technical requirements for segement

7/27/2019 Technical Requirements for Segement

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PART VIII - MATERIAL AND WORKMANSHIP SPECIFICATIONCIVIL, STRUCTURAL AND ARCHITECTURAL WORKS

268831MC/North-South Transmission Cable Tunnel Contract NS2 MNW/CSA/83

sequence, position of joints, treatment of projections, connection to waterstops,local reinforcements etc.

9.3.6 Interface with Other Contract

Details of interface with other contract shown in the Drawings are indicative only. Thecontractor shall develop the workable interface details to comply with his tunnellingmethodology and meet the approval of the Engineer/ Governmental Authoritiesand/or comply with the Law.

9.4 Bored Tunneling Works

9.4.1 TBM Requirements

Refer to the Material and Workmanship Specification Tunnel Boring Machine (TBM)Specification.

9.4.2 Segmental Lining

1. The segmental concrete lining shall consist of a number of tapered pre-castsegments bolted together to form a ring as shown on the Drawings.

2. Segmental permanent linings shall be marked with ring numbers in ascendingorder, and in direction of the tunnel drive. They shall be at least 150mm highand stencilled at five (5) rings interval on both compartments of the tunnellining and above the tunnel axis. The paint used shall be permanent,

waterproof, non-toxic and durable with luminous colour that can be easilyidentified and to the approval of the Engineer. The Contractor shall take intoconsideration of the future locations of brackets, cable circuits and other M&Efittings when siting the locations of such markings.

3. Each ring shall be bolted to the adjacent ring to form the tunnel lining. The boltsin this lining shall be permanent and shall be tightened to the fullest extentnecessary to ensure competent building of the lining and proper contactbetween faces of gaskets. Radial joints in adjacent rings shall be staggered sothat there are no continuous joints, except at sump locations.

4. The segmental lining shall be erected at the rear of the TBM by the purposebuilt erector mechanism in such a way that the plane of the rings shall always

be consistent with the attitude of the shield machine within the constraints ofthe tapered lining.

5. Variable width packings to correct for line and level shall not be used.

6. All segmental concrete lining shall have gaskets inserted into recessesprovided in all four mating surfaces of the individual segments as shown on theDrawings. The segments shall also have a provision for fixing a foam rubberstrip or similar in the extrados area of lining joints to contain the grout behindthe linings.


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7. The size and position of the gasket shall be sufficient to take into accountcasting and building tolerances and comply with the manufacturersrecommendations. In addition, all segments shall have an internal caulkinggroove.

8. All segments shall contain a grout hole with an insert capable of holding avalved grouting plug.

9. Any segment found to be cracked or spalled in the stockpile, duringtransportation or erection will be rejected. Any segments cracked or spalledafter erection and built into the tunnel shall be repaired to the acceptance of theEngineer.

10. Damage occurring to segments at any stage prior to erection shall be repairedin accordance with the guidelines provided in Appendix A. Repairs shall becompleted sufficiently early to allow time for the cementitious mortar to cureprior to the application of the waterproof coating and for the waterproof coating

to dry prior to taking the segment in to the tunnel.

11. Segments to which damage has occurred that cannot be repaired inaccordance with the requirements in Appendix A shall be rejected, indeliblymarked on the inner (concave) face and permanently removed from site.

12. A non-conformance report shall immediately be raised by the Contractor forany segment or ring, which is found to be damaged after erection. Should theEngineer deem that damage is sufficient to compromise the integrity of thelining or its long term durability then the Contractor shall remove it from thepermanent lining and propose remedial works to the Engineer for acceptance.

13. Any damage occurring to the waterproof coating prior to erection shall be

repaired in accordance with the coating manufacturers recommendations.

14. All segment repair materials shall be tested prior to using in the tunnels toensure their workability and colour compatibility with the segmental lining.

15. The method of lifting and handling, the type of equipment and method oftransport shall not damage the segments. Segments are to be stacked in amanner approved by the Engineer. If the grout hole is to be used for segmenthandling, the contractor shall ensure that this has been catered for in thedesign.

16. The Contractor shall keep daily records during construction as defined in thisSpecification. The Contractor shall maintain a full time independent inspection

team at the casting yard throughout the production period. Weekly reports areto be submitted to the Engineer highlighting production, quality and safetyissues.

17. Before the commencement of tunnelling, the Contractor shall submit for theconsent of the Engineer his proposals for setting out and correcting deviationsof line, level and plane.


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18. Database of As-Built Lining

The Contractor shall maintain a database of all as-built dimensions andconditions of the tunnel lining. For every ring built, the database shall include

the following:

diametric dimension of the lining vertically, diagonally (2 nos.) andhorizontally

maximum size of steps at each radial joint maximum size of steps at each circumferential joint with arc length for any

step exceeding 5mm

position of key

maximum roll of ring compared with adjoining ring

position, dimension and description of any crack

position and description of any other deviation geometry or damage.

The information shall be recorded for each ring when it is no more than 30m

from the last ring built. Information shall be recorded in a format acceptable tothe Engineer. Information shall be recorded in both hard and soft copies in aformat acceptable to the Engineer and submitted weekly.

The production of the database shall not relieve the Contractor from the needto produce a non-conformance report for any ring built outside therequirements of this Specification.

19. Construction Tolerances

After grouting, the ring of segments forming the tunnel lining shall conform tothe following tolerances:

(i) The overall deviation at any point on the internal circumference of thecompleted ring shall not exceed 50 mm from the design location includingring deformation of 1% maximum error in diameter.

(ii) The square and plumb (pitch and yaw) of the lining shall not differ bymore than 20mm from the design value measured over the internaldiameter horizontally and vertically.

(iii) The leading edge of the lining shall not be out-of-plane by more than 6mm.

(iv) Surfaces of the rings are to be smooth and durable.(v) Steps for circumferential and radial joints shall not exceed 5mm.(vi) The tolerance of internal diameter of the lining shall not exceed 25mm.(vii) The tolerance for absolute roll of the linings should not exceed 40mm.

Minimum of 1 in every 100 segments produced from each mould shall betested and check for compliance with the casting tolerances. Any ring or part ofa ring which does not satisfy these tolerances shall, if the Engineer so directs,be rebuilt by the Contractor.


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20. Re-alignment of Out-Of-Tolerance Lining

The Contractor shall propose immediate remedial actions to bring the ringcentre into tolerance. The Contractor shall stop the TBM in the event the tunnel

drive is out of tolerance by 5mm and no satisfactory remedial action isproposed and accepted by the Engineer.

21. Grouting of Lining

a) A suitable grout mix shall be proposed for each set of ground conditionsto be encountered along the tunnel drive.

b) The grout shall be sufficiently fluid as to ensure that it flows freely underpressure into all parts of the space to be filled.

c) All grout mixes and injection methods shall be submitted to the Engineer

for acceptance. Information given shall include:

mix designs

mixing and delivery systems which should be consistent withplanned maximum TBM advance rate

grout gel times design cube strengths at the end of one ring construction cycle

design cube strengths at specified times after placement

proposed operational and maximum grouting pressures with regardto the vertical tunnel alignment

requirements for sampling and testing during production

theoretical grout volume including considerations for use of any TBMcopy cutters

d) Site trials for each mix and delivery system shall be carried out prior tothe commencement of tunnelling to demonstrate that the proposedsystem works with the adopted tunnelling method and plant. The trialsshall also demonstrate the properties of each grout mix and its suitabilityfor the ground conditions.

e) During production strength testing of the primary grout at 1hour, 3 hours,and 6 hours after the time of placement shall be carried out at least onceevery five rings built or daily, whichever is more frequent. The testsamples shall be taken from the TBM. The timing for testing may beextended beyond 6 hours if this reflects the actual time between injectionand shoving. Other grouts shall be sampled and tested as appropriate fortheir use and to the acceptance of the Engineer.

f) All primary grouts shall achieve a minimum cube strength of 50kPabefore the next 'shove' commences and a minimum of 2MPa at 28 days.

g) During production grout pressures shall be continuously monitored at thepoint of injection using in-line pressure gauges and shall be restricted tovalues not greater than 1.2 x total overburden.


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h) The amount of grout used shall be recorded, and if the quantity falls shortof that required to fill the void, further investigation and grouting shall becarried out.

i) Where accelerators are used they shall be incorporated at the point ofinjection of the grout and not beforehand.

j) In tunnels driven with a closed face machine, primary grouting of theannular void behind the segments shall take place continuously andsimultaneously through grout ports as the shield progresses forward. Thegrout shall be injected automatically as the machine advances. In tunnelsdriven other than by closed face machine primary grouting may be byinjection through the grout holes in the tunnel lining segments. Wherethis method is used the primary grout shall be injected behind eachtunnel ring as the ring leaves the shield tailskin. In each case the voidshall be completely filled.

k) Primary grouting shall be carried out to ensure that the annular void iscompletely filled. Grouting shall continue until at least both the minimumvolume and minimum pressure criteria have been satisfied.

l) In the event that grout records indicate to the Engineer that a void orcavity is suspected the Contractor shall propose a method ofinvestigating for such a void or cavity. Following the investigation theContractor shall, if necessary, re-grout the tunnel lining to ensure allvoids are filled. Investigation and re-grouting of the lining shall take placewithin 24 hours of the void being suspected, unless otherwise agreedwith the Engineer. Following the discovery of one or more voids proofgrouting may be required in areas directed by the Engineer todemonstrate no further voids exist.

m) Secondary crown grouting shall be carried out from the machine backupat every second ring. The Contractor shall submit proposals for this workfor the Engineers acceptance prior to the commencement of tunnelling.

n) The Contractor shall maintain grouting records including volumes andpressures for each stage of grouting. These shall be submitted to theEngineer at the end of each shift. The Contractor shall also calculate arolling 10 ring average grout take which he shall submit to the Engineeron a weekly basis. All these submissions shall be made in both hard andsoft copy in formats acceptable to the Engineer.

o) For grouts that rely on rheology, trial mixes shall be tested for the

following, as a minimum:

(i) Grading curves: These should be obtained for the individualconstituents and the combined mix.

(ii) Cube Tests (compressive strength): Standard cubes, tested forcompressive strength in accordance with BS 1881

(iii) Segregation: A sample of fresh mortar is prepared in a graduatedtest cylinder. The bleed water volume and mortar volume aremeasured at 1, 2, 3 and 8 hours.


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(iv) Relaxation: Cylinders of mortar are made and cured for 15 and 45days. After curing the cylinder is stripped and the sample placedvertically, unsupported. The height of the sample is measured at

regular intervals up to 24 hours. Relaxation is reported as a loss ofheight of the mortar sample.

(v) Wash-out test: A sample of fresh mortar is placed in a perforatedcontainer of known volume and mass. The container and sample aredropped through a 1 metre column of water five times within 15minutes of mixing. The wash-out is calculated as the percentage lossof sample.

(vi) Bleeding under pressure: The mortar is tested in a Baroid filter pressfor 7.5 minutes under 1 bar.

(vii) Workability: Use either a standard slump cone or a Prepakt cone.

(viii) Cohesion. Measured using a laboratory vane apparatus.

(ix) Internal friction: A sample of mortar is prepared and fog cured at23oC until testing. The sample is placed in a triaxial cell and tested todetermine apparent cohesion and angle of internal friction. Thesample should not be consolidated or force saturated prior to testing.

p) The designer shall set limiting values for all of these tests. The designershall also establish a quality control regime, including some or all of thesetests, for the production grout.

q) In order to confirm the effectiveness of the grout used (whether

dependent on rapid setting or rheology), the change in level of the invertof at least five of the first 20 production rings, and at least 1 ring in 50thereafter, shall be measured. Measurement points shall be installedimmediately after primary grouting for that ring, and shall be measuredbefore and after shoving for the next five rings. Movement under theweight of the back-up shall also be measured. Unless acceptedotherwise by the Engineer, the vertical movement of the ring at any timefrom completing primary grouting to the end of the back-up shall notexceed 5mm. The grout shall remain effective for the design life of thetunnel.

r) The grout shall not degrade, shrink or lose strength to an extent that thetunnel would be damaged or become unserviceable as a result.

22. Grout Holes

a) Unless they are to be used for the injection of primary grout the groutholes shall terminate short of the outer surface of the segment.

b) Each grout hole shall include a threaded socket cast into the segmentunless otherwise accepted by the Engineer and a threaded grout plugwith a hydrophilic washer. The hydrophilic washer shall only be includedif the hole is used by the Contractor for grouting. The socket shall be


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arranged such that the grout plug in its final position does not protrudeinto the tunnel beyond the inner surface of the segment. The head of theplug shall incorporate a suitable means by which it can be tightened andremoved, for example a square or hexagonal socket or head, but shall be

of a design that cannot trap water when inserted below axis level. Thedesign of the socket, plug, washer and any ancillary material such asgrease or other coating to the threads shall be to the acceptance of theEngineer. All sockets shall be of metallic type.

c) The inner diameter of the socket shall be not less than 50mm. Groutsockets and plugs shall be capable of withstanding the ground waterpressure and any additional pressure caused by grouting without leakage.In any case, they shall be able to resist a working liquid pressure of notless than 10 bars above atmospheric pressure without leakage. A factorof safety of 1.5 shall be adopted by the Contractor in the design.

d) Upon completion of the contract the contractor shall leave each grout

hole in a condition in which the grout plug can be removed withoutdamage to it or to any part of the socket or the tunnel lining segments,the grout hole can be drilled out, grouting can be carried out and thegrout plug replaced such that all leaks are sealed.

e) The details of grout holes shall be determined by the contractor for adesign life of not less than 120 years and submitted to the Engineer forhis approval.

f) Grout hole is not designed as a lifting hole, should the contractor chooseto use the grout hole for lifting purpose, he shall revise the design of thegrout socket accordingly to the acceptance of the Engineer.

g) Lifting sockets, where used, shall be subjected to pullout tests. Aminimum of 2 trial tests before production and a minimum frequency of 1test per 2000 sockets during production shall be carried out. The testshall demonstrate a factor of safety of 3 against failure at the designpullout load. The design pullout load shall be equal to the dead load ofthe largest segment in the ring. An additional test shall be carried out onanother socket for every test that does not demonstrate this factor ofsafety to the satisfaction of the Engineer. Tested segments shall not beincorporated in the works.

h) The clear distance between the grout socket or hole and the reinforcingbars in the segments shall be not less than the specified concrete coverto the reinforcement. Immediately after the lining is erected each grout

plug shall be fully screwed into place. When the grout plug is in place, nowater or grout shall seep into the tunnel from around the outside of thesocket, from between the grout plug and the socket or through the groutplug.

i) When a grout hole is used for secondary or tertiary grouting it shall beextended through to the exterior surface of the segment by drilling in amanner that does not cause damage to the concrete beyond theintended diameter of the hole. The diameter of the drilled hole and themeans of drilling shall be to the acceptance of the Engineer.


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23. Caulking

Where leakage rates are outside the specified limits and the Contractor is ableto demonstrate to the Engineer that he has exhausted all means of methods to

remedy the situation, then he may propose to caulk the lining as an alternativemethod. Before caulking, the recesses shall be thoroughly cleaned to thesatisfaction of the Engineer.

The caulking material and method of placement shall be submitted to theEngineer for approval. A testing regime shall also be proposed by theContractor for the acceptance of the Engineer.

24. Grummets

All bolts shall be fitted with grummets inserted under the washers of bothheads and nuts.

25. Segment Casting Yard

a) The Contractor shall ensure that segment casting yard has a suitablequality assurance accreditation scheme and that it operates acomputerised recording system that is to the acceptance of the Engineer.

b) Prior to the Contractor awarding any sub-contract for the manufacture ofthe tunnel linings, the Contractor shall arrange a visit to the proposedcasting yard for the Engineer to inspect the facilities available. Theproposed sub-contractor shall demonstrate that he has the capacity tosupply the tunnel linings in accordance with the specification and

programme.

c) The Contractor shall ensure that the casting yard shall permit anyrepresentative of the Engineer, whether Company staff, a consultant orother independent inspector, full and unrestricted access to the castingyard facilities, including all records relevant to the Works and shall co-ordinate and assist such representative in his duties.

26. Concrete for Precast Segments

The mix design shall be selected by the Contractor to suit his chosen workmethods but shall achieve a minimum of 60 N/mm2 at 28 days. A dosage of

5% (minimum) to 10% of silica fume shall be used in the mix design. Testcubes shall be subjected to the same curing process as that proposed for thelining segments. The general requirements of Section 7 shall also apply.

(i) Cement

The type of cement used shall be selected having regard to the soil andgroundwater analysis in accordance with the design criteria. The type ofcement used shall be high slag blast furnace cement conforming to BS EN197-1, containing not less than 74% slag by mass of nucleus or combinations


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of Portland cement conforming to BS 12 with ggbs conforming to BS 6699where there is not less than 70% ggbs and not more than 85% ggbs by massof the combination.

The nominal cement content of the concrete shall not be less than 370 kg/m

3

and shall not be greater than 400 kg/m3 including silica fume.

(ii) Water Cement Ratio

The maximum free water/cement ratio shall not exceed 0.35.

(iii) Admixtures

An approved superplasticiser may be incorporated into the mix to ensure thatthe minimum possible water/cement ratio consistent with the Contractor's

workability requirements is achieved.

(iv) Aggregates

Aggregates for use in concrete shall conform in all respects with BS 882:1983and "Aggregates from natural sources for concrete".

(v) Water

Water shall be clean and free from harmful matter. If taken from a source otherthan the Public Utilities Board, water shall be tested in accordance with BS

3148:1980 Methods of test for water making concrete".

(vi) Rapid Chloride Test

Concrete shall satisfy the Rapid Chloride test of ASTM C1202-97 StandardTest Method for Electrical Indication of Concretes Ability to Resist Chloride IonPenetration. The acceptance criteria is an average 700 coulombs charge orbetter and not to exceed 1000 coulombs. The Contractor shall carry out aminimum of three preliminary tests prior to production to demonstrate that theproposed mix is appropriate. For at least the first five sets of production tests, 1in 20 rings shall be tested by taking a sample from both the internal andexternal faces of a segment. Once it is determined which is the worst face only

this face needs to be sampled. Once the test results indicate that theproduction concrete is of an acceptable quality and not before the first five setsof production tests have been completed, the Contractor may apply to theEngineer for a reduction in test frequency to 1 in 150 rings.

27. Reinforcement

Steel bar reinforcement shall be deformed high yield bars to BS 4466.


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The Contractor shall submit to the Engineer for approval his proposals forachieving the requirements for durability as specified.

28. Curing of Concrete in Segments

a) All precast concrete segments shall be cured using either moist curing,curing compounds or curing at elevated temperatures or a combination ofthese systems to the acceptance of the Engineer. The Contractor is tosubmit his proposals to the Engineer for approval prior to commencementof casting.

b) Where moist curing is used all exposed concrete surfaces shall becovered with hessian or similar fabric kept thoroughly wet throughout theprocess. Alternative a fog spray may be used or polythene sheet laid incontact with the wet concrete. Other proposals may be made by theContractor for the acceptance of the Engineer but the adopted method

shall be keep the surface of the concrete continuously moist untildemoulding.

c) Moist curing shall be accomplished in such a way that excess water shallbe available to the concrete throughout the curing process. It shall becarried out in an enclosed environment that protects the segments fromthe drying effect of wind and the sun and shall continue for a minimumperiod as required in Section 7 of this Specification.

d) Where used, curing compounds shall be applied only and immediatelyafter demoulding the segment and shall meet the requirements of ASTMC156-65. Moist curing shall be continued until the first coat of curingcompound is applied to all relevant surfaces.

e) For low pressure steam curing sufficient steam jets or steam-entry pointsshall be provided to ensure that a substantially uniform temperature ismaintained under the steam covers (such that the difference intemperature between any two points adjacent to the concrete mass is notmore than 10oC).

f) Under no circumstances during steam curing shall steam jets be allowedto impinge upon any part of the concrete mass or of a test specimen or oftheir formwork or moulds nor shall any steam delivery pipe be attacheddirectly to any formwork or moulds in such a manner as may causelocalised overheating of the concrete.

g) Where steam curing is to be used the steam covers shall be placed overthe concrete mass immediately following the concrete finishingoperations to prevent drying out. The concrete shall remain undisturbedand shall not be exposed to steam until it has reached a minimum initialstiffness of 0.5N/mm2 penetration resistance when tested in accordancewith SS 320: Specification for Concrete Admixtures. During this periodthe temperature at the surface of the concrete mass shall not exceed35oC. All concrete shall have an initial maturity of 1 hour before steammay be admitted to the steam covers except that, where necessary, asmall amount of steam may be used to maintain the concrete at thetemperature at which it was placed.


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h) The maximum rate of temperature rise under the steam covers shall besuch that the temperature at any time does not exceed the temperaturewhich would be predicted at that time for a uniform increase in

temperature at the rate of 24

o

C/h. In addition, the temperature rise in anyone 15-minute period shall not exceed 6oC.

i) Steaming during steam curing shall continue until the pre-determined

maximum temperature under the steam covers is reached. The steamsupply shall then be reduced so that this temperature is not exceededand steaming shall be continued until the required concrete propertieshave been obtained. Under no circumstances shall the maximumtemperature exceed 70oC for normal weight concrete.

j) On completion of the steaming period which shall be at least 6 hours,and if the concrete has reached the specified strength, segments may beremoved from the moulds. If there is visible evidence that any steamcured segments may be damaged by thermal shock or differential cooling,steam covers shall be left in place on completion of the steaming cycle,or replaced after removal of the element, until the temperature at thesurface of the concrete mass has fallen to within 20oC of the ambient

temperature.

k) If precast segments are exposed to ambient conditions immediately aftersteam curing the temperature change from curing to exposure toatmospheric conditions shall be regulated.

l) Alternatively an additional curing compound coat shall be applied to allfaces of the segment and it shall be demonstrated to the acceptance ofthe Engineer that the strength of all segments so treated is at least that ofstandard cured segments.


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m) If low pressure steam curing is used to reduce the demoulding periodprior to moist curing, the incompletely cured hot segments shall bewrapped in an impermeable plastic membrane and allowed to coolnaturally to ambient temperature. The segments shall then be subjected

to a full period of moist curing as described in this Specification.

29. Casting Tolerances for Segmental Concrete Lining

The Contractor may propose more stringent tolerances as may be required tosuit his chosen design method. However, the following tolerances should notbe exceeded:

(i) Arc lengths of circumferential 2 minutes of arc

(ii) Segment thickness +3 mm - 1 mm

(iii) Deviation of circumferential faces fromtheoretical circumferential planes 1 mm

(iv) Width of segment 1 mm

(v) Circumferential faces to be parallel to totheoretical planes along any radial line

0.5 mm

(vi) Square of circumferential face to inside face ofsegment

0.5 mm

(vii) Inside face of segment relative to theoretical 1 mm

(viii) Out-of-square of mean surface of end facesrelative to theoretical circumferential planes

1 mm

(ix) Deviation of end faces from mean surface 0.5 mm

(x) Diameter and position of bolt holes 1 mm

(xi) Edges of grooves for waterproofing gasket andsealing strips in end faces to match grooves incircumferential planes

1.0 mm

(xii) Width of groove for waterproofing gasketsealing strip

+0.3mm - 0 mm

(xiii) Depth of groove for waterproofing gasket/sealing strip

+0.2mm - 0 mm

The Contractor shall provide substantial steel templates to the approval of theEngineer for the control of the production of segments to the requiredtolerances. Illustration of construction tolerances for segmental concrete liningis given in Appendix B.


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30. Moulds and Surface Finishes

a) Moulds shall not be of timber or materials which may warp throughexposure. The dimensions of all segments shall be strictly in accordance

with the Drawings and Specification and segments shall be freelyinterchangeable so that they can be properly and easily bolted togetherat the longitudinal and circumferential joints to provide complete ringswithin the specified tolerances.

b) All formed surfaces shall have a Type C finish in accordance with BS8110 Clause 6.10.3.

c) All unformed surfaces shall be steel float finish with only the minimum ofsurface working, consistent with the requirement to achieve a smoothlevel uniform surface, being employed.

d) The contractor shall provide new mould for preparing the tunnel

segments. The life-cycle and dimensional tolerance of the mould shall besubmitted to the Engineer for approval. All segments are to be fire rated.

e) The moulds shall be fully checked by an independent party forcompliance with the requirements for dimensional tolerance and theresults accepted by the Engineer prior to the moulds being shipped.

31. Trial Assembly

a) All units of the same type shall be interchangeable and the dimensionsfor each unit shown on the Drawings shall be accurately reproduced

within the tolerances previously specified.

b) Before bulk manufacture is commenced the Contractor shall assembleand bolt together on a flat level base accepted by the Engineer segmentsto form three rings of lining in the presence of and to the satisfaction ofthe Engineer. The rings are to be built one above the other and breakingjoint by approximately half a segment. No packing or gaskets are to beused in the joints between segments in these check rings. The lowestring shall be retained as a master ring for the duration of the Contract.The segments forming this ring may be selectively hand picked and thesegments for the other two trial rings shall be picked at random.

c) From time to time, as the Engineer may direct, segments picked at

random shall be built to form rings on the master rings to ensure thattolerances and interchangeability of segments are being maintained.

32. Identification

The following information shall be 'cast' on the internal (concave) surface of allsegments:


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(i) SPPA - followed by the Contract No.

(ii) Date of Production

(iii) Mould Number

(iv) Ring Type e.g. Left or Right Taper

(v) Segment Type e.g. - Ordinary, Top, Key

In addition indents or dimples to identify future drilling points for bolt fixingshall be indented into the inner surface (intrados) of every segment.

The indents or dimples (typically 3mm max. depth) are to be shown on thecentre-line of the segments and to be located to avoid reinforcement bars bythe minimum cover specified.

Each end of the segments shall be clearly marked to ensure matching oftapers.

33. Handling

The Contractor shall make all arrangements for the proper delivery, handlingand stacking of the segments. Segments shall be handled in such a manner asto avoid overstress or damage. Segments which are found on inspection to bedamaged or substandard on delivery to the Site shall be indelibly marked andremoved from the Site.

34. Waterproofing Gaskets

a) All segments shall be provided with a water sealing system consisting ofEPDM (Ethylene Propylene Diene Monomer) gasket and hydrophilicrubber fixed to the complete perimeter of the segment. The minimumthickness of the hydrophilic rubber for the EPDM shall be 1mm.

b) The gasket shall be bonded to a groove formed in the concrete surfaceby an adhesive in accordance with the manufacturers recommendations.

c) The gaskets shall have the following physical properties:

A minimum volume increase of 10 times in clean water (for hydrophilic

rubber only) Resistance to acids to pH3

Unaffected by sustained exposure to operating temperatures of 40oC

d) The selected gasket shall have a proven reputation for satisfactoryperformance in tunnels with similar ground water pressure and full detailsof test results shall be submitted to the Engineer for his approval.

e) The installed gasket shall enable the tunnel lining to comply with thepermitted leakage rates given in the Design Criteria.


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g) At least three further samples of the proposed EPDM material shall besubjected to accelerated stress relaxation tests at elevated temperaturesof 60oC, 80oC and 100oC. The residual compressive stress in thedegraded specimens shall be measured at intervals of 1, 7, 14, 28, 56and 90 days in accordance with the general procedural requirements ofDIN 537 Sept 85 Method B or other procedure to the acceptance of the

Engineer. Based upon the results of these tests the projected residualcompressive stress in the EPDM material after a 120 years design life ata service temperature of 25oC shall be calculated in accordance with lessthan 65% of the short-term compressive force if the fresh material whenmeasured at a temperature of 25oC.

h) The hydrophilic facing material shall be vulcanised polychloroprenerubber formulated with hydrophilic polymers. The formulation of thehydrophilic material shall provide good water expansion properties withthe minimum of leaching of the active materials.

i) The hydrophilic material shall exhibit at least a 6-times volumetricswelling when immersed for a period of 28 days in clean tap water.

Further the hydrophilic material shall exhibit at lest a 4-times volumetricswelling when immersed for a period of 28 days in a salt water solutioncontaining 1% chloride ions and 0.5% sulphate ions measured as SO3.

j) A sample of the hydrophilic material shall also be weighed and thenfreely immersed in distilled water for a period of 28 days. On completionthe sample shall be oven dried at 50oC until no further weight change inrecorded. The percentage weight change after the wetting and dryingcycle shall not exceed 6% of the original weight.

k) Both the EPDM and hydrophilic material shall be resistant to acidity atleast as severe as pH5 and shall be unaffected by sustained exposure tooperating temperatures of up to 40oC.

l) The Contractor shall provide the Engineer with a detailed statementregarding the durability of the proposed materials demonstrating theirability to meet the specified performance criteria for the design life of thestructure. The material shall provide any further information and test datarelevant to the water absorption, long term swelling capacity, relaxation,chemical resistance and ageing of the materials. In particular thematerials shall be resistant to attack from all substances in the groundand groundwater at the concentrations found in the site investigation, tothe alkalinity of the tunnel lining concrete and tunnel grout and shall beresistant to microbiological attack. The statement shall include a list of

after a 120 years design life at a service temperature of 25oC shall becalculated in accordance with Arrheniuss Theory. This projected valueshall not differ by more than 35% from the short term elastic modulus of

f) At least three samples of the proposed EPDM material shall be subjectedto accelerated ageing tests at elevated temperatures of 60oC, 80oC and100oC. The elastic modulus of the degraded specimens shall be

measured at intervals of 1, 7, 14, 28, 56 and 90 days. Based upon theresults of these tests the projected elastic modulus of the EPDM material

the fresh material when measured at a temperature of 25oC.


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substances known to be deleterious to the materials, together with ananalysis of the risk of contact with such substances.

m) The Contractor shall ensure that the grout is not permitted to penetrate to

the gasket location as this would impair its function.

n) The selected gasket shall have a proven reputation for satisfactoryperformance in tunnels with similar ground water pressure.

o) The Contractor shall design, supply and install the gaskets and anygrooves into which or the surfaces onto which they fit to the acceptanceof the Engineer. They shall be in the locations shown on the Drawings oras otherwise accepted by the Engineer.

p) The Contractor shall carefully detail the size and depth of the gasketgroove to ensure that it is of sufficient volume that when the segmentfaces are fully closed, the volume of rubber in the gasket can be housed

within the groove. Unless otherwise accepted by the Engineer thevolume of the gasket groove shall be at least 5% larger than the volumeof rubber in the gasket. Where compressible joint packings aresystematically incorporated between the joint surfaces the compressedthickness of the packing may be considered in the calculation of thevolume of the gasket groove.

q) The gaskets shall form continuous loops (frames) around the segmentsand shall be bonded to the concrete surface with adhesivesrecommended by the gasket manufacturers and following the proceduresrecommended by the adhesive manufacturers.

r) The design of the gaskets shall be such as to render them inherently

resistant to damage during transport and erection of the linings.

s) The Contractor shall provide drawings of the principal dimensions andproposed tolerances on the gaskets. The drawings shall include thedimensions and positions of the gasket grooves or mounting surfaces.

t) The corners of the gaskets shall be moulded to the appropriate cornerangles of the segments. Detailed drawings of all segments shall besupplied by the Contractor to the gasket manufacturer. The corners of thegaskets shall be designed to ensure that the volume of rubber remainsconstant and that they have the same load and closure forces as themain body of the gasket. The corners of the gaskets shall be subject tofull opening and closure tests to ensure the integrity of each joint.

u) The gasket manufacturers shall be ISO 9001 (or equivalent national orinternational quality standard) certified and shall have in place detailedprocedures to ensure the quality control of the gaskets at each stage oftheir testing and manufacture.

v) The Contractor shall prepare detailed works procedures to cover theinstallation of the gaskets and the storage of segments to which thesehave been fitted. These procedures shall be developed from therequirements of this Specification and incorporate installation detailsdetermined from the literature of the manufacturers of the gasket and


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adhesive. These procedures shall be prepared for the information of theoperatives engaged on the Works and as far as practical shall be in theformat of cartoon drawings and diagrams illustrating the correct action ateach stage of the procedure. They shall include details of the accuracy

with which the gaskets have to be installed in order to obtain theperformance achieved in the tests. The method statement shall includedetails of how the segments will be installed in the tunnel without damageto, contamination of or displacement of the gaskets. Lubricants shall beproposed and used to the acceptance of the Engineer. Any lubricantsshall be as recommended by the supplier of the gaskets.

w) Prior to commencing manufacture of the gaskets prototype samples foreach segment type shall be subject to fitting trials in order to determinethe optimum tension for the gaskets. Each gasket shall be lightlytensioned to ensure that it grips the segment and fits snugly into thegasket groove. Corners of the gasket shall be square and tight fitting.These trial fittings shall be conducted by representatives of the gasket

manufacturer and witnessed by the Engineer.

x) Installed gaskets shall be free from surface imperfections, voids,inclusions or flow marks and other defects which would impairsatisfactory performance. The surfaces shall be smooth. Fabricationjoints in the gasket material shall be made with such accuracy as not toimpair satisfactory performance in the tunnel environment.

y) Prior to installation gaskets shall be stored under cover in a dry storagearea in an undeformed relaxed condition at moderate temperatures andprotected from direct sunlight. They shall be protected from circulating airand shall not be stored near equipment that can generate ozone (such aselectric motors). The gaskets shall be kept clean, particularly avoiding

contact with metals, solvents, oil and grease.

z) The Contractor shall specify the type of wrapping and packing heproposes for the gaskets and the conditions under which they will bestored. All deliveries shall be marked with the date of production andearly deliveries shall be used first to minimise storage times.

aa) If cleaning of gaskets is necessary only those approved for such use bythe manufacturer of the gaskets shall be accepted.

bb) Fitting of the gasket frame shall commence at the radial joint surfacesneatly pressing the gasket into the groove or on to the surface by hand.The circumferential joint surfaces shall then be fitted starting from the

middle and working towards the two corners on each face. Care shall betaken to ensure that the frame is accurately located and that the cornersare neither distorted nor loose. The frame may be lightly hammered intoposition using a rubber hammer and shall then be pressed onto thesurface for a minimum period of five minutes until the adhesive hashardened.

cc) Unless otherwise accepted by the Engineer gasket frames shall not beinstalled onto the segment prior to seven days before their installationinto the tunnel. Each completed segment shall be inspected for correctseating of the frame and uniform adhesion prior to storage. Completed


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segments shall be protected from precipitation and direct sunlight.Completed segments shall be stored under covered conditions ortarpaulins prior to installation in the tunnel.

35. Performance Testing of Gaskets

a) The Contractor shall provide a test rig or rigs and carry out tests of thegaskets in Singapore to demonstrate the water tightness of the system.Tests shall be witnessed by the Engineer. The gasket-mounting surfacesof the test rig platens shall be fabricated or finished in cement mortar andshall incorporate grooves and/or mounting surfaces of the samedimensions as those on the lining segments. The gaskets shall beinstalled in the same manner as those on the lining segments usingsimilar adhesives and installation procedures.

b) A series of tests shall be conducted for each gasket type. The tests shall

be carried out using water with chemical content equivalent to theconcentrations found in the ground water in the site investigation whichwill most impair their performance.

c) Each test series shall comprise the testing of a straight joint, a T jointsuch as occurs at the intersection of a radial joint and a circumferentialjoint in the tunnel lining and a cross joint. The configuration of the test rigshall be such that it can accurately simulate the combination of gaps,steps and lips defined herein.

d) The gap between the faces of the test pieces, representing gaps in thejoints of the tunnel lining, shall be 5mm greater than the theoretical valuecalculated from the shape of the joint surfaces and from the thickness of

any packing which is to be used. The tests shall be performed with alateral offset of 10mm at the groove in the following configurations.

(i) Straight joint: one side offset

(ii) T joint: one side of intersecting joint offset

(iii) Cross joint: one side of intersecting joint offset

e) The gasket test pressure shall be defined as twice the design hydrostatichead. Unless otherwise accepted by the Engineer, the design hydrostatichead shall be considered to be the maximum distance between the invertof the tunnel and the ground surface.

f) The test pressure shall be applied in 1.0 bar increments by means of avariable pressure reflux valve or other stabilising device, capable ofmaintaining the applied pressure within 1% of the desired pressure ateach pressure increment. The pressure shall be held for 15 minutes ateach increment. The final pressure shall be held for 24 hours duringwhich no visible sign of leakage shall be noticeable.

g) If the Contractor envisages that gaps larger than those indicated abovewill occur in the tunnel, due for example to the use of thicker packings,then the Contractor shall carry out tests with an appropriately larger gap.


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Only those gaps shall be used in the Works that are covered by arepresentative test.

h) The Contractor shall demonstrate that when the joints are closed to the

fullest extent that will occur in the Works, no damage will be caused tothe tunnel lining segments by the gaskets. The fullest extent that willoccur in the Works shall be deemed to be:

In the circumferential joints - Closed to the maximum extent that willbe allowed by the packings in the joints.

In the radial joints - Joint closed by the maximum extent that will beallowed by the gaskets

i) The Contractor shall provide evidence that with smaller joint gaps andoffsets than those specified above, the water pressure that can bewithstood by the gaskets will not be less than the specified test pressures.

This evidence can be in the form of further testing or certified results ofprevious tests on identical gaskets.

j) For hydraulic materials test results of volumetric change with time inclean fresh water shall be provided by the Contractor.

k) The Contractor shall prepare a prototype key/top plate test rig anddemonstrate that when fully compressed into the gasket groove thegasket surfaces may slide relative to each other without causing slippageof the gasket within the groove or on the mounting surface, unduedistortion of the corners of the gasket or, delamination of the hydrophilicfacing material from the EPDM carrier. The same lubricant material thatwill be used in the tunnel during the erection of the segments shall be

employed during the test. The test shall be repeated at increments oflipping between segments of 0, 5 and 10mm.

l) The Contractor shall prepare steel loading platens at least 100 mm inlength provided with grooves or mounting surfaces of the samedimensions as those on the lining segments. The gaskets shall beinstalled in the same manner as those on the lining segments usingsimilar adhesives and installation procedures. The Contractor shalldetermine the force required to compress the gasket during erection andprepare graphs of load and deflection. The Contractor shall ensure thatthe segment erector has sufficient power to compress the gasket on theradial joint surface and confirm that the tunnel lining bolts have adequatestrength to provide and maintain this force.

m) The Contractor shall also demonstrate by appropriate testing that whenfully compressed, the gasket corners do not deform to such an extentthat its sealing capacity reduced to less than the minimum requirementas defined herein.


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36. Packings

a) Compressible packing may be incorporated into all joint surfacesbetween segments. The packer material and details shall be selected by

the Contractor and submitted to the Engineer for approval.

b) Packing shall be formed from fire retardant material and shall not give offtoxic fumes in the event of a fire.

c) Packing shall generally be glued to the surface of the segments prior toerection, though insertion of packing for correction of plane will bepermitted during segment erection provided that safe working practicesare employed. Any glue used shall be non-flammable and suitable foruse in a confined space irrespective of the ventilation provided in thetunnel.

d) Non-compressible packing may only be used to correct for out-of-plane of

the segments. In all cases where packings are used the performancerequirements of the hydrophilic gasket shall be taken into account.

e) The Contractor shall maintain records that show the materialconsumption of the epoxy coating per segment. At all times these recordsshall be available to the Engineer.

37. Metalwork

Cast in fixings shall be of mild steel complying with BS 4360 and galvanised inaccordance with BS EN ISO 1461 or shall be in stainless steel.

Bolts, nuts and washers shall be of a steel grade as determined by theContractor in his detail design, and shall be sheradised in accordance withClass S1 BS 7371 Part 8.

38. Waterproof Coatings

a) The outer (convex) surface of all segments together with all side faces,gasket recesses, caulking grooves and insides of bolt holes and groutholes shall be painted with a solvent free or water based emulsion epoxycoating.

b) All epoxy materials shall be stored, mixed and applied in strict

accordance with the recommendations of the coating manufacturer.

c) Surfaces shall first be primed with either a penetrative primer, which maybe non-pigmented, or a thinned coating of the under coat of epoxy.

d) The waterproof coating shall then be applied in at least two further coats.When applying one coat of epoxy coating over another the top coat shallbe applied to the preceding coat within the time period for over-coatingstipulated by the manufacturer and generally in a direction perpendicularto the preceding coat. The top coat shall be a contrasting colour to thepreceding coat.


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e) When tested in accordance with DIN 1048 the epoxy coated surface shallhave a permeability of 3000 and an Equivalent Air LayerThickness of


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coats of material shall then be re-applied in a manner which is to theacceptance of the Engineer.

n) Where the dry film thickness is less than the minimum specified

requirement a further coat shall be applied in accordance with themanufacturers instructions to achieve the specified thickness. Theadditional coat shall comply with the overcoating requirements.

o) The contractor shall prepare and submit a method statement for a trialapplication to the acceptance of the Engineer. The contractor shall givethe Engineer 48 hours notice of his intent to commence the trialapplication.

p) A concrete panel shall be coated in accordance with the Specificationand the accepted method statement. The coated surfaces shall then beinspected for compliance.

q) The Engineer will only accept the proposed method of application of thecoating if the Contractor has demonstrated competence in using both theepoxy coating material and the application equipment. Productionapplication shall not proceed without the acceptance of the Engineer.

r) If the coatings are deemed not to comply the coating operation shall berepeated using a fresh concrete panel until compliance with theSpecification has been demonstrated and the method statementamended as appropriate.

s) The work practices adopted during the trial shall be adopted for allsubsequent coating application operations.

t) The Contractor shall supply material safety data sheets for allcomponents of the epoxy coating. The Contractor shall store, handle, mixand apply the coating in strict accordance with the material safety datasheets.

u) Particular care shall be paid to all health, safety and environmentalstatements contained in the material safety data sheets.

v) Products which are excess to requirements or which have exceeded theirshelf life or which the Engineer has not accepted for whatever reasonshall be disposed of in a safe and controlled manner. Empty packagingmay contain harmful residues. In any case disposal shall be arrangedthrough a licensed waste contractor in accordance with the current local

waste disposal regulations.

w) The properties of the epoxy resin coating shall be as follows:

- Pot life at least 30 minutes at 30C- Safe from exposure to rain after a minimum of 4 hours of storage at

30C- Solids content minimum 50%, maximum 55% by volume. This shall

be confirmed by the Contractor with an independent test report froman accredited laboratory

- A contrasting color for each coating shall be used. Colors are to be


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to the acceptance of the Engineer- Coverage rate 200 to 250 g/m2 per coat to provide a minimum total

dry film thickness of 200 microns- Fully compatible with the gasket adhesive

x) Alternative specifications may be proposed by the contractor for theacceptance of the Engineer.

39. Surface Preparation and Repair (in Casting Yard)

a) All blowholes, spalling of edges and gasket grooves and minor damage inthe formed concrete surfaces shall be filled with a fresh speciallyprepared cement mix whilst the concrete is still green to produce a TypeC finish to SS CP 65.

b) Cement mortar shall be used incorporating Styrene Butadiene Rubber(SBR) or Polyvinyl Acetate (PVA). Alternatively, polymer modified cementbased mortar shall be used in accordance with the requirements of SSCP 65.

c) Surface preparation is not generally required but contamination such asmud, dust, mould oil, grease or other substances that may adverselyaffect the bond of the coating to the concrete shall be removed by hosingand/or detergent scrubbing and/or high pressure water jetting as may berequired, all to the acceptance of the Engineer.

d) All projecting fins of hardened grout such as may occur at the jointsbetween the sides and base of the mould shall be removed by grinding.

e) All segment repairs carried out at casting yard shall be recorded andreported to the Engineer. Repairs shall be carried out in accordance withthe requirements in Appendix A.

f) Sufficient time shall be allowed for the cementitious mortar to cure prior toepoxy coating of the segment surfaces.

40. Segment Repair in Tunnel

All segment repairs shall be carried out to the acceptance of the Engineer.Detailed records shall be kept of each repair noting the position and type of

repair and the materials used. Materials shall be submitted to the Engineer foracceptance. All segment repair materials shall be tested prior to use in thetunnels to ensure their workability and colour compatibility with the segmentallining.

technical requirements for segement

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