. The open cut had beenmade behind where, at Chainage 2.275m,would later be built a 125m long concreteportal. The drive was to advance on anuphill slope of 1 per cent for approximately1.6km to crest, and then the excavationprogress down on a 3 per cent slope forapproximately 2km, to breakthrough atHedinsfjordur valley.

Excavation started well. The drivepassed a geothermal area that Siglufjordurdraws hot water from without causing anyknown disruption to the flow.

Geology along the alignment comprised

olivine basalt for the majority with someporphyritic basalt towards Hedinsfjordurand the final, downhill stages of theexcavation. There were regular, and somelarge, sub-vertical dykes along the majorityof the alignment, and faults.

Both the dykes and the faults were foundto be more concentrated after about 700minto the drive. The faults were particularlyintense around chainage 3.3km, wherethere were longitudinal failures and the firstgroundwater inflows of note began. Beyondthat zone the flows stopped, arising onlyalong relatively short sections at furtherfaults at the middle of the tunnel.

Three-quarters along, though, there weresome more longitudinal failures of the rock,again caused by sub-horizontal faults andmore inflows began. It was approachingthis portion of the drive that the firstgrouting was needed – in three sections,apart from some needed closer to the end.Overall, Siglu had proved to be areasonable tunnel to drive by the timeMetrostav holed through to Hedinsfjordur inMarch 2008, only to catch a surreal sight:from underground the tunnellers were lookingout at a green play of faint, wavy bands oflight in the sky – the Northern Lights.

‘Pretty good’ tunnellingThe relative ease of tunnelling in Siglu gaveno hint of the massive geologicalchallenges that would be met in Olafs.However, Iceland is known for its radicalvariability in geology, some road tunnelshave large groundwater problems whileothers let tunnellers drive forward, possiblywith some wetness or stability issues.Difficult to predict, although surface featuressuch as dykes slanting up from the depthscan give some potential insights, thoughnothing definite.

While Olafs would add its name to theannals of Icelandic tunnelling difficulties, itwas Siglu – which was ‘relatively prettygood’, says Ermin Stehlik, project managerwith Metrostav – that was to be the betterrun underground, giving no warning of whatlay deep in the hillside of the other valley.Even what groundwater there was in Siglu,at between 10 and 20 degrees C, wasn’t ascold as that to be encountered in high-pressure jets in Olafs.

Yet, it was fortunate, too, that as the faceadvanced ever closer to Hedinsfjordur andto the mountains that were to be blastedthrough for Olafs, there was not a generalrise in significant groundwater problems;not something to be easily faced in adownhill drive. But there was some inflow,which was dealt with by a system ofprovisional sumps with automatic pumps.

Two grouting solutions were used tostem water inflows. A total of 460 tonnes ofcement grout was used for pre-grouting onmost inflows using Atlas Copco’s UniGroutE 45 two x 100 pump. In rare cases, whenthe water remained close to the facedespite the regular probe hole drilling,polyurethane (PU) resin pre-grouting had tobe used. In total, the downhill stretch calledfor 40 tonnes of PU chemical grout.

In a few instances where there were largeinflows of groundwater from probe holesthe situation did become critical, requiringthe Sandvik Axera T11-315TCAD drill rig tobe removed from the face. Overall, thesewere exceptional. The advance ratesachieved in these occasional wetconditions were admirable, says Metrostav.

The biggest problem encountered in thedownhill section were caused by watershooting out of fissures after blasting and attimes excavation had to be suspended andthe fissures sealed. It was a difficultoperation using PU-soaked rags driven intothe fissures by wooden wedges or bunchedinside ‘cushions’ locked into the rock bybolted steel sheet plates over wider openings.

HEDINSFJORDUR TUNNEL | SIGLU TUNNEL

The best monthly advance on the 3,650mlong, mined section of Siglu was 302m

The average progress rate onSiglu in 20 calendar months

was 200m, allowing forplanned stoppages

Left: There were some groundwaterproblems for Siglu but nothing like on itssister project, Olafsfjordur (‘Olafs’) Tunnel


When fissures were successfully sealed,a borehole would be drilled close to thesource of the now-blocked flow, then ahydraulically expanded packer would beinserted. The packer would help to fill thefissure in the face area with a PU material,waterproofing the rock wall to enablelonger boreholes to be drilled fartherahead for cement pre-grouting. Theapproach prevented free-flow and loss ofthe cement suspension.

TunnellingThe excavation sequence usually involveddrilling two 51mm diameter probe holes inthe range of 25-32m beyond the face,ensuring a 6m overlap between eachinvestigation into the rock ahead. Based onvolume, pressure and temperature of thegroundwater in the probe holes there wouldbe a joint decision by Metrostav and theclient’s technical and contract supervisionservices engineer, from GeoTek – ‘TheSupervision’ - on whether grouting wouldbe required before proceeding.

A Sandvik Axera T11- 315TCAD drill rigwas used for both drilling the probe holesas well as the face pattern of 48mmdiameter blast holes. TCAD is a semi-automatic system using a softwareprogram to measure the position and thedirection of a drill bit using laser to correlatethe drilling pattern and boom positions withthe tunnel alignment coordinates. Theboom is then moved by the operator toensure the drill pattern remains accurate.

In both Siglu and Olafs the rounds wereusually drilled to the full length of 5.27m,giving a pull of between 4.7-5m. The roundlengths were reduced to 3m when moredifficult ground conditions were met.

Blast holes were usually packed withTitan 7000 blast emulsion – now renamedCivec – supplied by Orica Mining Services.A Mini Site Sensitized Emulsion (SSE)pumping unit completed the charging afterbeing transported to the tunnel face by asmall truck. The Mini SSE system meantthe emulsion could be pumped into twoholes at the same time. It also allowed theoperator to change the charge according tothe type of blast hole.

The emulsion proved effective forblasting in hard and brittle rock but whenmore porous patches were met the crewused classic explosives. In some cases acombination of both types of explosiveswas employed. The 25g Nobel Primedetonator amplifiers were chosen asboosters and inserted into the blast holestogether with non-electric detonatorsduring the emulsion pumping.

Mucking out was done by Komatsu

SIGLU TUNNEL | HEDINSFJORDUR TUNNEL

At times extra measures were requiredto stem ingress, such as plates to lock in

chemical resin soaked rags in fissures

Loading and mucking out worked well


dumpers, mostly with 35 tonne capacity,which were rented from local companyKraftvelar. Spoil was removed to temporaryand permanent dumping sites locatedclose to the portals, while suitable materialwas put in a crusher for rock fill to await thelater road works. The dumpers were loadedby Broyt C600Ws with 3.4m3 shovels. As aback-up, Volvo 180E wheel loaders wereavailable onsite.

Successful completionThe drill and blast work in Siglu progressedwith relatively few difficulties. Like on Olafs,the site personnel and crews – those incharge, the foremen, the miners were allCzech and lived in the adjacent town,Siglufjordur. They worked two 12-hourshifts on a six-day week. Catering wasprovided on site The week ran fromMonday morning to Sunday morning.

In almost 20 months of tunnelling theyhad achieved an average monthly advancerate of 200m. The record month on Sigluwas 302m.

HEDINSFJORDUR TUNNEL | SIGLU TUNNEL

Client’s Representative – SigurdurOddson and then Jon Magnusson

Supervision (GeoTek) – Bjorn AHardarson, Oddur Sigurdsson

METROSTAV

Project Director/Manager – Ermin Stehlik;started as Consultant in September 2006,then became Project Director in October2007; initial phase PMwas David Cyron

Deputy PM, Economist - Ales Richter

Purchase and logistic - Josef Malknecht

Quality - Jan Merenda

Site manager - Stanislav Novotny; IvanPirsc (during completion phase was alsosite manager for Olafs)

Assistant - Stefan Ivor

Surveyor - Stefan Orban

Underground Staff:

Foremen: David Albrecht, Ivan And� l,Matej Soltes

Gang leaders: Petr Schon, Petr Rudlof,Vaclav Fiala

Mechanical:

Jan Frankovic, Libor Sykora, LadislavRusinak and Kristinn S “Kiddi” Gylfson

HAFELL

Project Management: They were,consecutively, Magnus Jonsson,Gudmundur Bjornson and ValgeirBergmann

Key Personnel – Siglufjordur (‘Siglu’) Tunnel

Above: A well earned celebration at Siglu on holing through, in March 2008, toHedinsfjordur valley between the tunnels under construction


T he excavation of Olafsfjordur(‘Olafs’) Tunnel in theHedinsfjordur road project, innorth Iceland, is a story about

water. Lots of water – cold, often at highinflow rates and high pressures. Drivingthrough basalt with sedimentary inter-beds,the inflows mainly came through jointeddykes and fault zones scattered andclustered along the alignment.

Yet it hasn’t been the highestgroundwater inflow experienced in a roadtunnel excavation in Iceland. That was onthe Breidadalsheidi-Botnsheidi scheme inthe north west of the country in the mid-1990s and it is still flowing. The engineersestablished a work-round as a permanentsolution that channels off the water, forindustrial and water supply use, andenabled the project to complete.

But those Metrostav tunnellers whoconstructed Olafs, while not experiencing

rates as high, can claim to the largestinflow that has been effectively stoppedduring construction of a road tunnel inIceland. Hence, the recounting of thetunnelling experience at Olafs is also astory about grout, lots of grout – cement,of course, but especially chemical resinwhich, unusually, would turn out to beneeded in large volumes.

GeologyThe geology of the mountain range throughwhich Olafs passes comprises sub-horizontal basalts, mostly fine-to-mediumgrained, with porphyritic over tholeite andthe olivine formations – the tunnelalignment passing entirely through thelatter, except for some volcano clasticsediments, such as scoria and redsandstone. In addition, within the basaltformations there are some interbedded,near horizontal layers of fine-grained tuff.

The main joint sets are eitherperpendicular or parallel to the tunnelaxis, but are steeply dipping. In manyplaces the rock is heavily broken due totectonics. The tunnel encountered manybroken, brittle dykes.

There are geothermal water sources onthe portal areas nearest each town, andthere was the possibility for thermalinflows. But it was the opposite that wasthe problem – cold water which, in theworst zone, was believed to be linkedthrough fairly open joint channels up to theground surface with the resulting pressure,flow and chill. The danger in Olafs wasthat heavy inflows could reduce thenatural water pressure which is utilised forhot water supply.

The surface terrain has three mountainpeaks – Osbrekkufjall and the two highest,Pverfjall and Vatnsendahnjukur – with twovalleys in between, the largest beingSydrardalur and also the lowest in elevationand holding the Sydra stream. It was thisstream that, it is believed, is possibly linkedby open joints to the strata at depth andconsequently charged some of the inflowsto the tunnel excavation.

OLAFS TUNNEL | HEDINSFJORDUR TUNNEL

Excavating Olafs

Driving the Olafs Tunnel was the longer and the tougherchallenge by far of the two road tubes on the Hedinsfjordurproject, the main cause being groundwater


However, while indicative informationwas obtained from surface studies it wasnot clear from those examinations and thelimited core boreholes what was the nature,extent or detail of disruptions to the rockmass at depth. The overburden on thetunnel alignment at Olafs was up to 800m.

In all, almost two-thirds of Olafs hadgroundwater problems. Geologicalmapping of the features encountered wasdone by Mestrostav by Prague-basedArcadis Geotechnika, its geologist beingpermanently onsite.

The final geological section, afterconstruction, shows the highestconcentration of faults in the southeast, orearly excavated half, of the tunnelalignment. Over this stretch there are manydykes, too, especially below Sydrardalur

valley and then in the north west third of thetunnel, commencing below, and being mostconcentrated at, the other valley, betweenthe two highest peaks and whereoverburden is most.

Getting underwayIn mid-2006, Metrostav began assemblingthe team of 90 Metrostav workers (70specialised, 20 engineers) in preparationto be based in remote North Iceland tobuild the Olafs and Siglufjordur (‘Siglu’)tunnels for the Hedinsfjordur road project.The company thought it might bereasonably possible (and was somewhathopeful) that with its effectiveorganisational skills and extensiveconstruction experience it would be ableto complete the works programme,

scheduled to take just over three years, alittle earlier.

But the unexpected ground conditionswith cold inflows at Olafs would prove to beof such scale and occur over suchprotracted distances, that the contractor’sinitial goal would not prove to beachievable. The tunnelling difficulties beingexperienced were examined by the client –the Icelandic Road Administration(Vegagerdin) – and its contract andtechnical services supervisor, consultantGeoTek.

Once the nature and scope of theproblem had been established, it wasagreed to be outside the contractor’saccepted and competent approach, as theclient carried the geological risk as withother road tunnels in this land of variableand tectonically disrupted geology, theunit-price contract meant that thechallenge, and focus, was to find the bestengineering solutions.

As with practice on each blast along thedrive on Olafs and Siglu tunnels, therewould be discussion between Metrostav’sengineers and the supervisor to determinethe agreed nature of the ground conditionsand problems at specific chainages, thepotential solutions to try or step-up to next,and also the degree of permanent liningsupport required.

The ‘Scandinavian Method’ of tunnellingwas used, the design and specificationsbased on Norwegian practice was tomaximise installation of permanent supportduring the first pass of the excavationphase, while those support measures arethemselves to be minimum in relation to thelength of round, slightly over 5m. Therewere two support phases, first the initialsupport during excavation and then thepermanent after breakthrough. Primary andlater secondary layers of steel-fibreshotcrete, each 50mm-80mm in thickness,were applied. Permanent bolting used SNand CT bolts.

As the works advanced, and varioussolutions were tried and implemented, therewas growing recognition and admiration

HEDINSFJORDUR TUNNEL | OLAFS TUNNEL

Left: Olafsfjordur (‘Olafs’) Tunnel on theHedinsfjordur road project, in northIceland, called for almost 7km of minedtunnel to be blasted through a mountainrange with basalts and sedimentaryinter-beds that turned out to have manyjointed dykes and faults

Left: Groundwater problems quicklyarose in Olafs, just over 1km into the firstdrive and then didn’t let up for another3km. Soon chemical grout was required


from the experienced Icelandic tunnelengineers for the dedication andsteadfastness of Metrostav – the sheerpersistence of the company itself and thehard work of its engineers to ensure, andsecure, the delivery of Olafs, and so theHedinsfjordur project. For conditions wererelatively easier on Siglu. The shorter tunnelwas not throwing up such extremegroundwater conditions as beingrepeatedly met in Olafs.

There was a concern, however. When theSiglu drive crested on its vertical alignmentand then began blasting the downhill slopeto advance closer towards Olafs, - albeitseparated by a valley – might groundwaterproblems appear then? Fortunately, in theend, Siglu was completed without suchmajor difficulties arising although in its laststages there were some inflows, resultingfrom dykes and faults.

The first hurdlesExcavation started in November 2006 onthe almost 7km long mined length of Olafs.The drive would be approximately 5km

uphill from the portal at Olafsfjordur. But itwas not too long – approximately 800minto the drive that the first notablegroundwater difficulty was encountered.Then, within a further 160m the ingress hadreached more than 2000 litres per minute orapproximately 33 litres per second,pressures were 10-15 bar and the watertemperature was as low as 2-3 degrees C.

At this point there were no faults and thefirst mountain peak and valley hadn’t yetbeen reached overhead; dykes were the

problem. The contract provides for thepossibility of pre-grouting to help seal offleaks using cementitious or chemicalmethods with Metrostav and the supervisorhaving jointly assessed inflow from a pair ofprobe holes. The threshold inflow rate wasset as 600 litres per minute (10 litres persecond) to help determine between pre andpost-grouting in relation to excavation.Once a pre-grouting operation had beendone another, shorter pair of boreholeswould be drilled to check how well the leak


Above: The severe groundwater problemssometimes seeped and soaked theexcavation face …

Below:… and at other times, and fromother ground, erupted as a high pressure jet


had been stopped.Therefore, just over 1km into the drive it

was decided to commence grouting in thefront zone of the face by using cementitiousgrout. However, this proved unable to sealoff the inflow and the contractor andsupervisor agreed that polyuerethane (PU)resins be tried instead. Followingconfirmation of products being certified assuitable for use in area of health andenvironmental sensitivity, these weresupplied by Minova. They had been usedelsewhere in Iceland, including tunnellingon the Karahnjukar hydro tunnels thenunder construction in east of the country.

The chemical grouting set consisted ofGX-45 II pumps, BVS-40Khydropneumatic packers to fix thegrouting rods in the boreholes, andCarboPur WF and WFA two-componentpolyurethane (PU) resin includingCarboAdd Thix 1 and 2 accelerators.Minova trained select Metrostav crew in

both the theory and practice of workingwith the chemical grout systems, whichwould require procedures (such as pre-heating) as well as the drill patterns to beadjusted to handle different inflow rates,geology and technical condition forapplication of the product.

In addition, Metrostav was able to callupon the services of a grouting consultant,Tomasz Najder, as recommended by theclient’s supervisor and also working thenin Iceland dealing with inflows challengeson the Karahnjukar tunnels. Metrostav’sproject director, Ermin Stehlik, says due tothose many challenges on Karahnjukar thecontact with Najder was often phone, faxor email.

The contractor also installed interceptingtraps both within the tunnel and at the portalto catch any chemical leaks, if necessary.

At 1km into the drive on Olafs, therefore,the approach was recommended to be todrill 16-18 probe holes ahead of the face, of12m-20m lengths, from around itscircumference. The holes would then beused to inject the PU grout, which was to

form a protective ring-barrier againstinflows. This approach was used over asection of approximately 80m and took 1.5months, completing in July 2007.

Even tougher aheadHowever, the following month, more than800m further into the drive, the PUgrouting was to be called upon once againfor probe holes had found groundwaterpressures up to 30-32 bar, and there werefissures and cracks up to 500mm wide inthe rock mass ahead.

A higher performance SK-90 rotary gear-type pump was introduced, plus a suitablecompressor for compressed air, andGeofoam foam-producing resin was addedto the materials options. Dedicatedboreholes would be added to the drillpattern to pierce and attempt to fill thelarger voids with the foam. A CT-PM highperformance electric pump was alsoprepared on site, though eventually was notcalled upon.

There was also the challenge of having asufficient stock of the PU resins for both the


Above: …or many jets as more difficultlocations was reached


application rate, and volumes needed,would be higher than earlier in the drive.The time taken to source and have deliveryto near the Arctic Circle on Iceland ofrepeated, large truck loads of non-stackable cans of PU resins would be afactor that led to further delay in theprogramme.

Then, about 340m further ahead, a faultwas encountered with pronouncedtectonic breccia of stones up to 500mmwith clayey-sandy matrix. First met on theleft of the face, the breccia zone wasexposed to take up the entire left half ofthe area as the drive advanced only 4m.On the right was altered scoriaceousbasalt with a sedimentary inter-layer. Theclayey fill was blocked the drill bits. Largeinflows of 600-1200 litres per minute werefound during rock bolting beforehand andfrom probe holes. No jets of water cameout the face, only a continual extremewetness, which prevented application ofsteel-fibre shotcrete.

As a consequence, the solution conceptwas to view the material as soil. An array ofnine 12.6m long, 51mm diameter boreholeswere drilled, splaying outside the profilearea and PU resin injection significantlyreduced the flows leaving the remainder tobe drained by intermediate boreholes.Mesh and shotcrete were applied. Whererock bolting met water, there were parallelbore drilled for drainage set about 500mmaway, a packer fitted and groutingundertaken that would enable the rockboltto then be filled with grout.

Further ahead, worse was to come –single probe holes unleashing cold waterflows of up to 2500 litres per minute withrelatively constant pressures of 24-29 bar.The inflow was coming below Sydrardalurvalley where the basalt overburden wasfound to be intensely fractured. This wouldbe one of the worst areas on Olafs.Fissures were 2-50mm with clayey fill andthere were crushed zones with clearlydefined slickenslides. Beyond this sectionthere was a tectonic breccia of stones inclayey sand.

However, in July 2008, on a section ofthe tunnel there was a point where inflowswere so severe, reaching about 500 litresper second that pre-grouting wasimpossible and the tunnel wassubsequently flooded, but only for a period,whereas the inflow decreased significantlywithin a few days.

Stehlik says: “The difficult part was thatsometimes we thought that the worst wasbehind us, everything worked well, but all ofa sudden we would hit the water again.” Headds that tonnes of PU resin was being

used daily and there was the furtherincredible sight of large stocks of theexpensive, but highly effective product,rapidly depleting, knowing it takes sixweeks to get more to Iceland.

Completing the challengeBreakthrough in April 2009, meeting theSiglu crew who had crossed the valley andblasted on an uphill drive to close the gap.However, given the experience of Olafs,should they have reached the crest firstthen there was the risk of proceeding into adownhill slope.

So, with this potential foreseen early onand no-one wanting a submerged face, itwas agreed with the client sufficiently inadvance to drop the vertical slopes for thedrive in Olafs from Hedinsfjordur valley, andconsequently shifting the crest to the southeast by some five hundred metres, and socontinuing giving both crew uphill drives.

Two Sandvik Axera drill rigs were usedon the project, one per tunnel, and drilled atotal of 40km of holes for pre-grouting and32km of probe holes - both with 51mmdiameter. The blasting holes were 48mmdiameter. The drill rigs proved very reliableand were a good choice for the conditions,said the contractor.

With no access adits along the drives,the ventilation system was designed as aseparate blowing set up. On Olafs it wasprovided by 1 x 1800mm and 1 x 2100mmdiameter non-reinforced ducts and twoaxial Cogemacoustic, type T2 180ventilators with frequency converters forregulation suited to tunnel length.

The absence of an adit also presented achallenge to move construction equipmentto the face as well as mucking out. Adumper was used for transport. Formucking out, initially working with a loaderbrought a few problems, such as highbreakdown rate, mainly with operatortraining. That was overcome and loaderperformance is much better than wheelloaders, says the contractor. It was usedfor excavating the invert and the firstscaling operation.

While the best month’s advance onOlafs was 330m – higher than in Siglu –the average was reduced to less than180m over the 3km stretch of drive withinflow problems.

After negotiation between the client andcontractor, the extra time needed andfinancial cover for the additional worksdealing with the severe groundwatercomplications, the target for completing the


Above: A drive from Hedinsfjordur valley to blast Olafs from the oppositedirection started in May 2008 but at a shallower slope than first planned to givelonger distance uphill and avoid any downhill grade risk with groundwater beforebreakthrough underground


entire project was moved to the end ofSeptember 2010 from an original date oflate 2009. There was also a separateagreement by the client that helped topartly offset the exchange rate difficultybrought by the economic problems thatshook Icelandic and the consequent dropin the value of its currency.

The Hedinsfjordur road project wasofficially opened on 2 October.

The challenges faced by Metrostav andthe solutions used were discussed inFebruary 2010 at a presentation by ErminStehlik to the British Tunnelling Society(BTS) in London and since have beenshared with visiting tunnellers to Prague.

Recalling the BTS talk, Martin Knights,

global tunnelling director with HalcrowGroup and past president of theInternational Tunnelling and UndergroundSpace Association (ITA), praised thepresentation for being both highlyinformative and enjoyable. Not least, theassembled tunnellers were presented withan uncommon addition to a BTS talk –video footage of tunnelling work underextreme conditions, made at a face inOlafs where there was heavy groundwaterinflow, and all set to classical Czech musiccomposed by Smetana. The soundtrack ofAC/DC accompanies another videopresentation showing blasting and otheractivities in Olafs Tunnel.

Knights says: ‘The Project presentationwas first class and respected theaudience’s needs— to be informative,interesting, honest (in that problems wereclearly explained as were the consequential

solutions) and it was very entertaining.‘The project presentation had many sub-

themes regarding the construction of theunderground works including water ingressproblems. These issues were well explained– even with the appropriate musicalbackground!

‘Clearly the speaker had prepared thepresentation well and had mastered the artof storytelling of a complex technicalsubject for an English speaking audience.No mean feat!

‘BTS is indebted to Mr Stehlik for a wellresearched and presented presentation—infact the presentation was socomprehensive there were very fewquestions forthcoming after Ermin`spresentation—he should take that as acompliment!’


Olafsfjordur (‘Olafs’) TunnelClient’s Representative – Sigurdur Oddsonand then Jon Magnusson

Supervision (GeoTek) – Bjorn A Hardarson,Oddur Sigurdsson

METROSTAV

Project Director/Manager – Ermin Stehlik;started as Consultant in September 2006,then became Project Director in October2007; initial phase PMwas David Cyron

Deputy PM, Economist - Ales Richter

Purchase and logistic - Josef Malknecht

Quality - Jan Merenda

Site manager - Ivan Pirsc (during thecompletion phase was also site managerfor Siglu)

Assistant - Vaclav Pavlovsky

Surveyor - Jan Mleziva

Underground Staff:

Foremen: Pavel Celis, Patrik Stverak,Jaroslav Hrach, Rostislav Hesky

Gang leaders: Pavel Imrich, Pavel Rudlof,Frantisek Zifcak

Mechanical:

Jan Frankovic, Libor Sykora, LadislavRusinak and Kristinn S “Kiddi” Gylfson

HAFELL

Project Management: They were,consecutively, Magnus Jonsson,Gudmundur Bjornson and ValgeirBergmann

Key PersonnelRight: Outside the water froze and itsnowed, inside the tunnel and thework went on

Left: Celebrating the undergroundbreakthrough, in April 2009, when twouphill drives met completed thechallenging excavation of Olafs

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HEDINSFJORDUR TUNNEL | FINISHING TOUCHES

T here’s a name that keeps comingup, that of a go-to practical andresourceful Icelandic engineerand craftsman who has won the

praise of many and is experienced withtunnels. He came up with fresh concepts touse on the project that gathered innovativeideas and systems to help construct insituconcrete portals in exposed, harsh, andcold conditions and then developed anefficient manufacturing-style approach toinstallation of water and frost proof (WFP)lining in the tunnels.

‘Helgi’, is all that needs to be said, buthis full name is Helgi Valur Einarsson.

For construction of the concrete portalshe came up with a system like a port-stylestraddle crane to move assembled archesof steel reinforcement and shutters. Theformwork for casting the sections wasdesign and produced in Prague andsupplied to Iceland by Metrostav.

In the tunnel, a multi-platform gantry wascreated to have numerous operationsunderway consecutively for measurementand then installation of the WFP positioningbolts to achieve the finished profile for thelining, later to be shotcreted, despite thevaried cross-section of the drill and blastexcavated tunnels.

During the project, he helped to establishand co-owns VK Contractors, whichworked under a subcontract for theMetrostav-Hafell joint venture contractor.Other co-owners are Johann GunnarStefansson and Skarphedinn Omarsson.

In the portal and open-cut works, VKContractors was able to speed up the workcycles and increase both efficiency andproductivity compared to the initialapproach, resulting in much-needed costand time savings, benefiting theconstruction programme.

Concrete PortalsA total of 450m of concrete portals wereconstructed insitu for Hedinsfjordur Tunnel

project – half for each of the two tunnels,Olafsfjordur (‘Olafs’) Tunnel and Siglufjordur(‘Siglu’) Tunnel, that comprise the new roadlink. Olafs has portals of 150m and 75mlengths, respectively, while those at eitherend of Siglu are 125m and 100m.

In each case, a single tunnel has a totalof 225m of concrete portals to help keepaccess open especially in the extremelyheavy snows in this northern coastal partof Iceland, which is not too far from theArctic Circle.

Originally, the portals were to beconstructed traditionally by building thesteel reinforcement into the formwork andusing a number of shutter sections liftedby mobile crane. However, bad weatherwas interfering with the process, such asice build-up and snow entering theformwork, and scaffolding was neededevery time for assembly. Reinforcementplaced against formwork also causedextra wear and tear.

Helgi and his team came up with a newapproach of concurrent activities, leavingcuring time the prime time constraint. Thesystem allowed the portals to beconstructed insitu in 12m long sections,joined by a specially-designed membrane.Each 12m section took up to three days to

construct. The total volume of concreteused for their construction was 5007m3

and the tonnage of steel reinforcement was520 tonne.

Portal construction begins withpreparation of the reinforced concretefoundations strips while, not far away, aspecially-built, oval-shaped long multi-platform gantry is used as support forassembling of the steel reinforcement intoarches matching the tunnel geometry. Thegantry, running on wheels, then transportsthe reinforcement to the casting site whereit is lifted by a horseshoe-shaped gantrycrane and placed onto the awaiting full-size, inner formwork shell.

The crane then lifts the complete outerformwork in its entirety and places it on topof the reinforcement. Following bolting andsealing, the shuttered rebar is ready forconcreting. Meanwhile, the multi-platformgantry is being used to begin assemblingthe next arch of reinforcement.

After the outer formwork is struck it islifted by the crane, washed down and oiled,and then brought back to protectively coverthe thick canvas sheets that have beenplaced meantime on the hardeningconcrete to limit heat loss. Later, the innerformwork is struck and lowered for cleaning

Work on construction of insituconcrete portals and installation ofwater and frost protection (WFP)benefited from a gathering ofinnovative ideas and systems

Portals and protection

Above: Olafsfjordur Tunnel, at the south east end at Olafsfjordur town, where steelreinforcement was being assembled at the end of 2009 using a multi-platform gantryarrangement on a flat wagon to help with insitu concrete portal construction

DECEMBER 2010 Tunnels & Tunnelling Hedinsfjordur tunnel 27www.tunnelsonline.info

FINISHING TOUCHES | HEDINSFJORDUR TUNNEL

and oiling before being put into a newposition for construction of the next sectionof the portal – and, still having some heatfrom the curing concrete, there were few ifany problems with snow and ice.

Shorter time and simpler processesmeant fewer man and machine-hours, lessrisk of weather interference and betterdurability of equipment, and so overallbetter use of resources. The smooth, multi-activity operation became known as theNSH system – Non-Stop Helgi.

WFP LiningFollowing the success with themanufacturing approach to concrete portalconstruction, the team became involved inthe challenge of the WFP lining – how toefficiently and rapidly get the requiredlength of holding bolts in the correctpositions in each and every location in thetunnels, for nothing was standard.

Metrostav surveyors used SetOut

software from Leica for setting out the boltpositions. This is based on surveying thecross-sections of the excavated profile andrecording the data by chainage. Then,knowing the finished profile sought,software can calculate the necessarylengths of bolts for each position.

The challenge, then, was two-fold –accurately drilling at the necessary boltpositions to the required lengths, andorganising a system to ensure the right boltwas where it was needed to hand as theinstallation process moved along thetunnel. Again, a multi-platform gantrysystem would play a role.

However, due to specialist, andexpensive, equipment for bolt positioningand drilling not being available fromNorway, an alternative – and successful –solution was elected: to carefully use theSandvik Axera drill rig. About 46,000 boltswere installed, each 16mm in diameter. Theonly problem, especially during the starting

period, was consumption of special drillbits, because the small diameter is not socommonly produced or used.

Then, the WFP foam lining, supplied bySkumtech of Norway, would be preparedfor placement. To match the open decktransport available, the maximum length ofthe 2.7m wide sheets was 11.4m. Thesystem requires a 300mm overlap in alldirections – the key to prevent cold airgetting into the void that is left deliberatelybetween the lining and the excavated wallsfor groundwater drip space. Where thereare spots of slightly more, concentratedflow, extra protection such as stainlesssteel sheets or GSE membrane is used tostop the WFP foam being locallyweakened and ruined.

Under the brand name of Sleipnir, VK isexploring a patent for the system used forthe WFP installation at Hedinsfjordur. VKanticipates it could also be useful in tunnelrepair work.

Above: The horseshoe-shaped gantry crane running on trackswas used to lift reinforcement into place for the next stage ofportal construction

Below: Final preparations are made before the horseshoe-shaped gantry crane transports the outer formwork intoposition for the last stage of insitu concreting works at theportal. Plastics tubes protrude up from the formwork to receivethe pumped concrete

Above: Portal construction at Olafsfjordur in its final stages inFebruary 2010, with the outer formwork removed while theinner formwork remains in place.

Above: A new survey, calculation and organisational systemwas developed to speedily undertake installation of eachindividually-sized WFP positioning bolt at Hedinsfjordur

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OPENING| HEDINSFJORDUR TUNNEL

On the morning of 2 October,2010, as the wind picked upand clouds brushed the top themountains in Trollaskagi area of

North Iceland, a small group of cross-country skiers came down the main road inOlafsfjordur on their pre-winter, road-running roller blades and kept going, intothe tunnel that was to be officially openedthat afternoon.

They were followed by a spread of longdistance runners in a new race, then somecyclists, and locals out to walk and, ofcourse, some cars.

The snows would be here before longand the tunnels linking through toSiglufjordur, which had been eagerlyawaited for a long time, and were greatly

supported by both communities and manymore people, just had to be explored onthis exceptional, landmark day.

Hedinfjordur Tunnel was to beofficially opened.

Those who came from far and wide thatday from other parts of the north regionand the country and also from overseas,would see another sight as they madetheir way through either of the two tunnelsthat constitute the Hedinfjordur project -Olafsfjordur Tunnel and SiglufjordurTunnel. There was a scarf, a wanderingline of woollen multi-coloured links sewninto a chain more than 11km long, whichhad been patiently made by hundreds ofhands over many months, in Iceland andbeyond, and laid along the side of the road

and tunnels.The two small and vibrant communities

of Siglufjordur and Olafsfjordur hadbeen joined.

Opening CelebrationWhen the afternoon came round theclouds were parting and some sunshinefound hundreds of people gathered in thenormally still, uninhabited and peacefulvalley between the tunnels. They had comeby special buses and cars and includedthe President of Iceland, Olafur RagnarGrimsson, and the Transport Minister,Ogmundur Jonasson, and FinanceMinister, Steingrimur J. Sigfusson – for theofficial opening.

The representatives of the IcelandicRoad Administration (Vegagerdin) were ledby director general, Hreinn Haraldsson, andthe regional director Birgir Gudmundsson,client representative Jon Magnusson, andformer directors Jon Rognvaldsson andHelgi Hallgrimsson. Also important to thegathering was Kristjan Moller, the formerTransport Minister and a vital politicalsupporter of the project.

A local choir sang to the gathering,including one number sung in Icelandic butto a traditional Czech folk tune,

It’s Open!The opening of Hedinsfjordur Tunnel brought myriadcelebrations and activities. The eagerly awaited new road link ispopular and has strengthened yet further the bonds between thecommunities of Siglufjordur, Olafsfjordur and towns beyond

Right: A bracing, overcast morningbefore the official opening to explore thenew tunnel


internationally enjoyed and which was notlost on the Metrostav tunnellers who hadjoined the enlarged community andrepresentatives of the joint venture partner,Hafell, that day. A group of performers ofReykjavik played out their interpretation ofthe mountain barriers being overcome andnew friendships being won.

A religious blessing, then some officialwords and, finally, the ribbon in the nationalcolours of blue, red and white was cut.

CommunityEveryone was invited to the party, held inOlafsfjordur, which was only fair asSiglufjordur had been the venue of thecontract signing in May 2006 and hosted afete to celebrate work about to begin. Then,

for the occasion, there

had been baked a tunnel-like, 11m longstretch of confectionary – a cake – eachmetre representing a kilometre of tunnel.Following the official opening there was, inOlafsfjordur, cake again.

At the official party, held in the spaciouscommunity sports hall next to the town’sopen air hot baths, the contractors alsocommemorated the occasion with a fewwords. Hafell’s general manager, JohannGunnar Stefansson, spoke, as did VaclavSoukup, a divisional director of Metrostav.Both were joined at the event by manyengineers and managers from both firms,

including Metrostav’s project manager forHedinsfjordur, Ermin Stehlik, Hafell’sproject manager Valgeir Bergmann, andsome tunnel foremen and site staff. Alsothere were the client’s supervisionengineers from GeoTek, Bjorn A.Hardarson and Oddur Sigurdsson.

“In the last four years,” Soukup said,“Metrostav Prague and its peopleparticipated in the Hedinsfjardargongproject in the north of Iceland. More than 90people from the Czech Republic have beenregularly flown to Iceland to work on thisproject. On many occasions, they had tofight with hard conditions in the tunnels andthere were moments when they doubtedthe possibility to finish the project,especially during the time when the largevolume of cold water under high pressureleaked into the tunnel.”

He continued: “Today the tunnels areopen for public traffic and all difficulties areforgotten. I would like to thank all ourpartners, representatives of the client andsupervisors, our suppliers and, of course,our joint venture partner Hafell forcooperation on this project.”

“Special thanks belong to our peopleworking on the project and to the inhabitantsof Siglufjordur and Olafsfjordur for theirfriendly relationship with our people.”

The network of friendships, contact andcommunity is growing with the ease of all-year travel now possible for thecommunities, which transformed theirmunicipal arrangements to establish agreater group – Fjallabyggd – as well as theextra visitors and more tourists alreadycoming to the beautiful region.

Long and at times dangerous road tripsround the coast and over mountainpasses will no longer be journeys ofnecessity, but choice, in spring to autumn.Come winter, life and contacts will nowcontinue thanks to the tunnels. In thenorth, life has changed.

HEDINSFJORDUR TUNNEL | OPENING

Above: Entertainment at the ceremony included a local choir…

Left: Vegagerdin’s director general HreinnHaraldsson (left) and Metrostav’sdivisional director Vaclav Soukup (right)with the President of Iceland, OlafurRagnar GrimssonPhoto credit: Stepan Soukup

Above: … and interpretative theatre

Below: Tyra – man’s best friend, in thiscase the friend of Metrostav’s projectmanager, Ermin Stehlik

iceland hedinsfjordur tunnel 2010 page 22

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