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GNATM, EPBM and Cut and CoverTunnelling Applications in theProject of Izmir MetBy Basar Arioglu, Ali Yuksel, Sezgin Kurtuldu and Ergin Arioglu

NÖT, Erddruckschilde und offene Bauweisefür die Tunnel der U-Bahn Izmir

Die U-Bahn Izmir soll im Endausbau mit einer Länge von 45 km dieVerkehrsprobleme dieser Großstadt erleichtern. Der erste Ab-schnitt mit 11,4 km zwischen den Stadtteilen „Ucyol“ und „Borno-va“ wurde in den Jahren 1996 bis 2000 errichtet und in Betriebgenommen. Bedingt durch die komplexen Untergrundverhältnis-se, der unterschiedlichen Topographie und der Bebauungsdichtewaren für die Tunnel drei verschiedene Bauverfahren notwendig,die nachfolgend beschrieben werden.

The Izmir Metro System is planned as a high capacity system cover-ing the whole urban area according to the master transportationplan. It will reach 45 km of double track in total when completed.The first stage of 11.4 km including the backbone system betweenUcyol and Halkapinar, workshop, depot area and Bornova branchwere successfully constructed in the years 1996 to 2000 and is nowunder operation. Due to the complex soil conditions, changing to-pography and dense urbanization, three different tunnelling tech-niques were applied. This article deals with the results and evalua-tions of these different applications.

The Izmir Metro System is planned as a highcapacity system covering the whole urban

area according to the master transportationplan. It will consist of 45 km of double track intotal when completed. The first stage of 11.4 kmincluding backbone system between Ucyol andHalkapinar, workshop, depot area and Bornovabranch (Figure 1) were successfully constructedby Yapı Merkezi-Adtranz Consortium in lessthan four years. Due to the complex soil condi-tions, varying overburden and dense urbaniza-tion, three different tunnelling techniques wereapplied between Ucyol and Basmane Stations.

Nenehatun – NATM tunnel

The section of Izmir LRTS located between Ucyoland Konak Stations was constructed as deeptunnel because of the elevation difference of70 m and the high density of the buildings on thealignment.

Bahribaba and Yesilyurt shafts, 12 and 32 mdeep respectively, provided the access to tunnelentries. Two switch tunnels for Buca junctionwere located between the Yesilyurt access andthe Ucyol station tunnel. The Station Tunnel wassituated between 291th to 440th metres of align-ment. Inclined escalator tunnels provided theconnection of the station tunnel with the tickethall. A double track tunnel is constructed at theremaining 1 384.7 m (Table 1).

Geology – geomechanicalproperties of rocks

Upper Miocene aged sedimentary and volcanicrocks are encountered at Nenehatun tunnelalignment (Figure 2). The Andesites are moder-ately to highly weathered, slightly to highly joint-ed, between weak to strong. Cooling joints aresmooth and have clay fillings while tectonicjoints have rough surfaces. Sedimentary rocksare composed of interbeddings of claystone,sandstone, and conglomerate. They are classi-fied as weak rock.

Geological mapping was performed and geo-mechanical index properties like RQD, joint setnumber, condition of joint surfaces, condition ofweathering of the rock at the face, were deter-mined every 5 to 10 m along the tunnel align-ment. Variation of RQD and Q values are pre-sented in Figure 2.

Fig. 1 Alignment of the Izmir Metro.Bild 1 Linienführung der U-Bahn Izmir.

Fig. 2 Geological section of Nehehatun tunnel.Bild 2 Geologisches Längsprofil für den Nehehatun Tun-nel.

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Crushed zones that are 1 to 3 m in width inter-sect nearly perpendicular to tunnel axis in a dis-tance between 20 to 50 m and dip in direction ofthe advance. Rock is completely weathered inthese zones and overbreak occurred during theexcavation at the roof of the tunnel due to thetunnel water.

The section of the rock where the Ucyol Sta-tion is located is heavily jointed and heavilyweathered. This caused some overbreak andcreated difficulties in the installation of the rockbolts.

At the end of the Ucyol Station grey, mediumto slightly jointed, high strength andesite (UCS =100 to 120 MPa) was encountered. It was diffi-cult to excavate this section by road header. Pickconsumption increased by 33 % compared to theaverage value. The vibrations during the excava-tion caused serious problems on the gearbox ofthe cutterhead. For this reason, a hydraulichammer OK RH9 instead of Roadheader wasused for the excavation.

Between 850 to 1 130 m sedimentary rockscomposed of the interbeddings of claystone,sandstone and conglomerate were encountered.During the excavation of these slightly to medi-um cemented and low strength sedimentaryrocks, there was no difficulty of excavating butdue to the movements of the road header anddue to the seepage water, the rock at the bottomof the tunnel was disturbed and loss of strengthoccurred. Therefore the handling of the equip-ment became difficult. As the convergence of thetunnel increased, it was necessary to support thebottom with an invert.

A length of 150 m of the tunnel until Bahriba-ba exit was under sea level. In this section theandesite was medium to heavily weathered, me-dium to closely jointed and with clay fillings andmoderate to high strength.

Excavation and supportThe excavation and supporting operations weredesigned according to New Austrian TunnellingMethod (5). The variations in the geology anddeformations (convergence and surface settle-ment) were monitored by continuous geologicalmapping and surveying.

Excavation was done in a top heading andbench sequence. After two rounds of excavationat the top heading, the excavation of the benchstarted.

Under favourable ground conditions type Bsupport was applied allowing 3 to 6 m benchlength. It included 20 cm reinforced shotcrete,steel lattice girders with 1 to 1.3 m intervals, sev-en to eight rock bolts with 3.85 m length each.Under unfavourable conditions type C supportwas executed with a bench length of 2 to 4 m. Itincluded 25 cm shotcrete with a double layer ofsteel wire mesh, steel lattice girders with 0.8 to1 m intervals, and 11 to 12 rock bolts per round.As the geological conditions varied frequently

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and the alignment was located in an urban area,type A support (15 cm shotcrete, no lattice gird-ers) proposed during the design phase, was notused. The maximum settlement observed on the53 deformation points was 9 mm and no damagewas recorded (3).

The enlarged section of the first switch tunnelwas divided into left and right faces. In the sec-ond switch tunnel, the excavation method waschanged to the method used in the double tracktunnel, by observing convergence measure-ments and the evaluation of the advance rate.The advance rate was increased to 1.07 and1.22 m/d in the second and the third tunnel, re-spectively while 0.78 m/d were achieved in thefirst switch tunnel. Therefore there was a gain of136 days in total excavation time and 65 000man-hours, where saved compared to the meth-od applied in the first switch tunnel (4).

After the shafts were completed, tunnel exca-vation started at Üçyol access on 26. December1996 and at Bahri Baba access on 3. June 1997.The excavation was completed when the facesmet each other on 28. August 1998 – 808 m fromthe Üçyol Access (3).

Both from Üçyol and from Bahribaba, the ad-vance rate of the first 100 m was realized with anaverage of 1.5 m/d. Due to the learning effectand the better organisation in the loading andtransport operations, the production was in-creased and very high rates up to 5.2 m/d wasreached (Table 2). Considering working days,the average rate in the double truck tunnel wasdetermined as 2.6 m/d at each face (2, 4).

The amount of labour in the double truck tun-nel and enlarged tunnel were 14.5 and17.2 man-hours/m3, respectively. As a result ofthe evaluation of the different tasks of tunnel ex-cavation and support operations, it was conclud-ed that the necessary time for one excavationand support cycle (i.e. 0.8 to 1.3 m) was 670 min-utes: 29 % was for excavation, 27 % for shot-crete, 13 % for rock bolt, 11 % for wire mesh10 % for steel girder, and 9 % for standstill andbreakdown respectively (2, 4).

Ummuhan Ana – EPBMtwin tunnels

Due to the density of the buildings, main trafficlines of the city and the high costs for the reloca-tion of the infrastructure facilities located be-tween Konak, Cankaya and Basmane Stationsand in order to prevent damage to the archaeo-logical remains located in the recent fills, it wasdecided that this section should be constructedas a tunnel (6).

As the alignment included a small radius(R = 250 m) and as the neighbour and adjacentbuildings had pile foundations and/or deep base-ments (maximum 5 m), a twin tunnel system wasselected. Tunnels consisted of four tubes of a to-tal length of 2 753 m each having a 6,5 m exca-

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vation diameter with 5.7 m inside diameter.The section between Basmane and Cankaya

Stations is located under a street where two tothree storey historical masonry buildings and sixto eight storey modern buildings are situated ateach side. The section between Konak and Can-kaya Stations is underpassing buildings. Thedepth of the tunnel which was 6 to 7 m under thestreet, reached down to 13 m under the build-ings to avoid basements.

Geology – geomechanicalproperties of layers

In Ummuhan Ana Tunnel route clays, completelyweathered andesite and recent sea sediments,composed of silt, clayey silt and sandy gravelswere encountered (Figure 3). They were classi-fied as silt and clayey silt having cross beddedsand layers and sand pockets between Konakand Cankaya Stations. In the beginning of thetunnel from the Konak access, the tunnel passedthrough silt layers. Yellow clays were encoun-tered on lower parts of the face with increasingdepth of the tunnel, around the midway of theKonak and Cankaya alignment. The tunnel routepassed through the sandy gravel and silt layersbetween Basmane and Cankaya stations. Waterlevel is approximately 1.5 m below surface atKonak and 2.5 to 4 m and 5 to 6 m at around theCankaya and Basmane Stations respectively.

EPB tunnelling machineDue to the difficult geological conditions and thebuildings situated in the neighbourhood of thealignment, during the feasibility stage it was de-cided to excavate the tunnel by equipment thatwas capable to excavate the tunnel full face. AnEPB shield was selected (6, 7). The shield diame-ter was 6.54 m and the diameter of the cutterhead was 6.56 m. The total length of the shieldwas 7.3 m and its weight is 325 t. A screw con-veyor attached to the excavation chamber re-moved the excavated material from the front.For continuous monitoring of the face pressure,sensors were placed in the excavation chamberand the screw conveyor. For ensuring the facestability it was necessary to provide the correctface pressure and control the unloading of theexcavation chamber. Soil conditioning was doneto achieve suitable plasticity, lower internal fric-tion, lower permeability and soft consistency ofthe soil (8). Soil conditioning improved soil prop-erties thus it was possible to safely obtain theface stability. In addition to this, the requiredtorque of the cutter head was reduced and thewearing of the screw conveyor decreased.

The conditioning of the gravely sandy soilswas carried out by foam, which was composed ofenvironmental friendly polymers and sur-factants, and that of clayey, silty soils by ben-tonite slurry. The consumption of the foam perunit volume of the excavated material was 300 to500 l/m3, 0.01 to 0.5 kg/m3 and 0.5 to 1 kg/m3 of

Fig. 3 Geological section of Ummuhanana tunnel.Bild 3 Geologisches Längsprofil für den UmmuhananaTunnel.

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polymers and surfactants respectively. (9).

Excavation with EPB machineExcavated material from the face is passedthrough the openings on the cutter head to theexcavation chamber. By removing the excavatedmaterial from the excavation chamber, the ma-chine pushes itself ahead by a total 28 jacks witha capacity of maximum 44 300 kN. In the sametime, the void (≈12 cm thickness) between thesegments and the excavated ground was imme-diately filled by grout. Immediate filling of thisvoid and the controlled take of the excavatedmaterial minimized ground settlements. Ben-tonite was added to provide flowability and flyash was used to safe cement. Natural sand (0 to5 mm) was used as aggregate in the mix.

After the completion of one advance step(120 cm), The segments (seven plus one key-stone) were placed by an erector, equipped witha vacuum device. The Segments are 120 cm longand 30 cm thick. High strength concrete (BS 45)was used. Elastomeric gaskets were used to en-sure water tightness.

The excavated material was transferred tobelt conveyor and muck was carried with muckwagons pulled by diesel locomotives. Two serv-ice trains consisting of six muck cars, three seg-ment cars and one grout unit were used. TheTBM was guided with a single laser guidancesystem that was fully computer controlled.

Excavation progressThe TBM, which was specially designed and pro-duced by Herrenknecht for the Izmir MetroProject, arrived on site in May 1997. Preparationof the access shaft at Basmane Station, assem-bling of parts and installation of compressed air,water, and cooling units took four months. Exca-vation of drive 1 and drive 2 were executed fromBasmane Station to Cankaya Station, while drive3 and drive 4 were executed from Konak Stationto Cankaya Station.

The first ring was placed at Basmane Stationon 25. August 1997. Advance rates were realizedaround 3 m/d during the first month. Excavationwas done in one shift in the beginning. In thisperiod the crews became more skilled, workingsystems were established and clogging problemsof grout were solved by improvements of thegrout mix. Then the daily advance rates gradual-ly increased and reached up to 24 m/d. Averageadvance rate was 8 m/d for this drive.

The shield parts of the EPB machine were dis-mantled at Cankaya Station and transferred toBasmane Station and again assembled in twomonths. All TBM equipment and service unitswere moved to Konak Station area for the exca-vation of drives 3 and 4. The average advancerate was 12.5, 13.3 and 19.7 m/d for drive 2, 3and 4 respectively. The maximum advance rateachieved was 30 m/d during the excavation ofdrive 4.

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Unacceptable wearing of the screw conveyorwas found during the assembling at Konak sta-tion before the excavation of Drive 3. It was con-sidered that sandy andesitic gravels on the align-ment of Drive 1 and 2 caused the excessive wear.

Excavation performanceof EPB machine

The distributions of the average process dura-tion are shown in Figure 4. The intermediatedemobilization periods are not considered andonly the time intervals from the beginning to theend of the excavation are analysed.

As shown in Figure 4, unproductive time(waiting and breakdowns) made up 37 % of thetunnel excavation period and only 49 % of it wasdirectly related with production activities, whichcan be considered as “machine efficiency”. In thebeginning, the mentioned value was in a range of30 % and then increased to the level of 69 % atthe last drive of the excavation. This is totallyrelated to the increasing harmony between thecrews, equipment and the mastery of the craft.On the other hand, another indication showingthe increasing mastery of the craft is the short-ening in the preparation period.

Same results were also noticed while consid-ering the duration for the placement of the rings.Placement of a ring was reduced from 267 min-utes at the first drive to 88 minutes at the lastdrive and the average was 161 minutes.

Settlements and face stabilityBefore starting the excavation, measurementstations were designed and three to five settle-ment points were installed on ground and in thebuildings. The distance between the measure-ment stations was 30 to 100 m. Totally, 85 unitswere surface points while 317 units were in-stalled at buildings. In addition vertical incli-nometers were installed at eight measurementstations to measure lateral displacements. Onthe other hand, the existing condition of allbuildings located in the area affected by the tun-nel was determined photographically and wererecorded with sketches before the excavation.Crack meters also were installed on two impor-tant historical buildings. Totally, 5 040 deforma-tion readings were carried out during the exca-vation. Maximum settlement value was recordedas 21 mm.

Volume loss of ground (K) for unit advance oftunnel caused by surface settlement can be ex-pressed with following formula (12, 10):

KV

Vi S

D= =

⋅ ⋅

⋅

∆ 2 5

42

, max

π

wherei distance between inflexion point of settle-

ment curve and tunnel axis. It is possible to

Fig. 4 Efficiency of EPBM machine during four drives.Bild 4 Ausnutzungsgrade der TBM für die vier Vortriebe.

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determine empirically for silty clays andclays i = 0,5 · (H + D/2) (13, 10),

Smax maximum settlement value at the axis oftunnel,

D Diameter of tunnel, andH Depth of tunnel axis.

Volume loss of ground for the maximum valuecan be calculated as:

i m

mm= ⋅ + =0 5 8 4

6 52

5 8. ( ..

) .

Km m

=⋅ ⋅

⋅ ( )= =

2 5 5 8 0 0213 14

46 5

0 0092 0 92

. . ..

.. . %

Considering average values (Smax=7 mm,H = 9.62 m) volume loss can be calculated as:

Km m

=⋅ ⋅

⋅ ( )= =

2 5 8 6 0 0073 14

46 5

0 0045 0 452

. . ..

.. . %

It is clear that the ground loss value (K) is ex-tremely related to the applied tunnel technology.The mentioned values were between 0.77 % and1.32 % at Cairo Metro in Nile alluvial fine sands,where a 9.45 m shield diameter EPB machinewas used (14).

Soil stability number, N as a criterion of facestability is given below (10, 12)

N

ZC

S o F

U

= + ⋅ −σ γ σ

whereσs additional loads caused by traffic or buildings;

it was assumed as average σs =10 kPa,γ Unit weight of soil, from the laboratory tests it

was between γ = 17 to 21 kN/m3, assumed av-erage as 18 kN/m3 (15),

Zo depth of tunnel axis, Zo = (H+D/2),σF Face pressure at the tunnel axis level; it was

applied between σF = 160 to 240 kPa depend-ing on soil type and tunnel depth (11),

Cu Undrained cohesion of soils; it was found be-tween Cu = 30 to 80 kPa in laboratory tests(15).The stability number can be calculated from

the average values as follows:

N

kPa kN m m kPakPa

=+ ⋅ −

=10 18 12 8 200

500 8

3/ ..

This value is indicating “small movements –elastic conditions” (10).

An inverse correlation was found betweenface pressure values and settlements (Figure 5).Above calculations and mentioned correlationsshow that there is a harmony between the designpressures and the applied values, and the settle-

Fig. 5 Relationship between face pressure and settle-ments.Bild 5 Zusammenhang zwischen Ortsbrustdruck und Set-zungen.

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ments were successfully controlled.

Cut and cover tunnels

Cut and cover tunnels, one of the most significantstructures in the Izmir Metro system, were de-signed to meet very unstable and heterogeneoussoil conditions. No particularly new constructionmethods of constructing these tunnels or ofhandling the material were used, but some fea-tures of the work were of interest consideringthe difficult and uncertain nature of the encoun-tered geological conditions. A mixed formationthat included a wide variety of layers like gravelysands to sandy silts to silty clays and partiallydisintegrated material, tending to cause slipsand slides were encountered. Near the Konakand Çankaya stations where a lot of land wasclaimed from the sea through the centuries, thelevel of artificial fill was very deep, ranging up to6 m (16, 17). Making an open cut through thiskind of material under a street carrying heavytraffic, and with important buildings (two to ninestory buildings were as close as 2 m to the dia-phragm walls) close to the work on both sides,required the most careful excavation methods.

Summary of Case HistoriesThe structures built in open cut sections reason-ably could be subdivided into the track tunnels,the station tunnels and siding and turning units.In these connections the great variety of soils,the high ground water level, the consideration ofexisting compulsory points and the safety of thebuilt up area made high demands on the realisa-tion. The total length of the Izmir Metro align-ment between Konak and Basmane in the cutand cover tunnels is approximately 1 250 m.

In the downtown area, three undergroundstations Konak, Çankaya and Basmane were ex-cavated using the open cut and cover method.The depth of the excavation was ranging from 15to 18 m in Konak and Çankaya to 12 to 16 m inBasmane. Due to the very high ground water lev-el and very soft ground conditions, various typesof structural systems for the stations were con-sidered for the optimization of the design andconstruction. Both the conventional reinforcedconcrete inner framing and diaphragm wallswere adopted in the final design. A typical struc-tural system chosen for these three stations isshown in Figure 6. Diaphragm walls with athickness of 0.8 to 1.2 m and a depth rangingfrom 25 to 33 m were built first as barriers tofight the ground water. The excavation was car-ried out in three or four stages to allow placing ofsteel braces. The tunnel inner frames built in thedry work area consisted of a cast in-place con-crete U-structure with prestressed precastbeams forming the ceiling. In order to prevent aprobable water flow through the complete con-struction, transgression grooves were providedin the top floor of the stations, which allowed a

Fig. 6 Typical cross-section of cut and cover structures.Bild 6 Regelquerschnitt für die offene Bauweise.

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transgression in case of high water.

Evaluation of design assumptionsand site measurements

The initial design of the internally supported dia-phragm wall system was based on the assump-tion of triangular distribution of horizontal earthpressure up to the second excavation stage(Rankine), and an equivalent uniform earthpressure distribution was accepted in furtherexcavation stages where the strut rows in-creased (18). Additionally the hydrostatic waterpressure and the effects of surcharge loads re-sulting from buildings, traffic or other surfaceloads which were located above the active slid-ing plane (active wedge) were taken into consid-eration. Structural analysis was carried out forevery construction stage, such as excavation,pouring concrete to inner frame, strut placingand removing (19).

In each station, four chosen panels of braceddiaphragm wall, supported by internal pipestruts were instrumented so that both surfaceand internal displacements and loads could bemonitored during and after excavation (20).These panels were instrumented with load cellsand slope inclinometers. In addition piezometersand well points for observation of the waterpressure on the wall were installed. The incli-nometer readings provided a direct measure ofthe slope of the wall at any elevation and loadcells readings provided a direct measure of axialforce of the steel struts.

The structural system behaviour was under-stood more clearly with the comparison of themeasured values with the calculated ones. A sig-nificant difference was found between the meas-ured and calculated strut forces. Although great-er forces were expected at the lower layers, themeasurements showed that greater forces oc-curred at the upper rows. These observations ledto a reconsideration of the assumptions made atthe design stage concerning the structural be-haviour of the support system. The related eval-uations are summarised below.

According to the standard analysis proce-dures used, each excavation stage was consid-ered as a separate loading case during analysisand design. After analysing the system for eachexcavation stage, the most unsuitable strut forc-es are taken as design forces. In this practice,greater internal forces are obtained (as the ap-plied external forces are the determining factor)at the lower strut layers.

When the behaviour of structural system isobserved, it can be seen that, treating each exca-vation stage as an independent load case doesnot represent the true behaviour. Fundamental-ly, every strut supported excavation stage can beachieved by excavating the next level from theprevious one. It can be assumed that the recentlyplaced strut can resist almost all of the addition-al excavation loads. Displacements and strut

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forces should be calculated by this manner forevery excavation stage, and then should be su-perimposed. This analysis procedure can reflectthe excavation and strut placing stages more re-alistically. The analysis sequences and the re-sults found by this modified method are shown inFigure 7. Measured values for Konak Stationstruts show an accordance with results calculat-ed by this modified method, which considersconsecutive stages. Estimated results are givenin Table 3.

DiscussionShould these evaluations, concerning the calcu-lations of strut forces, suggest that standard cal-culation methods provide unreliable results?Strut forces are related to soil deformations. Ac-cording to these deformations, there should be a“redistribution” of the strut forces over the longterm and this would cause much greater loads atlower struts progressively. In case of cut andcover construction, casting the base slab imme-diately after reaching the excavation base, fixeslateral deformations. As a result of this no loadincrease it observed at lower layer struts.

Another result, reached by comparison of cal-culated and measured strut forces, is a risk ofdesigning on the unsafe side of the upper struts,by using forces obtained from the standardmethod. It will be useful to consider this point indesign tolerances (21).

Both the design and the construction stages ofthe cut and cover structures within the scope ofthe Izmir Metro System involved rich experiencefrom the civil engineering point of view. Progressof the design and construction stages in paralleland following the structural behaviour with con-tinuous observations and measurements ena-bled the evaluation and verification of the analy-sis. On the other hand, solving both unexpectedproblems arising from difficult soil conditionsand construction detail problems encountered atthe site let the engineers on the site and in thedesign office gain important experiences.

Conclusions

Tunnelling through dense urban settings is un-doubtedly difficult. When complex and changingsoil conditions, archaeological and various legal/political issues are also present, the challengesare almost insurmountable. The Izmir MetroProject was realised under the most difficult con-ditions and a wide range of techniques had to beapplied. Due to the design-build nature of thecontract, design and construction were carriedout almost simultaneously and valuable experi-ence was gained. Without excessive and costlydelays in overall delivery of the metro system

References1. Yüzer, E., et al.: Engineering Geology of Phase BetweenFahrettin Altay–Basmane of Izmir Metro (In Turkish). Engi-

Fig. 7 Modified analysis sequences of internally braceddiaphragm wall.Bild 7 Angepaßte schrittweise Analyse der Schlitzwände.

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neering Geology and Rock Mechanic Department, ITU Min-ing Engineering Faculty (September 1993), Istanbul.2. Arioglu, B. ; Yüksel, A. ; Arioglu, E.: Excavation Parametersand Evaluations of Nene Hatun Tunnel-Izmir Metro (In Turk-ish). Proceedings of the 5th National Rock Mechanics Sympo-sium (October 30-31,2000), Isparta , pp. 21-33.3. Yapı Merkezi: Site Records of Nene Hatun Tunnel-IzmirMetro. Yapı Merkezi Izmir Metro (1996-1998), Izmir.4. Yüksel, A.: Production Report of Nene Hatun Tunnel. YapıMerkezi (2000), Istanbul.5. Ayaydin, N. ; Jainz, O.: NATM Tunnelling for Izmir Metro.In: Felsbau 15 (1997), Nr.5, pp. 339-345.6. Arioglu, B.: Engineering Achivement at Ummuhan AnaTunnel. In: World Tunnelling, No. 1/2000, pp. 37-39.7. Yapı Merkezi Engineering Group: Izmir Metro UmmuhanAna Project. Yapı Merkezi, Istanbul, 1996.8. Arioglu, B. ; Arioglu, O.S. ; Arioglu, E.: Excavation Perform-ance of The EPBM Machine In The Izmir Metro. 16th MiningCongress of Turkey (June 1999), Chamber of the MiningEngineers of Turkey, Ankara, pp. 207-214.9. Jancsecz, S. ; Krause, R. ; Langmaack L.: Advantages ofSoil Conditioning in Schield Tunneling, Experiences of LRSTIzmir. Alten et al. (eds): Proceedings of The World TunnelCongress ’99, Oslo. Rotterdam: Balkema, 1999.10. Arioglu, E. ; Köylüoglu, O.S.: Evaluation of Settlementsand Face Pressure of TBM Tunnel Method for Izmir Metro.Yapı Merkezi Research Department, YM/ARGE/96-3/B, Is-tanbul, 1996.11. Yapı Merkezi: Site Records of Ummuhanana Tunnel-Iz-mir Metro. Yapı Merkezi Izmir Metro (1997-1998), Izmir.12. Léca, E.: Analysis of NATM and Shield Tunnel in SoftGrounds. PH Thesis , Virginia Polytechnic Institute and StateUniversity, Blacksburg, USA, 1989.13. Mair, R.J.: Geotechnical Aspects of Design Criteria forBored Tunnelling in Soft Ground. Negro Jr. & Ferrira (eds):Tunnels and Metropolises in Soft Ground. Rotterdam: Balke-ma, 1998.14. Rankin, W.J.: Ground Movements Resulting from UrbanTunneling; Prediction and Effects. Conference on Engineer-ing Geology of Underground Movements, Nottingham, 1988,pp. 79-92.15. Yapı Merkezi: Geotechnical Report of Between Ch1+550 and Ch 3+800. Report No 9210-TR-J058.T, YapıMerkezi, Istanbul, 1996.16. Kurtuldu, S. ; Müftüler, M.: Structural Analysis DesignReport of Konak Cut and Cover Structure: Izmir Light RapidTransit System. Report No 9210-TR-S087, Istanbul, 1996.17. Kurtuldu, S.: Structural Analysis Design Report ofÇankaya Cut and Cover Structure: Izmir Light Rapid TransitSystem. Report No 9210-TR-S162, Istanbul, 1997.18. AASHTO: Standard Specifications for Highway Bridges.15th Edition, 1992.19. Xanthakos, P.: Slurry walls as structural systems. 1994.20. ASTM: Slurry Walls: Design, construction and qualitycontrol. American Society for Testing and Materials, 1992.21. Cengizkan, K. ; Çivi, A. ; Kurtuldu, S. ; Oguzhan K. ;Tellioglu, V. ; Yalçın, E.: Izmir Light Rapid Transit System,Cut and Cover Structures. Civil Engineering and Technolo-gies Symposium. Izmir, 1998.

Authors Civ. Eng. Basar Arioglu, Dipl. Min. Eng. Ali Yuksel, Dipl. Civ.Eng. Sezgin Kurtuldu and Professor Dr. Eng. Ergin Arioglu,Yapı Merkezi Cons.& Ind. Inc., Istanbul, Turkey.

AcknowledgementsThe authors would like to express grateful acknowledgmentsto Dr. Eng. Ersin Arioglu, Chairman of Yapı Merkezi Inc., Dipl.Eng. Emre Aykar, Managing Director and Civ. Eng. Naim,ISLI-Project Manager of Izmir Metro Project for their supportsand suggestions.

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Tunnel Type Dimensions Excavated Area, Length(L x H) [m] [ m2] [m]

Double Track 9.7 x 7.10 65 1 384.7Enlarged Section 16.5 x 9.7 146 141.58(Switch Tunnel I, II)Station Tunnel 16.09 x 9.13 139 149Buca Connection 6.9 x 6.2 39 76.9Tunnels (SingleTrack)Escalator Tunnels 9.29 x 6.55 57 357.68Total - - 2 107.96

Table 1 Parameters of Nenehatun Tunnel.Tabelle 1 Daten des Nenehatun Tunnels.

Tunnel Type Location Daily Advance Rate

Average (working Average (calendar Maximum days) [m/d·face] days) [m/d·face] [m/d·face]

Double Track Üçyol Side 2.62 1.72 5.2Bahribaba Side 2.6 1.89 5.2

Enlarged Sections 1st Switch Tunnel 0.78 0.58 -2nd Switch Tunnel 1.07 0.87 2.4Station Tunnel 1.22 0.97 2.4

Single Track Buca Connection right 0.98 0.61 1.3Buca Connection left 1.46 1.17 2.6

Table 2 Daily advance rates of tunnels.Tabelle 2 Vortriebsleistungen.

Strut Row Calculated Loads Estimated Loads In-situ Measuredby Standard Method by Modified Method Loads

First Row 225 145 120Second Row 320 137 138Third Row 405 38 30

Table 3 Comparison of measured and calculated loads.Tabelle 3 Vergleich von gemessenen und berechneten Lasten.

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