The Design and Construction of No8 Dry Dock at North Shields for Smith's Dock Co. Ltd.

8/12/2019 The Design and Construction of No8 Dry Dock at North Shields for Smith's Dock Co. Ltd.

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BURNS ON THE DESIGN AND CONSTRUCTION OF NO. 8 355DRY DOCK AT NORTH SHIELDS FOR SMITHS DOCK CO. LTD

MARITIME AND WATERWAYS ENGINEERING DIVISIONMEETING

1 February, 1955Sir Arthur Whitaker, Member, Chairman of the Division, in the Chair

The following Paper was presented for discussion and, on the motionof the Chairman, the thanks of the Division were accorded to the Author.Maritime Paper No. 28

THEDESIGN AND CONSTRUCTIONOF NO. 8 DRY DOCKATNORTH SHIELDS FOR SMITHS DOCK CO. LTD

by* Thomas Frederick Burns, M.I.C.E.SYNOPSIS

The Paper deals with the construction of a new No. 8 dry dock a t North Shields forSmiths Dock Co. Ltd, a deep-water quay forming an extension of the existing quay,tankers.and the facilities necessary for the docking and repair of large ships, particularly oil

Steel sheet-pilingwas used for the dock and quay walls in view of the apparentlysuitable ground conditions.An underground pump-housewas built near the dock entrance insidea cofferdam ;the difficulties of construction and their consequences are described.The dewatering pumpingplant is operated throughan anti-siphonic system whicheliminates the use of sluice and reflux valves.A Box flap gate, believed to be the largest yet constructed, was installed to closethe entrance.The provisions for ancillary services are dealt with.An arch-dam cofferdam of steel sheet-pilingstiffened by arch ribs was constructeda t the dock entrance and theuse of a temporary abutment for i t is described.

INTRODUCTIONPOST-WARevelopments in the oil industry, and the resultant onstructionof many large oil tankers of between 26,000 and 45,000 tons deadweight toserve the new refineries in Britain and abroad, ave given the ship-repairingindustry much concern. These vessels are becoming due for survey in drydock, but available docking facilities owned by commercial concerns arerelatively few.Smiths Dock Co. Ltd, as one of the premier tanker-repairing firms,foresaw this situation n 1949, and the Authors firm was asked to advise

* The Author is a Partner in the irm of T. F. Burns Partnerm. London.


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356 BURNS ON THE DESIGN AND CONSTRUCTION OF NO. 8on the siting and construction of a new dock of adequate dimensions forsuch ships, together with all facilities necessary t o execute. their efficientrepair. These facilities included a comprehensive system of services,cranes, pumping equipment, boiler house, transformer station, and elec-trically operated lift fromdock bottom to theplaters shed area at the topof the bank, where the workshop area is located.

At that time it is believed the largest tanker being built was of 26,000tons deadweight and estimates were prepared for docks of various dimen-sions. After full consideration of further possible developments it wasdecided that the principal dimensions of the dock should be 700 feet long,95 feet wide a t the entrance with adepth of 27 feet below H.W.O.S.T. overthe sill, and that provision be made in the tenderdocuments for an alter-native price for a dock 650 feet long, the other dimensions being unchanged.It is to be noted that the imensions for the shorter dock coincide with thosementioned in the Memorandum on Construction and Equipment of DryDocks, subsequently issued by the Institution in 1952.

In view of the relatively small saving for the reduction of 5 0 feet inlength it was decided that 700 feet was justified and the contract was letfor a dock of this length. During the course of construction it was, how-ever, decided to extend the dock to a total length of 709 feet by makingminor modifications; the other dimensions remained unchanged.In a Paper read before the Institutionof Naval Architects 1 Champnessdiscussed the shortage in Britain of dry docks to accommodate the largertankers and outlined the facilities which he considered necessary for theexecution of efficient repairs ; many of these facilities had already beenembodied in the scheme described in the Paper.

The dock as built is capable of taking a 38,000-ton d.w. tanker withample working space and has ull facilities for extensive repair works.

Tenders were invited in August 1950 and the contractwas awarded toHolloway Bros (London)Ltd. Work nominally started in December 1950and was completed in June 1954. The dock was officially opened by theFirst Lord of the Admiralty, The Right Honourable Mr J. P. L Thomas,M.P., on the 18th June,1954.

SITEThe site of the work is on the north bank of the River Tyne about 2

m i l e s from its mouth and t theupstream end of Smiths Dock CO.Sdock-yard (see Fig. 1, Plate 1).To provide a satisfactory approach or large ships entering the dock andto reduce the amount of land which had to be acquired, the centre-line ofthe dock was set a t an ngle of 28 degrees to theriver face of the existingdeep-water quay, a80-footextension of which was included in the contract.

E. L. Champnesa, Large Dry Docks. Trans. Instn Nav. Archts, vol. 95,p. 2331(July 1953).


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DRY DOCK AT NORTH SHIELDS FOR SMITHS DOCK CO. LTD 357This location and alignment also had the advantage that it disturbed

relatively little of the existingdockyard facilities apart from the oldpontoon dock which, although more than 60 years old, was in use up to thedate of commencement of the construction work. Thesite of the con-structional works was almost entirely divorced from the dockyard.An old timber water-boat jetty mmediately upstream of Smiths DockCo.s premises was demolished and thewest roundhead to the ock entrancenow extends over this area. Facilities for the water boats were transferredto the adjacentTyne Improvement Commissions jetty.

The ground rises steeply to a level of about +SO.O O.D., that is, about48 feet above coping level of the dock, and about 250,000 cubic yardsof excavation was necessary to reduce the general ground level to copinglevel +12.50 O.D.).

One road belonging to he Tyne Improvement Commission givingaccess to the Albert Edward Dock and the public road to Robson Millerssaw mills, together with the various services, had to be diverted clear ofthe site before the main construction work began.

SITE INVESTIGATIONSEight borings were made by Soil Mechanics Ltd, the results of which

are illustrated in Pig. 2, Plate 1. Their locations are shown on the generalplan of the dock in Fig. 3, Plate 1.In general, these penetrated to about 25 feet below the bottom of the

dock floor and showed thick deposits of firm sandy clayey silt witha gravelmatrix and occasional sandstone boulders. Thin sand layers or pocketsa t irregular intervals existed a t various levels but, with this exception, theboreholes showed continuous boulder clay throughout the full depth.

No water was found in boreholes Nos 1,4 a),5, 6, and 7 during boring.In boreholes Nos 2,3, and 4 iver water was present throughout the boringand thewater levels varied with the tide.The shear value of the boulder clay ranged between 1,300 and 9,300lb. per square foot.Near the dock entrance where shear values of 2,000 lb. per square footexisted at formation level the ultimate bearing capacity was estimated a t5 tons per square foot and near the dock head where shear values of 6,000lb. per square footwere obtained, an ultimate bearing stress of 15 tons persquare foot was estimated.

Observations of the existing banks showed that, in general, they hadstood formany years at a slope of 1 :1.5and itwas, therefore, decided thatthe newly excavated slopes should be similar. Some previous pitchedslopes had stood a t a slope of 1 : 1. Calculations were made, however, onthe slip-plane theory and these gave a factor of safety of a t least two,assuming a shear resistance of 2,000 lb. per square foot.


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358 BURN: O N THE DESIGN AND CONSTRUCTION OF NO 8TIDALDATA

The spring tidal range inhe River Tyne is 15 feet and rdance Datumisapproximate mean tide level; H.W.O.S.T. is +7.92 and L.W.O.S.T.-7.08 O.D. Coping level of the dock and deep-waterquay s 12.50O.D., which is the level generallyadoptedby the TyneImprovementCommission.

Extreme high tides have reached a evel of about +l2.0 a t the SwingBridge, Newcastle, bu t at the ite the highest tide was estimated a t +11.0O.D.

DesignDOCKWALLS

The mass f ilrm impermeable trata revealed by the orings encouragedthe idea that a departure from the onventional mass-concretewalls was afeasible proposition. It was considered that this would reduce the cost ofthe dock very substantially, saving not only the cost of the gravity con-crete wall but also the expensive renchexcavation and temporaryrevetment of the earth faces by sheet-piling, or such like. Capital costsin such projects are obviously of great importance, particularly when adock has to pay itsway as a commercial proposition.

The idea was developed and steel sheet-piling was adopted for per-manently revetting the face of the dock below the subway construction.The dock profile was the subject of much consideration and t was decidedthat two upper altars for strutting and wo bilge altars would be adequate.In Fig. 4,Plate 2, is shown a typical cross-section.

Corrosion of the piling was seriously considered but, afterdrawing uponthe knowledge of various authorities and the piling company, i t was con-sidered tha t the risk of corrosion on the back, or earth face, of the pilingwas unlikely to be serious, bearing in mind the apparent impermeabilityof the ground retained. Drillings were made at t w o levels in some steelsheet-piling very lose to the ite and t was found that the orrosion during15 years was rather less than is generally expected. The dockside face ofthe piles could obviously be maintained adequately without any difficultyand Smiths Dock Co. decided to accept the scheme.

Protection of the piling generally by cathodic methods was consideredand may be applied after the results of experiments now being carried outin the Tyne and elsewhere have been fully analysed.No satisfactory methodof calculating the probable stresses inhe pilingappeared to be available for the prevailing ground conditions.

An analysis based on water pressure to mean tide level, with lateralpressures from the clay deduced from Bells formula, gave a maximumtheoretical stress in he piling of only about 3.3 tons per square inch.

In view, however, of the probability of hard driving, the possible effectsof softening of the clay, and theoverriding desire to have an ample reserve


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36 BURNS ON THE DESIGN AND CONSTRUCTION OF NO. 8The designof the length of about 220 feet of dock wall on the south-east

side, which was not constructed in virgin clay, was similar in principle butthe tie-rods were linked with those forming the anchorage of the deep-water-quay piling described later.

In this area the landward crane-trackwas formed of reinforced concretebeams carried by pairs of cast-in-situ piles raking 1 : 6. These beams alsosupport the decking between crane track and subway, whichwasalsosupported on bearing piles at therear.

DOCKLOORThe dock floor is not designed to act as an inverted arch as is usual in

the orthodox mass-concrete design. It was considered that he newlydeposited filling on the south-east dock side could not be relied upon totake the resulting thrust from the floor if designed as an arch.It was, therefore, decided to design it as a simple beamspanningbetween the sheet-piled walls with high-tensile square twisted reinforcing-bars n the top. The vertical reactions from hydrostatic pressure aretaken by the sheet-piles forming the dock walls. A bracket formed outof 14-inch-by-12-inchbroad-flange beam about 12 inches long was weldedto the piles within the floor thickness on every alternate pile to transmitthe load from floor to piles, and thereby mobilize adequate weight andfrictional resistance against uplift.

Although it was considered rather doubtful, in view of ground condi-tions, that full hydrostatic pressure would become operative on the floor,provision was made for such pressure up to mean tide level by the use ofhigh-tensile steel a t a working stress of 32,000 lb. per square inch. Thefloor was constructed in 1 :8.25 concrete throughout.

At the dock entrance the floor was 12 feet thick, reducing to 8 feet atthe dock head on the centre-line, and the corresponding side thicknesseswere 9 to 6 feet respectively.

DOCK RAINAGEIt will be noted that no drainage culverts or side channels are provided

since the atterhave been found unsatisfactory in practice, becomingclogged with dirt, refuse, etc., and the covers often being broken. In thiscase the floor is slightly depressed against the lower bilge altar so thatit can be easily cleaned. The whole floor is graded l :300 longitu-dinally to the entrance and 12-inch cross-fall is provided to the bilgealtars. A main ransversedrainage channel is provided about 40 feetfrom the entrance leading into the main sump under the pump-house.


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DRY DOCK AT NORTH SHIELDS FOR SMITHS DOCK CO. LTD 361DOCKFILLING

Pilling of the dock is effected by means of an equilibrium valve set ina concrete chamber on the west side of the dock. A 5-foot-diametercircular culvert connects the valve to themain sump under he pump-housewhich communicates directly with the dock through the dock-drainagesumps and transverse channel already described.

The filling valve was supplied and fked by Sir William Arrol Co.Ltd and consists of a vertical mild-steel cylinder 6 feet in diameter fittedwith counterweights. When the valve is closed a rubber seal attached t othe base of the cylinder is seated on the machined edge of a galvanizedangle ring set on, and bolted to, a cast-iron pipe tapering from 6 feet to 5feet. The top of the angle ring is -0.92 feet below L.W.O.S.T. so thatthe dock can be filled at any st at ef the tide.The cylinder can be raised a maximum of 18 inches by means of acapstan screw fitted in a steel cover a t coping level ; his capstan is easilyturned by two men. This type of valve has been used in other docks inthe area and hasbeen found effective and simple in use. Behind the screenstoplog grooves are provided for damming off the water when maintenanceis necessary.

The dock can be filled by this meam n 14 hour. In addition, there aretwo hand-operated 21-inch-square sluice valves in theentrance gate, whichcan be employed to accelerate the filling if required.

SERVICESUBWAYThe services are contained withina reinforced concrete subway forming

the upper portions of the dock walls and a typical cross-section is shownin Fig. 5. The subway is continuous from the pump-house on the westside to the east roundhead, where a connexion is made to the services ducton the deep-water quay. The dockside wall of the subway embodies thetwo upper altars on the outside and its nside face is thickened and steppedto provide supports for the various piped services so that each service isreadily accessible for maintenance and there is space for further servioesif required.

The rear wall of the subway is vertical and is provided with racks forthe various electrical cables ; switchgear also is mounted on this wall.

The connexions to the services in the subway are brought to a seriesof recesses on the face of the dock wall below the coping and areaccessiblefrom the top altar, thusermitting the unobstructed travel of the docksidecranes. Hinged covers are provided over these recesses for all the pipedservices. Openings are arranged a t frequent intervals for electrical cableawhich can be pulled through from connecting points inside the subway.Details of the servioes installed are given in Appendix 111.

Access is obtained by means of a staircase situated inside the boiler


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362 BURNS ON THE DESIGN AND CONSTRUCTION OF NO. 8

FIG. 6.-cROSS-SECTION OF SERVICES SUBWAY

house on the south-west dock side and therefrom by a branch subway aswell as by a number of other access points, which have removable coversand access ladders, ocated a t intervalsaround the dock. Openings,6 eet by 3feet, areprovided for the passage of long pipes for replacementsor additions, and for the installation of welding transformers which arelocated inside the subway.

The subway structure carries the dockside crane-track which is setalmost flush with the finished concrete surfacing.

Rubber expansion joints are provided at four points in the length ofthe subway.

CRANE TRACKSThe crane tracks consist of 85 lb. flat-bottom revised-section twin rails

28 inches apa rt at the heads and riveted to a sole plate 16 inches wide.The gauge of the trackon both sides of the dock is 25 feet.

Holding-down bolts Q inch in diameter were cast in the concrete inexpanded metal bolt-boxes a t 3-foot-6-inch centres. The sole plates weredrilled a t site and set , evelled, and packed with 3 inches of semi-dry whin-


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DRY D O C K AT NORTH SHIELDS FOR SMITHS D O C K CO. LTD 363stone concrete of 1 : 14 : 3 mix, Test cubes on this concrete reached astrength of 6,000 lb. per square incha t 7 days.

The groove between the rails was filled with a cement-and-sand mortarand topped up with 4 inch of Pliastic and pointed up at the sides ofthe rail-head with l Asbestumen to prevent water penetrating to theunderside of the rails.

CRANE COLLECTOR TRENCHAll dockside travelling cranes are electrically operated from 440-voltA.C. mains, and are supplied from an underground collector trench. A

continuous 2-inch-wide gap was formed for the passage of pick-up arms onthe cranes. A cross-section of this trench is shown in Fig. 6 and, in viewof its small dimensions and complexity, it was necessary to construct it inseveral stages as indicated. The top of the trench was designed for a 10-ton wheel load from a mobile crane. Insulator bays are provided a t 20-foot centres ; these are covered with galvanized-steel covers set-screwed tothe frames.

Provision is made a t the ends of the trenches for straining the copperconductor wires. The trenches are connected to the drainage system a tintervals.

DOCK NTRANCEThe entrance is formed by a concrete pier on each side. On the east

side it is embodied in the roundhead and was constructed in 1 : 8.25concrete.

On the west side it is embodied in the pump-house substructure andwas partially reinforced. An access staircase to he dock bottomhasbeen incorporated and the piers are designed to sustain adequately thepressure from the gate.

The sill is 16 feet thick and is splayed on the river side to form anapron to the dock entrance, enabling the gate to be fully lowered belowthe sill level.A line of steel sheet-piling 30 feet long was driven under the sill as a cut off with a further line about 30 feet riverwards forming the edgeof the apron. Both these lines were interlocked with the piling on bothsides of the dock.

PUMP-HOUSEND DRAINAGE SUMPThe pump-house and drainage sump were constructed near the dock

entrance on the south-west side, the pump-house being built immediatelyabove the drainage sump. The former has interior dimensions of about54 feet 6 inches by 30 feet 6 inches with a general floor level of -11.0024


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DRY DOCK AT NORTH SHIELDS FOR SMITHS DOCK CO. LTD 365O.U. and a sump floor level of -30.30 O.D. Plans and sections of thestructure are shown in Fig. 7, Plate 2.

The pump-house consists of a reinforced concrete box-structure tankedwith asphalt, the walls generally being 2 feet and the floor 4 eet thick.

The roof of the drainage sump was covered with asphalt on which thefloor of the reinforced concrete box was then constructed. The sideasphalt was applied to a 6-inch skin of concrete which was cast against thesteel sheet-piling and anchored to it by welded fish-tail lugs. The rein-forced concrete box was then completed inside the asphalt tanking.

The pump-house is partially covered a t coping level where the gate-winch platform and transformer cell are located, but generally it is builtabove coping level and a glazed roof is provided on steel framing, which isarranged to be readily dismantled if it is necessary to replace a main pumpor motor. The superstructure of the pump-house is embodied in the valvehouse and transformer cell and is designed as a comprehensive unit.

The design of the pump-house structure calls for no special comment.It was assumed that hydrostatic pressure to mean tide level wouldbepresent below theump floor. The pump-house box structure wasdesigned for water pressure up to H.W.O.S.T., which occurs when the dockis flooded, as well as for earth pressures on the walls. To provide for thecondition of exceptionally high tides a continuous anchoring band of rein-forced concrete was formed around the periphery of the walls at copmg levelto develop the necessary resistance against uplift. This band was anchoredt o the 6-inch concrete skin contiguous to the sheet-piling and by virtueof the lugs and the adhesion between the piling and the concrete it wasassumed that the extraction resistance of the sheet-piling would be mobi-lized to the necessary extent.

A switchgear gallery is included in the house a t a level of -2.00 O.D.,accommodating both high-tension and low-tension switchgear for most ofthe dock. Access stairs are provided with an entrance at the rear.

MAIN PUMPING AND ANCILLARYPLANTThere are two main dewatering electrically driven horizontal-spindle

centrifugal pumps which, when operating jointly, are apable of dewateringthe dock of 1%million cubic feet of water in 24 hours under the maximumhead conditions. This condition assumes a medium-sized ship in the dock.The overall water quantity to H.W.O.S.T. is 2,100,000 cubic feet.

There are also three 10-inch electrically operated pumps, one of whichis used as a permanent drainage pump,ne for ballasting ships n dock, andthe third can be used alternatively for dock drainage or for ballasting asmay be required. Arrangements have also been made to use one of theballast pumps for jetting silt off the apron by means of a 10-inch cast-ironheader pipe with twenty l -inch-diameter nozzles.


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366 BURNS ONTHE DESIGN AND CONSTRUCTION OF NO. 8Particulars of pumps, motors, and other plant in the pump-house are

given in Appendix I.When the scheme was originally planned the delivery time for sluice

valves of the size required was more than 3 years. To overcome this delaythe pump makers put forward a scheme for eliminating the use of sluiceand reflux valves by the formation of an anti-siphonic system for eachdewatering pump ; this scheme was ultimately embodied in the construc-tion and has operated satisfactorily.

The discharge from each main pump is taken into a reinforced concretepipe 4 eet in diameter, which is constructed in the form of a siphon andsurrounded by concrete ; it discharges into the river a t -24.50 O.D. Theinvert of the crest of each siphon is a t coping level ( +l250 O.D.) and ahydraulically operated siphon-breaking valve is fixed a t the summit ofeach siphon pipe. The hydraulic pressure is obtained by a geared-typepump chain-driven from the shaft of each main dewatering pump.

The operation of these pumps is such that when the main dewateringpump is started the hydraulic pump immediately begins to deliver oil a tpressure and closes its siphon-breaking valve located a t the top of thesiphon. When the dewatering pump is shut down the hydraulic pumpstopsand oil pressure is immediately relieved byanautomatic valvereleasing the pressure, the siphon-breaking valve opens, and thus preventswater from the river siphoning back into the dock.

There are several points in favour of the anti-siphonic system :-l )The elimination of sluice and reflux valves reduces maintenance

costs of the pumping machinery.(2) There is no need for stoplogs at theiver end of the discharge pipesfor the purpose of examining the valves on the outlet side.(3) The danger of waterhammer owing to unforeseen stoppagesduring the pumping period is eliminated.(4)The hydraulic resistance is reduced resulting in improvedpumping efficiency.

(5) A smaller advantage is that when the pumpis switched off at theend of the pumping period there is a back-flow for a fewmoments which results na wash-back through he pumpand suction piping. This clears any rubbish which might havelodged in the impeller or pump passages.

DEEP-WATERUAYThe deep-water quay was designed for a depth of water of 25 feet

belowL.W.O.S.T. and took the form of a cellular cofferdam which, inconjunction with the temporary arch offerdam, enabled the area betweenit and theexisting river bank t o be filled in the dry. It consists,of a frontline of Larssen No. 5 steel sheet-piling, 60 and 65 feet long, with a back


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368 BURNS O N THE DESIGN AND CONSTRUCTION O F NO. 8in the fendering since it was considered that blows from ships would bereadily absorbed by the mass of filling behind the piling.

ENTRANCEATEThe Box or flap type of gate was adopted and it s considered to be the

most economical of the various types for a dock of this size. It is believedto be the largest one of its kind in the world, although there are othersunderconstruction of greater dimensions. The overall length is 99 feet2 inches, the depth 32 feet 8 inches, the width 7 feet, and in airit weighsabout 190 tons.It is an entirely welded mild-steel cellular structure with solid plateddecks and intercostal bulkheads forming separate flood and air chambers.

The air chambers are so arranged as to minimize the pull on the opera-ting rope at the lowest water level, flooding holes being provided on theouter skin of the plating of the flood chambers to allow them to be filled asthey become submerged. The meeting face consists of 10-inch-by-7-inchgreenheart bedded on a non-setting bituminous paste and bolted betweentwo 4-inch-by-&-inch flats which are site-welded to the face of the gate.The greenheart is dressed to the same standard of accuracy as the quoinstones.

In addition an L-shaped rubber seal is attached by means of sherardizedcoach-screws and flats to the outer side of the greenheart. At both endsof the bottom of the gate a circular mild-steel trunnion is supported in acast-iron bearing block set on the concrete. Mild-steel hinged plates areattached to the inner face of the gate to protect the meeting faces at silllevel ; during the operation of the gate the nose-ends of these plates slideon the sill concrete. The decking consists of 3-inch-thick oak plankingbolted to the top deck of the gate to form a gangway across the dock.Galvanized steel hand-rail standards are provided on both sides of thegangway, the outer standards being fixed and the inner ones removable.Two steel stools filled with concrete support thegate when it is fullylowered.Two hand-operated sluices 21 inches square are fitted to the gate justabove sill level for use in an emergency.

The operating winch is electrically driven but has an emergency handdrive and is capable of exerting a pull of 30 tons on the rope. It is situatedwithin the pump-house on the west side of the dock. The rope is i +inches in circumference, galvanized, and has a breaking load of 186 tons.It is reeved over fairleads and pulleys on the gate and anchored at theopposite side of the entrance. The D.C. winch motor develops 65 brakehorse-power a t a speed of 1,000 revolutions per minute, and was manu-factured by Metropolitan Vickers Electrical Co. Ltd.The controller is of the cam type with crank operating handle and hassix notches in Qachdirection. There is an electro-mechanical brake of the


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DRY DOCK 4T NORTH SHIELDS FOR SMITHS DOCK C O . LTD 369standard type with series-wound coil so connected as to be released whenthe current is supplied to the motor. The time for opening and closingthe gate for high or low water conditions is between 3 and 4 minutes.Locking devices are provided on both sides of the gate.

BOLLARDSND CAPSTANSCast-iron bollards are provided a t about 75-foot centres on the landward

side of the crane track.Two 74-ton electric capstans capable of sustaining this load at a rate

of 50 feet per minute are provided a t the dock head and two of 15-toncapacity are fixed at the entrance.

HAND-RAILINGGalvanized hand-rails and standards have been installed round the

dock coping. All hand-railing is 1s-inch n nternal diameter and fit-tings are Kee Klamp pattern supplied by Gascoigne Co. Ltd.

The standards are fitted in cast-iron sockets cast in the concrete andthe railing is easily removable in sections, or separately if necessary. Alljunctions between tube and standard are torpedo-shaped, over which itwas considered ships ropes would ride easily when docking. Hand-railsare also fitted to the upper altars.

KEELBLOCKSThere are 144 keel blocks spaced a t 4-foot-6-inch centres on the dock

centre-line ; each consists of three cast-iron blocks 5 feet long by 2 feetwide at thebase, with a total height of 2 feet 9 inches. They are providedwith two oak capping blocks 18 inches by 12 inches and 18 inches by 6inches in section and with an 18-inch-by-3-inch softwood capping piece,the overall height being 4 eet 6 inches. The cast-iron blocks are beddedon 1 -inch-thick pitch-pine strips and each set of blocks is designed for aload of 125 tons. (SeeBig. 9, Plate 2.)The first fifty blocks from the dock entrance are fixed by cotters to thedock f loor ; the others have locating pins. Groups of four a t frequentintervals are tied together with a system of rolled-steel channel framing.

Twenty-six additional sets of blocks are provided as bilge blocks andare set in position as required.

TELESCOPICHORESIt was decided that theuse of mild-steel tubular shores gave an advan-

tage over the timber shores since they are easily adjustable in steps of onefoot to suit ships of varying beam ; twenty-four ranging from 12 to 20 feet


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370 BURNS O N THE DESIGN AND CONSTRUCTION OF NO. 8in length and twenty-four from 20 feet to 30 feet in length were suppliedby Tubewrights Ltd.

LIFT AND TOWERIn view of the difference in heightof 48 feet between the workshop area,that is, the platers shed, etc., and the dock coping it was decided to

install a lift capable of carrying a load of passengers and goods up to30 cwt between the bottom of the dock and the workshop area, with anintermediate stop a t dock coping level.

The lift shaft is 13 feet 10 inches by 9 feet 1 inch in plan, and is con-structed in reinforced concrete ; the walls being 7 inches thick with V-shapedhorizontal oints a t each lift. The motor-room floor is at+7245 O.D. with a flat roof a t 3-81.50 O.D. Electrical and mechanicalsafeguards are used to prevent the travel of the cage below coping levelwhen there is water in the dock.

Precast concrete grid windows form an architectural feature on thedock face and an electric clock and neon sign are fitted near the top.A prestressed concrete footbridge of 70-foot span is provided a t 60-00O.D. between the tower and the top of the bank. It is feet wide andconsists of three I-section beams each 2 feet wide and 2 feet 6 inches deepwith 4-inch-thick webs. Each beam was delivered in two sections,assembled on tubular steel scaffolding, and stressed with three Freysinnetcables. The deck was surfaced with asphalt.

BOILERHOUSE AND OIL-TANK COMPOUNDThe boiler house supplies steam to ships auxiliaries and for the cleaning

of ships tanks. The dimensions of the structure are 57 feet 9 inches by34 feet by 28 feet to the underside of the roof slab and it is constructedas a reinforced concrete frame clad with facing brick and sand-lime brickto the interior.

The columns and roof beams were precast on site and the roof slabwas cast in situ. The building is designea for the installation of a secondboiler ; this was catered for by arranging the framing on the dock facewith a structural opening 20 feet high and 42 feet wide, filled with patentglazing and dwarf brickwork which can readily be removed and replacedwhen the operation is carried out.

Three oil tanks each of 128 tons capacity are provided within a com-pound alongside the boiler house. The compound wall s of reinforcedconcrete 9 feet high to contain the full capacity of the tanks in the eventof a burst.

CRANAGEThe dock is provided with three electric travelling portal-type dockside

cranes, two on the east side and one on the west.


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.


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FIQ. I.-INSIDE OF ARCH DAM AFTERDEWATERIN(I


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FIG R.-GATE ASSEMBLEDREADY FOR STEPPISO

tl


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FIG. I . -DOcK ON O P E S I N G DAY


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DRY DOCK AT NORTH SHIELDS FOR SMITHS DOCK C O . LTD 371These cranes travel the full length of the dock on 25-foot-gauge twin

rails and electricity a t 440 volts A.C., 50 cycles, 3-phase, is supplied bypick-up arms from conductor wires in an underground trench. Details ofthe cranes are given in Appendix 11.

MOORINGDOLPHINFor the effective mooring of ships alongside the deep-water quay itwas

necessary to construct a dolphin beyond the boundary of Smiths DockCo. The Tyne Improvement Commission gave consent to he dolphinbeing constructed within an existing timber jetty.

The dolphin consists of thirteen reinforced concrete piles 15 inchessquare, 45 and 55 feet long, driven to a rake of 1 : 4-5, with an averagepenetration of 25 feet into the river-bed.The piles are embedded in areinforced concrete cap 2 feet 6 inches thickand 13 feet square with a cast-iron ollard in the centre.

Access to this dolphin can be obtained direct from Smiths Dock Co.syard bya @foot steel footbridge from the west roundhead, with a taircaseto L.W.O.S.T. for the use of launches.

PLATERSHEDA new steel-framed single-span shed 225 feet long by 87 feet wide and30 feet 6 inches to tie level was built at the topf the bank or the execution

of plate and frame members in ship-repair work.It is equipped with a 5-ton electric overhead travelling crane, punches,shears, plate bending and straightening rolls, and flame-cutting profilemachine, etc. The prepared units are transported o he dockside bymeans of a Scammel and trailer.

LAVATORYCCOMMODATIONTwo blocks of lavatories were provided for the use of the workmen and

for the officers and crews of the ships in dock.

LIGHTINGGeneral lighting is provided by 500-watt lamps fitted with dispersive

reflectors spaced a t about 100-foot centres around he dock, mountedon prestressed concrete columns approximately 25 feet high.

In addition, three tubular-steel lighting standards about 45 feet high,each fitted with two 1,500-wattloodlights are provided ; one is on the westside at theentrance and one at each side of the dock. At the head of thedock two similar lights are mounted on the lift tower, also 45 feet abovecoping level.


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372 BURNS ON THE DESIGN AND CONSTRUCTION OF NO. 8Lighting for work on ships plating is provided by lamps as required

hung from the dockside ; these are fed from points in the services subway.

ConstructionThe contractor commenced work on the diversion of the Tyne Improve-

ment Commissioners road to Albert Edward Dock and the public road toRobson Millers saw mills, and their respective services, in he earlymonths of 1950. At thesame time a star t was made with the bulk excava-tion necessary to reduce the ground to coping level of the dock. A 34-cubic-yardLimaexcavatorwith face shovel was used, together with afleet of about en Poden 9-cubic-yard ,road wagons to ransport heexcavated material to the tipping areas, which had been made availableby the Tyne Improvement Commission and the local authority.The contractors programme envisaged the use of an arch-type coffer-dam at the entrance for dewatering the area beyond the existing riverbank. For itsabutments on the east side they proposed to use theroundhead backed by the entrance pier and on the west side the pump-house. This necessitated thesubstantial completion of these two unitsin heir respective cofferdams within the first year of construction i norder to fulfil the programme.

PUMP-HOUSEOFFERDAMWork on the pump-house cofferdam commenced a t the end of April 1951

although some preparatory work on the removal of old structures hadpreviously been executed, but the Rtart of the work was delayed by thelate delivery of sheet-piling.

This cofferdam was about 90 feet average length by 50 feet wide withone oblique face and was constructed in Larssen No. 3 sheet-piling 55 feetlong, with three steel frames fabricated from Larssen No. 3 box-piles.The frames were welded in sections at the fabricators yard and assembledat the site as excavation proceeded within the dam and werefixed at-2.0, -13.0, and -26.0 feet 0 .D.

Some of the sheet-piles on the north and west faces of the dam metobstructions in the form of boulders and could not be fully driven. Asexcavation proceeded the damaged portions of the pileswere cut out,extensions welded on where necessary, and the piles driven on to belowformation level. It was not, however, foundpracticable to drive thesepiles to their intended penetration and it was fortunate that they weretoed into stiff clay. The piling on the east or river side was driven satis-factorily apart from a few piles.

When excavation had almost reached formation level a blow occurredunder the east-side piling while a sump was being formed. This wassatisfactorily sealed but another took place very soon afterwards. Further


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DRY DOCK AT NORTH SHIELDS FOR SMITH'S DOCK CO. LTD 373work was stopped while a series of core borings, supplemented by a numberof wash borings, was put down.

These revealed the presence of a fairly extensive sand pocket varyingin depth to a maximum of 11 feet, the top of which ranged between -35and -40 feet O.D. This was not revealed by boring No. 1 which appearedto be just on the edge of the pocket.

These events had already caused some delay and it was evident tha tfurther delay would occur in endeavouring to seal the cofferdam.Sincethe arch dam could not become effective until the pump-house was sub-stantially complete it was considered that itsconstruction in any indepen-dent cofferdam should be temporarily abandoned and alternative meansadopted to enable the construction of the arch dam to proceed a t theearliest opportunity with the use of an alternative abutment. It wouldthen seem possible for the whole site to be dewatered and the pump-houseconstructed without urther trouble from blows. After the arch-damcofferdam became effective n May 1953 the work on the pump-houserecommenced and proceeded without further interruption or unduedifficulty.

TEMPORARYBUTMENT T O ARCHDAMSince the arch-rib frames for the dam had already been fabricated, it

was decided to construct a temporaryabutment on the west side projectingabout 9 feet beyond the west roundhead piling and about 1 2 feet river-wards of its original position. This did not involve any alterations to theframes because the dam was virtually pivoted about the east abutmentwhich was alreadyubstantially completed. After consideration anddiscussion with the contractors the design shown in Fig. 10, Plate 2, wasadopted.

In order to sustain adequately the thrust from the arch ribs it wasnecessary to form the temporary abutment partly inside and partly out-side the permanent west roundhead piling.Two small c,offerdams were, therefore, formed of Appleby-FrodinghamNo. 4 piling 67 feet long, complete with four steel frames built up of broad-flange beams welded together.Excavation was carried down to -32.0O.D. in the outer one and -40.0 O.D. in the landward cofferdam andthey were illed with mass concrete. Arrangements were made in theouter cofferdam for an 18-inch-squarevertical hole to be formed with44-inch-diameter horizontal and radial cardboard tubes inserted a t verticalintervals of 3 feet to facilitate the demolition of this section upon com-pletion of the work. The landward cofferdam of the,abutment wasembodied in the permanent work.

The total estimated thrust from the arch was about 1,650 tons and itwas considered reasonable to assume that two-thirds of this would betaken by the firm clay in the lower portion of the temporary abutment.


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DRY DOCK AT NORTH SHIELDS FOR SMITH'S DOCK C O . LTD 375

Scale: inch - I

Al l i n te rna l memberI 0 " x 3 " x 19.28 lb. C ,

(stra ight between pantInner chordspoints)I 0 " x 8 " x 55 lb. R.S.J s

29.50

Precast concrete bloforming arch r ibs

W O S T:- 7 08

l so

Space betweenwal ing and pi l ingt i l led w i t h concre teOu te r chords (c ircular)w i t h t w o 1 2 " x g p l a t e rI0 x 3 f x 24.46 lb. C s19.50

1 5 . 0 0Appleby-FrodinghamNo 4 section pi l ing__c i les cut off

In-s i tu concrete packing

M level: -55.00

FIG,TYPICAL SECTION OB RCH OFFERDAM


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370 BURNS O N THE DESIGNANDCONSTRUCTION O F NO. 8were t o be driven on the outside of the arch frames with their tops at +l2.0 .0.D. and toes reaching -55-0 O.D., that is, 23 feet 6 inches below dredgedlevel. Unfortunately, some of the piles struck obstructions and fourteenrefused when more than 3 feet from full penetration ; four of these wereabout 10 feet above projected toe level.The contractor did not consider it safe to attempt to dewater underthese conditions and decided to form a concrete curtain in the gaps wherethe toes of the piles were standing high. This was done by the drilling offorty-five S-inch-diameter holes with a Bucyrus 22 W Churn drill intothe river-bed and through the obstructions to the projected toe level of-55.0 O.D. These holes were drilled cheek by jowl so that the facesof adjoining ones were in contact and, when filled with concrete, formeda complete curtain across the areas. The operation was carefully plannedand executed but progress was necessarily slow and it ook about 10 weeksto complete this work.

Furthermore, he contractor considered it essential to provide anadditional arch rib at dredged level ; this was achieved by means of pre-cast concrete segments about 5 feet by 2 feet by l1 feet long, set in aprepared trench and jointed together with Ciment Fondu sections about2 feet 6 inches wide. The top of this rib was placed a t dredged level sothat it was not necessary to remove it on completion of the work.

The operation of excavating the trench was carried out on neap tidesand on the following spring tides on the 2nd May, 1953;dewatering of thearea bypumps mounted on pontoons was commenced and carried throughwith complete success. The dam was exceptionally watertight throughoutthe whole period of its use.

After the gate had been stepped on the 27th March, 1954, and tested,demolition of the dam was commenced. The sheet-piles were burned offunder water a t dredged level and the steel frames were then dismantled.

SUBWAY AND N C L O R G EAfter the bulk excavation had been largely completed to a level of

+2.0 O.D. behind the river bank, the construction of the services subwayand concrete anchorage for the dock-wall piling wascommenced. Thesequence of this work was rather unusual inasmuch as the subway wasconstructed before the sheet-piles were driven. The clay was hand-trimmed to a vertical face so that it acted as shuttering. In one sectionthis face, about 10 eet high, stood for several months without any sign ofdisintegration, apart from some crazing of the faceowing to surfaceshrinkage.The procedure adopted by the contractor was to drill 4-inch-diameterholes in the boulder clay from the back face of the subway to the mass-concrete anchorage about 18 feet away by means of an Appleyard boringmachine which was found to be a very useful tool since it drilled a neat hole


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DRY DOCK AT NORTH SHIELDS FOR SMITHS DOCK C O . LTD 377and penetrated the sandstone boulders withoutundue rouble. On thefew occasions when a whinstone boulder was encountered a new hole, wasdrilled. The 2i-inch-diameter tie-rods were then inserted, washer plates,etc., were ixed, and the ubway was cast in the ifts shown in Fig. 5, p. 362.A txavelling internal shutter36 feet long, subsequently extended o 48 feet,was used after the loor had been cast and the outside shuttaring was builtup in panels of a similar length.

Since the dock-wall piling had not been driven a t this stage a con-struction oint was formed in the vertical plane of the coping so thatafter the piles were driven the two altars could be cast, securing the tapof the piles. Adequate joggles were formed and reinforcement left pro-jecting until the latter aperatian cauld be executed.

Excauatian for the anchorage trench was carried out by a 20. R.B.excavator with a baokacter bucket, concurrently with the subway con-struction. The clay was so firm that no timbering was required apartfrom a nominal top frame at someplaces. It was found that drillingoperations had been carried out satisfactorily since very few tie-rods werefound out of position when this trench was finally bottcrmed-up by hand.Washer plates were fixed and the trench was concreted in two lifts to theunderside of the crane-t,rack fornlation.

D O C K WALLSAs soon as an adequate length of subway and anchorage had been built,

work began on the dock-wall piling. (See Fig. 15, facing p. 370.) The con-tractor erected onc 70-foot and one 55-foot pile frame on the subway roofand with a gate at about +3*0 O.D. pitched and drove the steel pileswith a No. 10 B.3 double-acting hammer. Later, some driving was carriedout with a 4-ton drop hammer and a 5-ton single-acting hammer. Drivingresistance was very hard and it beeame obvious bhat the piles were beingdistmpted. Eqdorations were made and revealed that serious distartionhad taken place owing to the presence of many whinstone bouIders. Theform and extent of the damage varied according to where the pile hithe boulder ; one boulder sometimes affected several piles.Since the driving was generalip hard, it was not possible to detectwhen an obstruction was encountered and consequently the distortiolrbecame extensive before it was noticed.16 shoald be noted that the anticipated sandsbone,boulders gave Iittletrouble for the piles split them ; almost the whde difficnltyarose thoughthe incidence of wbinsto.ne boulders in large numbers, none of which wasdisclosed by any of the borings.At this stage piling to an approximate length of 200 feet had beenpaptly driven on the wesh side. After discussion with the contractox,it was decided that it would be necessary to excavate a trench ab m t 7feet 6 inches wide on the dockside down to the underside of the dock fioaa


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378 BURNS ON THE DESIGN AND CONSTRUCTION OF NO. 8and in contact with the piling, so that excavation and driving could becarried out in stages of about 5-foot depths. By this method the pileswere lightly driven and oed in, excavation followed, and any bouldersin thepath of the pileswere removed. This procedure was ollowedthroughout and was slow because the trench excavation was hand-dugwith pneumatic clay spades nd the renches and piling had tobe strutted,but by thismethod damage to the piling was almost entirely eliminated.

In the case of the fist 200-foot length or so, very extensive repairs tothe piling were necessary and the decision as to how and what to do wasoften very difficult bu t it is to the credit of both the contractors Agentand the Resident Engineer that a very satisfactory jobwas achieved. Theone good feature which assisted this work was tha t no water was present.

When the piles had been fully driven a section of the dock floor 7 feet6 inches wide and about5 feet 6 inches high was cast in trench against thepiling to augment the passive resistance. It was also realized that thiswould materially assist the method of excavation of the dumpling betweenthe walls which closely followed the piling.The removal of the boulders under the piles and the distorted piles leftcavities in the clay which were filled with concrete so far as possible butthere were others which could not be readily filled.It was, therefore, decided to grout these cavities and l&-inch-diameterholes were drilled and tapped with l-inch B.S.P. thread in alternate pilesand in three rows vertically and colloidal grout 1:2g mix) was pumpedin. It is not possible to say thatall cavities were filled but about 26 tonsof cement and 66 cubic yards of sand were used for this purpose.

DOCK LOORThe excavation of the dumpling was carried out by a O&~bic-yard

Lima dragline with the formation trimmed by a 20 R.B. shovel. Diggingwas carried out for the full width of the dock and concreting of the floorimmediately followed the preparation of the formation. Mechanical exca-vation for the full width was made possible by the concrete already placedin rench against the piling. The formation was practically dry in thearea behind the existing river bank and only one small pump was usedperiodically for disposing of surface water.The floor was divided into three lines of blocks with staggered jointsas shown in Big. 4, Plate 2.

The blocks were cast in chequer-board pattern with the formation ofa shrinkage channel between the centre and side blocks. This channel was6 feet 9 inches wide and 2 feet 9 inches deep and was concreted 28 daysafter he contiguous blocks. It was anticipated that some shrinkagewould be evident in the joints below the shrinkage channel, which wouldbe grouted, but no such sign became apparent. This is largely attributed


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DRY DOCK AT NORTH SHIELDS FOR SMITHS DOCK C O . LTD 379to the relatively dry mix (0- to l-inch slump) used and to the thoroughconsolidation by vibration and treading.

The side blocks were cast in two lifts, the second being poured on theday following the fist. They have two joggled joints in their full depth ofbetween 7 and 10eet and 50 per cent of the face was scabbled before castingtheadjacent block. The joints were run in a t floor level witha hotbituminous material 2 inches deep.

Nearly two-thirds of the floor was cast behind the clay barrier formedby theold river bank but the remainder could not be excavated until afterMay 1953 when the arch dam was capable of taking its full load, enablingthe area riverwards of the old bank to be dewatered.

When this stage had been reached the same procedure was employedto complete the remainder of the floor and the sill, which was cast in thesections shown in Pig. 4, Plate 2.

Into this area river water, which seeped through the clutches of thedeep-water-quay piling and hearchdam, was collected in a umpformed in the dock floor and ultimately pumped back.

The seepage from about 24,000 square feet of piling was adequatelydealt with by two 6-inch centrifugal sinking pumps. The seepage variedconsiderably depending upon the state of the tide.

SILLAND QUOIN STONESThe sill and quoin stones (see Pig. 12) were precast and made of ahigh-grade concrete by the Empire Stone Co. with a 2-inch-thick grano-

lithic meeting face 13 inches wide. Care was taken to see that they weretrue on the bedding and meeting faces and they were given a preliminarydressing in the contractors stonemasons yard before delivery to the site.

The sill stones were very carefully levelled and fully bedded on 2 : 1Ironite cement-mortar bed not more than inch thick on apreparedconcrete face on the sill without lead packs. Each sill stone was helddown by two -inch-diameter galvanized bolts set in the sill concrete,cored holes being provided in the stones which were ultimately grouted.

The quoin stones were similarly built and bedded and backed with.goodquality concrete. All stones were aligned as accuratelyas possible bymeans of piano wires stretched across the sill and from sill to coping(Fig. 16, between pp. 370 and 371). They were finally rubbed down withcarborundum where necessary to an accuracy of ten-thousandths of aninch measured on a 6-foot straight-edge throughout the whole meetingface.Only a comparatively small amount of rubbing was necessary whichreflected great credit on the contractors staff for the skill and accuracyemployed in etting he stones, which was fficiently organized andcompleted within 6 weeks.

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380 BURNS ON THE DESIGN AND CONSTRUCTION OF NO. 8

4 " x 4 charnler-

Meeting ace--

Box rype gate shown by\ brok en h--\

L EVATION ATJ UNCTIONOF SILL A N D Q U O I N

Llneof recess formedBackmg conc rete cast assectm of quofn stones proceeds .. L - -6----

tnentrancc p e r

s d t mch- l foot

Gnnolnhlc faceRece9.1 or I'.dia. hdding dawnboltsgrouted af ter SLOnes are set

slte-welded COgatePLANOF SIL L STONES SEC TIO NT HRO UG HU O I N

FIG.~ ~ . - D S T M L SF SILL AND QUOIN STONES

DEEP-WATERUAYThe conshuction of this section of the work commenced in ApriI 1951,and DO di cnbs arose with the driving of the sheet-piling, which wascarried out by a No. 9 B.3 double-acting hammer operating from a 10-ton

derrick crane. After fixing walings and tie-rods the cells were filled with


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DRY DOCK A T NORTH SHIELDS FOR SMITHS DOCK CO. LTD 381shale, some hardcore, and clay to a level of +3*5 O.D. (See Pig. 14,facing p. 370.)

Clay and shale hacking was deposited by means of skips and by ippingover the back row of piles from a lorry running on the deposited filling inthe cells. Rubbledrains were formed in he cell illing a t -8-0 O.D.and holes were cut in the back row of piling to enable the water to bedrained out rapidly when dewatering the area behind the dam.

On the 2nd May, 1953, the arch dam was completed and dewateringtook place in easy stages during a period of a few days in order to studythe effect of the load on the cellular structure. The resulting deflexion ofthe front and back lines of piling in relation to dewatering levels is shownin Pig. 13.

In view of this deflexion it was decided to tip further hale a t the backbefore fully dewatering the area. After this-tipping no further appreciabledeflexion occurred on the inner line of piling but the outer line continuedto deflect until the completion of dewatering. Clay from the dock excava-tion was tipped and thoroughly consolidated by loaded 9-cubic-yardtipping wagons, bulldozers, and rollers up to tie-rod level. The landwardtie-rods and anchorages were then placed and tipping proceeded to com-pletion as and when possible in relation to work on the south-east dockwall which was directly ied to he deep-water quay near theeastroundhead.

In view of the probability of some settlement on this reclaimed areano permanent surfacing was laid ; t was dressed with 9 inches of shale withtar-sprayed chippings on the surface.

ENTRANCEATEThe gate was delivered to the site nfourteen sections which were

assembled and site-welded on blocks placed on the dock floor. (SeeFig. 18, between pp. 370 and 371.) The whole of the external face steel-work was flame-cleaned and while the plating was still hot was given acoat of primer and one coat of bituminous enamel. The inside faceswere given two coatsof Camrex grease paint.The operation of setting the blocks, handling the sections, assembling,welding, testing air tanks andlooding tanks, fixing and dressing the green-heart,and painting was carried out in about 13 weeks.On the 27thMarch, 1954, the dock was flooded to a depth of about 10 feet over thesill, the gate was floated and manceuvred into position landwards of thearch dam, andsuccessfully stepped.All the manceuvring was carried out byhand ropes and the inal raisingof the gate was effected by the operating winch. The whole operation wasexecuted smoothly and efficiently and it is clear that the facility withwhich gates of this type can be handled is a great advantage from a main-tenance aspect.


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382 BURNS ON THE DESIGN AND CONSTRUCTION OF NO. 8Top of p i l e : + 10.00Deflexion measured at +&so Leve l of f inal fill_ __

Deflexion measured a t +4.00

D I A G R A M M A T C SKETCH OFQUAY

Cell No. 10 River T y n e AK E Y P L A N OF D E E P -W A T E R Q U A Y

FIG.13.-DEFLEXION N DEEP-WATER QUAY PILING IN RELATION TO DEWATERINGLEVELS


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DRY DOCK AT N O R T H SHIELDS FOR SMITHS DOCK CO. L T D 383CONCRETE, MIXING, AND DISTRIBUTION PLANT

Generally two classes of concrete were used :-lass B

Reinforced concrete work 1 : 5.5 parts by weight of inch aggregate andgenerally. sand. Specified strength requirements were2,000 lb. per square inch at 7 days and3,000 lb. per square inch a t 28 days.lass C

Dock floor and mass work 1 8.25 parts by weight of 2-inch aggregategenerally. and sand. Specified strength requirements

were 1,500 lb. per square inch a t 7 days and2,250 lb. per square inch a t 28 days.

Ordinary Portland cement was used almost throughout the work.Aggregates in the locality are generally poor and inconsistent in quality

and owing to the irregular quantities required during a relatively longperiod they had to e obtained from various sources which made accurategrading impossible. Difficulties occurred a t times in securing thespecified strengths, which were by no means high.

Test cube failures a t 7 and 28 days occurred but itwas found that cubestrengths considerably improved with age and the few tests which weremade a t 3 months showed satisfactory increases in strength.

The bulk of the concrete was mixed by a central mixing plant locatedo n the high ground at the head of the dock. It consisted of a l-cubic-yardBlaw Knox mixer with weigh-batcher equipment and. storage hoppersabove. A boom-scraper fed the aggregates in the stock bin to a bucketclcvator which discharged into the storage hoppers.A subsidiary plant was situated near the pump-house ; it consisted oftwo Blaw Knox Janior weigh-batchers each with a Rex 105 mixer.

Distribution of the concrete was carried out almost entirely by lorriescarrying l-cubic-yard skips which were lowered into position by derricksand mobile cranes operating from coping level.

Pumping of the concrete was attempted but was not found satisfactoryfor the class C concrete. This was attributed to the low slump require-ments and also to pumping down the steep slope.

PLANTA list of the principal plant used by thecontractor is given in AppendixIV.

LABOURThe maximum number of men employed on the site was about 300

supplemented by sub-contractors men from time to time.


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384 BURNS ON THE DESIGN A N D CONSTRUCTION OF NO. 8MATERIALS

The approximate quantities were as follow:: :--Excavated material . . . . .Filled material . . . . . .Concrete . . . . . . . .Steel sheet-piling (permanent) . .Steel sheet-piling (temporary) . .Mild-steel reinforcing bars . . .High-tensile-steel reinforcing barsStructural steelwork . . . .

TIMEThe difficulties mentioned extended the constructional period by about

twelve months beyond the contract period of 30 months, although addi-tional work was completed within this time which was not in the contrac-tors original contract, such as the platers shed and surrounding pavedareas, the lift shaft, boiler house, etc.

COSTThe total cost of the whole project was about f1,250,000.

ACKNOWLEDGEMENTSThe Author is indebted to Smiths Dock Co. Ltd for permission to

present this Paper.Holloway Bros (London) Ltd were the contractors for the main civilengineering work ; M r B I. Palmer, B.Sc., M.I.C.E., being Director in

charge of the work with Mr Robert Mitchell, B.Sc., A.M.I.C.E., acting astheir Site Agent.Mr A. Storrar, B.Sc., A.M.I.C.E., was the Resident Engineer acting forthe Authors firm, T. F. Burns Partners, who were responsible for theproject.Mr E. A. Parsons was the resident partner in the firms Newcastle-upon-Tyne office and to him the Author would express his thanks for assistancegiven in the preparation of this Paper.

The Paper, which was eceivedon 1st November, 1954, is accon-panied by eight photographs and ten sheets of drawings from which thehalf-tone page plates, the Figures in the text and folding Plates 1 and2 have been prepared, and by the following Appendices.


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DRY DOCK AT NORTH SHIELDS FOR SMITHS DOCK C O . LTD 385

APPENDIX IPUMP-HOUSE PLANT SUPPLIED BY DRYSDALE 00 LTD

Two 42 / 3 9 horizontal-spindle split-casing pumps each directly coupled and drivenby 400-h.p., 420 r.p.m.,5,500 v., 3-phase, 50-cycle, slip-ring motors with liquidsterters.These two pumps, when operating together, are capable of emptying the dock of 1%dematering period of 31.25 feet.million cubic feet of water in 29 hours with a maximum head at the end of the

440 v., 3-phase, 50-cycle, squirrel-cagemotor and starte r; and two similar pumps, oneOne lOjl0 Upright drainagepump completewith57&-h.p.,1,470 .p.m.,for ballast, and one for ballast and drainage. Each unit is capable of delivering 2 000g.p.m. against a total head from all causes of 67 feet or 2,500 g.p.m. against a totalhead of 60 feet. Themotorsare of the vertical-spindle type mounted on top ofthe pumps and together form self-contained units.One 6/6 Aquair rotary exhauster pump complete with 30-h.p., 577 r.p.m.,440 v., 3-phase, 50-cycle, squirrel-cage motor and starter. This pump is capable ofhandling 500 cubic feet per minute from 22 inches of vacuum and primes both themain dewatering pumps and also the drainage and ballast pumps.Two 1v/lY Horzoil pumps each chain-driven from the main dewatering pump,hydraulically operated valves at the top f each siphon. These are capable of deliver-complete with oil tank andnecessary inter-connecting piping and thesiphon breakinging 59 gallons of lubricating oil per minute a t a pressure of 50 lb. per sq. in., absorbless than 1 h.p. and run a t 1,000 r.p.m.depth of water in thedock.Depth Gauge-KelvinBottomley Baird Pneumercator type indicating the

APPENDIX I1DOCKSIDE CRANES SUPPLIED BY STOTHERT PITT, LTD

East side of dock30-TON ELECTRIC TRAVELLING LEVEL LUFFINO PORTAL CRANE

Main hoist 30 tons at 85 feet maximum radius ;40 feet minimum radius.Auxiliary hoist : 10 tons a t 135 feet maximum radius ;60 feet minimum radius.Height of l i f t above coping : main h o i s t 4 5 feet.auxiliary h o i s t 8 0 feet.Main hoist :45 h.p. 30 tons a t 15 f.p.m.Auxiliary hoist : 45 h.p. 10 tons a t 45 f.p.m.Luffing : 30 h.p. ; O f.p.m.Slewing : 25 h.p. ; .p.m.Travel : two 15 h.p. ;40 f.p.m.Gauge of track : 25 feet.No. of wheels : 16.

15 ,, 30 ,,5 ,, 90 1

5-TON ELECTRIC TRAVELLING LEVEL LUFFINQ PORTAL CRANEHoist : 6 tons at 85 feet maximum radius ; 30 feet minimum radius.Height of lift above coping : 8 feet.Hoist : 45 h.p. ; 5 tons at 90 f.p.m.Luffing : 74 h.p. ;70 f.p.m.Slewing : 129 h.p., 1 r.p.m.Travel : two 6 h.p. ;50 f.p.m.Gauge of track : 25 feet.No. of wheels : 8.

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IP: 92.22.57.167

On: Sun, 27 Oct 2013 20:25:41

386 BURNS ON THE DESIGN AND CONSTRUCTION OF NO. 8We st side of dock

&TON ELECTRIC TRAVELLINQ PORTAL CRANEHoist : 5 tons a t 40 feet ;23 tons at 55 feet;21 feet minimum radius.Height of lift above coping : 40 feet at maximum radius.Hoist 55 h.p. ; 5 tons a t 120 f.p.m.Lu g : 15h.p. ; 0 f.p.m.Slewing : 124 h.p. ;2 r.p.m.Travel : wo 5 h.D.. 67 f.D.m.

24 ,, 240 ,,

No. of wheels : 4.Gauge of track : 5 feet.LPower supply 440 volts, 3-phase, A.C. obtained from three bare copper conductorsenclosed in collector trench and picked up by means of a swinging travelling shoe.

APPENDIX I11SCHEDULE O F SERVICES I N DOCK SUBWAY

We st side4-inch-diameter steam.4-inch-diameter compressed air.440-volt 3-phaseA.C. for ships' power.14-inch ballast water (river water).110-volt single-phaseA.C. for temporary lighting, ships, or dock lighting.440-volt 3-phaseA.C. for A.C. welding or for supplying motor generators for D.C.welding.

East side6-inch-diameter compressed air.6-inch-diameter fresh'water (town supply).440-volt 3-phaseA.C. for A.C. welding or for supplying motor generators forD.C.110-volt single-phaseA.C. for temporary lighting, ships, or docklighting.

110-voltD.C. supply for ships.220-volt D.C. supply for ships.welding.

APPENDIX IVPRINCIPAL PLANT USED BY CONTRACTOR

Cranes . . . . . . . . . . . . . .10-ton ,,7-ton5-ton ,, S6-ton mobile crane .&ton ,, steam-locorane 1l3-ton ,, ,. . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . .

ExcavatorsLimaexcavatorwith3i-cubic yard shovel. Laterwith2g-cubic-yard43 R.B. dragline 1dragline 120 R.B. backacter nddragline . . . . . . . . . . . .. . . . . . . . . . . . . . . .


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DRY DO CK AT NORTH SHIELDS FOR SMITHS DOCK CO. LTD 387Transport9-cubic-yardoden wagons . . . . . . . . . . . . .

Muirhill dumper 1Tippingorriesp to &tonapacity 7Bulldozer D.8 . . . . . . . . . . . . . . . . .Bulldozer.4 . . . . . . . . . . . . . . . . .. . . . . . . . . . .. . . . . . . . . . . . . . . .

oncreting plantBlaw Knox l-cubic-yardbatcher . . . . . . . . . . . .Blaw Knoxuniorweigh-batchers . . . . . . . . . . .Piling plant . . . . . . . . . .

40 eet ,,70 feet raking pile frame.. with5-footxtension . . . . . . 1McKiernanTerry D.A. hammer No. 7 . . . . . . . . . . 1McKiernanerry ,, . . . . . . . . .McKiernanerry ,, hammers No. 1 B.3 2,, N o .9 B .3 1PileextractorZenith No. 80 . . . . . . . . . . . . . 1. . . . . . . . .Pumps12-inchCentrifugallectric (for dewatering) . . . . . . . .10-inch ,, Diesel (for dewatering) 1&inch ,, electric . . . . . . . . . . . . .5-inch ,, . . . . . . . . . . . . . 3MiscellaneousWelding transformers . . . . . . . . . . . . . . .Welding generator . . . . . . . . . . . . . . . .Air-compressor: 300 cubic feet per minute10-ton Dieseloller . . . . . . . . . . . . . . . .

AppleyardoringigAPPENDIX V

SUB-CONTRACTORSPrincipal sub-contractors and others employed on the work were :-Entrance gate and filling valve Sir William A L T O ~ & Co. Ltd.Pumpingequipment . . . . . Drysdale Co. Ltd.Sheet-piling BritishSteelPiling Co.Cranes (dockside) Stothert Pitt, Ltd.

Do (arch dam)nitedteel Co. Ltd.Capstans . . . . . . . Clarlre, Chapman Co. Ltd.Platersshedsteelwork . . . . Cargo Fleet Iron Co. Ltd.Keellocks ease and Partners.In-situ piling Holmpress Piles, Ltd.Quoin and sill stoneshempiretone Co. Ltd.Liftandmachinery Keighley Lifts, Ltd.Site investigation oil Mechanics, Ltd.Services miths Dock Co. Ltd.

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The Design and Construction of No8 Dry Dock at North Shields for Smith's Dock Co. Ltd.

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Transcript of The Design and Construction of No8 Dry Dock at North Shields for Smith's Dock Co. Ltd.